xz: Check the value of lzma_stream_flags.version in --list.

It is a no-op for now, but if an old xz version is used
together with a newer liblzma that supports something new,
then this check becomes important and will stop the old xz
from trying to parse files that it won't understand.

diff --git a/src/xz/list.c b/src/xz/list.c
index 13abd8f..449c2bc 100644 (file)
--- a/src/xz/list.c
+++ b/src/xz/list.c
@@ -230,6 +230,20 @@ parse_indexes(xz_file_info *xfi, file_pair *pair)
                        goto error;
                }
 
+               // Check that the Stream Footer doesn't specify something
+               // that we don't support. This can only happen if the xz
+               // version is older than liblzma and liblzma supports
+               // something new.
+               //
+               // It is enough to check Stream Footer. Stream Header must
+               // match when it is compared against Stream Footer with
+               // lzma_stream_flags_compare().
+               if (footer_flags.version != 0) {
+                       message_error("%s: %s", pair->src_name,
+                                       message_strm(LZMA_OPTIONS_ERROR));
+                       goto error;
+               }
+
                // Check that the size of the Index field looks sane.
                lzma_vli index_size = footer_flags.backward_size;
                if ((lzma_vli)(pos) < index_size + LZMA_STREAM_HEADER_SIZE) {