squashfs4: Add support for LZMA Magic to unsquashfs

Some vendor firmwares use a different super block magic to indicate LZMA
compression. This patches adds support for detecting this and enable
extraction for those firmware's root filesystems.

SVN-Revision: 28489

tools/squashfs4/patches/170-add_support_for_LZMA_MAGIC_to_unsqashfs.patch

@@ -0,0 +1,72 @@
+--- a/squashfs-tools/squashfs_fs.h
++++ b/squashfs-tools/squashfs_fs.h
+@@ -30,6 +30,13 @@
+ #define SQUASHFS_MAGIC_SWAP		0x68737173
+ #define SQUASHFS_START			0
+ 
++/*
++ * Squashfs + LZMA
++ */
++
++#define SQUASHFS_MAGIC_LZMA		0x71736873
++#define SQUASHFS_MAGIC_LZMA_SWAP	0x73687371
++
+ /* size of metadata (inode and directory) blocks */
+ #define SQUASHFS_METADATA_SIZE		8192
+ #define SQUASHFS_METADATA_LOG		13
+--- a/squashfs-tools/unsquashfs.c
++++ b/squashfs-tools/unsquashfs.c
+@@ -1463,10 +1463,12 @@ int read_super(char *source)
+ 	 */
+ 	read_fs_bytes(fd, SQUASHFS_START, sizeof(struct squashfs_super_block),
+ 		&sBlk_4);
+-	swap = sBlk_4.s_magic != SQUASHFS_MAGIC;
++	swap = (sBlk_4.s_magic != SQUASHFS_MAGIC &&
++		sBlk_4.s_magic != SQUASHFS_MAGIC_LZMA);
+ 	SQUASHFS_INSWAP_SUPER_BLOCK(&sBlk_4);
+ 
+-	if(sBlk_4.s_magic == SQUASHFS_MAGIC && sBlk_4.s_major == 4 &&
++	if((sBlk_4.s_magic == SQUASHFS_MAGIC || 
++	   sBlk_4.s_magic == SQUASHFS_MAGIC_LZMA) && sBlk_4.s_major == 4 &&
+ 			sBlk_4.s_minor == 0) {
+ 		s_ops.squashfs_opendir = squashfs_opendir_4;
+ 		s_ops.read_fragment = read_fragment_4;
+@@ -1479,7 +1481,11 @@ int read_super(char *source)
+ 		/*
+ 		 * Check the compression type
+ 		 */
+-		comp = lookup_compressor_id(sBlk.s.compression);
++		if (sBlk_4.s_magic == SQUASHFS_MAGIC_LZMA)
++			comp = lookup_compressor("lzma");
++		else
++			comp = lookup_compressor_id(sBlk.s.compression);
++
+ 		return TRUE;
+ 	}
+ 
+@@ -1494,8 +1500,10 @@ int read_super(char *source)
+ 	 * Check it is a SQUASHFS superblock
+ 	 */
+ 	swap = 0;
+-	if(sBlk_3.s_magic != SQUASHFS_MAGIC) {
+-		if(sBlk_3.s_magic == SQUASHFS_MAGIC_SWAP) {
++	if(sBlk_3.s_magic != SQUASHFS_MAGIC && 
++			sBlk_3.s_magic != SQUASHFS_MAGIC_LZMA) {
++		if(sBlk_3.s_magic == SQUASHFS_MAGIC_SWAP || 
++				sBlk_3.s_magic == SQUASHFS_MAGIC_LZMA_SWAP) {
+ 			squashfs_super_block_3 sblk;
+ 			ERROR("Reading a different endian SQUASHFS filesystem "
+ 				"on %s\n", source);
+@@ -1573,7 +1581,11 @@ int read_super(char *source)
+ 	/*
+ 	 * 1.x, 2.x and 3.x filesystems use gzip compression.
+ 	 */
+-	comp = lookup_compressor("gzip");
++	if (sBlk.s.s_magic == SQUASHFS_MAGIC_LZMA)
++		comp = lookup_compressor("lzma");
++	else
++		comp = lookup_compressor("gzip");
++
+ 	return TRUE;
+ 
+ failed_mount: