Commit b172fd88 authored by H. Peter Anvin's avatar H. Peter Anvin
Browse files

bzip2/lzma: use a table to search for initramfs compression formats 



Impact: Code simplification

Instead of open-coding testing for initramfs compression formats, use
a table.

Signed-off-by: default avatarH. Peter Anvin <hpa@zytor.com>
parent 30d65dbf

init/do_mounts_rd.c

+35 −47
Original line number Diff line number Diff line
@@ -49,6 +49,24 @@ static int __init crd_load(int in_fd, int out_fd, decompress_fn deco); 
 *	cramfs

 *	gzip

 */

static const struct compress_format {

	unsigned char magic[2];

	const char *name;

	decompress_fn decompressor;

} compressed_formats[] = {

#ifdef CONFIG_RD_GZIP

	{ {037, 0213}, "gzip", gunzip },

	{ {037, 0236}, "gzip", gunzip },

#endif

#ifdef CONFIG_RD_BZIP2

	{ {0x42, 0x5a}, "bzip2", bunzip2 },

#endif

#ifdef CONFIG_RD_LZMA

	{ {0x5d, 0x00}, "lzma", unlzma },

#endif

	{ {0, 0}, NULL, NULL }

};



static int __init

identify_ramdisk_image(int fd, int start_block, decompress_fn *decompressor)

{
@@ -59,6 +77,7 @@ identify_ramdisk_image(int fd, int start_block, decompress_fn *decompressor) 
	struct cramfs_super *cramfsb;

	int nblocks = -1;

	unsigned char *buf;

	const struct compress_format *cf;



	buf = kmalloc(size, GFP_KERNEL);

	if (!buf)
@@ -71,52 +90,21 @@ identify_ramdisk_image(int fd, int start_block, decompress_fn *decompressor) 
	memset(buf, 0xe5, size);



	/*

	 * Read block 0 to test for gzipped kernel

	 * Read block 0 to test for compressed kernel

	 */

	sys_lseek(fd, start_block * BLOCK_SIZE, 0);

	sys_read(fd, buf, size);



#ifdef CONFIG_RD_GZIP

	/*

	 * If it matches the gzip magic numbers, return 0

	 */

	if (buf[0] == 037 && ((buf[1] == 0213) || (buf[1] == 0236))) {

	for (cf = compressed_formats; cf->decompressor; cf++) {

		if (buf[0] == cf->magic[0] && buf[1] == cf->magic[1]) {

			printk(KERN_NOTICE

		       "RAMDISK: Compressed image found at block %d\n",

		       start_block);

		*decompressor = gunzip;

			       "RAMDISK: %s image found at block %d\n",

			       cf->name, start_block);

			*decompressor = cf->decompressor;

			nblocks = 0;

			goto done;

		}

#endif



#ifdef CONFIG_RD_BZIP2

	/*

	 * If it matches the bzip2 magic numbers, return -1

	 */

	if (buf[0] == 0x42 && (buf[1] == 0x5a)) {

		printk(KERN_NOTICE

		       "RAMDISK: Bzipped image found at block %d\n",

		       start_block);

		*decompressor = bunzip2;

		nblocks = 0;

		goto done;

	}

#endif



#ifdef CONFIG_RD_LZMA

	/*

	 * If it matches the lzma magic numbers, return -1

	 */

	if (buf[0] == 0x5d && (buf[1] == 0x00)) {

		printk(KERN_NOTICE

		       "RAMDISK: Lzma image found at block %d\n",

		       start_block);

		*decompressor = unlzma;

		nblocks = 0;

		goto done;

	}

#endif



	/* romfs is at block zero too */

	if (romfsb->word0 == ROMSB_WORD0 &&