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>

5 files changed, 72 insertions, 67 deletions

diff --git a/include/linux/decompress/generic.h b/include/linux/decompress/generic.h
index f847f514f78e..6dfb856327bb 100644
--- a/include/linux/decompress/generic.h
+++ b/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
diff --git a/init/do_mounts_rd.c b/init/do_mounts_rd.c
index 9c9d7dbcf9ca..a06ed4f92e0e 100644
--- a/init/do_mounts_rd.c
+++ b/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 */
diff --git a/init/initramfs.c b/init/initramfs.c
index a3ba91cdab89..2f42984e5582 100644
--- a/init/initramfs.c
+++ b/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;
diff --git a/lib/Makefile b/lib/Makefile
index d9ac5a414fa7..790de7c25d0d 100644
--- a/lib/Makefile
+++ b/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
diff --git a/lib/decompress.c b/lib/decompress.c
new file mode 100644
index 000000000000..edac55cc7823
--- /dev/null
+++ b/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;
+}