decompress_unxz: newer version, one which can unpack SHA-256 protected files

function                                             old     new   delta
check_sizes                                            -      16     +16
crc32_table                                            -       4      +4
index_update                                          47      40      -7
crc32_validate                                       110      93     -17
dec_vli                                              197     165     -32
unpack_xz_stream                                    4284    4014    -270
------------------------------------------------------------------------------
(add/remove: 2/0 grow/shrink: 0/4 up/down: 20/-326)          Total: -306 bytes

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

1 files changed, 12 insertions, 6 deletions

diff --git a/archival/libunarchive/decompress_unxz.c b/archival/libunarchive/decompress_unxz.c
index 924a525..374b76d 100644
--- a/archival/libunarchive/decompress_unxz.c
+++ b/archival/libunarchive/decompress_unxz.c
@@ -16,9 +16,13 @@
 #define XZ_FUNC FAST_FUNC
 #define XZ_EXTERN static
 
-#define xz_crc32_init(table) crc32_filltable(table, /*endian:*/ 0)
-static uint32_t xz_crc32(uint32_t *crc32_table,
-		const uint8_t *buf, size_t size, uint32_t crc)
+/* Skip check (rather than fail) of unsupported hash functions */
+#define XZ_DEC_ANY_CHECK  1
+
+/* We use our own crc32 function */
+#define XZ_INTERNAL_CRC32 0
+static uint32_t *crc32_table;
+static uint32_t xz_crc32(const uint8_t *buf, size_t size, uint32_t crc)
 {
 	crc = ~crc;
 
@@ -29,8 +33,8 @@ static uint32_t xz_crc32(uint32_t *crc32_table,
 
 	return ~crc;
 }
-#define xz_crc32 xz_crc32
 
+/* We use arch-optimized unaligned accessors */
 #define get_unaligned_le32(buf) ({ uint32_t v; move_from_unaligned32(v, buf); SWAP_LE32(v); })
 #define get_unaligned_be32(buf) ({ uint32_t v; move_from_unaligned32(v, buf); SWAP_BE32(v); })
 #define put_unaligned_le32(val, buf) move_to_unaligned16(buf, SWAP_LE32(val))
@@ -64,8 +68,10 @@ unpack_xz_stream(int src_fd, int dst_fd)
 	iobuf.out = membuf + IN_SIZE;
 	iobuf.out_size = OUT_SIZE;
 
+	if (!crc32_table)
+		crc32_table = crc32_filltable(NULL, /*endian:*/ 0);
+
 	state = xz_dec_init(64*1024); /* initial dict of 64k */
-	xz_crc32_init(state->crc32_table);
 
 	while (1) {
 		enum xz_ret r;
@@ -102,7 +108,7 @@ unpack_xz_stream(int src_fd, int dst_fd)
 		) {
 			break;
 		}
-		if (r != XZ_OK) {
+		if (r != XZ_OK && r != XZ_UNSUPPORTED_CHECK) {
 			bb_error_msg("corrupted data");
 			total = -1;
 			break;