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bzip2/lzma: centralize format detection

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>
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1 parent 6c11b12 commit 889c92d21db40be0b7d22a59395060237895bb85 H. Peter Anvin committed Jan 8, 2009
Showing with 72 additions and 67 deletions.
  1. +3 −0 include/linux/decompress/generic.h
  2. +7 −31 init/do_mounts_rd.c
  3. +7 −32 init/initramfs.c
  4. +5 −4 lib/Makefile
  5. +50 −0 lib/decompress.c
View
3 include/linux/decompress/generic.h
@@ -26,5 +26,8 @@ typedef int (*decompress_fn) (unsigned char *inbuf, int len,
*fill should be called (repeatedly...) to read data, at most IOBUF_SIZE
*/
+/* Utility routine to detect the decompression method */
+decompress_fn decompress_method(const unsigned char *inbuf, int len,
+ const char **name);
#endif
View
38 init/do_mounts_rd.c
@@ -12,9 +12,6 @@
#include <linux/decompress/generic.h>
-#include <linux/decompress/bunzip2.h>
-#include <linux/decompress/unlzma.h>
-#include <linux/decompress/inflate.h>
int __initdata rd_prompt = 1;/* 1 = prompt for RAM disk, 0 = don't prompt */
@@ -49,24 +46,6 @@ 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)
{
@@ -77,7 +56,7 @@ 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;
+ const char *compress_name;
buf = kmalloc(size, GFP_KERNEL);
if (!buf)
@@ -95,15 +74,12 @@ identify_ramdisk_image(int fd, int start_block, decompress_fn *decompressor)
sys_lseek(fd, start_block * BLOCK_SIZE, 0);
sys_read(fd, buf, size);
- 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;
- }
+ *decompressor = decompress_method(buf, size, &compress_name);
+ if (*decompressor) {
+ printk(KERN_NOTICE "RAMDISK: %s image found at block %d\n",
+ compress_name, start_block);
+ nblocks = 0;
+ goto done;
}
/* romfs is at block zero too */
View
39 init/initramfs.c
@@ -416,13 +416,13 @@ static int __init flush_buffer(void *bufv, unsigned len)
static unsigned my_inptr; /* index of next byte to be processed in inbuf */
-#include <linux/decompress/bunzip2.h>
-#include <linux/decompress/unlzma.h>
-#include <linux/decompress/inflate.h>
+#include <linux/decompress/generic.h>
static char * __init unpack_to_rootfs(char *buf, unsigned len, int check_only)
{
int written;
+ decompress_fn decompress;
+
dry_run = check_only;
header_buf = kmalloc(110, GFP_KERNEL);
symlink_buf = kmalloc(PATH_MAX + N_ALIGN(PATH_MAX) + 1, GFP_KERNEL);
@@ -450,35 +450,10 @@ static char * __init unpack_to_rootfs(char *buf, unsigned len, int check_only)
continue;
}
this_header = 0;
-#ifdef CONFIG_RD_GZIP
- if (!gunzip(buf, len, NULL, flush_buffer, NULL,
- &my_inptr, error) &&
- message == NULL)
- goto ok;
-#endif
-
-#ifdef CONFIG_RD_BZIP2
- message = NULL; /* Zero out message, or else cpio will
- think an error has already occured */
- if (!bunzip2(buf, len, NULL, flush_buffer, NULL,
- &my_inptr, error) &&
- message == NULL) {
- goto ok;
- }
-#endif
-
-#ifdef CONFIG_RD_LZMA
- message = NULL; /* Zero out message, or else cpio will
- think an error has already occured */
- if (!unlzma(buf, len, NULL, flush_buffer, NULL,
- &my_inptr, error) &&
- message == NULL) {
- goto ok;
- }
-#endif
-#if defined CONFIG_RD_GZIP || defined CONFIG_RD_BZIP2 || defined CONFIG_RD_LZMA
-ok:
-#endif
+ decompress = decompress_method(buf, len, NULL);
+ if (decompress)
+ decompress(buf, len, NULL, flush_buffer, NULL,
+ &my_inptr, error);
if (state != Reset)
error("junk in compressed archive");
this_header = saved_offset + my_inptr;
View
9 lib/Makefile
@@ -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
View
50 lib/decompress.c
@@ -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;
+}

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