Fix: allow concatenated xz streams

Some xz compressed tarballs (e.g. from kernel.org) are not made up of
a single xz stream, but rather contain several, independendly
compressed streams. In that case, the xz decompressor hits
an LZMA_STREAM_END early on and reports EOF. If you are lucky, the tar
reader bails (premature end-of-file). If you are unlucky, it happens
exactely between two records and is interpeted as regular end-of-file.

As this seems to be a normal use case for xz, it has a flag to just
read across the seams and only report end-of-stream if the action
is set to finish.

This commit adds the flag to the initialization propperly sets the
lzma_action depending on whether the underlying stream hit EOF or not.

Signed-off-by: David Oberhollenzer <david.oberhollenzer@sigma-star.at>

1 files changed, 5 insertions, 2 deletions

diff --git a/lib/fstream/uncompress/xz.c b/lib/fstream/uncompress/xz.c
index 0e48468..0fd9ce6 100644
--- a/lib/fstream/uncompress/xz.c
+++ b/lib/fstream/uncompress/xz.c
@@ -18,6 +18,7 @@ static int precache(istream_t *base)
 {
 	istream_xz_t *xz = (istream_xz_t *)base;
 	istream_t *wrapped = ((istream_comp_t *)base)->wrapped;
+	lzma_action action;
 	lzma_ret ret_xz;
 	int ret;
 
@@ -26,13 +27,15 @@ static int precache(istream_t *base)
 		if (ret != 0)
 			return ret;
 
+		action = wrapped->eof ? LZMA_FINISH : LZMA_RUN;
+
 		xz->strm.avail_in = wrapped->buffer_used;
 		xz->strm.next_in = wrapped->buffer;
 
 		xz->strm.avail_out = BUFSZ - base->buffer_used;
 		xz->strm.next_out = base->buffer + base->buffer_used;
 
-		ret_xz = lzma_code(&xz->strm, LZMA_RUN);
+		ret_xz = lzma_code(&xz->strm, action);
 
 		base->buffer_used = BUFSZ - xz->strm.avail_out;
 		wrapped->buffer_offset = wrapped->buffer_used -
@@ -77,7 +80,7 @@ istream_comp_t *istream_xz_create(const char *filename)
 		return NULL;
 	}
 
-	ret_xz = lzma_stream_decoder(&xz->strm, memlimit, 0);
+	ret_xz = lzma_stream_decoder(&xz->strm, memlimit, LZMA_CONCATENATED);
 
 	if (ret_xz != LZMA_OK) {
 		fprintf(stderr,