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3ebe12439b
This implements the API defined in <linux/decompress/generic.h> which is used for kernel, initramfs, and initrd decompression. This patch together with the first patch is enough for XZ-compressed initramfs and initrd; XZ-compressed kernel will need arch-specific changes. The buffering requirements described in decompress_unxz.c are stricter than with gzip, so the relevant changes should be done to the arch-specific code when adding support for XZ-compressed kernel. Similarly, the heap size in arch-specific pre-boot code may need to be increased (30 KiB is enough). The XZ decompressor needs memmove(), memeq() (memcmp() == 0), and memzero() (memset(ptr, 0, size)), which aren't available in all arch-specific pre-boot environments. I'm including simple versions in decompress_unxz.c, but a cleaner solution would naturally be nicer. Signed-off-by: Lasse Collin <lasse.collin@tukaani.org> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Alain Knaff <alain@knaff.lu> Cc: Albin Tonnerre <albin.tonnerre@free-electrons.com> Cc: Phillip Lougher <phillip@lougher.demon.co.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
65 lines
1.3 KiB
C
65 lines
1.3 KiB
C
/*
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* decompress.c
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*
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* Detect the decompression method based on magic number
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*/
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#include <linux/decompress/generic.h>
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#include <linux/decompress/bunzip2.h>
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#include <linux/decompress/unlzma.h>
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#include <linux/decompress/unxz.h>
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#include <linux/decompress/inflate.h>
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#include <linux/decompress/unlzo.h>
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#include <linux/types.h>
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#include <linux/string.h>
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#ifndef CONFIG_DECOMPRESS_GZIP
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# define gunzip NULL
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#endif
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#ifndef CONFIG_DECOMPRESS_BZIP2
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# define bunzip2 NULL
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#endif
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#ifndef CONFIG_DECOMPRESS_LZMA
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# define unlzma NULL
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#endif
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#ifndef CONFIG_DECOMPRESS_XZ
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# define unxz NULL
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#endif
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#ifndef CONFIG_DECOMPRESS_LZO
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# define unlzo NULL
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#endif
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static const struct compress_format {
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unsigned char magic[2];
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const char *name;
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decompress_fn decompressor;
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} compressed_formats[] = {
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{ {037, 0213}, "gzip", gunzip },
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{ {037, 0236}, "gzip", gunzip },
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{ {0x42, 0x5a}, "bzip2", bunzip2 },
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{ {0x5d, 0x00}, "lzma", unlzma },
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{ {0xfd, 0x37}, "xz", unxz },
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{ {0x89, 0x4c}, "lzo", unlzo },
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{ {0, 0}, NULL, NULL }
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};
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decompress_fn decompress_method(const unsigned char *inbuf, int len,
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const char **name)
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{
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const struct compress_format *cf;
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if (len < 2)
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return NULL; /* Need at least this much... */
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for (cf = compressed_formats; cf->name; cf++) {
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if (!memcmp(inbuf, cf->magic, 2))
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break;
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}
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if (name)
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*name = cf->name;
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return cf->decompressor;
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}
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