[git commit] xz: fix decoding of LZMA2 streams having no uncompressed data.

Denys Vlasenko vda.linux at googlemail.com
Wed Feb 27 15:38:06 UTC 2013


commit: http://git.busybox.net/busybox/commit/?id=a1ae2b75a71b4b99948aa0f9a15cf1de52bb40d6
branch: http://git.busybox.net/busybox/commit/?id=refs/heads/master

No .xz encoder creates files with empty LZMA2 streams,
but such files would still be valid and decompressors
must accept them.

Note that empty .xz files are a different thing than
empty LZMA2 streams. This bug didn't affect typical .xz
files that had no uncompressed data.

Signed-off-by: Lasse Collin <lasse.collin at tukaani.org>
Signed-off-by: Denys Vlasenko <vda.linux at googlemail.com>
---
 archival/libarchive/unxz/xz_dec_lzma2.c |    6 +++---
 1 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/archival/libarchive/unxz/xz_dec_lzma2.c b/archival/libarchive/unxz/xz_dec_lzma2.c
index b6d10af..3c2dc88 100644
--- a/archival/libarchive/unxz/xz_dec_lzma2.c
+++ b/archival/libarchive/unxz/xz_dec_lzma2.c
@@ -971,6 +971,9 @@ XZ_EXTERN NOINLINE enum xz_ret XZ_FUNC xz_dec_lzma2_run(
 			 */
 			tmp = b->in[b->in_pos++];
 
+			if (tmp == 0x00)
+				return XZ_STREAM_END;
+
 			if (tmp >= 0xE0 || tmp == 0x01) {
 				s->lzma2.need_props = true;
 				s->lzma2.need_dict_reset = false;
@@ -1003,9 +1006,6 @@ XZ_EXTERN NOINLINE enum xz_ret XZ_FUNC xz_dec_lzma2_run(
 						lzma_reset(s);
 				}
 			} else {
-				if (tmp == 0x00)
-					return XZ_STREAM_END;
-
 				if (tmp > 0x02)
 					return XZ_DATA_ERROR;
 


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