merge revision(s) 57187,57234: [Backport #13075]

	pack.c: avoid returning uninitialized String

	Fix unpacking with 'b', 'B', 'h' and 'H' format. Do not return an
	uninitialized String to Ruby before filling the content bytes.
	Fixes r11175 ("pack.c (pack_unpack): execute block if given with
	unpacked value instead of creating an array", 2006-10-15).
	[ruby-core:78841] [Bug #13075]
	test/ruby/test_pack.rb: fix test case added by r57187

	The test case for String#unpack added by r57187 is not properly testing
	because the String will be filled after the block invocation.
	[ruby-core:78841] [Bug #13075]

	Thanks to nagachika for pointing this out:

	  http://d.hatena.ne.jp/nagachika/20161226/ruby_trunk_changes_57184_57194#r57187

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_2_2@58088 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

1 files changed, 8 insertions, 4 deletions

diff --git a/pack.c b/pack.c
index 5c2b684cef..a5982c9c0f 100644
--- a/pack.c
+++ b/pack.c
@@ -1259,13 +1259,14 @@ pack_unpack(VALUE str, VALUE fmt)
 		if (p[-1] == '*' || len > (send - s) * 8)
 		    len = (send - s) * 8;
 		bits = 0;
-		UNPACK_PUSH(bitstr = rb_usascii_str_new(0, len));
+		bitstr = rb_usascii_str_new(0, len);
 		t = RSTRING_PTR(bitstr);
 		for (i=0; i<len; i++) {
 		    if (i & 7) bits >>= 1;
 		    else bits = (unsigned char)*s++;
 		    *t++ = (bits & 1) ? '1' : '0';
 		}
+		UNPACK_PUSH(bitstr);
 	    }
 	    break;
 
@@ -1279,13 +1280,14 @@ pack_unpack(VALUE str, VALUE fmt)
 		if (p[-1] == '*' || len > (send - s) * 8)
 		    len = (send - s) * 8;
 		bits = 0;
-		UNPACK_PUSH(bitstr = rb_usascii_str_new(0, len));
+		bitstr = rb_usascii_str_new(0, len);
 		t = RSTRING_PTR(bitstr);
 		for (i=0; i<len; i++) {
 		    if (i & 7) bits <<= 1;
 		    else bits = (unsigned char)*s++;
 		    *t++ = (bits & 128) ? '1' : '0';
 		}
+		UNPACK_PUSH(bitstr);
 	    }
 	    break;
 
@@ -1299,7 +1301,7 @@ pack_unpack(VALUE str, VALUE fmt)
 		if (p[-1] == '*' || len > (send - s) * 2)
 		    len = (send - s) * 2;
 		bits = 0;
-		UNPACK_PUSH(bitstr = rb_usascii_str_new(0, len));
+		bitstr = rb_usascii_str_new(0, len);
 		t = RSTRING_PTR(bitstr);
 		for (i=0; i<len; i++) {
 		    if (i & 1)
@@ -1308,6 +1310,7 @@ pack_unpack(VALUE str, VALUE fmt)
 			bits = (unsigned char)*s++;
 		    *t++ = hexdigits[bits & 15];
 		}
+		UNPACK_PUSH(bitstr);
 	    }
 	    break;
 
@@ -1321,7 +1324,7 @@ pack_unpack(VALUE str, VALUE fmt)
 		if (p[-1] == '*' || len > (send - s) * 2)
 		    len = (send - s) * 2;
 		bits = 0;
-		UNPACK_PUSH(bitstr = rb_usascii_str_new(0, len));
+		bitstr = rb_usascii_str_new(0, len);
 		t = RSTRING_PTR(bitstr);
 		for (i=0; i<len; i++) {
 		    if (i & 1)
@@ -1330,6 +1333,7 @@ pack_unpack(VALUE str, VALUE fmt)
 			bits = (unsigned char)*s++;
 		    *t++ = hexdigits[(bits >> 4) & 15];
 		}
+		UNPACK_PUSH(bitstr);
 	    }
 	    break;