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

Browse source 
Impact: Code simplification

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

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
This commit is contained in:
H. Peter Anvin 2009-01-04 14:42:52 -08:00
parent 30d65dbfe3
commit b172fd882d
1 changed files with 35 additions and 47 deletions
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82
init/do_mounts_rd.c
View file

@ -43,13 +43,31 @@ static int __init crd_load(int in_fd, int out_fd, decompress_fn deco);
* numbers could not be found.
*
* We currently check for the following magic numbers:
* minix
* ext2
* minix
* ext2
* romfs
* cramfs
* gzip
* gzip
*/
static int __init
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)
{
const int size = 512;
@ -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))) {
printk(KERN_NOTICE
"RAMDISK: Compressed image found at block %d\n",
start_block);
*decompressor = gunzip;
nblocks = 0;
goto done;
for (cf = compressed_formats; cf->decompressor; cf++) {
if (buf[0] == cf->magic[0] && buf[1] == cf->magic[1]) {
printk(KERN_NOTICE
"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 &&
@ -165,7 +153,7 @@ identify_ramdisk_image(int fd, int start_block, decompress_fn *decompressor)
printk(KERN_NOTICE
"RAMDISK: Couldn't find valid RAM disk image starting at %d.\n",
start_block);
done:
sys_lseek(fd, start_block * BLOCK_SIZE, 0);
kfree(buf);
@ -224,7 +212,7 @@ int __init rd_load_image(char *from)
nblocks, rd_blocks);
goto done;
}
/*
* OK, time to copy in the data
*/