add tag v1_9_3_426

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/tags/v1_9_3_426@40733 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 4393 insertions, 0 deletions

diff --git a/ruby_1_9_3/ext/zlib/zlib.c b/ruby_1_9_3/ext/zlib/zlib.c
new file mode 100644
index 0000000000..d5909d60c0
--- /dev/null
+++ b/ruby_1_9_3/ext/zlib/zlib.c
@@ -0,0 +1,4393 @@
+/*
+ * zlib.c - An interface for zlib.
+ *
+ *   Copyright (C) UENO Katsuhiro 2000-2003
+ *
+ * $Id$
+ */
+
+#include <ruby.h>
+#include <zlib.h>
+#include <time.h>
+#include <ruby/io.h>
+
+#ifdef HAVE_VALGRIND_MEMCHECK_H
+# include <valgrind/memcheck.h>
+# ifndef VALGRIND_MAKE_MEM_DEFINED
+#  define VALGRIND_MAKE_MEM_DEFINED(p, n) VALGRIND_MAKE_READABLE((p), (n))
+# endif
+# ifndef VALGRIND_MAKE_MEM_UNDEFINED
+#  define VALGRIND_MAKE_MEM_UNDEFINED(p, n) VALGRIND_MAKE_WRITABLE((p), (n))
+# endif
+#else
+# define VALGRIND_MAKE_MEM_DEFINED(p, n) /* empty */
+# define VALGRIND_MAKE_MEM_UNDEFINED(p, n) /* empty */
+#endif
+
+#define RUBY_ZLIB_VERSION  "0.6.0"
+
+
+#define OBJ_IS_FREED(val)  (RBASIC(val)->flags == 0)
+
+#ifndef GZIP_SUPPORT
+#define GZIP_SUPPORT  1
+#endif
+
+/* from zutil.h */
+#ifndef DEF_MEM_LEVEL
+#if MAX_MEM_LEVEL >= 8
+#define DEF_MEM_LEVEL  8
+#else
+#define DEF_MEM_LEVEL  MAX_MEM_LEVEL
+#endif
+#endif
+
+#if SIZEOF_LONG > SIZEOF_INT
+static inline uInt
+max_uint(long n)
+{
+    if (n > UINT_MAX) n = UINT_MAX;
+    return (uInt)n;
+}
+#define MAX_UINT(n) max_uint(n)
+#else
+#define MAX_UINT(n) (uInt)(n)
+#endif
+
+#define sizeof(x) ((int)sizeof(x))
+
+/*--------- Prototypes --------*/
+
+static NORETURN(void raise_zlib_error(int, const char*));
+static VALUE rb_zlib_version(VALUE);
+static VALUE do_checksum(int, VALUE*, uLong (*)(uLong, const Bytef*, uInt));
+static VALUE rb_zlib_adler32(int, VALUE*, VALUE);
+static VALUE rb_zlib_crc32(int, VALUE*, VALUE);
+static VALUE rb_zlib_crc_table(VALUE);
+static voidpf zlib_mem_alloc(voidpf, uInt, uInt);
+static void zlib_mem_free(voidpf, voidpf);
+static void finalizer_warn(const char*);
+
+struct zstream;
+struct zstream_funcs;
+static void zstream_init(struct zstream*, const struct zstream_funcs*);
+static void zstream_expand_buffer(struct zstream*);
+static void zstream_expand_buffer_into(struct zstream*, unsigned long);
+static void zstream_append_buffer(struct zstream*, const Bytef*, long);
+static VALUE zstream_detach_buffer(struct zstream*);
+static VALUE zstream_shift_buffer(struct zstream*, long);
+static void zstream_buffer_ungets(struct zstream*, const Bytef*, unsigned long);
+static void zstream_buffer_ungetbyte(struct zstream*, int);
+static void zstream_append_input(struct zstream*, const Bytef*, long);
+static void zstream_discard_input(struct zstream*, long);
+static void zstream_reset_input(struct zstream*);
+static void zstream_passthrough_input(struct zstream*);
+static VALUE zstream_detach_input(struct zstream*);
+static void zstream_reset(struct zstream*);
+static VALUE zstream_end(struct zstream*);
+static void zstream_run(struct zstream*, Bytef*, long, int);
+static VALUE zstream_sync(struct zstream*, Bytef*, long);
+static void zstream_mark(struct zstream*);
+static void zstream_free(struct zstream*);
+static VALUE zstream_new(VALUE, const struct zstream_funcs*);
+static struct zstream *get_zstream(VALUE);
+static void zstream_finalize(struct zstream*);
+
+static VALUE rb_zstream_end(VALUE);
+static VALUE rb_zstream_reset(VALUE);
+static VALUE rb_zstream_finish(VALUE);
+static VALUE rb_zstream_flush_next_in(VALUE);
+static VALUE rb_zstream_flush_next_out(VALUE);
+static VALUE rb_zstream_avail_out(VALUE);
+static VALUE rb_zstream_set_avail_out(VALUE, VALUE);
+static VALUE rb_zstream_avail_in(VALUE);
+static VALUE rb_zstream_total_in(VALUE);
+static VALUE rb_zstream_total_out(VALUE);
+static VALUE rb_zstream_data_type(VALUE);
+static VALUE rb_zstream_adler(VALUE);
+static VALUE rb_zstream_finished_p(VALUE);
+static VALUE rb_zstream_closed_p(VALUE);
+
+static VALUE rb_deflate_s_allocate(VALUE);
+static VALUE rb_deflate_initialize(int, VALUE*, VALUE);
+static VALUE rb_deflate_init_copy(VALUE, VALUE);
+static VALUE deflate_run(VALUE);
+static VALUE rb_deflate_s_deflate(int, VALUE*, VALUE);
+static void do_deflate(struct zstream*, VALUE, int);
+static VALUE rb_deflate_deflate(int, VALUE*, VALUE);
+static VALUE rb_deflate_addstr(VALUE, VALUE);
+static VALUE rb_deflate_flush(int, VALUE*, VALUE);
+static VALUE rb_deflate_params(VALUE, VALUE, VALUE);
+static VALUE rb_deflate_set_dictionary(VALUE, VALUE);
+
+static VALUE inflate_run(VALUE);
+static VALUE rb_inflate_s_allocate(VALUE);
+static VALUE rb_inflate_initialize(int, VALUE*, VALUE);
+static VALUE rb_inflate_s_inflate(VALUE, VALUE);
+static void do_inflate(struct zstream*, VALUE);
+static VALUE rb_inflate_inflate(VALUE, VALUE);
+static VALUE rb_inflate_addstr(VALUE, VALUE);
+static VALUE rb_inflate_sync(VALUE, VALUE);
+static VALUE rb_inflate_sync_point_p(VALUE);
+static VALUE rb_inflate_set_dictionary(VALUE, VALUE);
+
+#if GZIP_SUPPORT
+struct gzfile;
+static void gzfile_mark(struct gzfile*);
+static void gzfile_free(struct gzfile*);
+static VALUE gzfile_new(VALUE, const struct zstream_funcs*, void (*) _((struct gzfile*)));
+static void gzfile_reset(struct gzfile*);
+static void gzfile_close(struct gzfile*, int);
+static void gzfile_write_raw(struct gzfile*);
+static VALUE gzfile_read_raw_partial(VALUE);
+static VALUE gzfile_read_raw_rescue(VALUE);
+static VALUE gzfile_read_raw(struct gzfile*);
+static int gzfile_read_raw_ensure(struct gzfile*, long);
+static char *gzfile_read_raw_until_zero(struct gzfile*, long);
+static unsigned int gzfile_get16(const unsigned char*);
+static unsigned long gzfile_get32(const unsigned char*);
+static void gzfile_set32(unsigned long n, unsigned char*);
+static void gzfile_make_header(struct gzfile*);
+static void gzfile_make_footer(struct gzfile*);
+static void gzfile_read_header(struct gzfile*);
+static void gzfile_check_footer(struct gzfile*);
+static void gzfile_write(struct gzfile*, Bytef*, long);
+static long gzfile_read_more(struct gzfile*);
+static void gzfile_calc_crc(struct gzfile*, VALUE);
+static VALUE gzfile_read(struct gzfile*, long);
+static VALUE gzfile_read_all(struct gzfile*);
+static void gzfile_ungets(struct gzfile*, const Bytef*, long);
+static void gzfile_ungetbyte(struct gzfile*, int);
+static VALUE gzfile_writer_end_run(VALUE);
+static void gzfile_writer_end(struct gzfile*);
+static VALUE gzfile_reader_end_run(VALUE);
+static void gzfile_reader_end(struct gzfile*);
+static void gzfile_reader_rewind(struct gzfile*);
+static VALUE gzfile_reader_get_unused(struct gzfile*);
+static struct gzfile *get_gzfile(VALUE);
+static VALUE gzfile_ensure_close(VALUE);
+static VALUE rb_gzfile_s_wrap(int, VALUE*, VALUE);
+static VALUE gzfile_s_open(int, VALUE*, VALUE, const char*);
+NORETURN(static void gzfile_raise(struct gzfile *, VALUE, const char *));
+static VALUE gzfile_error_inspect(VALUE);
+
+static VALUE rb_gzfile_to_io(VALUE);
+static VALUE rb_gzfile_crc(VALUE);
+static VALUE rb_gzfile_mtime(VALUE);
+static VALUE rb_gzfile_level(VALUE);
+static VALUE rb_gzfile_os_code(VALUE);
+static VALUE rb_gzfile_orig_name(VALUE);
+static VALUE rb_gzfile_comment(VALUE);
+static VALUE rb_gzfile_lineno(VALUE);
+static VALUE rb_gzfile_set_lineno(VALUE, VALUE);
+static VALUE rb_gzfile_set_mtime(VALUE, VALUE);
+static VALUE rb_gzfile_set_orig_name(VALUE, VALUE);
+static VALUE rb_gzfile_set_comment(VALUE, VALUE);
+static VALUE rb_gzfile_close(VALUE);
+static VALUE rb_gzfile_finish(VALUE);
+static VALUE rb_gzfile_closed_p(VALUE);
+static VALUE rb_gzfile_eof_p(VALUE);
+static VALUE rb_gzfile_sync(VALUE);
+static VALUE rb_gzfile_set_sync(VALUE, VALUE);
+static VALUE rb_gzfile_total_in(VALUE);
+static VALUE rb_gzfile_total_out(VALUE);
+static VALUE rb_gzfile_path(VALUE);
+
+static VALUE rb_gzwriter_s_allocate(VALUE);
+static VALUE rb_gzwriter_s_open(int, VALUE*, VALUE);
+static VALUE rb_gzwriter_initialize(int, VALUE*, VALUE);
+static VALUE rb_gzwriter_flush(int, VALUE*, VALUE);
+static VALUE rb_gzwriter_write(VALUE, VALUE);
+static VALUE rb_gzwriter_putc(VALUE, VALUE);
+
+static VALUE rb_gzreader_s_allocate(VALUE);
+static VALUE rb_gzreader_s_open(int, VALUE*, VALUE);
+static VALUE rb_gzreader_initialize(int, VALUE*, VALUE);
+static VALUE rb_gzreader_rewind(VALUE);
+static VALUE rb_gzreader_unused(VALUE);
+static VALUE rb_gzreader_read(int, VALUE*, VALUE);
+static VALUE rb_gzreader_getc(VALUE);
+static VALUE rb_gzreader_readchar(VALUE);
+static VALUE rb_gzreader_each_byte(VALUE);
+static VALUE rb_gzreader_ungetc(VALUE, VALUE);
+static VALUE rb_gzreader_ungetbyte(VALUE, VALUE);
+static void gzreader_skip_linebreaks(struct gzfile*);
+static VALUE gzreader_gets(int, VALUE*, VALUE);
+static VALUE rb_gzreader_gets(int, VALUE*, VALUE);
+static VALUE rb_gzreader_readline(int, VALUE*, VALUE);
+static VALUE rb_gzreader_each(int, VALUE*, VALUE);
+static VALUE rb_gzreader_readlines(int, VALUE*, VALUE);
+#endif /* GZIP_SUPPORT */
+
+/*
+ * Document-module: Zlib
+ *
+ * == Overview
+ *
+ * Access to the zlib library.
+ *
+ * == Class tree
+ *
+ * - Zlib::Deflate
+ * - Zlib::Inflate
+ * - Zlib::ZStream
+ * - Zlib::Error
+ *   - Zlib::StreamEnd
+ *   - Zlib::NeedDict
+ *   - Zlib::DataError
+ *   - Zlib::StreamError
+ *   - Zlib::MemError
+ *   - Zlib::BufError
+ *   - Zlib::VersionError
+ *
+ * (if you have GZIP_SUPPORT)
+ * - Zlib::GzipReader
+ * - Zlib::GzipWriter
+ * - Zlib::GzipFile
+ * - Zlib::GzipFile::Error
+ *   - Zlib::GzipFile::LengthError
+ *   - Zlib::GzipFile::CRCError
+ *   - Zlib::GzipFile::NoFooter
+ *
+ * see also zlib.h
+ *
+ */
+void Init_zlib(void);
+
+/*--------- Exceptions --------*/
+
+static VALUE cZError, cStreamEnd, cNeedDict;
+static VALUE cStreamError, cDataError, cMemError, cBufError, cVersionError;
+
+static void
+raise_zlib_error(int err, const char *msg)
+{
+    VALUE exc;
+
+    if (!msg) {
+	msg = zError(err);
+    }
+
+    switch(err) {
+      case Z_STREAM_END:
+	exc = rb_exc_new2(cStreamEnd, msg);
+	break;
+      case Z_NEED_DICT:
+	exc = rb_exc_new2(cNeedDict, msg);
+	break;
+      case Z_STREAM_ERROR:
+	exc = rb_exc_new2(cStreamError, msg);
+	break;
+      case Z_DATA_ERROR:
+	exc = rb_exc_new2(cDataError, msg);
+	break;
+      case Z_BUF_ERROR:
+	exc = rb_exc_new2(cBufError, msg);
+	break;
+      case Z_VERSION_ERROR:
+	exc = rb_exc_new2(cVersionError, msg);
+	break;
+      case Z_MEM_ERROR:
+	exc = rb_exc_new2(cMemError, msg);
+	break;
+      case Z_ERRNO:
+	rb_sys_fail(msg);
+	/* no return */
+      default:
+      {
+	  char buf[BUFSIZ];
+	  snprintf(buf, BUFSIZ, "unknown zlib error %d: %s", err, msg);
+	  exc = rb_exc_new2(cZError, buf);
+      }
+    }
+
+    rb_exc_raise(exc);
+}
+
+
+/*--- Warning (in finalizer) ---*/
+
+static void
+finalizer_warn(const char *msg)
+{
+    fprintf(stderr, "zlib(finalizer): %s\n", msg);
+}
+
+
+/*-------- module Zlib --------*/
+
+/*
+ * Document-method: Zlib.zlib_version
+ *
+ * Returns the string which represents the version of zlib library.
+ */
+static VALUE
+rb_zlib_version(VALUE klass)
+{
+    VALUE str;
+
+    str = rb_str_new2(zlibVersion());
+    OBJ_TAINT(str);  /* for safe */
+    return str;
+}
+
+#if SIZEOF_LONG > SIZEOF_INT
+static uLong
+checksum_long(uLong (*func)(uLong, const Bytef*, uInt), uLong sum, const Bytef *ptr, long len)
+{
+    if (len > UINT_MAX) {
+	do {
+	    sum = func(sum, ptr, UINT_MAX);
+	    ptr += UINT_MAX;
+	    len -= UINT_MAX;
+	} while (len >= UINT_MAX);
+    }
+    if (len > 0) sum = func(sum, ptr, (uInt)len);
+    return sum;
+}
+#else
+#define checksum_long(func, sum, ptr, len) (func)((sum), (ptr), (len))
+#endif
+
+static VALUE
+do_checksum(argc, argv, func)
+    int argc;
+    VALUE *argv;
+    uLong (*func)(uLong, const Bytef*, uInt);
+{
+    VALUE str, vsum;
+    unsigned long sum;
+
+    rb_scan_args(argc, argv, "02", &str, &vsum);
+
+    if (!NIL_P(vsum)) {
+	sum = NUM2ULONG(vsum);
+    }
+    else if (NIL_P(str)) {
+	sum = 0;
+    }
+    else {
+	sum = func(0, Z_NULL, 0);
+    }
+
+    if (NIL_P(str)) {
+	sum = func(sum, Z_NULL, 0);
+    }
+    else {
+	StringValue(str);
+	sum = checksum_long(func, sum, (Bytef*)RSTRING_PTR(str), RSTRING_LEN(str));
+    }
+    return rb_uint2inum(sum);
+}
+
+/*
+ * Document-method: Zlib.adler32
+ *
+ * call-seq: Zlib.adler32(string, adler)
+ *
+ * Calculates Adler-32 checksum for +string+, and returns updated value of
+ * +adler+. If +string+ is omitted, it returns the Adler-32 initial value. If
+ * +adler+ is omitted, it assumes that the initial value is given to +adler+.
+ *
+ * FIXME: expression.
+ */
+static VALUE
+rb_zlib_adler32(int argc, VALUE *argv, VALUE klass)
+{
+    return do_checksum(argc, argv, adler32);
+}
+
+#ifdef HAVE_ADLER32_COMBINE
+/*
+ * Document-method: Zlib.adler32_combine
+ *
+ * call-seq: Zlib.adler32_combine(adler1, adler2, len2)
+ *
+ * Combine two Adler-32 check values in to one.  +alder1+ is the first Adler-32
+ * value, +adler2+ is the second Adler-32 value.  +len2+ is the length of the
+ * string used to generate +adler2+.
+ *
+ */
+static VALUE
+rb_zlib_adler32_combine(VALUE klass, VALUE adler1, VALUE adler2, VALUE len2)
+{
+  return ULONG2NUM(
+	adler32_combine(NUM2ULONG(adler1), NUM2ULONG(adler2), NUM2LONG(len2)));
+}
+#else
+#define rb_zlib_adler32_combine rb_f_notimplement
+#endif
+
+/*
+ * Document-method: Zlib.crc32
+ *
+ * call-seq: Zlib.crc32(string, adler)
+ *
+ * Calculates CRC checksum for +string+, and returns updated value of +crc+. If
+ * +string+ is omitted, it returns the CRC initial value. If +crc+ is omitted, it
+ * assumes that the initial value is given to +crc+.
+ *
+ * FIXME: expression.
+ */
+static VALUE
+rb_zlib_crc32(int argc, VALUE *argv, VALUE klass)
+{
+    return do_checksum(argc, argv, crc32);
+}
+
+#ifdef HAVE_CRC32_COMBINE
+/*
+ * Document-method: Zlib.crc32_combine
+ *
+ * call-seq: Zlib.crc32_combine(crc1, crc2, len2)
+ *
+ * Combine two CRC-32 check values in to one.  +crc1+ is the first CRC-32
+ * value, +crc2+ is the second CRC-32 value.  +len2+ is the length of the
+ * string used to generate +crc2+.
+ *
+ */
+static VALUE
+rb_zlib_crc32_combine(VALUE klass, VALUE crc1, VALUE crc2, VALUE len2)
+{
+  return ULONG2NUM(
+	crc32_combine(NUM2ULONG(crc1), NUM2ULONG(crc2), NUM2LONG(len2)));
+}
+#else
+#define rb_zlib_crc32_combine rb_f_notimplement
+#endif
+
+/*
+ * Document-method: Zlib.crc_table
+ *
+ * Returns the table for calculating CRC checksum as an array.
+ */
+static VALUE
+rb_zlib_crc_table(VALUE obj)
+{
+#if !defined(HAVE_TYPE_Z_CRC_T)
+    /* z_crc_t is defined since zlib-1.2.7. */
+    typedef unsigned long z_crc_t;
+#endif
+    const z_crc_t *crctbl;
+    VALUE dst;
+    int i;
+
+    crctbl = get_crc_table();
+    dst = rb_ary_new2(256);
+
+    for (i = 0; i < 256; i++) {
+	rb_ary_push(dst, rb_uint2inum(crctbl[i]));
+    }
+    return dst;
+}
+
+
+
+/*-------- zstream - internal APIs --------*/
+
+struct zstream {
+    unsigned long flags;
+    VALUE buf;
+    long buf_filled;
+    VALUE input;
+    z_stream stream;
+    const struct zstream_funcs {
+	int (*reset)(z_streamp);
+	int (*end)(z_streamp);
+	int (*run)(z_streamp, int);
+    } *func;
+};
+
+#define ZSTREAM_FLAG_READY      0x1
+#define ZSTREAM_FLAG_IN_STREAM  0x2
+#define ZSTREAM_FLAG_FINISHED   0x4
+#define ZSTREAM_FLAG_CLOSING    0x8
+#define ZSTREAM_FLAG_UNUSED     0x10
+
+#define ZSTREAM_READY(z)       ((z)->flags |= ZSTREAM_FLAG_READY)
+#define ZSTREAM_IS_READY(z)    ((z)->flags & ZSTREAM_FLAG_READY)
+#define ZSTREAM_IS_FINISHED(z) ((z)->flags & ZSTREAM_FLAG_FINISHED)
+#define ZSTREAM_IS_CLOSING(z)  ((z)->flags & ZSTREAM_FLAG_CLOSING)
+
+/* I think that more better value should be found,
+   but I gave up finding it. B) */
+#define ZSTREAM_INITIAL_BUFSIZE       1024
+#define ZSTREAM_AVAIL_OUT_STEP_MAX   16384
+#define ZSTREAM_AVAIL_OUT_STEP_MIN    2048
+
+static const struct zstream_funcs deflate_funcs = {
+    deflateReset, deflateEnd, deflate,
+};
+
+static const struct zstream_funcs inflate_funcs = {
+    inflateReset, inflateEnd, inflate,
+};
+
+
+static voidpf
+zlib_mem_alloc(voidpf opaque, uInt items, uInt size)
+{
+    voidpf p = xmalloc(items * size);
+    /* zlib FAQ: Valgrind (or some similar memory access checker) says that
+       deflate is performing a conditional jump that depends on an
+       uninitialized value.  Isn't that a bug?
+       http://www.zlib.net/zlib_faq.html#faq36 */
+    VALGRIND_MAKE_MEM_DEFINED(p, items * size);
+    return p;
+}
+
+static void
+zlib_mem_free(voidpf opaque, voidpf address)
+{
+    xfree(address);
+}
+
+static void
+zstream_init(struct zstream *z, const struct zstream_funcs *func)
+{
+    z->flags = 0;
+    z->buf = Qnil;
+    z->buf_filled = 0;
+    z->input = Qnil;
+    z->stream.zalloc = zlib_mem_alloc;
+    z->stream.zfree = zlib_mem_free;
+    z->stream.opaque = Z_NULL;
+    z->stream.msg = Z_NULL;
+    z->stream.next_in = Z_NULL;
+    z->stream.avail_in = 0;
+    z->stream.next_out = Z_NULL;
+    z->stream.avail_out = 0;
+    z->func = func;
+}
+
+#define zstream_init_deflate(z)   zstream_init((z), &deflate_funcs)
+#define zstream_init_inflate(z)   zstream_init((z), &inflate_funcs)
+
+static void
+zstream_expand_buffer(struct zstream *z)
+{
+    long inc;
+
+    if (NIL_P(z->buf)) {
+	    /* I uses rb_str_new here not rb_str_buf_new because
+	       rb_str_buf_new makes a zero-length string. */
+	z->buf = rb_str_new(0, ZSTREAM_INITIAL_BUFSIZE);
+	z->buf_filled = 0;
+	z->stream.next_out = (Bytef*)RSTRING_PTR(z->buf);
+	z->stream.avail_out = ZSTREAM_INITIAL_BUFSIZE;
+	RBASIC(z->buf)->klass = 0;
+	return;
+    }
+
+    if (RSTRING_LEN(z->buf) - z->buf_filled >= ZSTREAM_AVAIL_OUT_STEP_MAX) {
+	/* to keep other threads from freezing */
+	z->stream.avail_out = ZSTREAM_AVAIL_OUT_STEP_MAX;
+    }
+    else {
+	inc = z->buf_filled / 2;
+	if (inc < ZSTREAM_AVAIL_OUT_STEP_MIN) {
+	    inc = ZSTREAM_AVAIL_OUT_STEP_MIN;
+	}
+	rb_str_resize(z->buf, z->buf_filled + inc);
+	z->stream.avail_out = (inc < ZSTREAM_AVAIL_OUT_STEP_MAX) ?
+	    (int)inc : ZSTREAM_AVAIL_OUT_STEP_MAX;
+    }
+    z->stream.next_out = (Bytef*)RSTRING_PTR(z->buf) + z->buf_filled;
+}
+
+static void
+zstream_expand_buffer_into(struct zstream *z, unsigned long size)
+{
+    if (NIL_P(z->buf)) {
+	/* I uses rb_str_new here not rb_str_buf_new because
+	   rb_str_buf_new makes a zero-length string. */
+	z->buf = rb_str_new(0, size);
+	z->buf_filled = 0;
+	z->stream.next_out = (Bytef*)RSTRING_PTR(z->buf);
+	z->stream.avail_out = MAX_UINT(size);
+	RBASIC(z->buf)->klass = 0;
+    }
+    else if (z->stream.avail_out != size) {
+	rb_str_resize(z->buf, z->buf_filled + size);
+	z->stream.next_out = (Bytef*)RSTRING_PTR(z->buf) + z->buf_filled;
+	z->stream.avail_out = MAX_UINT(size);
+    }
+}
+
+static void
+zstream_append_buffer(struct zstream *z, const Bytef *src, long len)
+{
+    if (NIL_P(z->buf)) {
+	z->buf = rb_str_buf_new(len);
+	rb_str_buf_cat(z->buf, (const char*)src, len);
+	z->buf_filled = len;
+	z->stream.next_out = (Bytef*)RSTRING_PTR(z->buf);
+	z->stream.avail_out = 0;
+	RBASIC(z->buf)->klass = 0;
+	return;
+    }
+
+    if (RSTRING_LEN(z->buf) < z->buf_filled + len) {
+	rb_str_resize(z->buf, z->buf_filled + len);
+	z->stream.avail_out = 0;
+    }
+    else {
+	if (z->stream.avail_out >= (uInt)len) {
+	    z->stream.avail_out -= (uInt)len;
+	}
+	else {
+	    z->stream.avail_out = 0;
+	}
+    }
+    memcpy(RSTRING_PTR(z->buf) + z->buf_filled, src, len);
+    z->buf_filled += len;
+    z->stream.next_out = (Bytef*)RSTRING_PTR(z->buf) + z->buf_filled;
+}
+
+#define zstream_append_buffer2(z,v) \
+    zstream_append_buffer((z),(Bytef*)RSTRING_PTR(v),RSTRING_LEN(v))
+
+static VALUE
+zstream_detach_buffer(struct zstream *z)
+{
+    VALUE dst;
+
+    if (NIL_P(z->buf)) {
+	dst = rb_str_new(0, 0);
+    }
+    else {
+	dst = z->buf;
+	rb_str_resize(dst, z->buf_filled);
+	RBASIC(dst)->klass = rb_cString;
+    }
+
+    z->buf = Qnil;
+    z->buf_filled = 0;
+    z->stream.next_out = 0;
+    z->stream.avail_out = 0;
+    return dst;
+}
+
+static VALUE
+zstream_shift_buffer(struct zstream *z, long len)
+{
+    VALUE dst;
+    long buflen;
+
+    if (z->buf_filled <= len) {
+	return zstream_detach_buffer(z);
+    }
+
+    dst = rb_str_subseq(z->buf, 0, len);
+    RBASIC(dst)->klass = rb_cString;
+    z->buf_filled -= len;
+    memmove(RSTRING_PTR(z->buf), RSTRING_PTR(z->buf) + len,
+	    z->buf_filled);
+    z->stream.next_out = (Bytef*)RSTRING_PTR(z->buf) + z->buf_filled;
+    buflen = RSTRING_LEN(z->buf) - z->buf_filled;
+    if (buflen > ZSTREAM_AVAIL_OUT_STEP_MAX) {
+	buflen = ZSTREAM_AVAIL_OUT_STEP_MAX;
+    }
+    z->stream.avail_out = (uInt)buflen;
+
+    return dst;
+}
+
+static void
+zstream_buffer_ungets(struct zstream *z, const Bytef *b, unsigned long len)
+{
+    if (NIL_P(z->buf) || RSTRING_LEN(z->buf) - z->buf_filled == 0) {
+	zstream_expand_buffer_into(z, len);
+    }
+
+    memmove(RSTRING_PTR(z->buf) + len, RSTRING_PTR(z->buf), z->buf_filled);
+    memmove(RSTRING_PTR(z->buf), b, len);
+    z->buf_filled+=len;
+    if (z->stream.avail_out > 0) {
+	if (len > z->stream.avail_out) len = z->stream.avail_out;
+	z->stream.next_out+=len;
+	z->stream.avail_out-=(uInt)len;
+    }
+}
+
+static void
+zstream_buffer_ungetbyte(struct zstream *z, int c)
+{
+    if (NIL_P(z->buf) || RSTRING_LEN(z->buf) - z->buf_filled == 0) {
+	zstream_expand_buffer(z);
+    }
+
+    memmove(RSTRING_PTR(z->buf) + 1, RSTRING_PTR(z->buf), z->buf_filled);
+    RSTRING_PTR(z->buf)[0] = (char)c;
+    z->buf_filled++;
+    if (z->stream.avail_out > 0) {
+	z->stream.next_out++;
+	z->stream.avail_out--;
+    }
+}
+
+static void
+zstream_append_input(struct zstream *z, const Bytef *src, long len)
+{
+    if (len <= 0) return;
+
+    if (NIL_P(z->input)) {
+	z->input = rb_str_buf_new(len);
+	rb_str_buf_cat(z->input, (const char*)src, len);
+	RBASIC(z->input)->klass = 0;
+    }
+    else {
+	rb_str_buf_cat(z->input, (const char*)src, len);
+    }
+}
+
+#define zstream_append_input2(z,v)\
+    RB_GC_GUARD(v),\
+    zstream_append_input((z), (Bytef*)RSTRING_PTR(v), RSTRING_LEN(v))
+
+static void
+zstream_discard_input(struct zstream *z, long len)
+{
+    if (NIL_P(z->input) || RSTRING_LEN(z->input) <= len) {
+	z->input = Qnil;
+    }
+    else {
+	memmove(RSTRING_PTR(z->input), RSTRING_PTR(z->input) + len,
+		RSTRING_LEN(z->input) - len);
+	rb_str_resize(z->input, RSTRING_LEN(z->input) - len);
+    }
+}
+
+static void
+zstream_reset_input(struct zstream *z)
+{
+    z->input = Qnil;
+}
+
+static void
+zstream_passthrough_input(struct zstream *z)
+{
+    if (!NIL_P(z->input)) {
+	zstream_append_buffer2(z, z->input);
+	z->input = Qnil;
+    }
+}
+
+static VALUE
+zstream_detach_input(struct zstream *z)
+{
+    VALUE dst;
+
+    if (NIL_P(z->input)) {
+	dst = rb_str_new(0, 0);
+    }
+    else {
+	dst = z->input;
+	RBASIC(dst)->klass = rb_cString;
+    }
+    z->input = Qnil;
+    RBASIC(dst)->klass = rb_cString;
+    return dst;
+}
+
+static void
+zstream_reset(struct zstream *z)
+{
+    int err;
+
+    err = z->func->reset(&z->stream);
+    if (err != Z_OK) {
+	raise_zlib_error(err, z->stream.msg);
+    }
+    z->flags = ZSTREAM_FLAG_READY;
+    z->buf = Qnil;
+    z->buf_filled = 0;
+    z->stream.next_out = 0;
+    z->stream.avail_out = 0;
+    zstream_reset_input(z);
+}
+
+static VALUE
+zstream_end(struct zstream *z)
+{
+    int err;
+
+    if (!ZSTREAM_IS_READY(z)) {
+	rb_warning("attempt to close uninitialized zstream; ignored.");
+	return Qnil;
+    }
+    if (z->flags & ZSTREAM_FLAG_IN_STREAM) {
+	rb_warning("attempt to close unfinished zstream; reset forced.");
+	zstream_reset(z);
+    }
+
+    zstream_reset_input(z);
+    err = z->func->end(&z->stream);
+    if (err != Z_OK) {
+	raise_zlib_error(err, z->stream.msg);
+    }
+    z->flags = 0;
+    return Qnil;
+}
+
+static void
+zstream_run(struct zstream *z, Bytef *src, long len, int flush)
+{
+    uInt n;
+    int err;
+    volatile VALUE guard = Qnil;
+
+    if (NIL_P(z->input) && len == 0) {
+	z->stream.next_in = (Bytef*)"";
+	z->stream.avail_in = 0;
+    }
+    else {
+	zstream_append_input(z, src, len);
+	z->stream.next_in = (Bytef*)RSTRING_PTR(z->input);
+	z->stream.avail_in = MAX_UINT(RSTRING_LEN(z->input));
+	/* keep reference to `z->input' so as not to be garbage collected
+	   after zstream_reset_input() and prevent `z->stream.next_in'
+	   from dangling. */
+	guard = z->input;
+    }
+
+    if (z->stream.avail_out == 0) {
+	zstream_expand_buffer(z);
+    }
+
+    for (;;) {
+	/* VC allocates err and guard to same address.  accessing err and guard
+	   in same scope prevents it. */
+	RB_GC_GUARD(guard);
+	n = z->stream.avail_out;
+	err = z->func->run(&z->stream, flush);
+	z->buf_filled += n - z->stream.avail_out;
+	rb_thread_schedule();
+
+	if (err == Z_STREAM_END) {
+	    z->flags &= ~ZSTREAM_FLAG_IN_STREAM;
+	    z->flags |= ZSTREAM_FLAG_FINISHED;
+	    break;
+	}
+	if (err != Z_OK) {
+	    if (flush != Z_FINISH && err == Z_BUF_ERROR
+		&& z->stream.avail_out > 0) {
+		z->flags |= ZSTREAM_FLAG_IN_STREAM;
+		break;
+	    }
+	    zstream_reset_input(z);
+	    if (z->stream.avail_in > 0) {
+		zstream_append_input(z, z->stream.next_in, z->stream.avail_in);
+	    }
+	    raise_zlib_error(err, z->stream.msg);
+	}
+	if (z->stream.avail_out > 0) {
+	    z->flags |= ZSTREAM_FLAG_IN_STREAM;
+	    break;
+	}
+	zstream_expand_buffer(z);
+    }
+
+    zstream_reset_input(z);
+    if (z->stream.avail_in > 0) {
+	zstream_append_input(z, z->stream.next_in, z->stream.avail_in);
+        guard = Qnil; /* prevent tail call to make guard effective */
+    }
+}
+
+static VALUE
+zstream_sync(struct zstream *z, Bytef *src, long len)
+{
+    VALUE rest;
+    int err;
+
+    if (!NIL_P(z->input)) {
+	z->stream.next_in = (Bytef*)RSTRING_PTR(z->input);
+	z->stream.avail_in = MAX_UINT(RSTRING_LEN(z->input));
+	err = inflateSync(&z->stream);
+	if (err == Z_OK) {
+	    zstream_discard_input(z,
+				  RSTRING_LEN(z->input) - z->stream.avail_in);
+	    zstream_append_input(z, src, len);
+	    return Qtrue;
+	}
+	zstream_reset_input(z);
+	if (err != Z_DATA_ERROR) {
+	    rest = rb_str_new((char*)z->stream.next_in, z->stream.avail_in);
+	    raise_zlib_error(err, z->stream.msg);
+	}
+    }
+
+    if (len <= 0) return Qfalse;
+
+    z->stream.next_in = src;
+    z->stream.avail_in = MAX_UINT(len);
+    err = inflateSync(&z->stream);
+    if (err == Z_OK) {
+	zstream_append_input(z, z->stream.next_in, z->stream.avail_in);
+	return Qtrue;
+    }
+    if (err != Z_DATA_ERROR) {
+	rest = rb_str_new((char*)z->stream.next_in, z->stream.avail_in);
+	raise_zlib_error(err, z->stream.msg);
+    }
+    return Qfalse;
+}
+
+static void
+zstream_mark(struct zstream *z)
+{
+    rb_gc_mark(z->buf);
+    rb_gc_mark(z->input);
+}
+
+static void
+zstream_finalize(struct zstream *z)
+{
+    int err = z->func->end(&z->stream);
+    if (err == Z_STREAM_ERROR)
+	finalizer_warn("the stream state was inconsistent.");
+    if (err == Z_DATA_ERROR)
+	finalizer_warn("the stream was freed prematurely.");
+}
+
+static void
+zstream_free(struct zstream *z)
+{
+    if (ZSTREAM_IS_READY(z)) {
+	zstream_finalize(z);
+    }
+    xfree(z);
+}
+
+static VALUE
+zstream_new(VALUE klass, const struct zstream_funcs *funcs)
+{
+    VALUE obj;
+    struct zstream *z;
+
+    obj = Data_Make_Struct(klass, struct zstream,
+			   zstream_mark, zstream_free, z);
+    zstream_init(z, funcs);
+    return obj;
+}
+
+#define zstream_deflate_new(klass)  zstream_new((klass), &deflate_funcs)
+#define zstream_inflate_new(klass)  zstream_new((klass), &inflate_funcs)
+
+static struct zstream *
+get_zstream(VALUE obj)
+{
+    struct zstream *z;
+
+    Data_Get_Struct(obj, struct zstream, z);
+    if (!ZSTREAM_IS_READY(z)) {
+	rb_raise(cZError, "stream is not ready");
+    }
+    return z;
+}
+
+
+/* ------------------------------------------------------------------------- */
+
+/*
+ * Document-class: Zlib::ZStream
+ *
+ * Zlib::ZStream is the abstract class for the stream which handles the
+ * compressed data. The operations are defined in the subclasses:
+ * Zlib::Deflate for compression, and Zlib::Inflate for decompression.
+ *
+ * An instance of Zlib::ZStream has one stream (struct zstream in the source)
+ * and two variable-length buffers which associated to the input (next_in) of
+ * the stream and the output (next_out) of the stream. In this document,
+ * "input buffer" means the buffer for input, and "output buffer" means the
+ * buffer for output.
+ *
+ * Data input into an instance of Zlib::ZStream are temporally stored into
+ * the end of input buffer, and then data in input buffer are processed from
+ * the beginning of the buffer until no more output from the stream is
+ * produced (i.e. until avail_out > 0 after processing).  During processing,
+ * output buffer is allocated and expanded automatically to hold all output
+ * data.
+ *
+ * Some particular instance methods consume the data in output buffer and
+ * return them as a String.
+ *
+ * Here is an ascii art for describing above:
+ *
+ *    +================ an instance of Zlib::ZStream ================+
+ *    ||                                                            ||
+ *    ||     +--------+          +-------+          +--------+      ||
+ *    ||  +--| output |<---------|zstream|<---------| input  |<--+  ||
+ *    ||  |  | buffer |  next_out+-------+next_in   | buffer |   |  ||
+ *    ||  |  +--------+                             +--------+   |  ||
+ *    ||  |                                                      |  ||
+ *    +===|======================================================|===+
+ *        |                                                      |
+ *        v                                                      |
+ *    "output data"                                         "input data"
+ *
+ * If an error occurs during processing input buffer, an exception which is a
+ * subclass of Zlib::Error is raised.  At that time, both input and output
+ * buffer keep their conditions at the time when the error occurs.
+ *
+ * == Method Catalogue
+ *
+ * Many of the methods in this class are fairly low-level and unlikely to be
+ * of interest to users.  In fact, users are unlikely to use this class
+ * directly; rather they will be interested in Zlib::Inflate and
+ * Zlib::Deflate.
+ *
+ * The higher level methods are listed below.
+ *
+ * - #total_in
+ * - #total_out
+ * - #data_type
+ * - #adler
+ * - #reset
+ * - #finish
+ * - #finished?
+ * - #close
+ * - #closed?
+ */
+
+/*
+ * Closes the stream. All operations on the closed stream will raise an
+ * exception.
+ */
+static VALUE
+rb_zstream_end(VALUE obj)
+{
+    zstream_end(get_zstream(obj));
+    return Qnil;
+}
+
+/*
+ * Resets and initializes the stream. All data in both input and output buffer
+ * are discarded.
+ */
+static VALUE
+rb_zstream_reset(VALUE obj)
+{
+    zstream_reset(get_zstream(obj));
+    return Qnil;
+}
+
+/*
+ * Finishes the stream and flushes output buffer. See Zlib::Deflate#finish and
+ * Zlib::Inflate#finish for details of this behavior.
+ */
+static VALUE
+rb_zstream_finish(VALUE obj)
+{
+    struct zstream *z = get_zstream(obj);
+    VALUE dst;
+
+    zstream_run(z, (Bytef*)"", 0, Z_FINISH);
+    dst = zstream_detach_buffer(z);
+
+    OBJ_INFECT(dst, obj);
+    return dst;
+}
+
+/*
+ * Flushes input buffer and returns all data in that buffer.
+ */
+static VALUE
+rb_zstream_flush_next_in(VALUE obj)
+{
+    struct zstream *z;
+    VALUE dst;
+
+    Data_Get_Struct(obj, struct zstream, z);
+    dst = zstream_detach_input(z);
+    OBJ_INFECT(dst, obj);
+    return dst;
+}
+
+/*
+ * Flushes output buffer and returns all data in that buffer.
+ */
+static VALUE
+rb_zstream_flush_next_out(VALUE obj)
+{
+    struct zstream *z;
+    VALUE dst;
+
+    Data_Get_Struct(obj, struct zstream, z);
+    dst = zstream_detach_buffer(z);
+    OBJ_INFECT(dst, obj);
+    return dst;
+}
+
+/*
+ * Returns number of bytes of free spaces in output buffer.  Because the free
+ * space is allocated automatically, this method returns 0 normally.
+ */
+static VALUE
+rb_zstream_avail_out(VALUE obj)
+{
+    struct zstream *z;
+    Data_Get_Struct(obj, struct zstream, z);
+    return rb_uint2inum(z->stream.avail_out);
+}
+
+/*
+ * Allocates +size+ bytes of free space in the output buffer. If there are more
+ * than +size+ bytes already in the buffer, the buffer is truncated. Because
+ * free space is allocated automatically, you usually don't need to use this
+ * method.
+ */
+static VALUE
+rb_zstream_set_avail_out(VALUE obj, VALUE size)
+{
+    struct zstream *z = get_zstream(obj);
+
+    Check_Type(size, T_FIXNUM);
+    zstream_expand_buffer_into(z, FIX2INT(size));
+    return size;
+}
+
+/*
+ * Returns bytes of data in the input buffer. Normally, returns 0.
+ */
+static VALUE
+rb_zstream_avail_in(VALUE obj)
+{
+    struct zstream *z;
+    Data_Get_Struct(obj, struct zstream, z);
+    return INT2FIX(NIL_P(z->input) ? 0 : (int)(RSTRING_LEN(z->input)));
+}
+
+/*
+ * Returns the total bytes of the input data to the stream.  FIXME
+ */
+static VALUE
+rb_zstream_total_in(VALUE obj)
+{
+    return rb_uint2inum(get_zstream(obj)->stream.total_in);
+}
+
+/*
+ * Returns the total bytes of the output data from the stream.  FIXME
+ */
+static VALUE
+rb_zstream_total_out(VALUE obj)
+{
+    return rb_uint2inum(get_zstream(obj)->stream.total_out);
+}
+
+/*
+ * Guesses the type of the data which have been inputed into the stream. The
+ * returned value is either <tt>BINARY</tt>, <tt>ASCII</tt>, or
+ * <tt>UNKNOWN</tt>.
+ */
+static VALUE
+rb_zstream_data_type(VALUE obj)
+{
+    return INT2FIX(get_zstream(obj)->stream.data_type);
+}
+
+/*
+ * Returns the adler-32 checksum.
+ */
+static VALUE
+rb_zstream_adler(VALUE obj)
+{
+	return rb_uint2inum(get_zstream(obj)->stream.adler);
+}
+
+/*
+ * Returns true if the stream is finished.
+ */
+static VALUE
+rb_zstream_finished_p(VALUE obj)
+{
+    return ZSTREAM_IS_FINISHED(get_zstream(obj)) ? Qtrue : Qfalse;
+}
+
+/*
+ * Returns true if the stream is closed.
+ */
+static VALUE
+rb_zstream_closed_p(VALUE obj)
+{
+    struct zstream *z;
+    Data_Get_Struct(obj, struct zstream, z);
+    return ZSTREAM_IS_READY(z) ? Qfalse : Qtrue;
+}
+
+
+/* ------------------------------------------------------------------------- */
+
+/*
+ * Document-class: Zlib::Deflate
+ *
+ * Zlib::Deflate is the class for compressing data.  See Zlib::ZStream for more
+ * information.
+ */
+
+#define FIXNUMARG(val, ifnil) \
+    (NIL_P((val)) ? (ifnil) \
+    : ((void)Check_Type((val), T_FIXNUM), FIX2INT((val))))
+
+#define ARG_LEVEL(val)     FIXNUMARG((val), Z_DEFAULT_COMPRESSION)
+#define ARG_WBITS(val)     FIXNUMARG((val), MAX_WBITS)
+#define ARG_MEMLEVEL(val)  FIXNUMARG((val), DEF_MEM_LEVEL)
+#define ARG_STRATEGY(val)  FIXNUMARG((val), Z_DEFAULT_STRATEGY)
+#define ARG_FLUSH(val)     FIXNUMARG((val), Z_NO_FLUSH)
+
+
+static VALUE
+rb_deflate_s_allocate(VALUE klass)
+{
+    return zstream_deflate_new(klass);
+}
+
+/*
+ * Document-method: Zlib::Deflate.new
+ *
+ * call-seq: Zlib::Deflate.new(level=nil, windowBits=nil, memlevel=nil, strategy=nil)
+ *
+ * == Arguments
+ *
+ * +level+::
+ *   An Integer compression level between
+ *   BEST_SPEED and BEST_COMPRESSION
+ * +windowBits+::
+ *   An Integer for the windowBits size. Should be
+ *   in the range 8..15, larger values of this parameter
+ *   result in better at the expense of memory usage.
+ * +memlevel+::
+ *   Specifies how much memory should be allocated for
+ *   the internal compression state.
+ *   Between DEF_MEM_LEVEL and MAX_MEM_LEVEL
+ * +strategy+::
+ *   A parameter to tune the compression algorithm. Use the
+ *   DEFAULT_STRATEGY for normal data, FILTERED for data produced by a
+ *   filter (or predictor), HUFFMAN_ONLY to force Huffman encoding only (no
+ *   string match).
+ *
+ * == Description
+ *
+ * Creates a new deflate stream for compression. See zlib.h for details of
+ * each argument. If an argument is nil, the default value of that argument is
+ * used.
+ *
+ *
+ * == examples
+ *
+ * === basic
+ *
+ *   f = File.new("compressed.file","w+")
+ *   #=> #<File:compressed.file>
+ *   f << Zlib::Deflate.new().deflate(File.read("big.file"))
+ *   #=> #<File:compressed.file>
+ *   f.close
+ *   #=> nil
+ *
+ * === a little more robust
+ *
+ *   compressed_file = File.open("compressed.file", "w+")
+ *   #=> #<File:compressed.file>
+ *   zd = Zlib::Deflate.new(Zlib::BEST_COMPRESSION, 15, Zlib::MAX_MEM_LEVEL, Zlib::HUFFMAN_ONLY)
+ *   #=> #<Zlib::Deflate:0x000000008610a0>
+ *   compressed_file << zd.deflate(File.read("big.file"))
+ *   #=> "\xD4z\xC6\xDE\b\xA1K\x1Ej\x8A ..."
+ *   compressed_file.close
+ *   #=> nil
+ *   zd.close
+ *   #=> nil
+ *
+ * (while this example will work, for best optimization the flags need to be reviewed for your specific function)
+ *
+ */
+static VALUE
+rb_deflate_initialize(int argc, VALUE *argv, VALUE obj)
+{
+    struct zstream *z;
+    VALUE level, wbits, memlevel, strategy;
+    int err;
+
+    rb_scan_args(argc, argv, "04", &level, &wbits, &memlevel, &strategy);
+    Data_Get_Struct(obj, struct zstream, z);
+
+    err = deflateInit2(&z->stream, ARG_LEVEL(level), Z_DEFLATED,
+		       ARG_WBITS(wbits), ARG_MEMLEVEL(memlevel),
+		       ARG_STRATEGY(strategy));
+    if (err != Z_OK) {
+	raise_zlib_error(err, z->stream.msg);
+    }
+    ZSTREAM_READY(z);
+
+    return obj;
+}
+
+/*
+ * Document-method: Zlib::Deflate#initialize_copy
+ *
+ * Duplicates the deflate stream.
+ */
+static VALUE
+rb_deflate_init_copy(VALUE self, VALUE orig)
+{
+    struct zstream *z1, *z2;
+    int err;
+
+    Data_Get_Struct(self, struct zstream, z1);
+    z2 = get_zstream(orig);
+
+    err = deflateCopy(&z1->stream, &z2->stream);
+    if (err != Z_OK) {
+	raise_zlib_error(err, 0);
+    }
+    z1->input = NIL_P(z2->input) ? Qnil : rb_str_dup(z2->input);
+    z1->buf   = NIL_P(z2->buf)   ? Qnil : rb_str_dup(z2->buf);
+    z1->buf_filled = z2->buf_filled;
+    z1->flags = z2->flags;
+
+    return self;
+}
+
+static VALUE
+deflate_run(VALUE args)
+{
+    struct zstream *z = (struct zstream*)((VALUE*)args)[0];
+    VALUE src = ((VALUE*)args)[1];
+
+    zstream_run(z, (Bytef*)RSTRING_PTR(src), RSTRING_LEN(src), Z_FINISH);
+    return zstream_detach_buffer(z);
+}
+
+/*
+ * Document-method: Zlib::Deflate.deflate
+ *
+ * call-seq: Zlib.deflate(string[, level])
+ *           Zlib::Deflate.deflate(string[, level])
+ *
+ * Compresses the given +string+. Valid values of level are
+ * <tt>NO_COMPRESSION</tt>, <tt>BEST_SPEED</tt>,
+ * <tt>BEST_COMPRESSION</tt>, <tt>DEFAULT_COMPRESSION</tt>, and an
+ * integer from 0 to 9 (the default is 6).
+ *
+ * This method is almost equivalent to the following code:
+ *
+ *   def deflate(string, level)
+ *     z = Zlib::Deflate.new(level)
+ *     dst = z.deflate(string, Zlib::NO_FLUSH)
+ *     z.close
+ *     dst
+ *   end
+ *
+ * See also Zlib.inflate
+ *
+ */
+static VALUE
+rb_deflate_s_deflate(int argc, VALUE *argv, VALUE klass)
+{
+    struct zstream z;
+    VALUE src, level, dst, args[2];
+    int err, lev;
+
+    rb_scan_args(argc, argv, "11", &src, &level);
+
+    lev = ARG_LEVEL(level);
+    StringValue(src);
+    zstream_init_deflate(&z);
+    err = deflateInit(&z.stream, lev);
+    if (err != Z_OK) {
+	raise_zlib_error(err, z.stream.msg);
+    }
+    ZSTREAM_READY(&z);
+
+    args[0] = (VALUE)&z;
+    args[1] = src;
+    dst = rb_ensure(deflate_run, (VALUE)args, zstream_end, (VALUE)&z);
+
+    OBJ_INFECT(dst, src);
+    return dst;
+}
+
+static void
+do_deflate(struct zstream *z, VALUE src, int flush)
+{
+    if (NIL_P(src)) {
+	zstream_run(z, (Bytef*)"", 0, Z_FINISH);
+	return;
+    }
+    StringValue(src);
+    if (flush != Z_NO_FLUSH || RSTRING_LEN(src) > 0) { /* prevent BUF_ERROR */
+	zstream_run(z, (Bytef*)RSTRING_PTR(src), RSTRING_LEN(src), flush);
+    }
+}
+
+/*
+ * Document-method: Zlib.deflate
+ *
+ * call-seq: deflate(string[, flush])
+ *
+ * == Arguments
+ *
+ * +string+::
+ *   String
+ *
+ * +flush+::
+ *   Integer representing a flush code. Either NO_FLUSH,
+ *   SYNC_FLUSH, FULL_FLUSH, or FINISH. See zlib.h for details.
+ *   Normally the parameter flush is set to Z_NO_FLUSH, which allows deflate to
+ *   decide how much data to accumulate before producing output, in order to
+ *   maximize compression.
+ *
+ * == Description
+ *
+ * Inputs +string+ into the deflate stream and returns the output from the
+ * stream.  On calling this method, both the input and the output buffers of
+ * the stream are flushed.
+ *
+ * If +string+ is nil, this method finishes the
+ * stream, just like Zlib::ZStream#finish.
+ *
+ * == Usage
+ *
+ *   comp = Zlib.deflate(File.read("big.file"))
+ * or
+ *   comp = Zlib.deflate(File.read("big.file"), Zlib::FULL_FLUSH)
+ *
+ */
+static VALUE
+rb_deflate_deflate(int argc, VALUE *argv, VALUE obj)
+{
+    struct zstream *z = get_zstream(obj);
+    VALUE src, flush, dst;
+
+    rb_scan_args(argc, argv, "11", &src, &flush);
+    OBJ_INFECT(obj, src);
+    do_deflate(z, src, ARG_FLUSH(flush));
+    dst = zstream_detach_buffer(z);
+
+    OBJ_INFECT(dst, obj);
+    return dst;
+}
+
+/*
+ * Document-method: Zlib::Deflate.<<
+ *
+ * call-seq: << string
+ *
+ * Inputs +string+ into the deflate stream just like Zlib::Deflate#deflate, but
+ * returns the Zlib::Deflate object itself.  The output from the stream is
+ * preserved in output buffer.
+ */
+static VALUE
+rb_deflate_addstr(VALUE obj, VALUE src)
+{
+    OBJ_INFECT(obj, src);
+    do_deflate(get_zstream(obj), src, Z_NO_FLUSH);
+    return obj;
+}
+
+/*
+ * Document-method: Zlib::Deflate#flush
+ *
+ * call-seq: flush(flush)
+ *
+ * This method is equivalent to <tt>deflate('', flush)</tt>.  If flush is omitted,
+ * <tt>SYNC_FLUSH</tt> is used as flush.  This method is just provided
+ * to improve the readability of your Ruby program.
+ *
+ * Please visit your zlib.h for a deeper detail on NO_FLUSH, SYNC_FLUSH, FULL_FLUSH, and FINISH
+ *
+ */
+static VALUE
+rb_deflate_flush(int argc, VALUE *argv, VALUE obj)
+{
+    struct zstream *z = get_zstream(obj);
+    VALUE v_flush, dst;
+    int flush;
+
+    rb_scan_args(argc, argv, "01", &v_flush);
+    flush = FIXNUMARG(v_flush, Z_SYNC_FLUSH);
+    if (flush != Z_NO_FLUSH) {  /* prevent Z_BUF_ERROR */
+	zstream_run(z, (Bytef*)"", 0, flush);
+    }
+    dst = zstream_detach_buffer(z);
+
+    OBJ_INFECT(dst, obj);
+    return dst;
+}
+
+/*
+ * Document-method: Zlib::Deflate.params
+ *
+ * call-seq: params(level, strategy)
+ *
+ * Changes the parameters of the deflate stream. See zlib.h for details. The
+ * output from the stream by changing the params is preserved in output
+ * buffer.
+ *
+ * +level+::
+ *   An Integer compression level between
+ *   BEST_SPEED and BEST_COMPRESSION
+ * +strategy+::
+ *   A parameter to tune the compression algorithm. Use the
+ *   DEFAULT_STRATEGY for normal data, FILTERED for data produced by a
+ *   filter (or predictor), HUFFMAN_ONLY to force Huffman encoding only (no
+ *   string match).
+ *
+ */
+static VALUE
+rb_deflate_params(VALUE obj, VALUE v_level, VALUE v_strategy)
+{
+    struct zstream *z = get_zstream(obj);
+    int level, strategy;
+    int err;
+    uInt n;
+
+    level = ARG_LEVEL(v_level);
+    strategy = ARG_STRATEGY(v_strategy);
+
+    n = z->stream.avail_out;
+    err = deflateParams(&z->stream, level, strategy);
+    z->buf_filled += n - z->stream.avail_out;
+    while (err == Z_BUF_ERROR) {
+	rb_warning("deflateParams() returned Z_BUF_ERROR");
+	zstream_expand_buffer(z);
+	n = z->stream.avail_out;
+	err = deflateParams(&z->stream, level, strategy);
+	z->buf_filled += n - z->stream.avail_out;
+    }
+    if (err != Z_OK) {
+	raise_zlib_error(err, z->stream.msg);
+    }
+
+    return Qnil;
+}
+
+/*
+ * Document-method: Zlib::Deflate.set_dictionary
+ *
+ * call-seq: set_dictionary(string)
+ *
+ * Sets the preset dictionary and returns +string+. This method is available
+ * just only after Zlib::Deflate.new or Zlib::ZStream#reset method was called.
+ * See zlib.h for details.
+ *
+ * Can raise errors of Z_STREAM_ERROR if a parameter is invalid (such as
+ * NULL dictionary) or the stream state is inconsistent, Z_DATA_ERROR if
+ * the given dictionary doesn't match the expected one (incorrect adler32 value)
+ *
+ */
+static VALUE
+rb_deflate_set_dictionary(VALUE obj, VALUE dic)
+{
+    struct zstream *z = get_zstream(obj);
+    VALUE src = dic;
+    int err;
+
+    OBJ_INFECT(obj, dic);
+    StringValue(src);
+    err = deflateSetDictionary(&z->stream,
+			       (Bytef*)RSTRING_PTR(src), RSTRING_LENINT(src));
+    if (err != Z_OK) {
+	raise_zlib_error(err, z->stream.msg);
+    }
+
+    return dic;
+}
+
+
+/* ------------------------------------------------------------------------- */
+
+/*
+ * Document-class: Zlib::Inflate
+ *
+ * Zlib:Inflate is the class for decompressing compressed data.  Unlike
+ * Zlib::Deflate, an instance of this class is not able to duplicate (clone,
+ * dup) itself.
+ */
+
+
+
+static VALUE
+rb_inflate_s_allocate(VALUE klass)
+{
+    return zstream_inflate_new(klass);
+}
+
+/*
+ * Document-method: Zlib::Inflate.new
+ *
+ * call-seq: Zlib::Inflate.new(window_bits)
+ *
+ * == Arguments
+ *
+ * +windowBits+::
+ *   An Integer for the windowBits size. Should be
+ *   in the range 8..15, larger values of this parameter
+ *   result in better at the expense of memory usage.
+ *
+ * == Description
+ *
+ * Creates a new inflate stream for decompression. See zlib.h for details
+ * of the argument.  If +window_bits+ is +nil+, the default value is used.
+ *
+ * == Example
+ *
+ *   cf = File.open("compressed.file")
+ *   ucf = File.open("uncompressed.file", "w+")
+ *   zi = Zlib::Inflate.new(Zlib::MAX_WBITS)
+ *
+ *   ucf << zi.inflate(cf.read)
+ *
+ *   ucf.close
+ *   zi.close
+ *   cf.close
+ *
+ * or
+ *
+ *   File.open("compressed.file") {|cf|
+ *     zi = Zlib::Inflate.new
+ *     File.open("uncompressed.file", "w+") {|ucf|
+ *       ucf << zi.inflate(cf.read)
+ *     }
+ *     zi.close
+ *   }
+ *
+ */
+static VALUE
+rb_inflate_initialize(int argc, VALUE *argv, VALUE obj)
+{
+    struct zstream *z;
+    VALUE wbits;
+    int err;
+
+    rb_scan_args(argc, argv, "01", &wbits);
+    Data_Get_Struct(obj, struct zstream, z);
+
+    err = inflateInit2(&z->stream, ARG_WBITS(wbits));
+    if (err != Z_OK) {
+	raise_zlib_error(err, z->stream.msg);
+    }
+    ZSTREAM_READY(z);
+
+    return obj;
+}
+
+static VALUE
+inflate_run(VALUE args)
+{
+    struct zstream *z = (struct zstream*)((VALUE*)args)[0];
+    VALUE src = ((VALUE*)args)[1];
+
+    zstream_run(z, (Bytef*)RSTRING_PTR(src), RSTRING_LEN(src), Z_SYNC_FLUSH);
+    zstream_run(z, (Bytef*)"", 0, Z_FINISH);  /* for checking errors */
+    return zstream_detach_buffer(z);
+}
+
+/*
+ * Document-method: Zlib::Inflate.inflate
+ *
+ * call-seq: Zlib::Inflate.inflate(string)
+ *
+ * Decompresses +string+. Raises a Zlib::NeedDict exception if a preset
+ * dictionary is needed for decompression.
+ *
+ * This method is almost equivalent to the following code:
+ *
+ *   def inflate(string)
+ *     zstream = Zlib::Inflate.new
+ *     buf = zstream.inflate(string)
+ *     zstream.finish
+ *     zstream.close
+ *     buf
+ *   end
+ *
+ * See also Zlib.deflate
+ *
+ */
+static VALUE
+rb_inflate_s_inflate(VALUE obj, VALUE src)
+{
+    struct zstream z;
+    VALUE dst, args[2];
+    int err;
+
+    StringValue(src);
+    zstream_init_inflate(&z);
+    err = inflateInit(&z.stream);
+    if (err != Z_OK) {
+	raise_zlib_error(err, z.stream.msg);
+    }
+    ZSTREAM_READY(&z);
+
+    args[0] = (VALUE)&z;
+    args[1] = src;
+    dst = rb_ensure(inflate_run, (VALUE)args, zstream_end, (VALUE)&z);
+
+    OBJ_INFECT(dst, src);
+    return dst;
+}
+
+static void
+do_inflate(struct zstream *z, VALUE src)
+{
+    if (NIL_P(src)) {
+	zstream_run(z, (Bytef*)"", 0, Z_FINISH);
+	return;
+    }
+    StringValue(src);
+    if (RSTRING_LEN(src) > 0 || z->stream.avail_in > 0) { /* prevent Z_BUF_ERROR */
+	zstream_run(z, (Bytef*)RSTRING_PTR(src), RSTRING_LEN(src), Z_SYNC_FLUSH);
+    }
+}
+
+/*
+ * Document-method: Zlib::Inflate#inflate
+ *
+ * call-seq: inflate(string)
+ *
+ * Inputs +string+ into the inflate stream and returns the output from the
+ * stream.  Calling this method, both the input and the output buffer of the
+ * stream are flushed.  If string is +nil+, this method finishes the stream,
+ * just like Zlib::ZStream#finish.
+ *
+ * Raises a Zlib::NeedDict exception if a preset dictionary is needed to
+ * decompress.  Set the dictionary by Zlib::Inflate#set_dictionary and then
+ * call this method again with an empty string to flush the stream:
+ *
+ *   inflater = Zlib::Inflate.new
+ *
+ *   begin
+ *     out = inflater.inflate compressed
+ *   rescue Zlib::NeedDict
+ *     # ensure the dictionary matches the stream's required dictionary
+ *     raise unless inflater.adler == Zlib.adler32(dictionary)
+ *
+ *     inflater.set_dictionary dictionary
+ *     inflater.inflate ''
+ *   end
+ *
+ *   # ...
+ *
+ *   inflater.close
+ *
+ * See also Zlib::Inflate.new
+ */
+static VALUE
+rb_inflate_inflate(VALUE obj, VALUE src)
+{
+    struct zstream *z = get_zstream(obj);
+    VALUE dst;
+
+    OBJ_INFECT(obj, src);
+
+    if (ZSTREAM_IS_FINISHED(z)) {
+	if (NIL_P(src)) {
+	    dst = zstream_detach_buffer(z);
+	}
+	else {
+	    StringValue(src);
+	    zstream_append_buffer2(z, src);
+	    dst = rb_str_new(0, 0);
+	}
+    }
+    else {
+	do_inflate(z, src);
+	dst = zstream_detach_buffer(z);
+	if (ZSTREAM_IS_FINISHED(z)) {
+	    zstream_passthrough_input(z);
+	}
+    }
+
+    OBJ_INFECT(dst, obj);
+    return dst;
+}
+
+/*
+ * call-seq: << string
+ *
+ * Inputs +string+ into the inflate stream just like Zlib::Inflate#inflate, but
+ * returns the Zlib::Inflate object itself.  The output from the stream is
+ * preserved in output buffer.
+ */
+static VALUE
+rb_inflate_addstr(VALUE obj, VALUE src)
+{
+    struct zstream *z = get_zstream(obj);
+
+    OBJ_INFECT(obj, src);
+
+    if (ZSTREAM_IS_FINISHED(z)) {
+	if (!NIL_P(src)) {
+	    StringValue(src);
+	    zstream_append_buffer2(z, src);
+	}
+    }
+    else {
+	do_inflate(z, src);
+	if (ZSTREAM_IS_FINISHED(z)) {
+	    zstream_passthrough_input(z);
+	}
+    }
+
+    return obj;
+}
+
+/*
+ * call-seq: sync(string)
+ *
+ * Inputs +string+ into the end of input buffer and skips data until a full
+ * flush point can be found.  If the point is found in the buffer, this method
+ * flushes the buffer and returns false.  Otherwise it returns +true+ and the
+ * following data of full flush point is preserved in the buffer.
+ */
+static VALUE
+rb_inflate_sync(VALUE obj, VALUE src)
+{
+    struct zstream *z = get_zstream(obj);
+
+    OBJ_INFECT(obj, src);
+    StringValue(src);
+    return zstream_sync(z, (Bytef*)RSTRING_PTR(src), RSTRING_LEN(src));
+}
+
+/*
+ * Quoted verbatim from original documentation:
+ *
+ *   What is this?
+ *
+ * <tt>:)</tt>
+ */
+static VALUE
+rb_inflate_sync_point_p(VALUE obj)
+{
+    struct zstream *z = get_zstream(obj);
+    int err;
+
+    err = inflateSyncPoint(&z->stream);
+    if (err == 1) {
+	return Qtrue;
+    }
+    if (err != Z_OK) {
+	raise_zlib_error(err, z->stream.msg);
+    }
+    return Qfalse;
+}
+
+/*
+ * Document-method: Zlib::Inflate#set_dictionary
+ *
+ * Sets the preset dictionary and returns +string+.  This method is available just
+ * only after a Zlib::NeedDict exception was raised.  See zlib.h for details.
+ *
+ */
+static VALUE
+rb_inflate_set_dictionary(VALUE obj, VALUE dic)
+{
+    struct zstream *z = get_zstream(obj);
+    VALUE src = dic;
+    int err;
+
+    OBJ_INFECT(obj, dic);
+    StringValue(src);
+    err = inflateSetDictionary(&z->stream,
+			       (Bytef*)RSTRING_PTR(src), RSTRING_LENINT(src));
+    if (err != Z_OK) {
+	raise_zlib_error(err, z->stream.msg);
+    }
+
+    return dic;
+}
+
+
+
+#if GZIP_SUPPORT
+
+/* NOTE: Features for gzip files of Ruby/zlib are written from scratch
+ *       and using undocumented feature of zlib, negative wbits.
+ *       I don't think gzFile APIs of zlib are good for Ruby.
+ */
+
+/*------- .gz file header --------*/
+
+#define GZ_MAGIC1             0x1f
+#define GZ_MAGIC2             0x8b
+#define GZ_METHOD_DEFLATE     8
+#define GZ_FLAG_MULTIPART     0x2
+#define GZ_FLAG_EXTRA         0x4
+#define GZ_FLAG_ORIG_NAME     0x8
+#define GZ_FLAG_COMMENT       0x10
+#define GZ_FLAG_ENCRYPT       0x20
+#define GZ_FLAG_UNKNOWN_MASK  0xc0
+
+#define GZ_EXTRAFLAG_FAST     0x4
+#define GZ_EXTRAFLAG_SLOW     0x2
+
+/* from zutil.h */
+#define OS_MSDOS    0x00
+#define OS_AMIGA    0x01
+#define OS_VMS      0x02
+#define OS_UNIX     0x03
+#define OS_ATARI    0x05
+#define OS_OS2      0x06
+#define OS_MACOS    0x07
+#define OS_TOPS20   0x0a
+#define OS_WIN32    0x0b
+
+#define OS_VMCMS    0x04
+#define OS_ZSYSTEM  0x08
+#define OS_CPM      0x09
+#define OS_QDOS     0x0c
+#define OS_RISCOS   0x0d
+#define OS_UNKNOWN  0xff
+
+#ifndef OS_CODE
+#define OS_CODE  OS_UNIX
+#endif
+
+static ID id_write, id_read, id_readpartial, id_flush, id_seek, id_close, id_path, id_input;
+static VALUE cGzError, cNoFooter, cCRCError, cLengthError;
+
+
+
+/*-------- gzfile internal APIs --------*/
+
+struct gzfile {
+    struct zstream z;
+    VALUE io;
+    int level;
+    time_t mtime;       /* for header */
+    int os_code;        /* for header */
+    VALUE orig_name;    /* for header; must be a String */
+    VALUE comment;      /* for header; must be a String */
+    unsigned long crc;
+    int lineno;
+    long ungetc;
+    void (*end)(struct gzfile *);
+    rb_encoding *enc;
+    rb_encoding *enc2;
+    rb_econv_t *ec;
+    int ecflags;
+    VALUE ecopts;
+    char *cbuf;
+    VALUE path;
+};
+#define GZFILE_CBUF_CAPA 10
+
+#define GZFILE_FLAG_SYNC             ZSTREAM_FLAG_UNUSED
+#define GZFILE_FLAG_HEADER_FINISHED  (ZSTREAM_FLAG_UNUSED << 1)
+#define GZFILE_FLAG_FOOTER_FINISHED  (ZSTREAM_FLAG_UNUSED << 2)
+
+#define GZFILE_IS_FINISHED(gz) \
+    (ZSTREAM_IS_FINISHED(&(gz)->z) && (gz)->z.buf_filled == 0)
+
+#define GZFILE_READ_SIZE  2048
+
+
+static void
+gzfile_mark(struct gzfile *gz)
+{
+    rb_gc_mark(gz->io);
+    rb_gc_mark(gz->orig_name);
+    rb_gc_mark(gz->comment);
+    zstream_mark(&gz->z);
+    rb_gc_mark(gz->ecopts);
+    rb_gc_mark(gz->path);
+}
+
+static void
+gzfile_free(struct gzfile *gz)
+{
+    struct zstream *z = &gz->z;
+
+    if (ZSTREAM_IS_READY(z)) {
+	if (z->func == &deflate_funcs) {
+	    finalizer_warn("Zlib::GzipWriter object must be closed explicitly.");
+	}
+	zstream_finalize(z);
+    }
+    if (gz->cbuf) {
+	xfree(gz->cbuf);
+    }
+    xfree(gz);
+}
+
+static VALUE
+gzfile_new(klass, funcs, endfunc)
+    VALUE klass;
+    const struct zstream_funcs *funcs;
+    void (*endfunc)(struct gzfile *);
+{
+    VALUE obj;
+    struct gzfile *gz;
+
+    obj = Data_Make_Struct(klass, struct gzfile, gzfile_mark, gzfile_free, gz);
+    zstream_init(&gz->z, funcs);
+    gz->io = Qnil;
+    gz->level = 0;
+    gz->mtime = 0;
+    gz->os_code = OS_CODE;
+    gz->orig_name = Qnil;
+    gz->comment = Qnil;
+    gz->crc = crc32(0, Z_NULL, 0);
+    gz->lineno = 0;
+    gz->ungetc = 0;
+    gz->end = endfunc;
+    gz->enc = rb_default_external_encoding();
+    gz->enc2 = 0;
+    gz->ec = NULL;
+    gz->ecflags = 0;
+    gz->ecopts = Qnil;
+    gz->cbuf = 0;
+    gz->path = Qnil;
+
+    return obj;
+}
+
+#define gzfile_writer_new(gz) gzfile_new((gz),&deflate_funcs,gzfile_writer_end)
+#define gzfile_reader_new(gz) gzfile_new((gz),&inflate_funcs,gzfile_reader_end)
+
+static void
+gzfile_reset(struct gzfile *gz)
+{
+    zstream_reset(&gz->z);
+    gz->crc = crc32(0, Z_NULL, 0);
+    gz->lineno = 0;
+    gz->ungetc = 0;
+    if (gz->ec) {
+	rb_econv_close(gz->ec);
+	gz->ec = rb_econv_open_opts(gz->enc2->name, gz->enc->name,
+				    gz->ecflags, gz->ecopts);
+    }
+}
+
+static void
+gzfile_close(struct gzfile *gz, int closeflag)
+{
+    VALUE io = gz->io;
+
+    gz->end(gz);
+    gz->io = Qnil;
+    gz->orig_name = Qnil;
+    gz->comment = Qnil;
+    if (closeflag && rb_respond_to(io, id_close)) {
+	rb_funcall(io, id_close, 0);
+    }
+}
+
+static void
+gzfile_write_raw(struct gzfile *gz)
+{
+    VALUE str;
+
+    if (gz->z.buf_filled > 0) {
+	str = zstream_detach_buffer(&gz->z);
+	OBJ_TAINT(str);  /* for safe */
+	rb_funcall(gz->io, id_write, 1, str);
+	if ((gz->z.flags & GZFILE_FLAG_SYNC)
+	    && rb_respond_to(gz->io, id_flush))
+	    rb_funcall(gz->io, id_flush, 0);
+    }
+}
+
+static VALUE
+gzfile_read_raw_partial(VALUE arg)
+{
+    struct gzfile *gz = (struct gzfile*)arg;
+    VALUE str;
+
+    str = rb_funcall(gz->io, id_readpartial, 1, INT2FIX(GZFILE_READ_SIZE));
+    Check_Type(str, T_STRING);
+    return str;
+}
+
+static VALUE
+gzfile_read_raw_rescue(VALUE arg)
+{
+    struct gzfile *gz = (struct gzfile*)arg;
+    VALUE str = Qnil;
+    if (rb_obj_is_kind_of(rb_errinfo(), rb_eNoMethodError)) {
+        str = rb_funcall(gz->io, id_read, 1, INT2FIX(GZFILE_READ_SIZE));
+        if (!NIL_P(str)) {
+            Check_Type(str, T_STRING);
+        }
+    }
+    return str; /* return nil when EOFError */
+}
+
+static VALUE
+gzfile_read_raw(struct gzfile *gz)
+{
+    return rb_rescue2(gzfile_read_raw_partial, (VALUE)gz,
+                      gzfile_read_raw_rescue, (VALUE)gz,
+                      rb_eEOFError, rb_eNoMethodError, (VALUE)0);
+}
+
+static int
+gzfile_read_raw_ensure(struct gzfile *gz, long size)
+{
+    VALUE str;
+
+    while (NIL_P(gz->z.input) || RSTRING_LEN(gz->z.input) < size) {
+	str = gzfile_read_raw(gz);
+	if (NIL_P(str)) return 0;
+	zstream_append_input2(&gz->z, str);
+    }
+    return 1;
+}
+
+static char *
+gzfile_read_raw_until_zero(struct gzfile *gz, long offset)
+{
+    VALUE str;
+    char *p;
+
+    for (;;) {
+	p = memchr(RSTRING_PTR(gz->z.input) + offset, '\0',
+		   RSTRING_LEN(gz->z.input) - offset);
+	if (p) break;
+	str = gzfile_read_raw(gz);
+	if (NIL_P(str)) {
+	    rb_raise(cGzError, "unexpected end of file");
+	}
+	offset = RSTRING_LEN(gz->z.input);
+	zstream_append_input2(&gz->z, str);
+    }
+    return p;
+}
+
+static unsigned int
+gzfile_get16(const unsigned char *src)
+{
+    unsigned int n;
+    n  = *(src++) & 0xff;
+    n |= (*(src++) & 0xff) << 8;
+    return n;
+}
+
+static unsigned long
+gzfile_get32(const unsigned char *src)
+{
+    unsigned long n;
+    n  = *(src++) & 0xff;
+    n |= (*(src++) & 0xff) << 8;
+    n |= (*(src++) & 0xff) << 16;
+    n |= (*(src++) & 0xffU) << 24;
+    return n;
+}
+
+static void
+gzfile_set32(unsigned long n, unsigned char *dst)
+{
+    *(dst++) = n & 0xff;
+    *(dst++) = (n >> 8) & 0xff;
+    *(dst++) = (n >> 16) & 0xff;
+    *dst     = (n >> 24) & 0xff;
+}
+
+static void
+gzfile_raise(struct gzfile *gz, VALUE klass, const char *message)
+{
+    VALUE exc = rb_exc_new2(klass, message);
+    if (!NIL_P(gz->z.input)) {
+	rb_ivar_set(exc, id_input, rb_str_resurrect(gz->z.input));
+    }
+    rb_exc_raise(exc);
+}
+
+/*
+ * Document-method: Zlib::GzipFile::Error#inspect
+ *
+ * Constructs a String of the GzipFile Error
+ */
+static VALUE
+gzfile_error_inspect(VALUE error)
+{
+    VALUE str = rb_call_super(0, 0);
+    VALUE input = rb_attr_get(error, id_input);
+
+    if (!NIL_P(input)) {
+	rb_str_resize(str, RSTRING_LEN(str)-1);
+	rb_str_cat2(str, ", input=");
+	rb_str_append(str, rb_str_inspect(input));
+	rb_str_cat2(str, ">");
+    }
+    return str;
+}
+
+static void
+gzfile_make_header(struct gzfile *gz)
+{
+    Bytef buf[10];  /* the size of gzip header */
+    unsigned char flags = 0, extraflags = 0;
+
+    if (!NIL_P(gz->orig_name)) {
+	flags |= GZ_FLAG_ORIG_NAME;
+    }
+    if (!NIL_P(gz->comment)) {
+	flags |= GZ_FLAG_COMMENT;
+    }
+    if (gz->mtime == 0) {
+	gz->mtime = time(0);
+    }
+
+    if (gz->level == Z_BEST_SPEED) {
+	extraflags |= GZ_EXTRAFLAG_FAST;
+    }
+    else if (gz->level == Z_BEST_COMPRESSION) {
+	extraflags |= GZ_EXTRAFLAG_SLOW;
+    }
+
+    buf[0] = GZ_MAGIC1;
+    buf[1] = GZ_MAGIC2;
+    buf[2] = GZ_METHOD_DEFLATE;
+    buf[3] = flags;
+    gzfile_set32((unsigned long)gz->mtime, &buf[4]);
+    buf[8] = extraflags;
+    buf[9] = gz->os_code;
+    zstream_append_buffer(&gz->z, buf, sizeof(buf));
+
+    if (!NIL_P(gz->orig_name)) {
+	zstream_append_buffer2(&gz->z, gz->orig_name);
+	zstream_append_buffer(&gz->z, (Bytef*)"\0", 1);
+    }
+    if (!NIL_P(gz->comment)) {
+	zstream_append_buffer2(&gz->z, gz->comment);
+	zstream_append_buffer(&gz->z, (Bytef*)"\0", 1);
+    }
+
+    gz->z.flags |= GZFILE_FLAG_HEADER_FINISHED;
+}
+
+static void
+gzfile_make_footer(struct gzfile *gz)
+{
+    Bytef buf[8];  /* 8 is the size of gzip footer */
+
+    gzfile_set32(gz->crc, buf);
+    gzfile_set32(gz->z.stream.total_in, &buf[4]);
+    zstream_append_buffer(&gz->z, buf, sizeof(buf));
+    gz->z.flags |= GZFILE_FLAG_FOOTER_FINISHED;
+}
+
+static void
+gzfile_read_header(struct gzfile *gz)
+{
+    const unsigned char *head;
+    long len;
+    char flags, *p;
+
+    if (!gzfile_read_raw_ensure(gz, 10)) {  /* 10 is the size of gzip header */
+	gzfile_raise(gz, cGzError, "not in gzip format");
+    }
+
+    head = (unsigned char*)RSTRING_PTR(gz->z.input);
+
+    if (head[0] != GZ_MAGIC1 || head[1] != GZ_MAGIC2) {
+	gzfile_raise(gz, cGzError, "not in gzip format");
+    }
+    if (head[2] != GZ_METHOD_DEFLATE) {
+	rb_raise(cGzError, "unsupported compression method %d", head[2]);
+    }
+
+    flags = head[3];
+    if (flags & GZ_FLAG_MULTIPART) {
+	rb_raise(cGzError, "multi-part gzip file is not supported");
+    }
+    else if (flags & GZ_FLAG_ENCRYPT) {
+	rb_raise(cGzError, "encrypted gzip file is not supported");
+    }
+    else if (flags & GZ_FLAG_UNKNOWN_MASK) {
+	rb_raise(cGzError, "unknown flags 0x%02x", flags);
+    }
+
+    if (head[8] & GZ_EXTRAFLAG_FAST) {
+	gz->level = Z_BEST_SPEED;
+    }
+    else if (head[8] & GZ_EXTRAFLAG_SLOW) {
+	gz->level = Z_BEST_COMPRESSION;
+    }
+    else {
+	gz->level = Z_DEFAULT_COMPRESSION;
+    }
+
+    gz->mtime = gzfile_get32(&head[4]);
+    gz->os_code = head[9];
+    zstream_discard_input(&gz->z, 10);
+
+    if (flags & GZ_FLAG_EXTRA) {
+	if (!gzfile_read_raw_ensure(gz, 2)) {
+	    rb_raise(cGzError, "unexpected end of file");
+	}
+	len = gzfile_get16((Bytef*)RSTRING_PTR(gz->z.input));
+	if (!gzfile_read_raw_ensure(gz, 2 + len)) {
+	    rb_raise(cGzError, "unexpected end of file");
+	}
+	zstream_discard_input(&gz->z, 2 + len);
+    }
+    if (flags & GZ_FLAG_ORIG_NAME) {
+	if (!gzfile_read_raw_ensure(gz, 1)) {
+	    rb_raise(cGzError, "unexpected end of file");
+	}
+	p = gzfile_read_raw_until_zero(gz, 0);
+	len = p - RSTRING_PTR(gz->z.input);
+	gz->orig_name = rb_str_new(RSTRING_PTR(gz->z.input), len);
+	OBJ_TAINT(gz->orig_name);  /* for safe */
+	zstream_discard_input(&gz->z, len + 1);
+    }
+    if (flags & GZ_FLAG_COMMENT) {
+	if (!gzfile_read_raw_ensure(gz, 1)) {
+	    rb_raise(cGzError, "unexpected end of file");
+	}
+	p = gzfile_read_raw_until_zero(gz, 0);
+	len = p - RSTRING_PTR(gz->z.input);
+	gz->comment = rb_str_new(RSTRING_PTR(gz->z.input), len);
+	OBJ_TAINT(gz->comment);  /* for safe */
+	zstream_discard_input(&gz->z, len + 1);
+    }
+
+    if (gz->z.input != Qnil && RSTRING_LEN(gz->z.input) > 0) {
+	zstream_run(&gz->z, 0, 0, Z_SYNC_FLUSH);
+    }
+}
+
+static void
+gzfile_check_footer(struct gzfile *gz)
+{
+    unsigned long crc, length;
+
+    gz->z.flags |= GZFILE_FLAG_FOOTER_FINISHED;
+
+    if (!gzfile_read_raw_ensure(gz, 8)) { /* 8 is the size of gzip footer */
+	gzfile_raise(gz, cNoFooter, "footer is not found");
+    }
+
+    crc = gzfile_get32((Bytef*)RSTRING_PTR(gz->z.input));
+    length = gzfile_get32((Bytef*)RSTRING_PTR(gz->z.input) + 4);
+
+    gz->z.stream.total_in += 8;  /* to rewind correctly */
+    zstream_discard_input(&gz->z, 8);
+
+    if (gz->crc != crc) {
+	rb_raise(cCRCError, "invalid compressed data -- crc error");
+    }
+    if ((uint32_t)gz->z.stream.total_out != length) {
+	rb_raise(cLengthError, "invalid compressed data -- length error");
+    }
+}
+
+static void
+gzfile_write(struct gzfile *gz, Bytef *str, long len)
+{
+    if (!(gz->z.flags & GZFILE_FLAG_HEADER_FINISHED)) {
+	gzfile_make_header(gz);
+    }
+
+    if (len > 0 || (gz->z.flags & GZFILE_FLAG_SYNC)) {
+	gz->crc = checksum_long(crc32, gz->crc, str, len);
+	zstream_run(&gz->z, str, len, (gz->z.flags & GZFILE_FLAG_SYNC)
+		    ? Z_SYNC_FLUSH : Z_NO_FLUSH);
+    }
+    gzfile_write_raw(gz);
+}
+
+static long
+gzfile_read_more(struct gzfile *gz)
+{
+    volatile VALUE str;
+
+    while (!ZSTREAM_IS_FINISHED(&gz->z)) {
+	str = gzfile_read_raw(gz);
+	if (NIL_P(str)) {
+	    if (!ZSTREAM_IS_FINISHED(&gz->z)) {
+		rb_raise(cGzError, "unexpected end of file");
+	    }
+	    break;
+	}
+	if (RSTRING_LEN(str) > 0) { /* prevent Z_BUF_ERROR */
+	    zstream_run(&gz->z, (Bytef*)RSTRING_PTR(str), RSTRING_LEN(str),
+			Z_SYNC_FLUSH);
+	}
+	if (gz->z.buf_filled > 0) break;
+    }
+    return gz->z.buf_filled;
+}
+
+static void
+gzfile_calc_crc(struct gzfile *gz, VALUE str)
+{
+    if (RSTRING_LEN(str) <= gz->ungetc) {
+	gz->ungetc -= RSTRING_LEN(str);
+    }
+    else {
+	gz->crc = checksum_long(crc32, gz->crc, (Bytef*)RSTRING_PTR(str) + gz->ungetc,
+			RSTRING_LEN(str) - gz->ungetc);
+	gz->ungetc = 0;
+    }
+}
+
+static VALUE
+gzfile_newstr(struct gzfile *gz, VALUE str)
+{
+    if (!gz->enc2) {
+	rb_enc_associate(str, gz->enc);
+	OBJ_TAINT(str);  /* for safe */
+	return str;
+    }
+    if (gz->ec && rb_enc_dummy_p(gz->enc2)) {
+        str = rb_econv_str_convert(gz->ec, str, ECONV_PARTIAL_INPUT);
+	rb_enc_associate(str, gz->enc);
+	OBJ_TAINT(str);
+	return str;
+    }
+    return rb_str_conv_enc_opts(str, gz->enc2, gz->enc,
+				gz->ecflags, gz->ecopts);
+}
+
+static long
+gzfile_fill(struct gzfile *gz, long len)
+{
+    if (len < 0)
+        rb_raise(rb_eArgError, "negative length %ld given", len);
+    if (len == 0)
+	return 0;
+    while (!ZSTREAM_IS_FINISHED(&gz->z) && gz->z.buf_filled < len) {
+	gzfile_read_more(gz);
+    }
+    if (GZFILE_IS_FINISHED(gz)) {
+	if (!(gz->z.flags & GZFILE_FLAG_FOOTER_FINISHED)) {
+	    gzfile_check_footer(gz);
+	}
+	return -1;
+    }
+    return len < gz->z.buf_filled ? len : gz->z.buf_filled;
+}
+
+static VALUE
+gzfile_read(struct gzfile *gz, long len)
+{
+    VALUE dst;
+
+    len = gzfile_fill(gz, len);
+    if (len == 0) return rb_str_new(0, 0);
+    if (len < 0) return Qnil;
+    dst = zstream_shift_buffer(&gz->z, len);
+    gzfile_calc_crc(gz, dst);
+    return dst;
+}
+
+static VALUE
+gzfile_readpartial(struct gzfile *gz, long len, VALUE outbuf)
+{
+    VALUE dst;
+
+    if (len < 0)
+        rb_raise(rb_eArgError, "negative length %ld given", len);
+
+    if (!NIL_P(outbuf))
+	OBJ_TAINT(outbuf);
+
+    if (len == 0) {
+        if (NIL_P(outbuf))
+            return rb_str_new(0, 0);
+        else {
+            rb_str_resize(outbuf, 0);
+            return outbuf;
+        }
+    }
+    while (!ZSTREAM_IS_FINISHED(&gz->z) && gz->z.buf_filled == 0) {
+	gzfile_read_more(gz);
+    }
+    if (GZFILE_IS_FINISHED(gz)) {
+	if (!(gz->z.flags & GZFILE_FLAG_FOOTER_FINISHED)) {
+	    gzfile_check_footer(gz);
+	}
+        if (!NIL_P(outbuf))
+            rb_str_resize(outbuf, 0);
+	rb_raise(rb_eEOFError, "end of file reached");
+    }
+
+    dst = zstream_shift_buffer(&gz->z, len);
+    gzfile_calc_crc(gz, dst);
+
+    if (!NIL_P(outbuf)) {
+        rb_str_resize(outbuf, RSTRING_LEN(dst));
+        memcpy(RSTRING_PTR(outbuf), RSTRING_PTR(dst), RSTRING_LEN(dst));
+	dst = outbuf;
+    }
+    OBJ_TAINT(dst);  /* for safe */
+    return dst;
+}
+
+static VALUE
+gzfile_read_all(struct gzfile *gz)
+{
+    VALUE dst;
+
+    while (!ZSTREAM_IS_FINISHED(&gz->z)) {
+	gzfile_read_more(gz);
+    }
+    if (GZFILE_IS_FINISHED(gz)) {
+	if (!(gz->z.flags & GZFILE_FLAG_FOOTER_FINISHED)) {
+	    gzfile_check_footer(gz);
+	}
+	return rb_str_new(0, 0);
+    }
+
+    dst = zstream_detach_buffer(&gz->z);
+    gzfile_calc_crc(gz, dst);
+    OBJ_TAINT(dst);
+    return gzfile_newstr(gz, dst);
+}
+
+static VALUE
+gzfile_getc(struct gzfile *gz)
+{
+    VALUE buf, dst = 0;
+    int len;
+
+    len = rb_enc_mbmaxlen(gz->enc);
+    while (!ZSTREAM_IS_FINISHED(&gz->z) && gz->z.buf_filled < len) {
+	gzfile_read_more(gz);
+    }
+    if (GZFILE_IS_FINISHED(gz)) {
+	if (!(gz->z.flags & GZFILE_FLAG_FOOTER_FINISHED)) {
+	    gzfile_check_footer(gz);
+	}
+	return Qnil;
+    }
+
+    if (gz->ec && rb_enc_dummy_p(gz->enc2)) {
+	const unsigned char *ss, *sp, *se;
+	unsigned char *ds, *dp, *de;
+	rb_econv_result_t res;
+
+	if (!gz->cbuf) {
+	    gz->cbuf = ALLOC_N(char, GZFILE_CBUF_CAPA);
+	}
+        ss = sp = (const unsigned char*)RSTRING_PTR(gz->z.buf);
+        se = sp + gz->z.buf_filled;
+        ds = dp = (unsigned char *)gz->cbuf;
+        de = (unsigned char *)ds + GZFILE_CBUF_CAPA;
+        res = rb_econv_convert(gz->ec, &sp, se, &dp, de, ECONV_PARTIAL_INPUT|ECONV_AFTER_OUTPUT);
+        rb_econv_check_error(gz->ec);
+	dst = zstream_shift_buffer(&gz->z, sp - ss);
+	gzfile_calc_crc(gz, dst);
+	dst = rb_str_new(gz->cbuf, dp - ds);
+	rb_enc_associate(dst, gz->enc);
+	OBJ_TAINT(dst);
+	return dst;
+    }
+    else {
+	buf = gz->z.buf;
+	len = rb_enc_mbclen(RSTRING_PTR(buf), RSTRING_END(buf), gz->enc);
+	dst = gzfile_read(gz, len);
+	return gzfile_newstr(gz, dst);
+    }
+}
+
+static void
+gzfile_ungets(struct gzfile *gz, const Bytef *b, long len)
+{
+    zstream_buffer_ungets(&gz->z, b, len);
+    gz->ungetc+=len;
+}
+
+static void
+gzfile_ungetbyte(struct gzfile *gz, int c)
+{
+    zstream_buffer_ungetbyte(&gz->z, c);
+    gz->ungetc++;
+}
+
+static VALUE
+gzfile_writer_end_run(VALUE arg)
+{
+    struct gzfile *gz = (struct gzfile *)arg;
+
+    if (!(gz->z.flags & GZFILE_FLAG_HEADER_FINISHED)) {
+	gzfile_make_header(gz);
+    }
+
+    zstream_run(&gz->z, (Bytef*)"", 0, Z_FINISH);
+    gzfile_make_footer(gz);
+    gzfile_write_raw(gz);
+
+    return Qnil;
+}
+
+static void
+gzfile_writer_end(struct gzfile *gz)
+{
+    if (ZSTREAM_IS_CLOSING(&gz->z)) return;
+    gz->z.flags |= ZSTREAM_FLAG_CLOSING;
+
+    rb_ensure(gzfile_writer_end_run, (VALUE)gz, zstream_end, (VALUE)&gz->z);
+}
+
+static VALUE
+gzfile_reader_end_run(VALUE arg)
+{
+    struct gzfile *gz = (struct gzfile *)arg;
+
+    if (GZFILE_IS_FINISHED(gz)
+	&& !(gz->z.flags & GZFILE_FLAG_FOOTER_FINISHED)) {
+	gzfile_check_footer(gz);
+    }
+
+    return Qnil;
+}
+
+static void
+gzfile_reader_end(struct gzfile *gz)
+{
+    if (ZSTREAM_IS_CLOSING(&gz->z)) return;
+    gz->z.flags |= ZSTREAM_FLAG_CLOSING;
+
+    rb_ensure(gzfile_reader_end_run, (VALUE)gz, zstream_end, (VALUE)&gz->z);
+}
+
+static void
+gzfile_reader_rewind(struct gzfile *gz)
+{
+    long n;
+
+    n = gz->z.stream.total_in;
+    if (!NIL_P(gz->z.input)) {
+	n += RSTRING_LEN(gz->z.input);
+    }
+
+    rb_funcall(gz->io, id_seek, 2, rb_int2inum(-n), INT2FIX(1));
+    gzfile_reset(gz);
+}
+
+static VALUE
+gzfile_reader_get_unused(struct gzfile *gz)
+{
+    VALUE str;
+
+    if (!ZSTREAM_IS_READY(&gz->z)) return Qnil;
+    if (!GZFILE_IS_FINISHED(gz)) return Qnil;
+    if (!(gz->z.flags & GZFILE_FLAG_FOOTER_FINISHED)) {
+	gzfile_check_footer(gz);
+    }
+    if (NIL_P(gz->z.input)) return Qnil;
+
+    str = rb_str_resurrect(gz->z.input);
+    OBJ_TAINT(str);  /* for safe */
+    return str;
+}
+
+static struct gzfile *
+get_gzfile(VALUE obj)
+{
+    struct gzfile *gz;
+
+    Data_Get_Struct(obj, struct gzfile, gz);
+    if (!ZSTREAM_IS_READY(&gz->z)) {
+	rb_raise(cGzError, "closed gzip stream");
+    }
+    return gz;
+}
+
+
+/* ------------------------------------------------------------------------- */
+
+/*
+ * Document-class: Zlib::GzipFile
+ *
+ * Zlib::GzipFile is an abstract class for handling a gzip formatted
+ * compressed file. The operations are defined in the subclasses,
+ * Zlib::GzipReader for reading, and Zlib::GzipWriter for writing.
+ *
+ * GzipReader should be used by associating an IO, or IO-like, object.
+ *
+ * == Method Catalogue
+ *
+ * - ::wrap
+ * - ::open (Zlib::GzipReader::open and Zlib::GzipWriter::open)
+ * - #close
+ * - #closed?
+ * - #comment
+ * - comment= (Zlib::GzipWriter#comment=)
+ * - #crc
+ * - eof? (Zlib::GzipReader#eof?)
+ * - #finish
+ * - #level
+ * - lineno (Zlib::GzipReader#lineno)
+ * - lineno= (Zlib::GzipReader#lineno=)
+ * - #mtime
+ * - mtime= (Zlib::GzipWriter#mtime=)
+ * - #orig_name
+ * - orig_name (Zlib::GzipWriter#orig_name=)
+ * - #os_code
+ * - path (when the underlying IO supports #path)
+ * - #sync
+ * - #sync=
+ * - #to_io
+ *
+ * (due to internal structure, documentation may appear under Zlib::GzipReader
+ * or Zlib::GzipWriter)
+ */
+
+
+typedef struct {
+    int argc;
+    VALUE *argv;
+    VALUE klass;
+} new_wrap_arg_t;
+
+static VALUE
+new_wrap(VALUE tmp)
+{
+    new_wrap_arg_t *arg = (new_wrap_arg_t *)tmp;
+    return rb_class_new_instance(arg->argc, arg->argv, arg->klass);
+}
+
+static VALUE
+gzfile_ensure_close(VALUE obj)
+{
+    struct gzfile *gz;
+
+    Data_Get_Struct(obj, struct gzfile, gz);
+    if (ZSTREAM_IS_READY(&gz->z)) {
+	gzfile_close(gz, 1);
+    }
+    return Qnil;
+}
+
+static VALUE
+gzfile_wrap(int argc, VALUE *argv, VALUE klass, int close_io_on_error)
+{
+    VALUE obj;
+
+    if (close_io_on_error) {
+	int state = 0;
+	new_wrap_arg_t arg;
+	arg.argc = argc;
+	arg.argv = argv;
+	arg.klass = klass;
+	obj = rb_protect(new_wrap, (VALUE)&arg, &state);
+	if (state) {
+	    rb_io_close(argv[0]);
+	    rb_jump_tag(state);
+	}
+    }
+    else {
+	obj = rb_class_new_instance(argc, argv, klass);
+    }
+
+    if (rb_block_given_p()) {
+	return rb_ensure(rb_yield, obj, gzfile_ensure_close, obj);
+    }
+    else {
+	return obj;
+    }
+}
+
+/*
+ * Document-method: Zlib::GzipFile.wrap
+ *
+ * call-seq: Zlib::GzipFile.wrap(io) { |gz| ... }
+ *
+ * Creates a GzipFile object associated with +io+, and
+ * executes the block with the newly created GzipFile object,
+ * just like File.open. The GzipFile object will be closed
+ * automatically after executing the block. If you want to keep
+ * the associated IO object opening, you may call
+ * +Zlib::GzipFile#finish+ method in the block.
+ */
+static VALUE
+rb_gzfile_s_wrap(int argc, VALUE *argv, VALUE klass)
+{
+    return gzfile_wrap(argc, argv, klass, 0);
+}
+
+/*
+ * Document-method: Zlib::GzipFile.open
+ *
+ * See Zlib::GzipReader#open and Zlib::GzipWriter#open.
+ */
+static VALUE
+gzfile_s_open(int argc, VALUE *argv, VALUE klass, const char *mode)
+{
+    VALUE io, filename;
+
+    if (argc < 1) {
+	rb_raise(rb_eArgError, "wrong number of arguments (0 for 1)");
+    }
+    filename = argv[0];
+    io = rb_file_open_str(filename, mode);
+    argv[0] = io;
+    return gzfile_wrap(argc, argv, klass, 1);
+}
+
+/*
+ * Document-method: Zlib::GzipFile#to_io
+ *
+ * Same as IO.
+ */
+static VALUE
+rb_gzfile_to_io(VALUE obj)
+{
+    return get_gzfile(obj)->io;
+}
+
+/*
+ * Document-method: Zlib::GzipFile#crc
+ *
+ * Returns CRC value of the uncompressed data.
+ */
+static VALUE
+rb_gzfile_crc(VALUE obj)
+{
+    return rb_uint2inum(get_gzfile(obj)->crc);
+}
+
+/*
+ * Document-method: Zlib::GzipFile#mtime
+ *
+ * Returns last modification time recorded in the gzip file header.
+ */
+static VALUE
+rb_gzfile_mtime(VALUE obj)
+{
+    return rb_time_new(get_gzfile(obj)->mtime, (time_t)0);
+}
+
+/*
+ * Document-method: Zlib::GzipFile#level
+ *
+ * Returns compression level.
+ */
+static VALUE
+rb_gzfile_level(VALUE obj)
+{
+    return INT2FIX(get_gzfile(obj)->level);
+}
+
+/*
+ * Document-method: Zlib::GzipFile#os_code
+ *
+ * Returns OS code number recorded in the gzip file header.
+ */
+static VALUE
+rb_gzfile_os_code(VALUE obj)
+{
+    return INT2FIX(get_gzfile(obj)->os_code);
+}
+
+/*
+ * Document-method: Zlib::GzipFile#orig_name
+ *
+ * Returns original filename recorded in the gzip file header, or +nil+ if
+ * original filename is not present.
+ */
+static VALUE
+rb_gzfile_orig_name(VALUE obj)
+{
+    VALUE str = get_gzfile(obj)->orig_name;
+    if (!NIL_P(str)) {
+	str = rb_str_dup(str);
+    }
+    OBJ_TAINT(str);  /* for safe */
+    return str;
+}
+
+/*
+ * Document-method: Zlib::GzipFile#comment
+ *
+ * Returns comments recorded in the gzip file header, or nil if the comments
+ * is not present.
+ */
+static VALUE
+rb_gzfile_comment(VALUE obj)
+{
+    VALUE str = get_gzfile(obj)->comment;
+    if (!NIL_P(str)) {
+	str = rb_str_dup(str);
+    }
+    OBJ_TAINT(str);  /* for safe */
+    return str;
+}
+
+/*
+ * Document-method: Zlib::GzipFile#lineno
+ *
+ * The line number of the last row read from this file.
+ */
+static VALUE
+rb_gzfile_lineno(VALUE obj)
+{
+    return INT2NUM(get_gzfile(obj)->lineno);
+}
+
+/*
+ * Document-method: Zlib::GzipReader#lineno=
+ *
+ * Specify line number of the last row read from this file.
+ */
+static VALUE
+rb_gzfile_set_lineno(VALUE obj, VALUE lineno)
+{
+    struct gzfile *gz = get_gzfile(obj);
+    gz->lineno = NUM2INT(lineno);
+    return lineno;
+}
+
+/*
+ * Document-method: Zlib::GzipWriter#mtime=
+ *
+ * Specify the modification time (+mtime+) in the gzip header.
+ * Using a Fixnum or Integer
+ */
+static VALUE
+rb_gzfile_set_mtime(VALUE obj, VALUE mtime)
+{
+    struct gzfile *gz = get_gzfile(obj);
+    VALUE val;
+
+    if (gz->z.flags & GZFILE_FLAG_HEADER_FINISHED) {
+	rb_raise(cGzError, "header is already written");
+    }
+
+    if (FIXNUM_P(mtime)) {
+	gz->mtime = FIX2INT(mtime);
+    }
+    else {
+	val = rb_Integer(mtime);
+	gz->mtime = FIXNUM_P(val) ? FIX2UINT(val) : rb_big2ulong(val);
+    }
+    return mtime;
+}
+
+/*
+ * Document-method: Zlib::GzipFile#orig_name=
+ *
+ * Specify the original name (+str+) in the gzip header.
+ */
+static VALUE
+rb_gzfile_set_orig_name(VALUE obj, VALUE str)
+{
+    struct gzfile *gz = get_gzfile(obj);
+    VALUE s;
+    char *p;
+
+    if (gz->z.flags & GZFILE_FLAG_HEADER_FINISHED) {
+	rb_raise(cGzError, "header is already written");
+    }
+    s = rb_str_dup(rb_str_to_str(str));
+    p = memchr(RSTRING_PTR(s), '\0', RSTRING_LEN(s));
+    if (p) {
+	rb_str_resize(s, p - RSTRING_PTR(s));
+    }
+    gz->orig_name = s;
+    return str;
+}
+
+/*
+ * Document-method: Zlib::GzipFile#comment=
+ *
+ * Specify the comment (+str+) in the gzip header.
+ */
+static VALUE
+rb_gzfile_set_comment(VALUE obj, VALUE str)
+{
+    struct gzfile *gz = get_gzfile(obj);
+    VALUE s;
+    char *p;
+
+    if (gz->z.flags & GZFILE_FLAG_HEADER_FINISHED) {
+	rb_raise(cGzError, "header is already written");
+    }
+    s = rb_str_dup(rb_str_to_str(str));
+    p = memchr(RSTRING_PTR(s), '\0', RSTRING_LEN(s));
+    if (p) {
+	rb_str_resize(s, p - RSTRING_PTR(s));
+    }
+    gz->comment = s;
+    return str;
+}
+
+/*
+ * Document-method: Zlib::GzipFile#close
+ *
+ * Closes the GzipFile object. This method calls close method of the
+ * associated IO object. Returns the associated IO object.
+ */
+static VALUE
+rb_gzfile_close(VALUE obj)
+{
+    struct gzfile *gz = get_gzfile(obj);
+    VALUE io;
+
+    io = gz->io;
+    gzfile_close(gz, 1);
+    return io;
+}
+
+/*
+ * Document-method: Zlib::GzipFile#finish
+ *
+ * Closes the GzipFile object. Unlike Zlib::GzipFile#close, this method never
+ * calls the close method of the associated IO object. Returns the associated IO
+ * object.
+ */
+static VALUE
+rb_gzfile_finish(VALUE obj)
+{
+    struct gzfile *gz = get_gzfile(obj);
+    VALUE io;
+
+    io = gz->io;
+    gzfile_close(gz, 0);
+    return io;
+}
+
+/*
+ * Document-method: Zlib::GzipFile#closed?
+ *
+ * Same as IO#closed?
+ *
+ */
+static VALUE
+rb_gzfile_closed_p(VALUE obj)
+{
+    struct gzfile *gz;
+    Data_Get_Struct(obj, struct gzfile, gz);
+    return NIL_P(gz->io) ? Qtrue : Qfalse;
+}
+
+/*
+ * Document-method: Zlib::GzipFile#eof?
+ *
+ * Returns +true+ or +false+ whether the stream has reached the end.
+ */
+static VALUE
+rb_gzfile_eof_p(VALUE obj)
+{
+    struct gzfile *gz = get_gzfile(obj);
+    return GZFILE_IS_FINISHED(gz) ? Qtrue : Qfalse;
+}
+
+/*
+ * Document-method: Zlib::GzipFile#sync
+ *
+ * Same as IO#sync
+ *
+ */
+static VALUE
+rb_gzfile_sync(VALUE obj)
+{
+    return (get_gzfile(obj)->z.flags & GZFILE_FLAG_SYNC) ? Qtrue : Qfalse;
+}
+
+/*
+ * Document-method: Zlib::GzipFile#sync=
+ *
+ * call-seq: sync = flag
+ *
+ * Same as IO.  If flag is +true+, the associated IO object must respond to the
+ * +flush+ method.  While +sync+ mode is +true+, the compression ratio
+ * decreases sharply.
+ */
+static VALUE
+rb_gzfile_set_sync(VALUE obj, VALUE mode)
+{
+    struct gzfile *gz = get_gzfile(obj);
+
+    if (RTEST(mode)) {
+	gz->z.flags |= GZFILE_FLAG_SYNC;
+    }
+    else {
+	gz->z.flags &= ~GZFILE_FLAG_SYNC;
+    }
+    return mode;
+}
+
+/*
+ * Document-method: Zlib::GzipFile#total_in
+ *
+ * Total number of input bytes read so far.
+ */
+static VALUE
+rb_gzfile_total_in(VALUE obj)
+{
+    return rb_uint2inum(get_gzfile(obj)->z.stream.total_in);
+}
+
+/*
+ * Document-method: Zlib::GzipFile#total_out
+ *
+ * Total number of output bytes output so far.
+ */
+static VALUE
+rb_gzfile_total_out(VALUE obj)
+{
+    struct gzfile *gz = get_gzfile(obj);
+    return rb_uint2inum(gz->z.stream.total_out - gz->z.buf_filled);
+}
+
+/*
+ * Document-method: Zlib::GzipFile#path
+ *
+ * call-seq: path
+ *
+ * Returns the path string of the associated IO-like object.  This
+ * method is only defined when the IO-like object responds to #path().
+ */
+static VALUE
+rb_gzfile_path(VALUE obj)
+{
+    struct gzfile *gz;
+    Data_Get_Struct(obj, struct gzfile, gz);
+    return gz->path;
+}
+
+static void
+rb_gzfile_ecopts(struct gzfile *gz, VALUE opts)
+{
+    if (!NIL_P(opts)) {
+	rb_io_extract_encoding_option(opts, &gz->enc, &gz->enc2, NULL);
+    }
+    if (gz->enc2) {
+	gz->ecflags = rb_econv_prepare_opts(opts, &opts);
+	gz->ec = rb_econv_open_opts(gz->enc2->name, gz->enc->name,
+				    gz->ecflags, opts);
+	gz->ecopts = opts;
+    }
+}
+
+/* ------------------------------------------------------------------------- */
+
+/*
+ * Document-class: Zlib::GzipWriter
+ *
+ * Zlib::GzipWriter is a class for writing gzipped files.  GzipWriter should
+ * be used with an instance of IO, or IO-like, object.
+ *
+ * Following two example generate the same result.
+ *
+ *   Zlib::GzipWriter.open('hoge.gz') do |gz|
+ *     gz.write 'jugemu jugemu gokou no surikire...'
+ *   end
+ *
+ *   File.open('hoge.gz', 'w') do |f|
+ *     gz = Zlib::GzipWriter.new(f)
+ *     gz.write 'jugemu jugemu gokou no surikire...'
+ *     gz.close
+ *   end
+ *
+ * To make like gzip(1) does, run following:
+ *
+ *   orig = 'hoge.txt'
+ *   Zlib::GzipWriter.open('hoge.gz') do |gz|
+ *     gz.mtime = File.mtime(orig)
+ *     gz.orig_name = orig
+ *     gz.write IO.binread(orig)
+ *   end
+ *
+ * NOTE: Due to the limitation of Ruby's finalizer, you must explicitly close
+ * GzipWriter objects by Zlib::GzipWriter#close etc.  Otherwise, GzipWriter
+ * will be not able to write the gzip footer and will generate a broken gzip
+ * file.
+ */
+
+static VALUE
+rb_gzwriter_s_allocate(VALUE klass)
+{
+    return gzfile_writer_new(klass);
+}
+
+/*
+ * call-seq: Zlib::GzipWriter.open(filename, level=nil, strategy=nil) { |gz| ... }
+ *
+ * Opens a file specified by +filename+ for writing gzip compressed data, and
+ * returns a GzipWriter object associated with that file.  Further details of
+ * this method are found in Zlib::GzipWriter.new and Zlib::GzipFile.wrap.
+ */
+static VALUE
+rb_gzwriter_s_open(int argc, VALUE *argv, VALUE klass)
+{
+    return gzfile_s_open(argc, argv, klass, "wb");
+}
+
+/*
+ * call-seq: Zlib::GzipWriter.new(io, level, strategy)
+ *
+ * Creates a GzipWriter object associated with +io+. +level+ and +strategy+
+ * should be the same as the arguments of Zlib::Deflate.new.  The GzipWriter
+ * object writes gzipped data to +io+.  At least, +io+ must respond to the
+ * +write+ method that behaves same as write method in IO class.
+ */
+static VALUE
+rb_gzwriter_initialize(int argc, VALUE *argv, VALUE obj)
+{
+    struct gzfile *gz;
+    VALUE io, level, strategy, opt = Qnil;
+    int err;
+
+    if (argc > 1) {
+	opt = rb_check_convert_type(argv[argc-1], T_HASH, "Hash", "to_hash");
+	if (!NIL_P(opt)) argc--;
+    }
+
+    rb_scan_args(argc, argv, "12", &io, &level, &strategy);
+    Data_Get_Struct(obj, struct gzfile, gz);
+
+    /* this is undocumented feature of zlib */
+    gz->level = ARG_LEVEL(level);
+    err = deflateInit2(&gz->z.stream, gz->level, Z_DEFLATED,
+		       -MAX_WBITS, DEF_MEM_LEVEL, ARG_STRATEGY(strategy));
+    if (err != Z_OK) {
+	raise_zlib_error(err, gz->z.stream.msg);
+    }
+    gz->io = io;
+    ZSTREAM_READY(&gz->z);
+    rb_gzfile_ecopts(gz, opt);
+
+    if (rb_respond_to(io, id_path)) {
+	gz->path = rb_funcall(gz->io, id_path, 0);
+	rb_define_singleton_method(obj, "path", rb_gzfile_path, 0);
+    }
+
+    return obj;
+}
+
+/*
+ * call-seq: flush(flush=nil)
+ *
+ * Flushes all the internal buffers of the GzipWriter object.  The meaning of
+ * +flush+ is same as in Zlib::Deflate#deflate.  <tt>Zlib::SYNC_FLUSH</tt> is used if
+ * +flush+ is omitted.  It is no use giving flush <tt>Zlib::NO_FLUSH</tt>.
+ */
+static VALUE
+rb_gzwriter_flush(int argc, VALUE *argv, VALUE obj)
+{
+    struct gzfile *gz = get_gzfile(obj);
+    VALUE v_flush;
+    int flush;
+
+    rb_scan_args(argc, argv, "01", &v_flush);
+
+    flush = FIXNUMARG(v_flush, Z_SYNC_FLUSH);
+    if (flush != Z_NO_FLUSH) {  /* prevent Z_BUF_ERROR */
+	zstream_run(&gz->z, (Bytef*)"", 0, flush);
+    }
+
+    gzfile_write_raw(gz);
+    if (rb_respond_to(gz->io, id_flush)) {
+	rb_funcall(gz->io, id_flush, 0);
+    }
+    return obj;
+}
+
+/*
+ * Same as IO.
+ */
+static VALUE
+rb_gzwriter_write(VALUE obj, VALUE str)
+{
+    struct gzfile *gz = get_gzfile(obj);
+
+    if (TYPE(str) != T_STRING)
+	str = rb_obj_as_string(str);
+    if (gz->enc2 && gz->enc2 != rb_ascii8bit_encoding()) {
+	str = rb_str_conv_enc(str, rb_enc_get(str), gz->enc2);
+    }
+    gzfile_write(gz, (Bytef*)RSTRING_PTR(str), RSTRING_LEN(str));
+    return INT2FIX(RSTRING_LEN(str));
+}
+
+/*
+ * Same as IO.
+ */
+static VALUE
+rb_gzwriter_putc(VALUE obj, VALUE ch)
+{
+    struct gzfile *gz = get_gzfile(obj);
+    char c = NUM2CHR(ch);
+
+    gzfile_write(gz, (Bytef*)&c, 1);
+    return ch;
+}
+
+
+
+/*
+ * Document-method: <<
+ * Same as IO.
+ */
+#define rb_gzwriter_addstr  rb_io_addstr
+/*
+ * Document-method: printf
+ * Same as IO.
+ */
+#define rb_gzwriter_printf  rb_io_printf
+/*
+ * Document-method: print
+ * Same as IO.
+ */
+#define rb_gzwriter_print  rb_io_print
+/*
+ * Document-method: puts
+ * Same as IO.
+ */
+#define rb_gzwriter_puts  rb_io_puts
+
+
+/* ------------------------------------------------------------------------- */
+
+/*
+ * Document-class: Zlib::GzipReader
+ *
+ * Zlib::GzipReader is the class for reading a gzipped file.  GzipReader should
+ * be used an IO, or -IO-lie, object.
+ *
+ *   Zlib::GzipReader.open('hoge.gz') {|gz|
+ *     print gz.read
+ *   }
+ *
+ *   File.open('hoge.gz') do |f|
+ *     gz = Zlib::GzipReader.new(f)
+ *     print gz.read
+ *     gz.close
+ *   end
+ *
+ * == Method Catalogue
+ *
+ * The following methods in Zlib::GzipReader are just like their counterparts
+ * in IO, but they raise Zlib::Error or Zlib::GzipFile::Error exception if an
+ * error was found in the gzip file.
+ * - #each
+ * - #each_line
+ * - #each_byte
+ * - #gets
+ * - #getc
+ * - #lineno
+ * - #lineno=
+ * - #read
+ * - #readchar
+ * - #readline
+ * - #readlines
+ * - #ungetc
+ *
+ * Be careful of the footer of the gzip file. A gzip file has the checksum of
+ * pre-compressed data in its footer. GzipReader checks all uncompressed data
+ * against that checksum at the following cases, and if it fails, raises
+ * <tt>Zlib::GzipFile::NoFooter</tt>, <tt>Zlib::GzipFile::CRCError</tt>, or
+ * <tt>Zlib::GzipFile::LengthError</tt> exception.
+ *
+ * - When an reading request is received beyond the end of file (the end of
+ *   compressed data). That is, when Zlib::GzipReader#read,
+ *   Zlib::GzipReader#gets, or some other methods for reading returns nil.
+ * - When Zlib::GzipFile#close method is called after the object reaches the
+ *   end of file.
+ * - When Zlib::GzipReader#unused method is called after the object reaches
+ *   the end of file.
+ *
+ * The rest of the methods are adequately described in their own
+ * documentation.
+ */
+
+static VALUE
+rb_gzreader_s_allocate(VALUE klass)
+{
+    return gzfile_reader_new(klass);
+}
+
+/*
+ * Document-method: Zlib::GzipReader.open
+ *
+ * call-seq: Zlib::GzipReader.open(filename) {|gz| ... }
+ *
+ * Opens a file specified by +filename+ as a gzipped file, and returns a
+ * GzipReader object associated with that file.  Further details of this method
+ * are in Zlib::GzipReader.new and ZLib::GzipFile.wrap.
+ */
+static VALUE
+rb_gzreader_s_open(int argc, VALUE *argv, VALUE klass)
+{
+    return gzfile_s_open(argc, argv, klass, "rb");
+}
+
+/*
+ * Document-method: Zlib::GzipReader.new
+ *
+ * call-seq: Zlib::GzipReader.new(io)
+ *
+ * Creates a GzipReader object associated with +io+. The GzipReader object reads
+ * gzipped data from +io+, and parses/decompresses them.  At least, +io+ must have
+ * a +read+ method that behaves same as the +read+ method in IO class.
+ *
+ * If the gzip file header is incorrect, raises an Zlib::GzipFile::Error
+ * exception.
+ */
+static VALUE
+rb_gzreader_initialize(int argc, VALUE *argv, VALUE obj)
+{
+    VALUE io, opt = Qnil;
+    struct gzfile *gz;
+    int err;
+
+    Data_Get_Struct(obj, struct gzfile, gz);
+    rb_scan_args(argc, argv, "1:", &io, &opt);
+
+    /* this is undocumented feature of zlib */
+    err = inflateInit2(&gz->z.stream, -MAX_WBITS);
+    if (err != Z_OK) {
+	raise_zlib_error(err, gz->z.stream.msg);
+    }
+    gz->io = io;
+    ZSTREAM_READY(&gz->z);
+    gzfile_read_header(gz);
+    rb_gzfile_ecopts(gz, opt);
+
+    if (rb_respond_to(io, id_path)) {
+	gz->path = rb_funcall(gz->io, id_path, 0);
+	rb_define_singleton_method(obj, "path", rb_gzfile_path, 0);
+    }
+
+    return obj;
+}
+
+/*
+ * Document-method: Zlib::GzipReader#rewind
+ *
+ * Resets the position of the file pointer to the point created the GzipReader
+ * object.  The associated IO object needs to respond to the +seek+ method.
+ */
+static VALUE
+rb_gzreader_rewind(VALUE obj)
+{
+    struct gzfile *gz = get_gzfile(obj);
+    gzfile_reader_rewind(gz);
+    return INT2FIX(0);
+}
+
+/*
+ * Document-method: Zlib::GzipReader#unused
+ *
+ * Returns the rest of the data which had read for parsing gzip format, or
+ * +nil+ if the whole gzip file is not parsed yet.
+ */
+static VALUE
+rb_gzreader_unused(VALUE obj)
+{
+    struct gzfile *gz;
+    Data_Get_Struct(obj, struct gzfile, gz);
+    return gzfile_reader_get_unused(gz);
+}
+
+/*
+ * Document-method: Zlib::GzipReader#read
+ *
+ * See Zlib::GzipReader documentation for a description.
+ */
+static VALUE
+rb_gzreader_read(int argc, VALUE *argv, VALUE obj)
+{
+    struct gzfile *gz = get_gzfile(obj);
+    VALUE vlen;
+    long len;
+
+    rb_scan_args(argc, argv, "01", &vlen);
+    if (NIL_P(vlen)) {
+	return gzfile_read_all(gz);
+    }
+
+    len = NUM2INT(vlen);
+    if (len < 0) {
+	rb_raise(rb_eArgError, "negative length %ld given", len);
+    }
+    return gzfile_read(gz, len);
+}
+
+/*
+ * Document-method: Zlib::GzipReader#readpartial
+ *
+ *  call-seq:
+ *     gzipreader.readpartial(maxlen [, outbuf]) => string, outbuf
+ *
+ *  Reads at most <i>maxlen</i> bytes from the gziped stream but
+ *  it blocks only if <em>gzipreader</em> has no data immediately available.
+ *  If the optional <i>outbuf</i> argument is present,
+ *  it must reference a String, which will receive the data.
+ *  It raises <code>EOFError</code> on end of file.
+ */
+static VALUE
+rb_gzreader_readpartial(int argc, VALUE *argv, VALUE obj)
+{
+    struct gzfile *gz = get_gzfile(obj);
+    VALUE vlen, outbuf;
+    long len;
+
+    rb_scan_args(argc, argv, "11", &vlen, &outbuf);
+
+    len = NUM2INT(vlen);
+    if (len < 0) {
+	rb_raise(rb_eArgError, "negative length %ld given", len);
+    }
+    if (!NIL_P(outbuf))
+        Check_Type(outbuf, T_STRING);
+    return gzfile_readpartial(gz, len, outbuf);
+}
+
+/*
+ * Document-method: Zlib::GzipReader#getc
+ *
+ * See Zlib::GzipReader documentation for a description.
+ */
+static VALUE
+rb_gzreader_getc(VALUE obj)
+{
+    struct gzfile *gz = get_gzfile(obj);
+
+    return gzfile_getc(gz);
+}
+
+/*
+ * Document-method: Zlib::GzipReader#readchar
+ *
+ * See Zlib::GzipReader documentation for a description.
+ */
+static VALUE
+rb_gzreader_readchar(VALUE obj)
+{
+    VALUE dst;
+    dst = rb_gzreader_getc(obj);
+    if (NIL_P(dst)) {
+	rb_raise(rb_eEOFError, "end of file reached");
+    }
+    return dst;
+}
+
+/*
+ * Document-method: Zlib::GzipReader#getbyte
+ *
+ * See Zlib::GzipReader documentation for a description.
+ */
+static VALUE
+rb_gzreader_getbyte(VALUE obj)
+{
+    struct gzfile *gz = get_gzfile(obj);
+    VALUE dst;
+
+    dst = gzfile_read(gz, 1);
+    if (!NIL_P(dst)) {
+	dst = INT2FIX((unsigned int)(RSTRING_PTR(dst)[0]) & 0xff);
+    }
+    return dst;
+}
+
+/*
+ * Document-method: Zlib::GzipReader#readbyte
+ *
+ * See Zlib::GzipReader documentation for a description.
+ */
+static VALUE
+rb_gzreader_readbyte(VALUE obj)
+{
+    VALUE dst;
+    dst = rb_gzreader_getbyte(obj);
+    if (NIL_P(dst)) {
+	rb_raise(rb_eEOFError, "end of file reached");
+    }
+    return dst;
+}
+
+/*
+ * Document-method: Zlib::GzipReader#each_char
+ *
+ * See Zlib::GzipReader documentation for a description.
+ */
+static VALUE
+rb_gzreader_each_char(VALUE obj)
+{
+    VALUE c;
+
+    RETURN_ENUMERATOR(obj, 0, 0);
+
+    while (!NIL_P(c = rb_gzreader_getc(obj))) {
+	rb_yield(c);
+    }
+    return Qnil;
+}
+
+/*
+ * Document-method: Zlib::GzipReader#each_byte
+ *
+ * See Zlib::GzipReader documentation for a description.
+ */
+static VALUE
+rb_gzreader_each_byte(VALUE obj)
+{
+    VALUE c;
+
+    RETURN_ENUMERATOR(obj, 0, 0);
+
+    while (!NIL_P(c = rb_gzreader_getbyte(obj))) {
+	rb_yield(c);
+    }
+    return Qnil;
+}
+
+/*
+ * Document-method: Zlib::GzipReader#ungetc
+ *
+ * See Zlib::GzipReader documentation for a description.
+ */
+static VALUE
+rb_gzreader_ungetc(VALUE obj, VALUE s)
+{
+    struct gzfile *gz;
+
+    if (FIXNUM_P(s))
+	return rb_gzreader_ungetbyte(obj, s);
+    gz = get_gzfile(obj);
+    StringValue(s);
+    if (gz->enc2 && gz->enc2 != rb_ascii8bit_encoding()) {
+	s = rb_str_conv_enc(s, rb_enc_get(s), gz->enc2);
+    }
+    gzfile_ungets(gz, (const Bytef*)RSTRING_PTR(s), RSTRING_LEN(s));
+    return Qnil;
+}
+
+/*
+ * Document-method: Zlib::GzipReader#ungetbyte
+ *
+ * See Zlib::GzipReader documentation for a description.
+ */
+static VALUE
+rb_gzreader_ungetbyte(VALUE obj, VALUE ch)
+{
+    struct gzfile *gz = get_gzfile(obj);
+    gzfile_ungetbyte(gz, NUM2CHR(ch));
+    return Qnil;
+}
+
+static void
+gzreader_skip_linebreaks(struct gzfile *gz)
+{
+    VALUE str;
+    char *p;
+    int n;
+
+    while (gz->z.buf_filled == 0) {
+	if (GZFILE_IS_FINISHED(gz)) return;
+	gzfile_read_more(gz);
+    }
+    n = 0;
+    p = RSTRING_PTR(gz->z.buf);
+
+    while (n++, *(p++) == '\n') {
+	if (n >= gz->z.buf_filled) {
+	    str = zstream_detach_buffer(&gz->z);
+	    gzfile_calc_crc(gz, str);
+	    while (gz->z.buf_filled == 0) {
+		if (GZFILE_IS_FINISHED(gz)) return;
+		gzfile_read_more(gz);
+	    }
+	    n = 0;
+	    p = RSTRING_PTR(gz->z.buf);
+	}
+    }
+
+    str = zstream_shift_buffer(&gz->z, n - 1);
+    gzfile_calc_crc(gz, str);
+}
+
+static void
+rscheck(const char *rsptr, long rslen, VALUE rs)
+{
+    if (RSTRING_PTR(rs) != rsptr && RSTRING_LEN(rs) != rslen)
+	rb_raise(rb_eRuntimeError, "rs modified");
+}
+
+static long
+gzreader_charboundary(struct gzfile *gz, long n)
+{
+    char *s = RSTRING_PTR(gz->z.buf);
+    char *e = s + gz->z.buf_filled;
+    char *p = rb_enc_left_char_head(s, s + n, e, gz->enc);
+    long l = p - s;
+    if (l < n) {
+	n = rb_enc_precise_mbclen(p, e, gz->enc);
+	if (MBCLEN_NEEDMORE_P(n)) {
+	    if ((l = gzfile_fill(gz, l + MBCLEN_NEEDMORE_LEN(n))) > 0) {
+		return l;
+	    }
+	}
+	else if (MBCLEN_CHARFOUND_P(n)) {
+	    return l + MBCLEN_CHARFOUND_LEN(n);
+	}
+    }
+    return n;
+}
+
+static VALUE
+gzreader_gets(int argc, VALUE *argv, VALUE obj)
+{
+    struct gzfile *gz = get_gzfile(obj);
+    volatile VALUE rs;
+    VALUE dst;
+    const char *rsptr;
+    char *p, *res;
+    long rslen, n, limit = -1;
+    int rspara;
+    rb_encoding *enc = gz->enc;
+    int maxlen = rb_enc_mbmaxlen(enc);
+
+    if (argc == 0) {
+	rs = rb_rs;
+    }
+    else {
+	VALUE lim, tmp;
+
+	rb_scan_args(argc, argv, "11", &rs, &lim);
+	if (!NIL_P(lim)) {
+	    if (!NIL_P(rs)) StringValue(rs);
+	}
+	else if (!NIL_P(rs)) {
+	    tmp = rb_check_string_type(rs);
+	    if (NIL_P(tmp)) {
+		lim = rs;
+		rs = rb_rs;
+	    }
+	    else {
+		rs = tmp;
+	    }
+	}
+	if (!NIL_P(lim)) {
+	    limit = NUM2LONG(lim);
+	    if (limit == 0) return rb_str_new(0,0);
+	}
+    }
+
+    if (NIL_P(rs)) {
+	if (limit < 0) {
+	    dst = gzfile_read_all(gz);
+	    if (RSTRING_LEN(dst) == 0) return Qnil;
+	}
+	else if ((n = gzfile_fill(gz, limit)) <= 0) {
+	    return Qnil;
+	}
+	else {
+	    if (maxlen > 1 && n >= limit && !GZFILE_IS_FINISHED(gz)) {
+		n = gzreader_charboundary(gz, n);
+	    }
+	    else {
+		n = limit;
+	    }
+	    dst = zstream_shift_buffer(&gz->z, n);
+	    gzfile_calc_crc(gz, dst);
+	    dst = gzfile_newstr(gz, dst);
+	}
+	gz->lineno++;
+	return dst;
+    }
+
+    if (RSTRING_LEN(rs) == 0) {
+	rsptr = "\n\n";
+	rslen = 2;
+	rspara = 1;
+    } else {
+	rsptr = RSTRING_PTR(rs);
+	rslen = RSTRING_LEN(rs);
+	rspara = 0;
+    }
+
+    if (rspara) {
+	gzreader_skip_linebreaks(gz);
+    }
+
+    while (gz->z.buf_filled < rslen) {
+	if (ZSTREAM_IS_FINISHED(&gz->z)) {
+	    if (gz->z.buf_filled > 0) gz->lineno++;
+	    return gzfile_read(gz, rslen);
+	}
+	gzfile_read_more(gz);
+    }
+
+    p = RSTRING_PTR(gz->z.buf);
+    n = rslen;
+    for (;;) {
+	long filled;
+	if (n > gz->z.buf_filled) {
+	    if (ZSTREAM_IS_FINISHED(&gz->z)) break;
+	    gzfile_read_more(gz);
+	    p = RSTRING_PTR(gz->z.buf) + n - rslen;
+	}
+	if (!rspara) rscheck(rsptr, rslen, rs);
+	filled = gz->z.buf_filled;
+	if (limit > 0 && filled >= limit) {
+	    filled = limit;
+	}
+	res = memchr(p, rsptr[0], (filled - n + 1));
+	if (!res) {
+	    n = filled;
+	    if (limit > 0 && filled >= limit) break;
+	    n++;
+	} else {
+	    n += (long)(res - p);
+	    p = res;
+	    if (rslen == 1 || memcmp(p, rsptr, rslen) == 0) break;
+	    p++, n++;
+	}
+    }
+    if (maxlen > 1 && n == limit && (gz->z.buf_filled > n || !ZSTREAM_IS_FINISHED(&gz->z))) {
+	n = gzreader_charboundary(gz, n);
+    }
+
+    gz->lineno++;
+    dst = gzfile_read(gz, n);
+    if (rspara) {
+	gzreader_skip_linebreaks(gz);
+    }
+
+    return gzfile_newstr(gz, dst);
+}
+
+/*
+ * Document-method: Zlib::GzipReader#gets
+ *
+ * See Zlib::GzipReader documentation for a description.
+ */
+static VALUE
+rb_gzreader_gets(int argc, VALUE *argv, VALUE obj)
+{
+    VALUE dst;
+    dst = gzreader_gets(argc, argv, obj);
+    if (!NIL_P(dst)) {
+	rb_lastline_set(dst);
+    }
+    return dst;
+}
+
+/*
+ * Document-method: Zlib::GzipReader#readline
+ *
+ * See Zlib::GzipReader documentation for a description.
+ */
+static VALUE
+rb_gzreader_readline(int argc, VALUE *argv, VALUE obj)
+{
+    VALUE dst;
+    dst = rb_gzreader_gets(argc, argv, obj);
+    if (NIL_P(dst)) {
+	rb_raise(rb_eEOFError, "end of file reached");
+    }
+    return dst;
+}
+
+/*
+ * Document-method: Zlib::GzipReader#each
+ *
+ * See Zlib::GzipReader documentation for a description.
+ */
+static VALUE
+rb_gzreader_each(int argc, VALUE *argv, VALUE obj)
+{
+    VALUE str;
+
+    RETURN_ENUMERATOR(obj, 0, 0);
+
+    while (!NIL_P(str = gzreader_gets(argc, argv, obj))) {
+	rb_yield(str);
+    }
+    return obj;
+}
+
+/*
+ * Document-method: Zlib::GzipReader#readlines
+ *
+ * See Zlib::GzipReader documentation for a description.
+ */
+static VALUE
+rb_gzreader_readlines(int argc, VALUE *argv, VALUE obj)
+{
+    VALUE str, dst;
+    dst = rb_ary_new();
+    while (!NIL_P(str = gzreader_gets(argc, argv, obj))) {
+	rb_ary_push(dst, str);
+    }
+    return dst;
+}
+
+#endif /* GZIP_SUPPORT */
+
+
+
+/*
+ * Document-module: Zlib
+ *
+ * The Zlib module contains several classes for compressing and decompressing
+ * streams, and for working with "gzip" files.
+ *
+ * == Classes
+ *
+ * Following are the classes that are most likely to be of interest to the
+ * user:
+ * Zlib::Inflate
+ * Zlib::Deflate
+ * Zlib::GzipReader
+ * Zlib::GzipWriter
+ *
+ * There are two important base classes for the classes above: Zlib::ZStream
+ * and Zlib::GzipFile.  Everything else is an error class.
+ *
+ * == Constants
+ *
+ * Here's a list.
+ *
+ *   Zlib::VERSION
+ *       The Ruby/zlib version string.
+ *
+ *   Zlib::ZLIB_VERSION
+ *       The string which represents the version of zlib.h.
+ *
+ *   Zlib::BINARY
+ *   Zlib::ASCII
+ *   Zlib::UNKNOWN
+ *       The integers representing data types which Zlib::ZStream#data_type
+ *       method returns.
+ *
+ *   Zlib::NO_COMPRESSION
+ *   Zlib::BEST_SPEED
+ *   Zlib::BEST_COMPRESSION
+ *   Zlib::DEFAULT_COMPRESSION
+ *       The integers representing compression levels which are an argument
+ *       for Zlib::Deflate.new, Zlib::Deflate#deflate, and so on.
+ *
+ *   Zlib::FILTERED
+ *   Zlib::HUFFMAN_ONLY
+ *   Zlib::DEFAULT_STRATEGY
+ *       The integers representing compression methods which are an argument
+ *       for Zlib::Deflate.new and Zlib::Deflate#params.
+ *
+ *   Zlib::DEF_MEM_LEVEL
+ *   Zlib::MAX_MEM_LEVEL
+ *       The integers representing memory levels which are an argument for
+ *       Zlib::Deflate.new, Zlib::Deflate#params, and so on.
+ *
+ *   Zlib::MAX_WBITS
+ *       The default value of windowBits which is an argument for
+ *       Zlib::Deflate.new and Zlib::Inflate.new.
+ *
+ *   Zlib::NO_FLUSH
+ *   Zlib::SYNC_FLUSH
+ *   Zlib::FULL_FLUSH
+ *   Zlib::FINISH
+ *       The integers to control the output of the deflate stream, which are
+ *       an argument for Zlib::Deflate#deflate and so on.
+ *
+ *   Zlib::OS_CODE
+ *   Zlib::OS_MSDOS
+ *   Zlib::OS_AMIGA
+ *   Zlib::OS_VMS
+ *   Zlib::OS_UNIX
+ *   Zlib::OS_VMCMS
+ *   Zlib::OS_ATARI
+ *   Zlib::OS_OS2
+ *   Zlib::OS_MACOS
+ *   Zlib::OS_ZSYSTEM
+ *   Zlib::OS_CPM
+ *   Zlib::OS_TOPS20
+ *   Zlib::OS_WIN32
+ *   Zlib::OS_QDOS
+ *   Zlib::OS_RISCOS
+ *   Zlib::OS_UNKNOWN
+ *       The return values of Zlib::GzipFile#os_code method.
+ */
+void
+Init_zlib()
+{
+    VALUE mZlib, cZStream, cDeflate, cInflate;
+#if GZIP_SUPPORT
+    VALUE cGzipFile, cGzipWriter, cGzipReader;
+#endif
+
+    mZlib = rb_define_module("Zlib");
+
+    cZError = rb_define_class_under(mZlib, "Error", rb_eStandardError);
+    cStreamEnd    = rb_define_class_under(mZlib, "StreamEnd", cZError);
+    cNeedDict     = rb_define_class_under(mZlib, "NeedDict", cZError);
+    cDataError    = rb_define_class_under(mZlib, "DataError", cZError);
+    cStreamError  = rb_define_class_under(mZlib, "StreamError", cZError);
+    cMemError     = rb_define_class_under(mZlib, "MemError", cZError);
+    cBufError     = rb_define_class_under(mZlib, "BufError", cZError);
+    cVersionError = rb_define_class_under(mZlib, "VersionError", cZError);
+
+    rb_define_module_function(mZlib, "zlib_version", rb_zlib_version, 0);
+    rb_define_module_function(mZlib, "adler32", rb_zlib_adler32, -1);
+    rb_define_module_function(mZlib, "adler32_combine", rb_zlib_adler32_combine, 3);
+    rb_define_module_function(mZlib, "crc32", rb_zlib_crc32, -1);
+    rb_define_module_function(mZlib, "crc32_combine", rb_zlib_crc32_combine, 3);
+    rb_define_module_function(mZlib, "crc_table", rb_zlib_crc_table, 0);
+
+    /* The Ruby/zlib version string. */
+    rb_define_const(mZlib, "VERSION", rb_str_new2(RUBY_ZLIB_VERSION));
+    /*  The string which represents the version of zlib.h */
+    rb_define_const(mZlib, "ZLIB_VERSION", rb_str_new2(ZLIB_VERSION));
+
+    cZStream = rb_define_class_under(mZlib, "ZStream", rb_cObject);
+    rb_undef_alloc_func(cZStream);
+    rb_define_method(cZStream, "avail_out", rb_zstream_avail_out, 0);
+    rb_define_method(cZStream, "avail_out=", rb_zstream_set_avail_out, 1);
+    rb_define_method(cZStream, "avail_in", rb_zstream_avail_in, 0);
+    rb_define_method(cZStream, "total_in", rb_zstream_total_in, 0);
+    rb_define_method(cZStream, "total_out", rb_zstream_total_out, 0);
+    rb_define_method(cZStream, "data_type", rb_zstream_data_type, 0);
+    rb_define_method(cZStream, "adler", rb_zstream_adler, 0);
+    rb_define_method(cZStream, "finished?", rb_zstream_finished_p, 0);
+    rb_define_method(cZStream, "stream_end?", rb_zstream_finished_p, 0);
+    rb_define_method(cZStream, "closed?", rb_zstream_closed_p, 0);
+    rb_define_method(cZStream, "ended?", rb_zstream_closed_p, 0);
+    rb_define_method(cZStream, "close", rb_zstream_end, 0);
+    rb_define_method(cZStream, "end", rb_zstream_end, 0);
+    rb_define_method(cZStream, "reset", rb_zstream_reset, 0);
+    rb_define_method(cZStream, "finish", rb_zstream_finish, 0);
+    rb_define_method(cZStream, "flush_next_in", rb_zstream_flush_next_in, 0);
+    rb_define_method(cZStream, "flush_next_out", rb_zstream_flush_next_out, 0);
+
+    /* Integer representing date types which
+     * ZStream#data_type method returns */
+    rb_define_const(mZlib, "BINARY", INT2FIX(Z_BINARY));
+    /* Integer representing date types which
+     * ZStream#data_type method returns */
+    rb_define_const(mZlib, "ASCII", INT2FIX(Z_ASCII));
+    /* Integer representing date types which
+     * ZStream#data_type method returns */
+    rb_define_const(mZlib, "UNKNOWN", INT2FIX(Z_UNKNOWN));
+
+    cDeflate = rb_define_class_under(mZlib, "Deflate", cZStream);
+    rb_define_singleton_method(cDeflate, "deflate", rb_deflate_s_deflate, -1);
+    rb_define_singleton_method(mZlib, "deflate", rb_deflate_s_deflate, -1);
+    rb_define_alloc_func(cDeflate, rb_deflate_s_allocate);
+    rb_define_method(cDeflate, "initialize", rb_deflate_initialize, -1);
+    rb_define_method(cDeflate, "initialize_copy", rb_deflate_init_copy, 1);
+    rb_define_method(cDeflate, "deflate", rb_deflate_deflate, -1);
+    rb_define_method(cDeflate, "<<", rb_deflate_addstr, 1);
+    rb_define_method(cDeflate, "flush", rb_deflate_flush, -1);
+    rb_define_method(cDeflate, "params", rb_deflate_params, 2);
+    rb_define_method(cDeflate, "set_dictionary", rb_deflate_set_dictionary, 1);
+
+    cInflate = rb_define_class_under(mZlib, "Inflate", cZStream);
+    rb_define_singleton_method(cInflate, "inflate", rb_inflate_s_inflate, 1);
+    rb_define_singleton_method(mZlib, "inflate", rb_inflate_s_inflate, 1);
+    rb_define_alloc_func(cInflate, rb_inflate_s_allocate);
+    rb_define_method(cInflate, "initialize", rb_inflate_initialize, -1);
+    rb_define_method(cInflate, "inflate", rb_inflate_inflate, 1);
+    rb_define_method(cInflate, "<<", rb_inflate_addstr, 1);
+    rb_define_method(cInflate, "sync", rb_inflate_sync, 1);
+    rb_define_method(cInflate, "sync_point?", rb_inflate_sync_point_p, 0);
+    rb_define_method(cInflate, "set_dictionary", rb_inflate_set_dictionary, 1);
+
+    /* compression level 0
+     *
+     * Which is an argument for Deflate.new, Deflate#deflate, and so on. */
+    rb_define_const(mZlib, "NO_COMPRESSION", INT2FIX(Z_NO_COMPRESSION));
+    /* compression level 1
+     *
+     * Which is an argument for Deflate.new, Deflate#deflate, and so on. */
+    rb_define_const(mZlib, "BEST_SPEED", INT2FIX(Z_BEST_SPEED));
+    /* compression level 9
+     *
+     * Which is an argument for Deflate.new, Deflate#deflate, and so on. */
+    rb_define_const(mZlib, "BEST_COMPRESSION", INT2FIX(Z_BEST_COMPRESSION));
+    /* compression level -1
+     *
+     * Which is an argument for Deflate.new, Deflate#deflate, and so on. */
+    rb_define_const(mZlib, "DEFAULT_COMPRESSION",
+		    INT2FIX(Z_DEFAULT_COMPRESSION));
+
+    /* compression method 1
+     *
+     * Which is an argument for Deflate.new and Deflate#params. */
+    rb_define_const(mZlib, "FILTERED", INT2FIX(Z_FILTERED));
+    /* compression method 2
+     *
+     * Which is an argument for Deflate.new and Deflate#params. */
+    rb_define_const(mZlib, "HUFFMAN_ONLY", INT2FIX(Z_HUFFMAN_ONLY));
+    /* compression method 0
+     *
+     * Which is an argument for Deflate.new and Deflate#params. */
+    rb_define_const(mZlib, "DEFAULT_STRATEGY", INT2FIX(Z_DEFAULT_STRATEGY));
+
+     /* The default value of windowBits which is an argument for
+      * Deflate.new and Inflate.new.
+      */
+    rb_define_const(mZlib, "MAX_WBITS", INT2FIX(MAX_WBITS));
+    /* Default value is 8
+     *
+     * The integer representing memory levels.
+     * Which are an argument for Deflate.new, Deflate#params, and so on. */
+    rb_define_const(mZlib, "DEF_MEM_LEVEL", INT2FIX(DEF_MEM_LEVEL));
+    /* Maximum level is 9
+     *
+     * The integers representing memory levels which are an argument for
+     * Deflate.new, Deflate#params, and so on. */
+    rb_define_const(mZlib, "MAX_MEM_LEVEL", INT2FIX(MAX_MEM_LEVEL));
+
+    /* Output control - 0
+     *
+     * The integers to control the output of the deflate stream, which are
+     * an argument for Deflate#deflate and so on. */
+    rb_define_const(mZlib, "NO_FLUSH", INT2FIX(Z_NO_FLUSH));
+    /* Output control - 2
+     *
+     * The integers to control the output of the deflate stream, which are
+     * an argument for Deflate#deflate and so on. */
+    rb_define_const(mZlib, "SYNC_FLUSH", INT2FIX(Z_SYNC_FLUSH));
+    /* Output control - 3
+     *
+     * The integers to control the output of the deflate stream, which are
+     * an argument for Deflate#deflate and so on. */
+    rb_define_const(mZlib, "FULL_FLUSH", INT2FIX(Z_FULL_FLUSH));
+    /* Oputput control - 4
+     *
+     * The integers to control the output of the deflate stream, which are
+     * an argument for Deflate#deflate and so on. */
+    rb_define_const(mZlib, "FINISH", INT2FIX(Z_FINISH));
+
+#if GZIP_SUPPORT
+    id_write = rb_intern("write");
+    id_read = rb_intern("read");
+    id_readpartial = rb_intern("readpartial");
+    id_flush = rb_intern("flush");
+    id_seek = rb_intern("seek");
+    id_close = rb_intern("close");
+    id_path = rb_intern("path");
+    id_input = rb_intern("@input");
+
+    cGzipFile = rb_define_class_under(mZlib, "GzipFile", rb_cObject);
+    cGzError = rb_define_class_under(cGzipFile, "Error", cZError);
+
+    /* input gzipped string */
+    rb_define_attr(cGzError, "input", 1, 0);
+    rb_define_method(cGzError, "inspect", gzfile_error_inspect, 0);
+
+    cNoFooter = rb_define_class_under(cGzipFile, "NoFooter", cGzError);
+    cCRCError = rb_define_class_under(cGzipFile, "CRCError", cGzError);
+    cLengthError = rb_define_class_under(cGzipFile,"LengthError",cGzError);
+
+    cGzipWriter = rb_define_class_under(mZlib, "GzipWriter", cGzipFile);
+    cGzipReader = rb_define_class_under(mZlib, "GzipReader", cGzipFile);
+    rb_include_module(cGzipReader, rb_mEnumerable);
+
+    rb_define_singleton_method(cGzipFile, "wrap", rb_gzfile_s_wrap, -1);
+    rb_undef_alloc_func(cGzipFile);
+    rb_define_method(cGzipFile, "to_io", rb_gzfile_to_io, 0);
+    rb_define_method(cGzipFile, "crc", rb_gzfile_crc, 0);
+    rb_define_method(cGzipFile, "mtime", rb_gzfile_mtime, 0);
+    rb_define_method(cGzipFile, "level", rb_gzfile_level, 0);
+    rb_define_method(cGzipFile, "os_code", rb_gzfile_os_code, 0);
+    rb_define_method(cGzipFile, "orig_name", rb_gzfile_orig_name, 0);
+    rb_define_method(cGzipFile, "comment", rb_gzfile_comment, 0);
+    rb_define_method(cGzipReader, "lineno", rb_gzfile_lineno, 0);
+    rb_define_method(cGzipReader, "lineno=", rb_gzfile_set_lineno, 1);
+    rb_define_method(cGzipWriter, "mtime=", rb_gzfile_set_mtime, 1);
+    rb_define_method(cGzipWriter, "orig_name=", rb_gzfile_set_orig_name,1);
+    rb_define_method(cGzipWriter, "comment=", rb_gzfile_set_comment, 1);
+    rb_define_method(cGzipFile, "close", rb_gzfile_close, 0);
+    rb_define_method(cGzipFile, "finish", rb_gzfile_finish, 0);
+    rb_define_method(cGzipFile, "closed?", rb_gzfile_closed_p, 0);
+    rb_define_method(cGzipReader, "eof", rb_gzfile_eof_p, 0);
+    rb_define_method(cGzipReader, "eof?", rb_gzfile_eof_p, 0);
+    rb_define_method(cGzipFile, "sync", rb_gzfile_sync, 0);
+    rb_define_method(cGzipFile, "sync=", rb_gzfile_set_sync, 1);
+    rb_define_method(cGzipReader, "pos", rb_gzfile_total_out, 0);
+    rb_define_method(cGzipWriter, "pos", rb_gzfile_total_in, 0);
+    rb_define_method(cGzipReader, "tell", rb_gzfile_total_out, 0);
+    rb_define_method(cGzipWriter, "tell", rb_gzfile_total_in, 0);
+
+    rb_define_singleton_method(cGzipWriter, "open", rb_gzwriter_s_open,-1);
+    rb_define_alloc_func(cGzipWriter, rb_gzwriter_s_allocate);
+    rb_define_method(cGzipWriter, "initialize", rb_gzwriter_initialize,-1);
+    rb_define_method(cGzipWriter, "flush", rb_gzwriter_flush, -1);
+    rb_define_method(cGzipWriter, "write", rb_gzwriter_write, 1);
+    rb_define_method(cGzipWriter, "putc", rb_gzwriter_putc, 1);
+    rb_define_method(cGzipWriter, "<<", rb_gzwriter_addstr, 1);
+    rb_define_method(cGzipWriter, "printf", rb_gzwriter_printf, -1);
+    rb_define_method(cGzipWriter, "print", rb_gzwriter_print, -1);
+    rb_define_method(cGzipWriter, "puts", rb_gzwriter_puts, -1);
+
+    rb_define_singleton_method(cGzipReader, "open", rb_gzreader_s_open,-1);
+    rb_define_alloc_func(cGzipReader, rb_gzreader_s_allocate);
+    rb_define_method(cGzipReader, "initialize", rb_gzreader_initialize, -1);
+    rb_define_method(cGzipReader, "rewind", rb_gzreader_rewind, 0);
+    rb_define_method(cGzipReader, "unused", rb_gzreader_unused, 0);
+    rb_define_method(cGzipReader, "read", rb_gzreader_read, -1);
+    rb_define_method(cGzipReader, "readpartial", rb_gzreader_readpartial, -1);
+    rb_define_method(cGzipReader, "getc", rb_gzreader_getc, 0);
+    rb_define_method(cGzipReader, "getbyte", rb_gzreader_getbyte, 0);
+    rb_define_method(cGzipReader, "readchar", rb_gzreader_readchar, 0);
+    rb_define_method(cGzipReader, "readbyte", rb_gzreader_readbyte, 0);
+    rb_define_method(cGzipReader, "each_byte", rb_gzreader_each_byte, 0);
+    rb_define_method(cGzipReader, "each_char", rb_gzreader_each_char, 0);
+    rb_define_method(cGzipReader, "bytes", rb_gzreader_each_byte, 0);
+    rb_define_method(cGzipReader, "ungetc", rb_gzreader_ungetc, 1);
+    rb_define_method(cGzipReader, "ungetbyte", rb_gzreader_ungetbyte, 1);
+    rb_define_method(cGzipReader, "gets", rb_gzreader_gets, -1);
+    rb_define_method(cGzipReader, "readline", rb_gzreader_readline, -1);
+    rb_define_method(cGzipReader, "each", rb_gzreader_each, -1);
+    rb_define_method(cGzipReader, "each_line", rb_gzreader_each, -1);
+    rb_define_method(cGzipReader, "lines", rb_gzreader_each, -1);
+    rb_define_method(cGzipReader, "readlines", rb_gzreader_readlines, -1);
+
+    /* From GzipFile#os_code - code of current host */
+    rb_define_const(mZlib, "OS_CODE", INT2FIX(OS_CODE));
+    /* From GzipFile#os_code - 0x00 */
+    rb_define_const(mZlib, "OS_MSDOS", INT2FIX(OS_MSDOS));
+    /* From GzipFile#os_code - 0x01 */
+    rb_define_const(mZlib, "OS_AMIGA", INT2FIX(OS_AMIGA));
+    /* From GzipFile#os_code - 0x02 */
+    rb_define_const(mZlib, "OS_VMS", INT2FIX(OS_VMS));
+    /* From GzipFile#os_code - 0x03 */
+    rb_define_const(mZlib, "OS_UNIX", INT2FIX(OS_UNIX));
+    /* From GzipFile#os_code - 0x05 */
+    rb_define_const(mZlib, "OS_ATARI", INT2FIX(OS_ATARI));
+    /* From GzipFile#os_code - 0x06 */
+    rb_define_const(mZlib, "OS_OS2", INT2FIX(OS_OS2));
+    /* From GzipFile#os_code - 0x07 */
+    rb_define_const(mZlib, "OS_MACOS", INT2FIX(OS_MACOS));
+    /* From GzipFile#os_code - 0x0a */
+    rb_define_const(mZlib, "OS_TOPS20", INT2FIX(OS_TOPS20));
+    /* From GzipFile#os_code - 0x0b */
+    rb_define_const(mZlib, "OS_WIN32", INT2FIX(OS_WIN32));
+
+    /* From GzipFile#os_code - 0x04 */
+    rb_define_const(mZlib, "OS_VMCMS", INT2FIX(OS_VMCMS));
+    /* From GzipFile#os_code - 0x08 */
+    rb_define_const(mZlib, "OS_ZSYSTEM", INT2FIX(OS_ZSYSTEM));
+    /* From GzipFile#os_code - 0x09 */
+    rb_define_const(mZlib, "OS_CPM", INT2FIX(OS_CPM));
+    /* From GzipFile#os_code - 0x0c */
+    rb_define_const(mZlib, "OS_QDOS", INT2FIX(OS_QDOS));
+    /* From GzipFile#os_code - 0x0d */
+    rb_define_const(mZlib, "OS_RISCOS", INT2FIX(OS_RISCOS));
+    /* From GzipFile#os_code - 0xff */
+    rb_define_const(mZlib, "OS_UNKNOWN", INT2FIX(OS_UNKNOWN));
+
+#endif /* GZIP_SUPPORT */
+}
+
+/* Document error classes. */
+
+/*
+ * Document-class: Zlib::Error
+ *
+ * The superclass for all exceptions raised by Ruby/zlib.
+ *
+ * The following exceptions are defined as subclasses of Zlib::Error. These
+ * exceptions are raised when zlib library functions return with an error
+ * status.
+ *
+ * - Zlib::StreamEnd
+ * - Zlib::NeedDict
+ * - Zlib::DataError
+ * - Zlib::StreamError
+ * - Zlib::MemError
+ * - Zlib::BufError
+ * - Zlib::VersionError
+ *
+ */
+
+/*
+ * Document-class: Zlib::StreamEnd
+ *
+ * Subclass of Zlib::Error
+ *
+ * When zlib returns a Z_STREAM_END
+ * is return if the end of the compressed data has been reached
+ * and all uncompressed out put has been produced.
+ *
+ */
+
+/*
+ * Document-class: Zlib::NeedDict
+ *
+ * Subclass of Zlib::Error
+ *
+ * When zlib returns a Z_NEED_DICT
+ * if a preset dictionary is needed at this point.
+ *
+ * Used by Zlib::Inflate.inflate and <tt>Zlib.inflate</tt>
+ */
+
+/*
+ * Document-class: Zlib::VersionError
+ *
+ * Subclass of Zlib::Error
+ *
+ * When zlib returns a Z_VERSION_ERROR,
+ * usually if the zlib library version is incompatible with the
+ * version assumed by the caller.
+ *
+ */
+
+/*
+ * Document-class: Zlib::MemError
+ *
+ * Subclass of Zlib::Error
+ *
+ * When zlib returns a Z_MEM_ERROR,
+ * usually if there was not enough memory.
+ *
+ */
+
+/*
+ * Document-class: Zlib::StreamError
+ *
+ * Subclass of Zlib::Error
+ *
+ * When zlib returns a Z_STREAM_ERROR,
+ * usually if the stream state was inconsistent.
+ *
+ */
+
+/*
+ * Document-class: Zlib::BufError
+ *
+ * Subclass of Zlib::Error when zlib returns a Z_BUF_ERROR.
+ *
+ * Usually if no progress is possible.
+ *
+ */
+
+/*
+ * Document-class: Zlib::DataError
+ *
+ * Subclass of Zlib::Error when zlib returns a Z_DATA_ERROR.
+ *
+ * Usually if a stream was prematurely freed.
+ *
+ */
+
+/*
+ * Document-class: Zlib::GzipFile::Error
+ *
+ * Base class of errors that occur when processing GZIP files.
+ */
+
+/*
+ * Document-class: Zlib::GzipFile::NoFooter
+ *
+ * Raised when gzip file footer is not found.
+ */
+
+/*
+ * Document-class: Zlib::GzipFile::CRCError
+ *
+ * Raised when the CRC checksum recorded in gzip file footer is not equivalent
+ * to the CRC checksum of the actual uncompressed data.
+ */
+
+/*
+ * Document-class: Zlib::GzipFile::LengthError
+ *
+ * Raised when the data length recorded in the gzip file footer is not equivalent
+ * to the length of the actual uncompressed data.
+ */
+
+