merge revision(s) 59333,59337: [Backport #13616]

	Zlib::GzipReader#pos underflows after calling #ungetbyte or #ungetc at start of file [Bug #13616]

	patched by Andrew Haines <andrew@haines.org.nz> [ruby-core:81488]
	zlib.c: fix unnormalized Fixnum

	* ext/zlib/zlib.c (rb_gzfile_total_out): cast to long not to
	  result in an unsigned long to normalized to Fixnum on LLP64
	  platforms.  [ruby-core:81488]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_3@59532 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

3 files changed, 21 insertions, 2 deletions

diff --git a/ext/zlib/zlib.c b/ext/zlib/zlib.c
index 25b3e7afab..c7604211bb 100644
--- a/ext/zlib/zlib.c
+++ b/ext/zlib/zlib.c
@@ -3407,7 +3407,14 @@ 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);
+    uLong total_out = gz->z.stream.total_out;
+    long buf_filled = gz->z.buf_filled;
+
+    if (total_out >= (uLong)buf_filled) {
+        return rb_uint2inum(total_out - buf_filled);
+    } else {
+        return LONG2FIX(-(buf_filled - (long)total_out));
+    }
 }
 
 /*
diff --git a/test/zlib/test_zlib.rb b/test/zlib/test_zlib.rb
index 0092daf0d9..c8c917cb9c 100644
--- a/test/zlib/test_zlib.rb
+++ b/test/zlib/test_zlib.rb
@@ -650,6 +650,18 @@ if defined? Zlib
       }
     end
 
+    def test_ungetc_at_start_of_file
+      s = "".dup
+      w = Zlib::GzipWriter.new(StringIO.new(s))
+      w << "abc"
+      w.close
+      r = Zlib::GzipReader.new(StringIO.new(s))
+
+      r.ungetc ?!
+
+      assert_equal(-1, r.pos, "[ruby-core:81488][Bug #13616]")
+    end
+
     def test_open
       Tempfile.create("test_zlib_gzip_reader_open") {|t|
         t.close
diff --git a/version.h b/version.h
index f47967bb5d..da35261ff3 100644
--- a/version.h
+++ b/version.h
@@ -1,6 +1,6 @@
 #define RUBY_VERSION "2.3.5"
 #define RUBY_RELEASE_DATE "2017-08-09"
-#define RUBY_PATCHLEVEL 344
+#define RUBY_PATCHLEVEL 345
 
 #define RUBY_RELEASE_YEAR 2017
 #define RUBY_RELEASE_MONTH 8