xz: fix decoding of LZMA2 streams having no uncompressed data.

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@tukaani.org>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

diff --git a/archival/libarchive/unxz/xz_dec_lzma2.c b/archival/libarchive/unxz/xz_dec_lzma2.c
index b6d10af9d0ba3d74167422ae84371821cc6ca578..3c2dc88b71fbc407294d26b18ecede471c22900d 100644 (file)
--- 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;