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bzip2/lzma: centralize format detection

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Centralize the compression format detection to a common routine in the
lib directory, and use it for both initramfs and initrd.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
This commit is contained in:
H. Peter Anvin
2009-01-08 15:14:17 -08:00
parent 6c11b12ac6
commit 889c92d21d
5 changed files with 72 additions and 67 deletions
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9
lib/Makefile
View File

@@ -11,7 +11,8 @@ lib-y := ctype.o string.o vsprintf.o cmdline.o \
rbtree.o radix-tree.o dump_stack.o \
idr.o int_sqrt.o extable.o prio_tree.o \
sha1.o irq_regs.o reciprocal_div.o argv_split.o \
proportions.o prio_heap.o ratelimit.o show_mem.o is_single_threaded.o
proportions.o prio_heap.o ratelimit.o show_mem.o \
is_single_threaded.o decompress.o
lib-$(CONFIG_MMU) += ioremap.o
lib-$(CONFIG_SMP) += cpumask.o
@@ -65,9 +66,9 @@ obj-$(CONFIG_REED_SOLOMON) += reed_solomon/
obj-$(CONFIG_LZO_COMPRESS) += lzo/
obj-$(CONFIG_LZO_DECOMPRESS) += lzo/
obj-$(CONFIG_DECOMPRESS_GZIP) += decompress_inflate.o
obj-$(CONFIG_DECOMPRESS_BZIP2) += decompress_bunzip2.o
obj-$(CONFIG_DECOMPRESS_LZMA) += decompress_unlzma.o
lib-$(CONFIG_DECOMPRESS_GZIP) += decompress_inflate.o
lib-$(CONFIG_DECOMPRESS_BZIP2) += decompress_bunzip2.o
lib-$(CONFIG_DECOMPRESS_LZMA) += decompress_unlzma.o
obj-$(CONFIG_TEXTSEARCH) += textsearch.o
obj-$(CONFIG_TEXTSEARCH_KMP) += ts_kmp.o

50
lib/decompress.c Normal file
View File

@@ -0,0 +1,50 @@
/*
* decompress.c
*
* Detect the decompression method based on magic number
*/
#include <linux/decompress/generic.h>
#include <linux/decompress/bunzip2.h>
#include <linux/decompress/unlzma.h>
#include <linux/decompress/inflate.h>
#include <linux/types.h>
#include <linux/string.h>
static const struct compress_format {
unsigned char magic[2];
const char *name;
decompress_fn decompressor;
} compressed_formats[] = {
#ifdef CONFIG_DECOMPRESS_GZIP
{ {037, 0213}, "gzip", gunzip },
{ {037, 0236}, "gzip", gunzip },
#endif
#ifdef CONFIG_DECOMPRESS_BZIP2
{ {0x42, 0x5a}, "bzip2", bunzip2 },
#endif
#ifdef CONFIG_DECOMPRESS_LZMA
{ {0x5d, 0x00}, "lzma", unlzma },
#endif
{ {0, 0}, NULL, NULL }
};
decompress_fn decompress_method(const unsigned char *inbuf, int len,
const char **name)
{
const struct compress_format *cf;
if (len < 2)
return NULL; /* Need at least this much... */
for (cf = compressed_formats; cf->decompressor; cf++) {
if (!memcmp(inbuf, cf->magic, 2))
break;
}
if (name)
*name = cf->name;
return cf->decompressor;
}