MfP4: Big read filter refactoring.

This is an attempt to eliminate a lot of redundant
code from the read ("decompression") filters by
changing them to juggle arbitrary-sized blocks
and consolidate reblocking code at a single point
in archive_read.c.

Along the way, I've changed the internal read/consume
API used by the format handlers to a slightly
different style originally suggested by des@.  It
does seem to simplify a lot of common cases.

The most dramatic change is, of course, to
archive_read_support_compression_none(), which
has just evaporated into a no-op as the blocking
code this used to hold has all been moved up
a level.

There's at least one more big round of refactoring
yet to come before the individual filters are as
straightforward as I think they should be...

1 files changed, 6 insertions, 0 deletions

diff --git a/lib/libarchive/archive_read_support_compression_all.c b/lib/libarchive/archive_read_support_compression_all.c
index de3d585..967546d 100644
--- a/lib/libarchive/archive_read_support_compression_all.c
+++ b/lib/libarchive/archive_read_support_compression_all.c
@@ -39,5 +39,11 @@ archive_read_support_compression_all(struct archive *a)
 #if HAVE_ZLIB_H
 	archive_read_support_compression_gzip(a);
 #endif
+#if HAVE_LZMADEC_H
+	/* LZMA bidding is subject to false positives because
+	 * the LZMA file format has a very weak signature.  It
+	 * may not be feasible to include LZMA detection here. */
+	/* archive_read_support_compression_lzma(a); */
+#endif
 	return (ARCHIVE_OK);
 }