[linux.git] / lib / decompress_unxz.c

/*
 * Wrapper for decompressing XZ-compressed kernel, initramfs, and initrd
 *
 * Author: Lasse Collin <[email protected]>
 *
 * This file has been put into the public domain.
 * You can do whatever you want with this file.
 */

/*
 * Important notes about in-place decompression
 *
 * At least on x86, the kernel is decompressed in place: the compressed data
 * is placed to the end of the output buffer, and the decompressor overwrites
 * most of the compressed data. There must be enough safety margin to
 * guarantee that the write position is always behind the read position.
 *
 * The safety margin for XZ with LZMA2 or BCJ+LZMA2 is calculated below.
 * Note that the margin with XZ is bigger than with Deflate (gzip)!
 *
 * The worst case for in-place decompression is that the beginning of
 * the file is compressed extremely well, and the rest of the file is
 * uncompressible. Thus, we must look for worst-case expansion when the
 * compressor is encoding uncompressible data.
 *
 * The structure of the .xz file in case of a compressed kernel is as follows.
 * Sizes (as bytes) of the fields are in parenthesis.
 *
 *    Stream Header (12)
 *    Block Header:
 *      Block Header (8-12)
 *      Compressed Data (N)
 *      Block Padding (0-3)
 *      CRC32 (4)
 *    Index (8-20)
 *    Stream Footer (12)
 *
 * Normally there is exactly one Block, but let's assume that there are
 * 2-4 Blocks just in case. Because Stream Header and also Block Header
 * of the first Block don't make the decompressor produce any uncompressed
 * data, we can ignore them from our calculations. Block Headers of possible
 * additional Blocks have to be taken into account still. With these
 * assumptions, it is safe to assume that the total header overhead is
 * less than 128 bytes.
 *
 * Compressed Data contains LZMA2 or BCJ+LZMA2 encoded data. Since BCJ
 * doesn't change the size of the data, it is enough to calculate the
 * safety margin for LZMA2.
 *
 * LZMA2 stores the data in chunks. Each chunk has a header whose size is
 * a maximum of 6 bytes, but to get round 2^n numbers, let's assume that
 * the maximum chunk header size is 8 bytes. After the chunk header, there
 * may be up to 64 KiB of actual payload in the chunk. Often the payload is
 * quite a bit smaller though; to be safe, let's assume that an average
 * chunk has only 32 KiB of payload.
 *
 * The maximum uncompressed size of the payload is 2 MiB. The minimum
 * uncompressed size of the payload is in practice never less than the
 * payload size itself. The LZMA2 format would allow uncompressed size
 * to be less than the payload size, but no sane compressor creates such
 * files. LZMA2 supports storing uncompressible data in uncompressed form,
 * so there's never a need to create payloads whose uncompressed size is
 * smaller than the compressed size.
 *
 * The assumption, that the uncompressed size of the payload is never
 * smaller than the payload itself, is valid only when talking about
 * the payload as a whole. It is possible that the payload has parts where
 * the decompressor consumes more input than it produces output. Calculating
 * the worst case for this would be tricky. Instead of trying to do that,
 * let's simply make sure that the decompressor never overwrites any bytes
 * of the payload which it is currently reading.
 *
 * Now we have enough information to calculate the safety margin. We need
 *   - 128 bytes for the .xz file format headers;
 *   - 8 bytes per every 32 KiB of uncompressed size (one LZMA2 chunk header
 *     per chunk, each chunk having average payload size of 32 KiB); and
 *   - 64 KiB (biggest possible LZMA2 chunk payload size) to make sure that
 *     the decompressor never overwrites anything from the LZMA2 chunk
 *     payload it is currently reading.
 *
 * We get the following formula:
 *
 *    safety_margin = 128 + uncompressed_size * 8 / 32768 + 65536
 *                  = 128 + (uncompressed_size >> 12) + 65536
 *
 * For comparison, according to arch/x86/boot/compressed/misc.c, the
 * equivalent formula for Deflate is this:
 *
 *    safety_margin = 18 + (uncompressed_size >> 12) + 32768
 *
 * Thus, when updating Deflate-only in-place kernel decompressor to
 * support XZ, the fixed overhead has to be increased from 18+32768 bytes
 * to 128+65536 bytes.
 */

/*
 * STATIC is defined to "static" if we are being built for kernel
 * decompression (pre-boot code). <linux/decompress/mm.h> will define
 * STATIC to empty if it wasn't already defined. Since we will need to
 * know later if we are being used for kernel decompression, we define
 * XZ_PREBOOT here.
 */
#ifdef STATIC
#	define XZ_PREBOOT
#endif
#ifdef __KERNEL__
#	include <linux/decompress/mm.h>
#endif
#define XZ_EXTERN STATIC

#ifndef XZ_PREBOOT
#	include <linux/slab.h>
#	include <linux/xz.h>
#else
/*
 * Use the internal CRC32 code instead of kernel's CRC32 module, which
 * is not available in early phase of booting.
 */
#define XZ_INTERNAL_CRC32 1

/*
 * For boot time use, we enable only the BCJ filter of the current
 * architecture or none if no BCJ filter is available for the architecture.
 */
#ifdef CONFIG_X86
#	define XZ_DEC_X86
#endif
#ifdef CONFIG_PPC
#	define XZ_DEC_POWERPC
#endif
#ifdef CONFIG_ARM
#	define XZ_DEC_ARM
#endif
#ifdef CONFIG_IA64
#	define XZ_DEC_IA64
#endif
#ifdef CONFIG_SPARC
#	define XZ_DEC_SPARC
#endif

/*
 * This will get the basic headers so that memeq() and others
 * can be defined.
 */
#include "xz/xz_private.h"

/*
 * Replace the normal allocation functions with the versions from
 * <linux/decompress/mm.h>. vfree() needs to support vfree(NULL)
 * when XZ_DYNALLOC is used, but the pre-boot free() doesn't support it.
 * Workaround it here because the other decompressors don't need it.
 */
#undef kmalloc
#undef kfree
#undef vmalloc
#undef vfree
#define kmalloc(size, flags) malloc(size)
#define kfree(ptr) free(ptr)
#define vmalloc(size) malloc(size)
#define vfree(ptr) do { if (ptr != NULL) free(ptr); } while (0)

/*
 * FIXME: Not all basic memory functions are provided in architecture-specific
 * files (yet). We define our own versions here for now, but this should be
 * only a temporary solution.
 *
 * memeq and memzero are not used much and any remotely sane implementation
 * is fast enough. memcpy/memmove speed matters in multi-call mode, but
 * the kernel image is decompressed in single-call mode, in which only
 * memcpy speed can matter and only if there is a lot of uncompressible data
 * (LZMA2 stores uncompressible chunks in uncompressed form). Thus, the
 * functions below should just be kept small; it's probably not worth
 * optimizing for speed.
 */

#ifndef memeq
static bool memeq(const void *a, const void *b, size_t size)
{
	const uint8_t *x = a;
	const uint8_t *y = b;
	size_t i;

	for (i = 0; i < size; ++i)
		if (x[i] != y[i])
			return false;

	return true;
}
#endif

#ifndef memzero
static void memzero(void *buf, size_t size)
{
	uint8_t *b = buf;
	uint8_t *e = b + size;

	while (b != e)
		*b++ = '\0';
}
#endif

#ifndef memmove
/* Not static to avoid a conflict with the prototype in the Linux headers. */
void *memmove(void *dest, const void *src, size_t size)
{
	uint8_t *d = dest;
	const uint8_t *s = src;
	size_t i;

	if (d < s) {
		for (i = 0; i < size; ++i)
			d[i] = s[i];
	} else if (d > s) {
		i = size;
		while (i-- > 0)
			d[i] = s[i];
	}

	return dest;
}
#endif

/*
 * Since we need memmove anyway, would use it as memcpy too.
 * Commented out for now to avoid breaking things.
 */
/*
#ifndef memcpy
#	define memcpy memmove
#endif
*/

#include "xz/xz_crc32.c"
#include "xz/xz_dec_stream.c"
#include "xz/xz_dec_lzma2.c"
#include "xz/xz_dec_bcj.c"

#endif /* XZ_PREBOOT */

/* Size of the input and output buffers in multi-call mode */
#define XZ_IOBUF_SIZE 4096

/*
 * This function implements the API defined in <linux/decompress/generic.h>.
 *
 * This wrapper will automatically choose single-call or multi-call mode
 * of the native XZ decoder API. The single-call mode can be used only when
 * both input and output buffers are available as a single chunk, i.e. when
 * fill() and flush() won't be used.
 */
STATIC int INIT unxz(unsigned char *in, long in_size,
		     long (*fill)(void *dest, unsigned long size),
		     long (*flush)(void *src, unsigned long size),
		     unsigned char *out, long *in_used,
		     void (*error)(char *x))
{
	struct xz_buf b;
	struct xz_dec *s;
	enum xz_ret ret;
	bool must_free_in = false;

#if XZ_INTERNAL_CRC32
	xz_crc32_init();
#endif

	if (in_used != NULL)
		*in_used = 0;

	if (fill == NULL && flush == NULL)
		s = xz_dec_init(XZ_SINGLE, 0);
	else
		s = xz_dec_init(XZ_DYNALLOC, (uint32_t)-1);

	if (s == NULL)
		goto error_alloc_state;

	if (flush == NULL) {
		b.out = out;
		b.out_size = (size_t)-1;
	} else {
		b.out_size = XZ_IOBUF_SIZE;
		b.out = malloc(XZ_IOBUF_SIZE);
		if (b.out == NULL)
			goto error_alloc_out;
	}

	if (in == NULL) {
		must_free_in = true;
		in = malloc(XZ_IOBUF_SIZE);
		if (in == NULL)
			goto error_alloc_in;
	}

	b.in = in;
	b.in_pos = 0;
	b.in_size = in_size;
	b.out_pos = 0;

	if (fill == NULL && flush == NULL) {
		ret = xz_dec_run(s, &b);
	} else {
		do {
			if (b.in_pos == b.in_size && fill != NULL) {
				if (in_used != NULL)
					*in_used += b.in_pos;

				b.in_pos = 0;

				in_size = fill(in, XZ_IOBUF_SIZE);
				if (in_size < 0) {
					/*
					 * This isn't an optimal error code
					 * but it probably isn't worth making
					 * a new one either.
					 */
					ret = XZ_BUF_ERROR;
					break;
				}

				b.in_size = in_size;
			}

			ret = xz_dec_run(s, &b);

			if (flush != NULL && (b.out_pos == b.out_size
					|| (ret != XZ_OK && b.out_pos > 0))) {
				/*
				 * Setting ret here may hide an error
				 * returned by xz_dec_run(), but probably
				 * it's not too bad.
				 */
				if (flush(b.out, b.out_pos) != (long)b.out_pos)
					ret = XZ_BUF_ERROR;

				b.out_pos = 0;
			}
		} while (ret == XZ_OK);

		if (must_free_in)
			free(in);

		if (flush != NULL)
			free(b.out);
	}

	if (in_used != NULL)
		*in_used += b.in_pos;

	xz_dec_end(s);

	switch (ret) {
	case XZ_STREAM_END:
		return 0;

	case XZ_MEM_ERROR:
		/* This can occur only in multi-call mode. */
		error("XZ decompressor ran out of memory");
		break;

	case XZ_FORMAT_ERROR:
		error("Input is not in the XZ format (wrong magic bytes)");
		break;

	case XZ_OPTIONS_ERROR:
		error("Input was encoded with settings that are not "
				"supported by this XZ decoder");
		break;

	case XZ_DATA_ERROR:
	case XZ_BUF_ERROR:
		error("XZ-compressed data is corrupt");
		break;

	default:
		error("Bug in the XZ decompressor");
		break;
	}

	return -1;

error_alloc_in:
	if (flush != NULL)
		free(b.out);

error_alloc_out:
	xz_dec_end(s);

error_alloc_state:
	error("XZ decompressor ran out of memory");
	return -1;
}

/*
 * This macro is used by architecture-specific files to decompress
 * the kernel image.
 */
#ifdef XZ_PREBOOT
STATIC int INIT __decompress(unsigned char *buf, long len,
			   long (*fill)(void*, unsigned long),
			   long (*flush)(void*, unsigned long),
			   unsigned char *out_buf, long olen,
			   long *pos,
			   void (*error)(char *x))
{
	return unxz(buf, len, fill, flush, out_buf, pos, error);
}
#endif
Commit	Line	Data
3ebe1243 LC	1	/*
	2	* Wrapper for decompressing XZ-compressed kernel, initramfs, and initrd
	3	*
	4	* Author: Lasse Collin <[email protected]>
	5	*
	6	* This file has been put into the public domain.
	7	* You can do whatever you want with this file.
	8	*/
	9
	10	/*
	11	* Important notes about in-place decompression
	12	*
	13	* At least on x86, the kernel is decompressed in place: the compressed data
	14	* is placed to the end of the output buffer, and the decompressor overwrites
	15	* most of the compressed data. There must be enough safety margin to
	16	* guarantee that the write position is always behind the read position.
	17	*
	18	* The safety margin for XZ with LZMA2 or BCJ+LZMA2 is calculated below.
	19	* Note that the margin with XZ is bigger than with Deflate (gzip)!
	20	*
	21	* The worst case for in-place decompression is that the beginning of
	22	* the file is compressed extremely well, and the rest of the file is
	23	* uncompressible. Thus, we must look for worst-case expansion when the
	24	* compressor is encoding uncompressible data.
	25	*
05911c5d	26	* The structure of the .xz file in case of a compressed kernel is as follows.
3ebe1243 LC	27	* Sizes (as bytes) of the fields are in parenthesis.
	28	*
	29	* Stream Header (12)
	30	* Block Header:
	31	* Block Header (8-12)
	32	* Compressed Data (N)
	33	* Block Padding (0-3)
	34	* CRC32 (4)
	35	* Index (8-20)
	36	* Stream Footer (12)
	37	*
	38	* Normally there is exactly one Block, but let's assume that there are
	39	* 2-4 Blocks just in case. Because Stream Header and also Block Header
	40	* of the first Block don't make the decompressor produce any uncompressed
	41	* data, we can ignore them from our calculations. Block Headers of possible
	42	* additional Blocks have to be taken into account still. With these
	43	* assumptions, it is safe to assume that the total header overhead is
	44	* less than 128 bytes.
	45	*
	46	* Compressed Data contains LZMA2 or BCJ+LZMA2 encoded data. Since BCJ
	47	* doesn't change the size of the data, it is enough to calculate the
	48	* safety margin for LZMA2.
	49	*
	50	* LZMA2 stores the data in chunks. Each chunk has a header whose size is
	51	* a maximum of 6 bytes, but to get round 2^n numbers, let's assume that
	52	* the maximum chunk header size is 8 bytes. After the chunk header, there
	53	* may be up to 64 KiB of actual payload in the chunk. Often the payload is
	54	* quite a bit smaller though; to be safe, let's assume that an average
	55	* chunk has only 32 KiB of payload.
	56	*
	57	* The maximum uncompressed size of the payload is 2 MiB. The minimum
	58	* uncompressed size of the payload is in practice never less than the
	59	* payload size itself. The LZMA2 format would allow uncompressed size
	60	* to be less than the payload size, but no sane compressor creates such
	61	* files. LZMA2 supports storing uncompressible data in uncompressed form,
	62	* so there's never a need to create payloads whose uncompressed size is
	63	* smaller than the compressed size.
	64	*
	65	* The assumption, that the uncompressed size of the payload is never
	66	* smaller than the payload itself, is valid only when talking about
	67	* the payload as a whole. It is possible that the payload has parts where
	68	* the decompressor consumes more input than it produces output. Calculating
	69	* the worst case for this would be tricky. Instead of trying to do that,
	70	* let's simply make sure that the decompressor never overwrites any bytes
	71	* of the payload which it is currently reading.
	72	*
	73	* Now we have enough information to calculate the safety margin. We need
	74	* - 128 bytes for the .xz file format headers;
	75	* - 8 bytes per every 32 KiB of uncompressed size (one LZMA2 chunk header
	76	* per chunk, each chunk having average payload size of 32 KiB); and
	77	* - 64 KiB (biggest possible LZMA2 chunk payload size) to make sure that
	78	* the decompressor never overwrites anything from the LZMA2 chunk
	79	* payload it is currently reading.
	80	*
	81	* We get the following formula:
	82	*
	83	* safety_margin = 128 + uncompressed_size * 8 / 32768 + 65536
	84	* = 128 + (uncompressed_size >> 12) + 65536
	85	*
25985edc	86	* For comparison, according to arch/x86/boot/compressed/misc.c, the
3ebe1243 LC	87	* equivalent formula for Deflate is this:
	88	*
	89	* safety_margin = 18 + (uncompressed_size >> 12) + 32768
	90	*
	91	* Thus, when updating Deflate-only in-place kernel decompressor to
	92	* support XZ, the fixed overhead has to be increased from 18+32768 bytes
	93	* to 128+65536 bytes.
	94	*/
	95
	96	/*
	97	* STATIC is defined to "static" if we are being built for kernel
	98	* decompression (pre-boot code). <linux/decompress/mm.h> will define
	99	* STATIC to empty if it wasn't already defined. Since we will need to
	100	* know later if we are being used for kernel decompression, we define
	101	* XZ_PREBOOT here.
	102	*/
	103	#ifdef STATIC
	104	# define XZ_PREBOOT
	105	#endif
	106	#ifdef __KERNEL__
	107	# include <linux/decompress/mm.h>
	108	#endif
	109	#define XZ_EXTERN STATIC
	110
	111	#ifndef XZ_PREBOOT
	112	# include <linux/slab.h>
	113	# include <linux/xz.h>
	114	#else
	115	/*
	116	* Use the internal CRC32 code instead of kernel's CRC32 module, which
	117	* is not available in early phase of booting.
	118	*/
	119	#define XZ_INTERNAL_CRC32 1
	120
	121	/*
	122	* For boot time use, we enable only the BCJ filter of the current
	123	* architecture or none if no BCJ filter is available for the architecture.
	124	*/
	125	#ifdef CONFIG_X86
	126	# define XZ_DEC_X86
	127	#endif
	128	#ifdef CONFIG_PPC
	129	# define XZ_DEC_POWERPC
	130	#endif
	131	#ifdef CONFIG_ARM
	132	# define XZ_DEC_ARM
	133	#endif
	134	#ifdef CONFIG_IA64
	135	# define XZ_DEC_IA64
	136	#endif
	137	#ifdef CONFIG_SPARC
	138	# define XZ_DEC_SPARC
	139	#endif
	140
	141	/*
	142	* This will get the basic headers so that memeq() and others
	143	* can be defined.
	144	*/
	145	#include "xz/xz_private.h"
	146
	147	/*
	148	* Replace the normal allocation functions with the versions from
	149	* <linux/decompress/mm.h>. vfree() needs to support vfree(NULL)
	150	* when XZ_DYNALLOC is used, but the pre-boot free() doesn't support it.
151	* Workaround it here because the other decompressors don't need it.
152	*/
153	#undef kmalloc
154	#undef kfree
155	#undef vmalloc
156	#undef vfree
157	#define kmalloc(size, flags) malloc(size)
158	#define kfree(ptr) free(ptr)
159	#define vmalloc(size) malloc(size)
160	#define vfree(ptr) do { if (ptr != NULL) free(ptr); } while (0)
161
162	/*
163	* FIXME: Not all basic memory functions are provided in architecture-specific
164	* files (yet). We define our own versions here for now, but this should be
165	* only a temporary solution.
166	*
167	* memeq and memzero are not used much and any remotely sane implementation
168	* is fast enough. memcpy/memmove speed matters in multi-call mode, but
169	* the kernel image is decompressed in single-call mode, in which only
170	* memcpy speed can matter and only if there is a lot of uncompressible data
171	* (LZMA2 stores uncompressible chunks in uncompressed form). Thus, the
172	* functions below should just be kept small; it's probably not worth
173	* optimizing for speed.
174	*/
175
176	#ifndef memeq
177	static bool memeq(const void a, const void b, size_t size)
178	{
179	const uint8_t *x = a;
180	const uint8_t *y = b;
181	size_t i;
182
183	for (i = 0; i < size; ++i)
184	if (x[i] != y[i])
185	return false;
186
187	return true;
188	}
189	#endif
190
191	#ifndef memzero
192	static void memzero(void *buf, size_t size)
193	{
194	uint8_t *b = buf;
195	uint8_t *e = b + size;
196
197	while (b != e)
198	*b++ = '\0';
199	}
200	#endif
201
202	#ifndef memmove
203	/* Not static to avoid a conflict with the prototype in the Linux headers. */
204	void memmove(void dest, const void *src, size_t size)
205	{
206	uint8_t *d = dest;
207	const uint8_t *s = src;
208	size_t i;
209
210	if (d < s) {
211	for (i = 0; i < size; ++i)
212	d[i] = s[i];
213	} else if (d > s) {
214	i = size;
215	while (i-- > 0)
216	d[i] = s[i];
217	}
218
219	return dest;
220	}
221	#endif
222
223	/*
224	* Since we need memmove anyway, would use it as memcpy too.
225	* Commented out for now to avoid breaking things.
226	*/
227	/*
228	#ifndef memcpy
229	# define memcpy memmove
230	#endif
231	*/
232
233	#include "xz/xz_crc32.c"
234	#include "xz/xz_dec_stream.c"
235	#include "xz/xz_dec_lzma2.c"
236	#include "xz/xz_dec_bcj.c"
237
238	#endif /* XZ_PREBOOT */
239
240	/* Size of the input and output buffers in multi-call mode */
241	#define XZ_IOBUF_SIZE 4096
242
243	/*
244	* This function implements the API defined in <linux/decompress/generic.h>.
245	*
246	* This wrapper will automatically choose single-call or multi-call mode
247	* of the native XZ decoder API. The single-call mode can be used only when
248	* both input and output buffers are available as a single chunk, i.e. when
249	* fill() and flush() won't be used.
250	*/
d97b07c5 YL	251	STATIC int INIT unxz(unsigned char *in, long in_size,
	252	long (fill)(void dest, unsigned long size),
	253	long (flush)(void src, unsigned long size),
	254	unsigned char out, long in_used,
3ebe1243 LC	255	void (error)(char x))
	256	{
	257	struct xz_buf b;
	258	struct xz_dec *s;
	259	enum xz_ret ret;
	260	bool must_free_in = false;
	261
	262	#if XZ_INTERNAL_CRC32
	263	xz_crc32_init();
	264	#endif
	265
	266	if (in_used != NULL)
	267	*in_used = 0;
	268
	269	if (fill == NULL && flush == NULL)
	270	s = xz_dec_init(XZ_SINGLE, 0);
	271	else
	272	s = xz_dec_init(XZ_DYNALLOC, (uint32_t)-1);
	273
	274	if (s == NULL)
	275	goto error_alloc_state;
	276
	277	if (flush == NULL) {
	278	b.out = out;
	279	b.out_size = (size_t)-1;
	280	} else {
	281	b.out_size = XZ_IOBUF_SIZE;
	282	b.out = malloc(XZ_IOBUF_SIZE);
	283	if (b.out == NULL)
	284	goto error_alloc_out;
	285	}
	286
	287	if (in == NULL) {
	288	must_free_in = true;
	289	in = malloc(XZ_IOBUF_SIZE);
	290	if (in == NULL)
	291	goto error_alloc_in;
	292	}
	293
	294	b.in = in;
	295	b.in_pos = 0;
	296	b.in_size = in_size;
	297	b.out_pos = 0;
	298
	299	if (fill == NULL && flush == NULL) {
	300	ret = xz_dec_run(s, &b);
	301	} else {
	302	do {
	303	if (b.in_pos == b.in_size && fill != NULL) {
	304	if (in_used != NULL)
	305	*in_used += b.in_pos;
	306
	307	b.in_pos = 0;
	308
	309	in_size = fill(in, XZ_IOBUF_SIZE);
	310	if (in_size < 0) {
	311	/*
	312	* This isn't an optimal error code
	313	* but it probably isn't worth making
	314	* a new one either.
	315	*/
	316	ret = XZ_BUF_ERROR;
	317	break;
	318	}
319
320	b.in_size = in_size;
321	}
322
323	ret = xz_dec_run(s, &b);
324
325	if (flush != NULL && (b.out_pos == b.out_size
326	\|\| (ret != XZ_OK && b.out_pos > 0))) {
327	/*
328	* Setting ret here may hide an error
329	* returned by xz_dec_run(), but probably
330	* it's not too bad.
331	*/
d97b07c5	332	if (flush(b.out, b.out_pos) != (long)b.out_pos)
3ebe1243 LC	333	ret = XZ_BUF_ERROR;
	334
	335	b.out_pos = 0;
	336	}
	337	} while (ret == XZ_OK);
	338
	339	if (must_free_in)
	340	free(in);
	341
	342	if (flush != NULL)
	343	free(b.out);
	344	}
	345
	346	if (in_used != NULL)
	347	*in_used += b.in_pos;
	348
	349	xz_dec_end(s);
	350
	351	switch (ret) {
	352	case XZ_STREAM_END:
	353	return 0;
	354
	355	case XZ_MEM_ERROR:
	356	/* This can occur only in multi-call mode. */
	357	error("XZ decompressor ran out of memory");
	358	break;
	359
	360	case XZ_FORMAT_ERROR:
	361	error("Input is not in the XZ format (wrong magic bytes)");
	362	break;
	363
	364	case XZ_OPTIONS_ERROR:
	365	error("Input was encoded with settings that are not "
	366	"supported by this XZ decoder");
	367	break;
	368
	369	case XZ_DATA_ERROR:
	370	case XZ_BUF_ERROR:
	371	error("XZ-compressed data is corrupt");
	372	break;
	373
	374	default:
	375	error("Bug in the XZ decompressor");
	376	break;
	377	}
	378
	379	return -1;
	380
	381	error_alloc_in:
	382	if (flush != NULL)
	383	free(b.out);
	384
	385	error_alloc_out:
	386	xz_dec_end(s);
	387
	388	error_alloc_state:
	389	error("XZ decompressor ran out of memory");
	390	return -1;
	391	}
	392
	393	/*
	394	* This macro is used by architecture-specific files to decompress
	395	* the kernel image.
	396	*/
2d3862d2 YL	397	#ifdef XZ_PREBOOT
	398	STATIC int INIT __decompress(unsigned char *buf, long len,
	399	long (fill)(void, unsigned long),
	400	long (flush)(void, unsigned long),
	401	unsigned char *out_buf, long olen,
	402	long *pos,
	403	void (error)(char x))
	404	{
	405	return unxz(buf, len, fill, flush, out_buf, pos, error);
	406	}
	407	#endif