merge revision(s) r46360,r46372: [Backport #8625]

	* io.c (io_setstrbuf, io_read): should not shorten the given buffer until
	  read succeeds.  [ruby-core:55951] [Bug #8625]

	* io.c (read_all): truncate the buffer before appending read data,
	  instead of truncating before reading.
	  [ruby-core:55951] [Bug #8625]


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_1@46629 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 8 insertions, 4 deletions

diff --git a/io.c b/io.c
index 6deb44187f..e5a4d3b40c 100644
--- a/io.c
+++ b/io.c
@@ -2291,9 +2291,6 @@ io_setstrbuf(VALUE *str, long len)
 	long clen = RSTRING_LEN(s);
 	if (clen >= len) {
 	    rb_str_modify(s);
-	    if (clen != len) {
-		rb_str_set_len(s, len);
-	    }
 	    return;
 	}
 	len -= clen;
@@ -2320,23 +2317,27 @@ read_all(rb_io_t *fptr, long siz, VALUE str)
     int cr;
 
     if (NEED_READCONV(fptr)) {
+	int first = !NIL_P(str);
 	SET_BINARY_MODE(fptr);
 	io_setstrbuf(&str,0);
         make_readconv(fptr, 0);
         while (1) {
             VALUE v;
             if (fptr->cbuf.len) {
+		if (first) rb_str_set_len(str, first = 0);
                 io_shift_cbuf(fptr, fptr->cbuf.len, &str);
             }
             v = fill_cbuf(fptr, 0);
             if (v != MORE_CHAR_SUSPENDED && v != MORE_CHAR_FINISHED) {
                 if (fptr->cbuf.len) {
+		    if (first) rb_str_set_len(str, first = 0);
                     io_shift_cbuf(fptr, fptr->cbuf.len, &str);
                 }
                 rb_exc_raise(v);
             }
             if (v == MORE_CHAR_FINISHED) {
                 clear_readconv(fptr);
+		if (first) rb_str_set_len(str, first = 0);
                 return io_enc_str(str, fptr);
             }
         }
@@ -2807,7 +2808,10 @@ io_read(int argc, VALUE *argv, VALUE io)
 
     GetOpenFile(io, fptr);
     rb_io_check_byte_readable(fptr);
-    if (len == 0) return str;
+    if (len == 0) {
+	io_set_read_length(str, 0);
+	return str;
+    }
 
     READ_CHECK(fptr);
 #if defined(RUBY_TEST_CRLF_ENVIRONMENT) || defined(_WIN32)