Путь: Toys/Pending, команды версии: Ver.4 Ver.9 xzcat Комментарии в файле xzcat.c :
Исходный текст в файле xzcat.c #define FOR_xzcat
#include "toys.h"
// BEGIN xz.h
/**
* enum xz_ret - Return codes
* @XZ_OK: Everything is OK so far. More input or more
* output space is required to continue.
* @XZ_STREAM_END: Operation finished successfully.
* @XZ_UNSUPPORTED_CHECK: Integrity check type is not supported. Decoding
* is still possible in multi-call mode by simply
* calling xz_dec_run() again.
* Note that this return value is used only if
* XZ_DEC_ANY_CHECK was defined at build time,
* which is not used in the kernel. Unsupported
* check types return XZ_OPTIONS_ERROR if
* XZ_DEC_ANY_CHECK was not defined at build time.
* @XZ_MEM_ERROR: Allocating memory failed. The amount of memory
* that was tried to be allocated was no more than the
* dict_max argument given to xz_dec_init().
* @XZ_MEMLIMIT_ERROR: A bigger LZMA2 dictionary would be needed than
* allowed by the dict_max argument given to
* xz_dec_init().
* @XZ_FORMAT_ERROR: File format was not recognized (wrong magic
* bytes).
* @XZ_OPTIONS_ERROR: This implementation doesn't support the requested
* compression options. In the decoder this means
* that the header CRC32 matches, but the header
* itself specifies something that we don't support.
* @XZ_DATA_ERROR: Compressed data is corrupt.
* @XZ_BUF_ERROR: Cannot make any progress. Details are slightly
* different between multi-call and single-call
* mode; more information below.
*
* XZ_BUF_ERROR is returned when two consecutive calls to XZ code cannot
* consume any input and cannot produce any new output. This happens when
* there is no new input available, or the output buffer is full while at
* least one output byte is still pending. Assuming your code is not buggy,
* you can get this error only when decoding a compressed stream that is
* truncated or otherwise corrupt.
*/
enum xz_ret {
XZ_OK,
XZ_STREAM_END,
XZ_UNSUPPORTED_CHECK,
XZ_MEM_ERROR,
XZ_MEMLIMIT_ERROR,
XZ_FORMAT_ERROR,
XZ_OPTIONS_ERROR,
XZ_DATA_ERROR,
XZ_BUF_ERROR
};
/**
* struct xz_buf - Passing input and output buffers to XZ code
* @in: Beginning of the input buffer. This may be NULL if and only
* if in_pos is equal to in_size.
* @in_pos: Current position in the input buffer. This must not exceed
* in_size.
* @in_size: Size of the input buffer
* @out: Beginning of the output buffer. This may be NULL if and only
* if out_pos is equal to out_size.
* @out_pos: Current position in the output buffer. This must not exceed
* out_size.
* @out_size: Size of the output buffer
*
* Only the contents of the output buffer from out[out_pos] onward, and
* the variables in_pos and out_pos are modified by the XZ code.
*/
struct xz_buf {
const uint8_t *in;
size_t in_pos;
size_t in_size;
uint8_t *out;
size_t out_pos;
size_t out_size;
};
/**
* struct xz_dec - Opaque type to hold the XZ decoder state
*/
struct xz_dec;
/**
* xz_dec_init() - Allocate and initialize a XZ decoder state
* @mode: Operation mode
* @dict_max: Maximum size of the LZMA2 dictionary (history buffer) for
* multi-call decoding. LZMA2 dictionary is always 2^n bytes
* or 2^n + 2^(n-1) bytes (the latter sizes are less common
* in practice), so other values for dict_max don't make sense.
* In the kernel, dictionary sizes of 64 KiB, 128 KiB, 256 KiB,
* 512 KiB, and 1 MiB are probably the only reasonable values,
* except for kernel and initramfs images where a bigger
* dictionary can be fine and useful.
*
* dict_max specifies the maximum allowed dictionary size that xz_dec_run()
* may allocate once it has parsed the dictionary size from the stream
* headers. This way excessive allocations can be avoided while still
* limiting the maximum memory usage to a sane value to prevent running the
* system out of memory when decompressing streams from untrusted sources.
*
* On success, xz_dec_init() returns a pointer to struct xz_dec, which is
* ready to be used with xz_dec_run(). If memory allocation fails,
* xz_dec_init() returns NULL.
*/
struct xz_dec *xz_dec_init(uint32_t dict_max);
/**
* xz_dec_run() - Run the XZ decoder
* @s: Decoder state allocated using xz_dec_init()
* @b: Input and output buffers
*
* The possible return values depend on build options and operation mode.
* See enum xz_ret for details.
*
* Note that if an error occurs in single-call mode (return value is not
* XZ_STREAM_END), b->in_pos and b->out_pos are not modified and the
* contents of the output buffer from b->out[b->out_pos] onward are
* undefined. This is true even after XZ_BUF_ERROR, because with some filter
* chains, there may be a second pass over the output buffer, and this pass
* cannot be properly done if the output buffer is truncated. Thus, you
* cannot give the single-call decoder a too small buffer and then expect to
* get that amount valid data from the beginning of the stream. You must use
* the multi-call decoder if you don't want to uncompress the whole stream.
*/
enum xz_ret xz_dec_run(struct xz_dec *s, struct xz_buf *b);
/**
* xz_dec_reset() - Reset an already allocated decoder state
* @s: Decoder state allocated using xz_dec_init()
*
* This function can be used to reset the multi-call decoder state without
* freeing and reallocating memory with xz_dec_end() and xz_dec_init().
*
* In single-call mode, xz_dec_reset() is always called in the beginning of
* xz_dec_run(). Thus, explicit call to xz_dec_reset() is useful only in
* multi-call mode.
*/
void xz_dec_reset(struct xz_dec *s);
/**
* xz_dec_end() - Free the memory allocated for the decoder state
* @s: Decoder state allocated using xz_dec_init(). If s is NULL,
* this function does nothing.
*/
void xz_dec_end(struct xz_dec *s);
/*
* Update CRC32 value using the polynomial from IEEE-802.3. To start a new
* calculation, the third argument must be zero. To continue the calculation,
* the previously returned value is passed as the third argument.
*/
static uint32_t xz_crc32_table[256];
uint32_t xz_crc32(const uint8_t *buf, size_t size, uint32_t crc)
{
crc = ~crc;
while (size != 0) {
crc = xz_crc32_table[*buf++ ^ (crc & 0xFF)] ^ (crc >> 8);
--size;
}
return ~crc;
}
static uint64_t xz_crc64_table[256];
// END xz.h
static uint8_t in[BUFSIZ];
static uint8_t out[BUFSIZ];
void do_xzcat(int fd, char *name)
{
struct xz_buf b;
struct xz_dec *s;
enum xz_ret ret;
const char *msg;
crc_init(xz_crc32_table, 1);
const uint64_t poly = 0xC96C5795D7870F42ULL;
uint32_t i;
uint32_t j;
uint64_t r;
/* initialize CRC64 table*/
for (i = 0; i < 256; ++i) {
r = i;
for (j = 0; j < 8; ++j)
r = (r >> 1) ^ (poly & ~((r & 1) - 1));
xz_crc64_table[i] = r;
}
/*
* Support up to 64 MiB dictionary. The actually needed memory
* is allocated once the headers have been parsed.
*/
s = xz_dec_init(1 << 26);
if (s == NULL) {
msg = "Memory allocation failed\n";
goto error;
}
b.in = in;
b.in_pos = 0;
b.in_size = 0;
b.out = out;
b.out_pos = 0;
b.out_size = BUFSIZ;
for (;;) {
if (b.in_pos == b.in_size) {
b.in_size = read(fd, in, sizeof(in));
b.in_pos = 0;
}
ret = xz_dec_run(s, &b);
if (b.out_pos == sizeof(out)) {
if (fwrite(out, 1, b.out_pos, stdout) != b.out_pos) {
msg = "Write error\n";
goto error;
}
b.out_pos = 0;
}
if (ret == XZ_OK)
continue;
if (ret == XZ_UNSUPPORTED_CHECK)
continue;
if (fwrite(out, 1, b.out_pos, stdout) != b.out_pos) {
msg = "Write error\n";
goto error;
}
switch (ret) {
case XZ_STREAM_END:
xz_dec_end(s);
return;
case XZ_MEM_ERROR:
msg = "Memory allocation failed\n";
goto error;
case XZ_MEMLIMIT_ERROR:
msg = "Memory usage limit reached\n";
goto error;
case XZ_FORMAT_ERROR:
msg = "Not a .xz file\n";
goto error;
case XZ_OPTIONS_ERROR:
msg = "Unsupported options in the .xz headers\n";
goto error;
case XZ_DATA_ERROR:
case XZ_BUF_ERROR:
msg = "File is corrupt\n";
goto error;
default:
msg = "Bug!\n";
goto error;
}
}
error:
xz_dec_end(s);
error_exit("%s", msg);
}
void xzcat_main(void)
{
loopfiles(toys.optargs, do_xzcat);
}
// BEGIN xz_private.h
/* Uncomment as needed to enable BCJ filter decoders.
* These cost about 2.5 k when all are enabled; SPARC and IA64 make 0.7 k
* */
#define XZ_DEC_X86
#define XZ_DEC_POWERPC
#define XZ_DEC_IA64
#define XZ_DEC_ARM
#define XZ_DEC_ARMTHUMB
#define XZ_DEC_SPARC
#define memeq(a, b, size) (memcmp(a, b, size) == 0)
/* Inline functions to access unaligned unsigned 32-bit integers */
#ifndef get_unaligned_le32
static inline uint32_t get_unaligned_le32(const uint8_t *buf)
{
return (uint32_t)buf[0]
| ((uint32_t)buf[1] << 8)
| ((uint32_t)buf[2] << 16)
| ((uint32_t)buf[3] << 24);
}
#endif
#ifndef get_unaligned_be32
static inline uint32_t get_unaligned_be32(const uint8_t *buf)
{
return (uint32_t)(buf[0] << 24)
| ((uint32_t)buf[1] << 16)
| ((uint32_t)buf[2] << 8)
| (uint32_t)buf[3];
}
#endif
#ifndef put_unaligned_le32
static inline void put_unaligned_le32(uint32_t val, uint8_t *buf)
{
buf[0] = (uint8_t)val;
buf[1] = (uint8_t)(val >> 8);
buf[2] = (uint8_t)(val >> 16);
buf[3] = (uint8_t)(val >> 24);
}
#endif
#ifndef put_unaligned_be32
static inline void put_unaligned_be32(uint32_t val, uint8_t *buf)
{
buf[0] = (uint8_t)(val >> 24);
buf[1] = (uint8_t)(val >> 16);
buf[2] = (uint8_t)(val >> 8);
buf[3] = (uint8_t)val;
}
#endif
/*
* Use get_unaligned_le32() also for aligned access for simplicity. On
* little endian systems, #define get_le32(ptr) (*(const uint32_t *)(ptr))
* could save a few bytes in code size.
*/
#ifndef get_le32
# define get_le32 get_unaligned_le32
#endif
/*
* If any of the BCJ filter decoders are wanted, define XZ_DEC_BCJ.
* XZ_DEC_BCJ is used to enable generic support for BCJ decoders.
*/
#ifndef XZ_DEC_BCJ
# if defined(XZ_DEC_X86) || defined(XZ_DEC_POWERPC) \
|| defined(XZ_DEC_IA64) || defined(XZ_DEC_ARM) \
|| defined(XZ_DEC_ARM) || defined(XZ_DEC_ARMTHUMB) \
|| defined(XZ_DEC_SPARC)
# define XZ_DEC_BCJ
# endif
#endif
/*
* Allocate memory for LZMA2 decoder. xz_dec_lzma2_reset() must be used
* before calling xz_dec_lzma2_run().
*/
struct xz_dec_lzma2 *xz_dec_lzma2_create(uint32_t dict_max);
/*
* Decode the LZMA2 properties (one byte) and reset the decoder. Return
* XZ_OK on success, XZ_MEMLIMIT_ERROR if the preallocated dictionary is not
* big enough, and XZ_OPTIONS_ERROR if props indicates something that this
* decoder doesn't support.
*/
enum xz_ret xz_dec_lzma2_reset(struct xz_dec_lzma2 *s,
uint8_t props);
/* Decode raw LZMA2 stream from b->in to b->out. */
enum xz_ret xz_dec_lzma2_run(struct xz_dec_lzma2 *s,
struct xz_buf *b);
// END "xz_private.h"
/*
* Branch/Call/Jump (BCJ) filter decoders
* The rest of the code is inside this ifdef. It makes things a little more
* convenient when building without support for any BCJ filters.
*/
#ifdef XZ_DEC_BCJ
struct xz_dec_bcj {
/* Type of the BCJ filter being used */
enum {
BCJ_X86 = 4, /* x86 or x86-64 */
BCJ_POWERPC = 5, /* Big endian only */
BCJ_IA64 = 6, /* Big or little endian */
BCJ_ARM = 7, /* Little endian only */
BCJ_ARMTHUMB = 8, /* Little endian only */
BCJ_SPARC = 9 /* Big or little endian */
} type;
/*
* Return value of the next filter in the chain. We need to preserve
* this information across calls, because we must not call the next
* filter anymore once it has returned XZ_STREAM_END.
*/
enum xz_ret ret;
/*
* Absolute position relative to the beginning of the uncompressed
* data (in a single .xz Block). We care only about the lowest 32
* bits so this doesn't need to be uint64_t even with big files.
*/
uint32_t pos;
/* x86 filter state */
uint32_t x86_prev_mask;
/* Temporary space to hold the variables from struct xz_buf */
uint8_t *out;
size_t out_pos;
size_t out_size;
struct {
/* Amount of already filtered data in the beginning of buf */
size_t filtered;
/* Total amount of data currently stored in buf */
size_t size;
/*
* Buffer to hold a mix of filtered and unfiltered data. This
* needs to be big enough to hold Alignment + 2 * Look-ahead:
*
* Type Alignment Look-ahead
* x86 1 4
* PowerPC 4 0
* IA-64 16 0
* ARM 4 0
* ARM-Thumb 2 2
* SPARC 4 0
*/
uint8_t buf[16];
} temp;
};
/*
* Decode the Filter ID of a BCJ filter. This implementation doesn't
* support custom start offsets, so no decoding of Filter Properties
* is needed. Returns XZ_OK if the given Filter ID is supported.
* Otherwise XZ_OPTIONS_ERROR is returned.
*/
enum xz_ret xz_dec_bcj_reset(struct xz_dec_bcj *s, uint8_t id);
/*
* Decode raw BCJ + LZMA2 stream. This must be used only if there actually is
* a BCJ filter in the chain. If the chain has only LZMA2, xz_dec_lzma2_run()
* must be called directly.
*/
enum xz_ret xz_dec_bcj_run(struct xz_dec_bcj *s,
struct xz_dec_lzma2 *lzma2,
struct xz_buf *b);
#ifdef XZ_DEC_X86
/*
* This is used to test the most significant byte of a memory address
* in an x86 instruction.
*/
static inline int bcj_x86_test_msbyte(uint8_t b)
{
return b == 0x00 || b == 0xFF;
}
static size_t bcj_x86(struct xz_dec_bcj *s, uint8_t *buf, size_t size)
{
static const int mask_to_allowed_status[8]
= { 1,1,1,0,1,0,0,0 };
static const uint8_t mask_to_bit_num[8] = { 0, 1, 2, 2, 3, 3, 3, 3 };
size_t i;
size_t prev_pos = (size_t)-1;
uint32_t prev_mask = s->x86_prev_mask;
uint32_t src;
uint32_t dest;
uint32_t j;
uint8_t b;
if (size <= 4)
return 0;
size -= 4;
for (i = 0; i < size; ++i) {
if ((buf[i] & 0xFE) != 0xE8)
continue;
prev_pos = i - prev_pos;
if (prev_pos > 3) {
prev_mask = 0;
} else {
prev_mask = (prev_mask << (prev_pos - 1)) & 7;
if (prev_mask != 0) {
b = buf[i + 4 - mask_to_bit_num[prev_mask]];
if (!mask_to_allowed_status[prev_mask]
|| bcj_x86_test_msbyte(b)) {
prev_pos = i;
prev_mask = (prev_mask << 1) | 1;
continue;
}
}
}
prev_pos = i;
if (bcj_x86_test_msbyte(buf[i + 4])) {
src = get_unaligned_le32(buf + i + 1);
for (;;) {
dest = src - (s->pos + (uint32_t)i + 5);
if (prev_mask == 0)
break;
j = mask_to_bit_num[prev_mask] * 8;
b = (uint8_t)(dest >> (24 - j));
if (!bcj_x86_test_msbyte(b))
break;
src = dest ^ (((uint32_t)1 << (32 - j)) - 1);
}
dest &= 0x01FFFFFF;
dest |= (uint32_t)0 - (dest & 0x01000000);
put_unaligned_le32(dest, buf + i + 1);
i += 4;
} else {
prev_mask = (prev_mask << 1) | 1;
}
}
prev_pos = i - prev_pos;
s->x86_prev_mask = prev_pos > 3 ? 0 : prev_mask << (prev_pos - 1);
return i;
}
#endif
#ifdef XZ_DEC_POWERPC
static size_t bcj_powerpc(struct xz_dec_bcj *s, uint8_t *buf, size_t size)
{
size_t i;
uint32_t instr;
for (i = 0; i + 4 <= size; i += 4) {
instr = get_unaligned_be32(buf + i);
if ((instr & 0xFC000003) == 0x48000001) {
instr &= 0x03FFFFFC;
instr -= s->pos + (uint32_t)i;
instr &= 0x03FFFFFC;
instr |= 0x48000001;
put_unaligned_be32(instr, buf + i);
}
}
return i;
}
#endif
#ifdef XZ_DEC_IA64
static size_t bcj_ia64(struct xz_dec_bcj *s, uint8_t *buf, size_t size)
{
static const uint8_t branch_table[32] = {
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
4, 4, 6, 6, 0, 0, 7, 7,
4, 4, 0, 0, 4, 4, 0, 0
};
/*
* The local variables take a little bit stack space, but it's less
* than what LZMA2 decoder takes, so it doesn't make sense to reduce
* stack usage here without doing that for the LZMA2 decoder too.
*/
/* Loop counters */
size_t i;
size_t j;
/* Instruction slot (0, 1, or 2) in the 128-bit instruction word */
uint32_t slot;
/* Bitwise offset of the instruction indicated by slot */
uint32_t bit_pos;
/* bit_pos split into byte and bit parts */
uint32_t byte_pos;
uint32_t bit_res;
/* Address part of an instruction */
uint32_t addr;
/* Mask used to detect which instructions to convert */
uint32_t mask;
/* 41-bit instruction stored somewhere in the lowest 48 bits */
uint64_t instr;
/* Instruction normalized with bit_res for easier manipulation */
uint64_t norm;
for (i = 0; i + 16 <= size; i += 16) {
mask = branch_table[buf[i] & 0x1F];
for (slot = 0, bit_pos = 5; slot < 3; ++slot, bit_pos += 41) {
if (((mask >> slot) & 1) == 0)
continue;
byte_pos = bit_pos >> 3;
bit_res = bit_pos & 7;
instr = 0;
for (j = 0; j < 6; ++j)
instr |= (uint64_t)(buf[i + j + byte_pos])
<< (8 * j);
norm = instr >> bit_res;
if (((norm >> 37) & 0x0F) == 0x05
&& ((norm >> 9) & 0x07) == 0) {
addr = (norm >> 13) & 0x0FFFFF;
addr |= ((uint32_t)(norm >> 36) & 1) << 20;
addr <<= 4;
addr -= s->pos + (uint32_t)i;
addr >>= 4;
norm &= ~((uint64_t)0x8FFFFF << 13);
norm |= (uint64_t)(addr & 0x0FFFFF) << 13;
norm |= (uint64_t)(addr & 0x100000)
<< (36 - 20);
instr &= (1 << bit_res) - 1;
instr |= norm << bit_res;
for (j = 0; j < 6; j++)
buf[i + j + byte_pos]
= (uint8_t)(instr >> (8 * j));
}
}
}
return i;
}
#endif
#ifdef XZ_DEC_ARM
static size_t bcj_arm(struct xz_dec_bcj *s, uint8_t *buf, size_t size)
{
size_t i;
uint32_t addr;
for (i = 0; i + 4 <= size; i += 4) {
if (buf[i + 3] == 0xEB) {
addr = (uint32_t)buf[i] | ((uint32_t)buf[i + 1] << 8)
| ((uint32_t)buf[i + 2] << 16);
addr <<= 2;
addr -= s->pos + (uint32_t)i + 8;
addr >>= 2;
buf[i] = (uint8_t)addr;
buf[i + 1] = (uint8_t)(addr >> 8);
buf[i + 2] = (uint8_t)(addr >> 16);
}
}
return i;
}
#endif
#ifdef XZ_DEC_ARMTHUMB
static size_t bcj_armthumb(struct xz_dec_bcj *s, uint8_t *buf, size_t size)
{
size_t i;
uint32_t addr;
for (i = 0; i + 4 <= size; i += 2) {
if ((buf[i + 1] & 0xF8) == 0xF0
&& (buf[i + 3] & 0xF8) == 0xF8) {
addr = (((uint32_t)buf[i + 1] & 0x07) << 19)
| ((uint32_t)buf[i] << 11)
| (((uint32_t)buf[i + 3] & 0x07) << 8)
| (uint32_t)buf[i + 2];
addr <<= 1;
addr -= s->pos + (uint32_t)i + 4;
addr >>= 1;
buf[i + 1] = (uint8_t)(0xF0 | ((addr >> 19) & 0x07));
buf[i] = (uint8_t)(addr >> 11);
buf[i + 3] = (uint8_t)(0xF8 | ((addr >> 8) & 0x07));
buf[i + 2] = (uint8_t)addr;
i += 2;
}
}
return i;
}
#endif
#ifdef XZ_DEC_SPARC
static size_t bcj_sparc(struct xz_dec_bcj *s, uint8_t *buf, size_t size)
{
size_t i;
uint32_t instr;
for (i = 0; i + 4 <= size; i += 4) {
instr = get_unaligned_be32(buf + i);
if ((instr >> 22) == 0x100 || (instr >> 22) == 0x1FF) {
instr <<= 2;
instr -= s->pos + (uint32_t)i;
instr >>= 2;
instr = ((uint32_t)0x40000000 - (instr & 0x400000))
| 0x40000000 | (instr & 0x3FFFFF);
put_unaligned_be32(instr, buf + i);
}
}
return i;
}
#endif
/*
* Apply the selected BCJ filter. Update *pos and s->pos to match the amount
* of data that got filtered.
*
* NOTE: This is implemented as a switch statement to avoid using function
* pointers, which could be problematic in the kernel boot code, which must
* avoid pointers to static data (at least on x86).
*/
static void bcj_apply(struct xz_dec_bcj *s,
uint8_t *buf, size_t *pos, size_t size)
{
size_t filtered;
buf += *pos;
size -= *pos;
switch (s->type) {
#ifdef XZ_DEC_X86
case BCJ_X86:
filtered = bcj_x86(s, buf, size);
break;
#endif
#ifdef XZ_DEC_POWERPC
case BCJ_POWERPC:
filtered = bcj_powerpc(s, buf, size);
break;
#endif
#ifdef XZ_DEC_IA64
case BCJ_IA64:
filtered = bcj_ia64(s, buf, size);
break;
#endif
#ifdef XZ_DEC_ARM
case BCJ_ARM:
filtered = bcj_arm(s, buf, size);
break;
#endif
#ifdef XZ_DEC_ARMTHUMB
case BCJ_ARMTHUMB:
filtered = bcj_armthumb(s, buf, size);
break;
#endif
#ifdef XZ_DEC_SPARC
case BCJ_SPARC:
filtered = bcj_sparc(s, buf, size);
break;
#endif
default:
/* Never reached but silence compiler warnings. */
filtered = 0;
break;
}
*pos += filtered;
s->pos += filtered;
}
/*
* Flush pending filtered data from temp to the output buffer.
* Move the remaining mixture of possibly filtered and unfiltered
* data to the beginning of temp.
*/
static void bcj_flush(struct xz_dec_bcj *s, struct xz_buf *b)
{
size_t copy_size;
copy_size = minof(s->temp.filtered, b->out_size - b->out_pos);
memcpy(b->out + b->out_pos, s->temp.buf, copy_size);
b->out_pos += copy_size;
s->temp.filtered -= copy_size;
s->temp.size -= copy_size;
memmove(s->temp.buf, s->temp.buf + copy_size, s->temp.size);
}
/*
* The BCJ filter functions are primitive in sense that they process the
* data in chunks of 1-16 bytes. To hide this issue, this function does
* some buffering.
*/
enum xz_ret xz_dec_bcj_run(struct xz_dec_bcj *s,
struct xz_dec_lzma2 *lzma2,
struct xz_buf *b)
{
size_t out_start;
/*
* Flush pending already filtered data to the output buffer. Return
* immediatelly if we couldn't flush everything, or if the next
* filter in the chain had already returned XZ_STREAM_END.
*/
if (s->temp.filtered > 0) {
bcj_flush(s, b);
if (s->temp.filtered > 0)
return XZ_OK;
if (s->ret == XZ_STREAM_END)
return XZ_STREAM_END;
}
/*
* If we have more output space than what is currently pending in
* temp, copy the unfiltered data from temp to the output buffer
* and try to fill the output buffer by decoding more data from the
* next filter in the chain. Apply the BCJ filter on the new data
* in the output buffer. If everything cannot be filtered, copy it
* to temp and rewind the output buffer position accordingly.
*
* This needs to be always run when temp.size == 0 to handle a special
* case where the output buffer is full and the next filter has no
* more output coming but hasn't returned XZ_STREAM_END yet.
*/
if (s->temp.size < b->out_size - b->out_pos || s->temp.size == 0) {
out_start = b->out_pos;
memcpy(b->out + b->out_pos, s->temp.buf, s->temp.size);
b->out_pos += s->temp.size;
s->ret = xz_dec_lzma2_run(lzma2, b);
if (s->ret != XZ_STREAM_END
&& (s->ret != XZ_OK ))
return s->ret;
bcj_apply(s, b->out, &out_start, b->out_pos);
/*
* As an exception, if the next filter returned XZ_STREAM_END,
* we can do that too, since the last few bytes that remain
* unfiltered are meant to remain unfiltered.
*/
if (s->ret == XZ_STREAM_END)
return XZ_STREAM_END;
s->temp.size = b->out_pos - out_start;
b->out_pos -= s->temp.size;
memcpy(s->temp.buf, b->out + b->out_pos, s->temp.size);
/*
* If there wasn't enough input to the next filter to fill
* the output buffer with unfiltered data, there's no point
* to try decoding more data to temp.
*/
if (b->out_pos + s->temp.size < b->out_size)
return XZ_OK;
}
/*
* We have unfiltered data in temp. If the output buffer isn't full
* yet, try to fill the temp buffer by decoding more data from the
* next filter. Apply the BCJ filter on temp. Then we hopefully can
* fill the actual output buffer by copying filtered data from temp.
* A mix of filtered and unfiltered data may be left in temp; it will
* be taken care on the next call to this function.
*/
if (b->out_pos < b->out_size) {
/* Make b->out{,_pos,_size} temporarily point to s->temp. */
s->out = b->out;
s->out_pos = b->out_pos;
s->out_size = b->out_size;
b->out = s->temp.buf;
b->out_pos = s->temp.size;
b->out_size = sizeof(s->temp.buf);
s->ret = xz_dec_lzma2_run(lzma2, b);
s->temp.size = b->out_pos;
b->out = s->out;
b->out_pos = s->out_pos;
b->out_size = s->out_size;
if (s->ret != XZ_OK && s->ret != XZ_STREAM_END)
return s->ret;
bcj_apply(s, s->temp.buf, &s->temp.filtered, s->temp.size);
/*
* If the next filter returned XZ_STREAM_END, we mark that
* everything is filtered, since the last unfiltered bytes
* of the stream are meant to be left as is.
*/
if (s->ret == XZ_STREAM_END)
s->temp.filtered = s->temp.size;
bcj_flush(s, b);
if (s->temp.filtered > 0)
return XZ_OK;
}
return s->ret;
}
enum xz_ret xz_dec_bcj_reset(struct xz_dec_bcj *s, uint8_t id)
{
switch (id) {
#ifdef XZ_DEC_X86
case BCJ_X86:
#endif
#ifdef XZ_DEC_POWERPC
case BCJ_POWERPC:
#endif
#ifdef XZ_DEC_IA64
case BCJ_IA64:
#endif
#ifdef XZ_DEC_ARM
case BCJ_ARM:
#endif
#ifdef XZ_DEC_ARMTHUMB
case BCJ_ARMTHUMB:
#endif
#ifdef XZ_DEC_SPARC
case BCJ_SPARC:
#endif
break;
default:
/* Unsupported Filter ID */
return XZ_OPTIONS_ERROR;
}
s->type = id;
s->ret = XZ_OK;
s->pos = 0;
s->x86_prev_mask = 0;
s->temp.filtered = 0;
s->temp.size = 0;
return XZ_OK;
}
#endif
/*
* LZMA2 decoder
*/
// BEGIN xz_lzma2.h
/*
* LZMA2 definitions
*
*/
/* Range coder constants */
#define RC_SHIFT_BITS 8
#define RC_TOP_BITS 24
#define RC_TOP_VALUE (1 << RC_TOP_BITS)
#define RC_BIT_MODEL_TOTAL_BITS 11
#define RC_BIT_MODEL_TOTAL (1 << RC_BIT_MODEL_TOTAL_BITS)
#define RC_MOVE_BITS 5
/*
* Maximum number of position states. A position state is the lowest pb
* number of bits of the current uncompressed offset. In some places there
* are different sets of probabilities for different position states.
*/
#define POS_STATES_MAX (1 << 4)
/*
* This enum is used to track which LZMA symbols have occurred most recently
* and in which order. This information is used to predict the next symbol.
*
* Symbols:
* - Literal: One 8-bit byte
* - Match: Repeat a chunk of data at some distance
* - Long repeat: Multi-byte match at a recently seen distance
* - Short repeat: One-byte repeat at a recently seen distance
*
* The symbol names are in from STATE_oldest_older_previous. REP means
* either short or long repeated match, and NONLIT means any non-literal.
*/
enum lzma_state {
STATE_LIT_LIT,
STATE_MATCH_LIT_LIT,
STATE_REP_LIT_LIT,
STATE_SHORTREP_LIT_LIT,
STATE_MATCH_LIT,
STATE_REP_LIT,
STATE_SHORTREP_LIT,
STATE_LIT_MATCH,
STATE_LIT_LONGREP,
STATE_LIT_SHORTREP,
STATE_NONLIT_MATCH,
STATE_NONLIT_REP
};
/* Total number of states */
#define STATES 12
/* The lowest 7 states indicate that the previous state was a literal. */
#define LIT_STATES 7
/* Indicate that the latest symbol was a literal. */
static inline void lzma_state_literal(enum lzma_state *state)
{
if (*state <= STATE_SHORTREP_LIT_LIT)
*state = STATE_LIT_LIT;
else if (*state <= STATE_LIT_SHORTREP)
*state -= 3;
else
*state -= 6;
}
/* Indicate that the latest symbol was a match. */
static inline void lzma_state_match(enum lzma_state *state)
{
*state = *state < LIT_STATES ? STATE_LIT_MATCH : STATE_NONLIT_MATCH;
}
/* Indicate that the latest state was a long repeated match. */
static inline void lzma_state_long_rep(enum lzma_state *state)
{
*state = *state < LIT_STATES ? STATE_LIT_LONGREP : STATE_NONLIT_REP;
}
/* Indicate that the latest symbol was a short match. */
static inline void lzma_state_short_rep(enum lzma_state *state)
{
*state = *state < LIT_STATES ? STATE_LIT_SHORTREP : STATE_NONLIT_REP;
}
/* Test if the previous symbol was a literal. */
static inline int lzma_state_is_literal(enum lzma_state state)
{
return state < LIT_STATES;
}
/* Each literal coder is divided in three sections:
* - 0x001-0x0FF: Without match byte
* - 0x101-0x1FF: With match byte; match bit is 0
* - 0x201-0x2FF: With match byte; match bit is 1
*
* Match byte is used when the previous LZMA symbol was something else than
* a literal (that is, it was some kind of match).
*/
#define LITERAL_CODER_SIZE 0x300
/* Maximum number of literal coders */
#define LITERAL_CODERS_MAX (1 << 4)
/* Minimum length of a match is two bytes. */
#define MATCH_LEN_MIN 2
/* Match length is encoded with 4, 5, or 10 bits.
*
* Length Bits
* 2-9 4 = Choice=0 + 3 bits
* 10-17 5 = Choice=1 + Choice2=0 + 3 bits
* 18-273 10 = Choice=1 + Choice2=1 + 8 bits
*/
#define LEN_LOW_BITS 3
#define LEN_LOW_SYMBOLS (1 << LEN_LOW_BITS)
#define LEN_MID_BITS 3
#define LEN_MID_SYMBOLS (1 << LEN_MID_BITS)
#define LEN_HIGH_BITS 8
#define LEN_HIGH_SYMBOLS (1 << LEN_HIGH_BITS)
#define LEN_SYMBOLS (LEN_LOW_SYMBOLS + LEN_MID_SYMBOLS + LEN_HIGH_SYMBOLS)
/*
* Maximum length of a match is 273 which is a result of the encoding
* described above.
*/
#define MATCH_LEN_MAX (MATCH_LEN_MIN + LEN_SYMBOLS - 1)
/*
* Different sets of probabilities are used for match distances that have
* very short match length: Lengths of 2, 3, and 4 bytes have a separate
* set of probabilities for each length. The matches with longer length
* use a shared set of probabilities.
*/
#define DIST_STATES 4
/*
* Get the index of the appropriate probability array for decoding
* the distance slot.
*/
static inline uint32_t lzma_get_dist_state(uint32_t len)
{
return len < DIST_STATES + MATCH_LEN_MIN
? len - MATCH_LEN_MIN : DIST_STATES - 1;
}
/*
* The highest two bits of a 32-bit match distance are encoded using six bits.
* This six-bit value is called a distance slot. This way encoding a 32-bit
* value takes 6-36 bits, larger values taking more bits.
*/
#define DIST_SLOT_BITS 6
#define DIST_SLOTS (1 << DIST_SLOT_BITS)
/* Match distances up to 127 are fully encoded using probabilities. Since
* the highest two bits (distance slot) are always encoded using six bits,
* the distances 0-3 don't need any additional bits to encode, since the
* distance slot itself is the same as the actual distance. DIST_MODEL_START
* indicates the first distance slot where at least one additional bit is
* needed.
*/
#define DIST_MODEL_START 4
/*
* Match distances greater than 127 are encoded in three pieces:
* - distance slot: the highest two bits
* - direct bits: 2-26 bits below the highest two bits
* - alignment bits: four lowest bits
*
* Direct bits don't use any probabilities.
*
* The distance slot value of 14 is for distances 128-191.
*/
#define DIST_MODEL_END 14
/* Distance slots that indicate a distance <= 127. */
#define FULL_DISTANCES_BITS (DIST_MODEL_END / 2)
#define FULL_DISTANCES (1 << FULL_DISTANCES_BITS)
/*
* For match distances greater than 127, only the highest two bits and the
* lowest four bits (alignment) is encoded using probabilities.
*/
#define ALIGN_BITS 4
#define ALIGN_SIZE (1 << ALIGN_BITS)
#define ALIGN_MASK (ALIGN_SIZE - 1)
/* Total number of all probability variables */
#define PROBS_TOTAL (1846 + LITERAL_CODERS_MAX * LITERAL_CODER_SIZE)
/*
* LZMA remembers the four most recent match distances. Reusing these
* distances tends to take less space than re-encoding the actual
* distance value.
*/
#define REPS 4
// END xz_lzma2.h
/*
* Range decoder initialization eats the first five bytes of each LZMA chunk.
*/
#define RC_INIT_BYTES 5
/*
* Minimum number of usable input buffer to safely decode one LZMA symbol.
* The worst case is that we decode 22 bits using probabilities and 26
* direct bits. This may decode at maximum of 20 bytes of input. However,
* lzma_main() does an extra normalization before returning, thus we
* need to put 21 here.
*/
#define LZMA_IN_REQUIRED 21
/*
* Dictionary (history buffer)
*
* These are always true:
* start <= pos <= full <= end
* pos <= limit <= end
* end == size
* size <= size_max
* allocated <= size
*
* Most of these variables are size_t as a relic of single-call mode,
* in which the dictionary variables address the actual output
* buffer directly.
*/
struct dictionary {
/* Beginning of the history buffer */
uint8_t *buf;
/* Old position in buf (before decoding more data) */
size_t start;
/* Position in buf */
size_t pos;
/*
* How full dictionary is. This is used to detect corrupt input that
* would read beyond the beginning of the uncompressed stream.
*/
size_t full;
/* Write limit; we don't write to buf[limit] or later bytes. */
size_t limit;
/* End of the dictionary buffer. This is the same as the dictionary size. */
size_t end;
/*
* Size of the dictionary as specified in Block Header. This is used
* together with "full" to detect corrupt input that would make us
* read beyond the beginning of the uncompressed stream.
*/
uint32_t size;
/*
* Maximum allowed dictionary size.
*/
uint32_t size_max;
/*
* Amount of memory currently allocated for the dictionary.
*/
uint32_t allocated;
};
/* Range decoder */
struct rc_dec {
uint32_t range;
uint32_t code;
/*
* Number of initializing bytes remaining to be read
* by rc_read_init().
*/
uint32_t init_bytes_left;
/*
* Buffer from which we read our input. It can be either
* temp.buf or the caller-provided input buffer.
*/
const uint8_t *in;
size_t in_pos;
size_t in_limit;
};
/* Probabilities for a length decoder. */
struct lzma_len_dec {
/* Probability of match length being at least 10 */
uint16_t choice;
/* Probability of match length being at least 18 */
uint16_t choice2;
/* Probabilities for match lengths 2-9 */
uint16_t low[POS_STATES_MAX][LEN_LOW_SYMBOLS];
/* Probabilities for match lengths 10-17 */
uint16_t mid[POS_STATES_MAX][LEN_MID_SYMBOLS];
/* Probabilities for match lengths 18-273 */
uint16_t high[LEN_HIGH_SYMBOLS];
};
struct lzma_dec {
/* Distances of latest four matches */
uint32_t rep0;
uint32_t rep1;
uint32_t rep2;
uint32_t rep3;
/* Types of the most recently seen LZMA symbols */
enum lzma_state state;
/*
* Length of a match. This is updated so that dict_repeat can
* be called again to finish repeating the whole match.
*/
uint32_t len;
/*
* LZMA properties or related bit masks (number of literal
* context bits, a mask dervied from the number of literal
* position bits, and a mask dervied from the number
* position bits)
*/
uint32_t lc;
uint32_t literal_pos_mask; /* (1 << lp) - 1 */
uint32_t pos_mask; /* (1 << pb) - 1 */
/* If 1, it's a match. Otherwise it's a single 8-bit literal. */
uint16_t is_match[STATES][POS_STATES_MAX];
/* If 1, it's a repeated match. The distance is one of rep0 .. rep3. */
uint16_t is_rep[STATES];
/*
* If 0, distance of a repeated match is rep0.
* Otherwise check is_rep1.
*/
uint16_t is_rep0[STATES];
/*
* If 0, distance of a repeated match is rep1.
* Otherwise check is_rep2.
*/
uint16_t is_rep1[STATES];
/* If 0, distance of a repeated match is rep2. Otherwise it is rep3. */
uint16_t is_rep2[STATES];
/*
* If 1, the repeated match has length of one byte. Otherwise
* the length is decoded from rep_len_decoder.
*/
uint16_t is_rep0_long[STATES][POS_STATES_MAX];
/*
* Probability tree for the highest two bits of the match
* distance. There is a separate probability tree for match
* lengths of 2 (i.e. MATCH_LEN_MIN), 3, 4, and [5, 273].
*/
uint16_t dist_slot[DIST_STATES][DIST_SLOTS];
/*
* Probility trees for additional bits for match distance
* when the distance is in the range [4, 127].
*/
uint16_t dist_special[FULL_DISTANCES - DIST_MODEL_END];
/*
* Probability tree for the lowest four bits of a match
* distance that is equal to or greater than 128.
*/
uint16_t dist_align[ALIGN_SIZE];
/* Length of a normal match */
struct lzma_len_dec match_len_dec;
/* Length of a repeated match */
struct lzma_len_dec rep_len_dec;
/* Probabilities of literals */
uint16_t literal[LITERAL_CODERS_MAX][LITERAL_CODER_SIZE];
};
struct lzma2_dec {
/* Position in xz_dec_lzma2_run(). */
enum lzma2_seq {
SEQ_CONTROL,
SEQ_UNCOMPRESSED_1,
SEQ_UNCOMPRESSED_2,
SEQ_COMPRESSED_0,
SEQ_COMPRESSED_1,
SEQ_PROPERTIES,
SEQ_LZMA_PREPARE,
SEQ_LZMA_RUN,
SEQ_COPY
} sequence;
/* Next position after decoding the compressed size of the chunk. */
enum lzma2_seq next_sequence;
/* Uncompressed size of LZMA chunk (2 MiB at maximum) */
uint32_t uncompressed;
/*
* Compressed size of LZMA chunk or compressed/uncompressed
* size of uncompressed chunk (64 KiB at maximum)
*/
uint32_t compressed;
/*
* True if dictionary reset is needed. This is false before
* the first chunk (LZMA or uncompressed).
*/
int need_dict_reset;
/*
* True if new LZMA properties are needed. This is false
* before the first LZMA chunk.
*/
int need_props;
};
struct xz_dec_lzma2 {
/*
* The order below is important on x86 to reduce code size and
* it shouldn't hurt on other platforms. Everything up to and
* including lzma.pos_mask are in the first 128 bytes on x86-32,
* which allows using smaller instructions to access those
* variables. On x86-64, fewer variables fit into the first 128
* bytes, but this is still the best order without sacrificing
* the readability by splitting the structures.
*/
struct rc_dec rc;
struct dictionary dict;
struct lzma2_dec lzma2;
struct lzma_dec lzma;
/*
* Temporary buffer which holds small number of input bytes between
* decoder calls. See lzma2_lzma() for details.
*/
struct {
uint32_t size;
uint8_t buf[3 * LZMA_IN_REQUIRED];
} temp;
};
/**************
* Dictionary *
**************/
/* Reset the dictionary state. */
static void dict_reset(struct dictionary *dict)
{
dict->start = 0;
dict->pos = 0;
dict->limit = 0;
dict->full = 0;
}
/* Set dictionary write limit */
static void dict_limit(struct dictionary *dict, size_t out_max)
{
if (dict->end - dict->pos <= out_max)
dict->limit = dict->end;
else
dict->limit = dict->pos + out_max;
}
/* Return true if at least one byte can be written into the dictionary. */
static inline int dict_has_space(const struct dictionary *dict)
{
return dict->pos < dict->limit;
}
/*
* Get a byte from the dictionary at the given distance. The distance is
* assumed to valid, or as a special case, zero when the dictionary is
* still empty. This special case is needed for single-call decoding to
* avoid writing a '\0' to the end of the destination buffer.
*/
static inline uint32_t dict_get(const struct dictionary *dict, uint32_t dist)
{
size_t offset = dict->pos - dist - 1;
if (dist >= dict->pos)
offset += dict->end;
return dict->full > 0 ? dict->buf[offset] : 0;
}
/*
* Put one byte into the dictionary. It is assumed that there is space for it.
*/
static inline void dict_put(struct dictionary *dict, uint8_t byte)
{
dict->buf[dict->pos++] = byte;
if (dict->full < dict->pos)
dict->full = dict->pos;
}
/*
* Repeat given number of bytes from the given distance. If the distance is
* invalid, false is returned. On success, true is returned and *len is
* updated to indicate how many bytes were left to be repeated.
*/
static int dict_repeat(struct dictionary *dict, uint32_t *len, uint32_t dist)
{
size_t back;
uint32_t left;
if (dist >= dict->full || dist >= dict->size) return 0;
left = minof(dict->limit - dict->pos, *len);
*len -= left;
back = dict->pos - dist - 1;
if (dist >= dict->pos)
back += dict->end;
do {
dict->buf[dict->pos++] = dict->buf[back++];
if (back == dict->end)
back = 0;
} while (--left > 0);
if (dict->full < dict->pos)
dict->full = dict->pos;
return 1;
}
/* Copy uncompressed data as is from input to dictionary and output buffers. */
static void dict_uncompressed(struct dictionary *dict, struct xz_buf *b,
uint32_t *left)
{
size_t copy_size;
while (*left > 0 && b->in_pos < b->in_size
&& b->out_pos < b->out_size) {
copy_size = minof(b->in_size - b->in_pos,
b->out_size - b->out_pos);
if (copy_size > dict->end - dict->pos)
copy_size = dict->end - dict->pos;
if (copy_size > *left)
copy_size = *left;
*left -= copy_size;
memcpy(dict->buf + dict->pos, b->in + b->in_pos, copy_size);
dict->pos += copy_size;
if (dict->full < dict->pos)
dict->full = dict->pos;
if (dict->pos == dict->end)
dict->pos = 0;
memcpy(b->out + b->out_pos, b->in + b->in_pos,
copy_size);
dict->start = dict->pos;
b->out_pos += copy_size;
b->in_pos += copy_size;
}
}
/*
* Flush pending data from dictionary to b->out. It is assumed that there is
* enough space in b->out. This is guaranteed because caller uses dict_limit()
* before decoding data into the dictionary.
*/
static uint32_t dict_flush(struct dictionary *dict, struct xz_buf *b)
{
size_t copy_size = dict->pos - dict->start;
if (dict->pos == dict->end)
dict->pos = 0;
memcpy(b->out + b->out_pos, dict->buf + dict->start,
copy_size);
dict->start = dict->pos;
b->out_pos += copy_size;
return copy_size;
}
/*****************
* Range decoder *
*****************/
/* Reset the range decoder. */
static void rc_reset(struct rc_dec *rc)
{
rc->range = (uint32_t)-1;
rc->code = 0;
rc->init_bytes_left = RC_INIT_BYTES;
}
/*
* Read the first five initial bytes into rc->code if they haven't been
* read already. (Yes, the first byte gets completely ignored.)
*/
static int rc_read_init(struct rc_dec *rc, struct xz_buf *b)
{
while (rc->init_bytes_left > 0) {
if (b->in_pos == b->in_size) return 0;
rc->code = (rc->code << 8) + b->in[b->in_pos++];
--rc->init_bytes_left;
}
return 1;
}
/* Return true if there may not be enough input for the next decoding loop. */
static inline int rc_limit_exceeded(const struct rc_dec *rc)
{
return rc->in_pos > rc->in_limit;
}
/*
* Return true if it is possible (from point of view of range decoder) that
* we have reached the end of the LZMA chunk.
*/
static inline int rc_is_finished(const struct rc_dec *rc)
{
return rc->code == 0;
}
/* Read the next input byte if needed. */
static inline void rc_normalize(struct rc_dec *rc)
{
if (rc->range < RC_TOP_VALUE) {
rc->range <<= RC_SHIFT_BITS;
rc->code = (rc->code << RC_SHIFT_BITS) + rc->in[rc->in_pos++];
}
}
/*
* Decode one bit. In some versions, this function has been splitted in three
* functions so that the compiler is supposed to be able to more easily avoid
* an extra branch. In this particular version of the LZMA decoder, this
* doesn't seem to be a good idea (tested with GCC 3.3.6, 3.4.6, and 4.3.3
* on x86). Using a non-splitted version results in nicer looking code too.
*
* NOTE: This must return an int. Do not make it return a bool or the speed
* of the code generated by GCC 3.x decreases 10-15 %. (GCC 4.3 doesn't care,
* and it generates 10-20 % faster code than GCC 3.x from this file anyway.)
*/
static inline int rc_bit(struct rc_dec *rc, uint16_t *prob)
{
uint32_t bound;
int bit;
rc_normalize(rc);
bound = (rc->range >> RC_BIT_MODEL_TOTAL_BITS) * *prob;
if (rc->code < bound) {
rc->range = bound;
*prob += (RC_BIT_MODEL_TOTAL - *prob) >> RC_MOVE_BITS;
bit = 0;
} else {
rc->range -= bound;
rc->code -= bound;
*prob -= *prob >> RC_MOVE_BITS;
bit = 1;
}
return bit;
}
/* Decode a bittree starting from the most significant bit. */
static inline uint32_t rc_bittree(struct rc_dec *rc,
uint16_t *probs, uint32_t limit)
{
uint32_t symbol = 1;
do {
if (rc_bit(rc, &probs[symbol]))
symbol = (symbol << 1) + 1;
else
symbol <<= 1;
} while (symbol < limit);
return symbol;
}
/* Decode a bittree starting from the least significant bit. */
static inline void rc_bittree_reverse(struct rc_dec *rc,
uint16_t *probs,
uint32_t *dest, uint32_t limit)
{
uint32_t symbol = 1;
uint32_t i = 0;
do {
if (rc_bit(rc, &probs[symbol])) {
symbol = (symbol << 1) + 1;
*dest += 1 << i;
} else {
symbol <<= 1;
}
} while (++i < limit);
}
/* Decode direct bits (fixed fifty-fifty probability) */
static inline void rc_direct(struct rc_dec *rc, uint32_t *dest, uint32_t limit)
{
uint32_t mask;
do {
rc_normalize(rc);
rc->range >>= 1;
rc->code -= rc->range;
mask = (uint32_t)0 - (rc->code >> 31);
rc->code += rc->range & mask;
*dest = (*dest << 1) + (mask + 1);
} while (--limit > 0);
}
/********
* LZMA *
********/
/* Get pointer to literal coder probability array. */
static uint16_t *lzma_literal_probs(struct xz_dec_lzma2 *s)
{
uint32_t prev_byte = dict_get(&s->dict, 0);
uint32_t low = prev_byte >> (8 - s->lzma.lc);
uint32_t high = (s->dict.pos & s->lzma.literal_pos_mask) << s->lzma.lc;
return s->lzma.literal[low + high];
}
/* Decode a literal (one 8-bit byte) */
static void lzma_literal(struct xz_dec_lzma2 *s)
{
uint16_t *probs;
uint32_t symbol;
uint32_t match_byte;
uint32_t match_bit;
uint32_t offset;
uint32_t i;
probs = lzma_literal_probs(s);
if (lzma_state_is_literal(s->lzma.state)) {
symbol = rc_bittree(&s->rc, probs, 0x100);
} else {
symbol = 1;
match_byte = dict_get(&s->dict, s->lzma.rep0) << 1;
offset = 0x100;
do {
match_bit = match_byte & offset;
match_byte <<= 1;
i = offset + match_bit + symbol;
if (rc_bit(&s->rc, &probs[i])) {
symbol = (symbol << 1) + 1;
offset &= match_bit;
} else {
symbol <<= 1;
offset &= ~match_bit;
}
} while (symbol < 0x100);
}
dict_put(&s->dict, (uint8_t)symbol);
lzma_state_literal(&s->lzma.state);
}
/* Decode the length of the match into s->lzma.len. */
static void lzma_len(struct xz_dec_lzma2 *s, struct lzma_len_dec *l,
uint32_t pos_state)
{
uint16_t *probs;
uint32_t limit;
if (!rc_bit(&s->rc, &l->choice)) {
probs = l->low[pos_state];
limit = LEN_LOW_SYMBOLS;
s->lzma.len = MATCH_LEN_MIN;
} else {
if (!rc_bit(&s->rc, &l->choice2)) {
probs = l->mid[pos_state];
limit = LEN_MID_SYMBOLS;
s->lzma.len = MATCH_LEN_MIN + LEN_LOW_SYMBOLS;
} else {
probs = l->high;
limit = LEN_HIGH_SYMBOLS;
s->lzma.len = MATCH_LEN_MIN + LEN_LOW_SYMBOLS
+ LEN_MID_SYMBOLS;
}
}
s->lzma.len += rc_bittree(&s->rc, probs, limit) - limit;
}
/* Decode a match. The distance will be stored in s->lzma.rep0. */
static void lzma_match(struct xz_dec_lzma2 *s, uint32_t pos_state)
{
uint16_t *probs;
uint32_t dist_slot;
uint32_t limit;
lzma_state_match(&s->lzma.state);
s->lzma.rep3 = s->lzma.rep2;
s->lzma.rep2 = s->lzma.rep1;
s->lzma.rep1 = s->lzma.rep0;
lzma_len(s, &s->lzma.match_len_dec, pos_state);
probs = s->lzma.dist_slot[lzma_get_dist_state(s->lzma.len)];
dist_slot = rc_bittree(&s->rc, probs, DIST_SLOTS) - DIST_SLOTS;
if (dist_slot < DIST_MODEL_START) {
s->lzma.rep0 = dist_slot;
} else {
limit = (dist_slot >> 1) - 1;
s->lzma.rep0 = 2 + (dist_slot & 1);
if (dist_slot < DIST_MODEL_END) {
s->lzma.rep0 <<= limit;
probs = s->lzma.dist_special + s->lzma.rep0
- dist_slot - 1;
rc_bittree_reverse(&s->rc, probs,
&s->lzma.rep0, limit);
} else {
rc_direct(&s->rc, &s->lzma.rep0, limit - ALIGN_BITS);
s->lzma.rep0 <<= ALIGN_BITS;
rc_bittree_reverse(&s->rc, s->lzma.dist_align,
&s->lzma.rep0, ALIGN_BITS);
}
}
}
/*
* Decode a repeated match. The distance is one of the four most recently
* seen matches. The distance will be stored in s->lzma.rep0.
*/
static void lzma_rep_match(struct xz_dec_lzma2 *s, uint32_t pos_state)
{
uint32_t tmp;
if (!rc_bit(&s->rc, &s->lzma.is_rep0[s->lzma.state])) {
if (!rc_bit(&s->rc, &s->lzma.is_rep0_long[
s->lzma.state][pos_state])) {
lzma_state_short_rep(&s->lzma.state);
s->lzma.len = 1;
return;
}
} else {
if (!rc_bit(&s->rc, &s->lzma.is_rep1[s->lzma.state])) {
tmp = s->lzma.rep1;
} else {
if (!rc_bit(&s->rc, &s->lzma.is_rep2[s->lzma.state])) {
tmp = s->lzma.rep2;
} else {
tmp = s->lzma.rep3;
s->lzma.rep3 = s->lzma.rep2;
}
s->lzma.rep2 = s->lzma.rep1;
}
s->lzma.rep1 = s->lzma.rep0;
s->lzma.rep0 = tmp;
}
lzma_state_long_rep(&s->lzma.state);
lzma_len(s, &s->lzma.rep_len_dec, pos_state);
}
/* LZMA decoder core */
static int lzma_main(struct xz_dec_lzma2 *s)
{
uint32_t pos_state;
/*
* If the dictionary was reached during the previous call, try to
* finish the possibly pending repeat in the dictionary.
*/
if (dict_has_space(&s->dict) && s->lzma.len > 0)
dict_repeat(&s->dict, &s->lzma.len, s->lzma.rep0);
/*
* Decode more LZMA symbols. One iteration may consume up to
* LZMA_IN_REQUIRED - 1 bytes.
*/
while (dict_has_space(&s->dict) && !rc_limit_exceeded(&s->rc)) {
pos_state = s->dict.pos & s->lzma.pos_mask;
if (!rc_bit(&s->rc, &s->lzma.is_match[
s->lzma.state][pos_state])) {
lzma_literal(s);
} else {
if (rc_bit(&s->rc, &s->lzma.is_rep[s->lzma.state]))
lzma_rep_match(s, pos_state);
else
lzma_match(s, pos_state);
if (!dict_repeat(&s->dict, &s->lzma.len, s->lzma.rep0))
return 0;
}
}
/*
* Having the range decoder always normalized when we are outside
* this function makes it easier to correctly handle end of the chunk.
*/
rc_normalize(&s->rc);
return 1;
}
/*
* Reset the LZMA decoder and range decoder state. Dictionary is nore reset
* here, because LZMA state may be reset without resetting the dictionary.
*/
static void lzma_reset(struct xz_dec_lzma2 *s)
{
uint16_t *probs;
size_t i;
s->lzma.state = STATE_LIT_LIT;
s->lzma.rep0 = 0;
s->lzma.rep1 = 0;
s->lzma.rep2 = 0;
s->lzma.rep3 = 0;
/*
* All probabilities are initialized to the same value. This hack
* makes the code smaller by avoiding a separate loop for each
* probability array.
*
* This could be optimized so that only that part of literal
* probabilities that are actually required. In the common case
* we would write 12 KiB less.
*/
probs = s->lzma.is_match[0];
for (i = 0; i < PROBS_TOTAL; ++i)
probs[i] = RC_BIT_MODEL_TOTAL / 2;
rc_reset(&s->rc);
}
/*
* Decode and validate LZMA properties (lc/lp/pb) and calculate the bit masks
* from the decoded lp and pb values. On success, the LZMA decoder state is
* reset and true is returned.
*/
static int lzma_props(struct xz_dec_lzma2 *s, uint8_t props)
{
if (props > (4 * 5 + 4) * 9 + 8)
return 0;
s->lzma.pos_mask = 0;
while (props >= 9 * 5) {
props -= 9 * 5;
++s->lzma.pos_mask;
}
s->lzma.pos_mask = (1 << s->lzma.pos_mask) - 1;
s->lzma.literal_pos_mask = 0;
while (props >= 9) {
props -= 9;
++s->lzma.literal_pos_mask;
}
s->lzma.lc = props;
if (s->lzma.lc + s->lzma.literal_pos_mask > 4)
return 0;
s->lzma.literal_pos_mask = (1 << s->lzma.literal_pos_mask) - 1;
lzma_reset(s);
return 1;
}
/*********
* LZMA2 *
*********/
/*
* The LZMA decoder assumes that if the input limit (s->rc.in_limit) hasn't
* been exceeded, it is safe to read up to LZMA_IN_REQUIRED bytes. This
* wrapper function takes care of making the LZMA decoder's assumption safe.
*
* As long as there is plenty of input left to be decoded in the current LZMA
* chunk, we decode directly from the caller-supplied input buffer until
* there's LZMA_IN_REQUIRED bytes left. Those remaining bytes are copied into
* s->temp.buf, which (hopefully) gets filled on the next call to this
* function. We decode a few bytes from the temporary buffer so that we can
* continue decoding from the caller-supplied input buffer again.
*/
static int lzma2_lzma(struct xz_dec_lzma2 *s, struct xz_buf *b)
{
size_t in_avail;
uint32_t tmp;
in_avail = b->in_size - b->in_pos;
if (s->temp.size > 0 || s->lzma2.compressed == 0) {
tmp = 2 * LZMA_IN_REQUIRED - s->temp.size;
if (tmp > s->lzma2.compressed - s->temp.size)
tmp = s->lzma2.compressed - s->temp.size;
if (tmp > in_avail)
tmp = in_avail;
memcpy(s->temp.buf + s->temp.size, b->in + b->in_pos, tmp);
if (s->temp.size + tmp == s->lzma2.compressed) {
memset(s->temp.buf + s->temp.size + tmp, 0,
sizeof(s->temp.buf)
- s->temp.size - tmp);
s->rc.in_limit = s->temp.size + tmp;
} else if (s->temp.size + tmp < LZMA_IN_REQUIRED) {
s->temp.size += tmp;
b->in_pos += tmp;
return 1;
} else {
s->rc.in_limit = s->temp.size + tmp - LZMA_IN_REQUIRED;
}
s->rc.in = s->temp.buf;
s->rc.in_pos = 0;
if (!lzma_main(s) || s->rc.in_pos > s->temp.size + tmp)
return 0;
s->lzma2.compressed -= s->rc.in_pos;
if (s->rc.in_pos < s->temp.size) {
s->temp.size -= s->rc.in_pos;
memmove(s->temp.buf, s->temp.buf + s->rc.in_pos,
s->temp.size);
return 1;
}
b->in_pos += s->rc.in_pos - s->temp.size;
s->temp.size = 0;
}
in_avail = b->in_size - b->in_pos;
if (in_avail >= LZMA_IN_REQUIRED) {
s->rc.in = b->in;
s->rc.in_pos = b->in_pos;
if (in_avail >= s->lzma2.compressed + LZMA_IN_REQUIRED)
s->rc.in_limit = b->in_pos + s->lzma2.compressed;
else
s->rc.in_limit = b->in_size - LZMA_IN_REQUIRED;
if (!lzma_main(s))
return 0;
in_avail = s->rc.in_pos - b->in_pos;
if (in_avail > s->lzma2.compressed) return 0;
s->lzma2.compressed -= in_avail;
b->in_pos = s->rc.in_pos;
}
in_avail = b->in_size - b->in_pos;
if (in_avail < LZMA_IN_REQUIRED) {
if (in_avail > s->lzma2.compressed)
in_avail = s->lzma2.compressed;
memcpy(s->temp.buf, b->in + b->in_pos, in_avail);
s->temp.size = in_avail;
b->in_pos += in_avail;
}
return 1;
}
/*
* Take care of the LZMA2 control layer, and forward the job of actual LZMA
* decoding or copying of uncompressed chunks to other functions.
*/
enum xz_ret xz_dec_lzma2_run(struct xz_dec_lzma2 *s,
struct xz_buf *b)
{
uint32_t tmp;
while (b->in_pos < b->in_size || s->lzma2.sequence == SEQ_LZMA_RUN) {
switch (s->lzma2.sequence) {
case SEQ_CONTROL:
/*
* LZMA2 control byte
*
* Exact values:
* 0x00 End marker
* 0x01 Dictionary reset followed by
* an uncompressed chunk
* 0x02 Uncompressed chunk (no dictionary reset)
*
* Highest three bits (s->control & 0xE0):
* 0xE0 Dictionary reset, new properties and state
* reset, followed by LZMA compressed chunk
* 0xC0 New properties and state reset, followed
* by LZMA compressed chunk (no dictionary
* reset)
* 0xA0 State reset using old properties,
* followed by LZMA compressed chunk (no
* dictionary reset)
* 0x80 LZMA chunk (no dictionary or state reset)
*
* For LZMA compressed chunks, the lowest five bits
* (s->control & 1F) are the highest bits of the
* uncompressed size (bits 16-20).
*
* A new LZMA2 stream must begin with a dictionary
* reset. The first LZMA chunk must set new
* properties and reset the LZMA state.
*
* Values that don't match anything described above
* are invalid and we return XZ_DATA_ERROR.
*/
tmp = b->in[b->in_pos++];
if (tmp == 0x00)
return XZ_STREAM_END;
if (tmp >= 0xE0 || tmp == 0x01) {
s->lzma2.need_props = 1;
s->lzma2.need_dict_reset = 0;
dict_reset(&s->dict);
} else if (s->lzma2.need_dict_reset) {
return XZ_DATA_ERROR;
}
if (tmp >= 0x80) {
s->lzma2.uncompressed = (tmp & 0x1F) << 16;
s->lzma2.sequence = SEQ_UNCOMPRESSED_1;
if (tmp >= 0xC0) {
/*
* When there are new properties,
* state reset is done at
* SEQ_PROPERTIES.
*/
s->lzma2.need_props = 0;
s->lzma2.next_sequence
= SEQ_PROPERTIES;
} else if (s->lzma2.need_props) {
return XZ_DATA_ERROR;
} else {
s->lzma2.next_sequence
= SEQ_LZMA_PREPARE;
if (tmp >= 0xA0)
lzma_reset(s);
}
} else {
if (tmp > 0x02)
return XZ_DATA_ERROR;
s->lzma2.sequence = SEQ_COMPRESSED_0;
s->lzma2.next_sequence = SEQ_COPY;
}
break;
case SEQ_UNCOMPRESSED_1:
s->lzma2.uncompressed
+= (uint32_t)b->in[b->in_pos++] << 8;
s->lzma2.sequence = SEQ_UNCOMPRESSED_2;
break;
case SEQ_UNCOMPRESSED_2:
s->lzma2.uncompressed
+= (uint32_t)b->in[b->in_pos++] + 1;
s->lzma2.sequence = SEQ_COMPRESSED_0;
break;
case SEQ_COMPRESSED_0:
s->lzma2.compressed
= (uint32_t)b->in[b->in_pos++] << 8;
s->lzma2.sequence = SEQ_COMPRESSED_1;
break;
case SEQ_COMPRESSED_1:
s->lzma2.compressed
+= (uint32_t)b->in[b->in_pos++] + 1;
s->lzma2.sequence = s->lzma2.next_sequence;
break;
case SEQ_PROPERTIES:
if (!lzma_props(s, b->in[b->in_pos++]))
return XZ_DATA_ERROR;
s->lzma2.sequence = SEQ_LZMA_PREPARE;
case SEQ_LZMA_PREPARE:
if (s->lzma2.compressed < RC_INIT_BYTES)
return XZ_DATA_ERROR;
if (!rc_read_init(&s->rc, b))
return XZ_OK;
s->lzma2.compressed -= RC_INIT_BYTES;
s->lzma2.sequence = SEQ_LZMA_RUN;
case SEQ_LZMA_RUN:
/*
* Set dictionary limit to indicate how much we want
* to be encoded at maximum. Decode new data into the
* dictionary. Flush the new data from dictionary to
* b->out. Check if we finished decoding this chunk.
* In case the dictionary got full but we didn't fill
* the output buffer yet, we may run this loop
* multiple times without changing s->lzma2.sequence.
*/
dict_limit(&s->dict, minof(b->out_size - b->out_pos,
s->lzma2.uncompressed));
if (!lzma2_lzma(s, b))
return XZ_DATA_ERROR;
s->lzma2.uncompressed -= dict_flush(&s->dict, b);
if (s->lzma2.uncompressed == 0) {
if (s->lzma2.compressed > 0 || s->lzma.len > 0
|| !rc_is_finished(&s->rc))
return XZ_DATA_ERROR;
rc_reset(&s->rc);
s->lzma2.sequence = SEQ_CONTROL;
} else if (b->out_pos == b->out_size
|| (b->in_pos == b->in_size
&& s->temp.size
< s->lzma2.compressed)) {
return XZ_OK;
}
break;
case SEQ_COPY:
dict_uncompressed(&s->dict, b, &s->lzma2.compressed);
if (s->lzma2.compressed > 0)
return XZ_OK;
s->lzma2.sequence = SEQ_CONTROL;
break;
}
}
return XZ_OK;
}
struct xz_dec_lzma2 *xz_dec_lzma2_create(uint32_t dict_max)
{
struct xz_dec_lzma2 *s = malloc(sizeof(*s));
if (s == NULL)
return NULL;
s->dict.size_max = dict_max;
s->dict.buf = NULL;
s->dict.allocated = 0;
return s;
}
enum xz_ret xz_dec_lzma2_reset(struct xz_dec_lzma2 *s, uint8_t props)
{
/* This limits dictionary size to 3 GiB to keep parsing simpler. */
if (props > 39)
return XZ_OPTIONS_ERROR;
s->dict.size = 2 + (props & 1);
s->dict.size <<= (props >> 1) + 11;
if (s->dict.size > s->dict.size_max)
return XZ_MEMLIMIT_ERROR;
s->dict.end = s->dict.size;
if (s->dict.allocated < s->dict.size) {
free(s->dict.buf);
s->dict.buf = malloc(s->dict.size);
if (s->dict.buf == NULL) {
s->dict.allocated = 0;
return XZ_MEM_ERROR;
}
}
s->lzma.len = 0;
s->lzma2.sequence = SEQ_CONTROL;
s->lzma2.need_dict_reset = 1;
s->temp.size = 0;
return XZ_OK;
}
/*
* .xz Stream decoder
*/
// BEGIN xz_stream.h
/*
* Definitions for handling the .xz file format
*/
/*
* See the .xz file format specification at
* http://tukaani.org/xz/xz-file-format.txt
* to understand the container format.
*/
#define STREAM_HEADER_SIZE 12
#define HEADER_MAGIC "\3757zXZ"
#define HEADER_MAGIC_SIZE 6
#define FOOTER_MAGIC "YZ"
#define FOOTER_MAGIC_SIZE 2
/*
* Variable-length integer can hold a 63-bit unsigned integer or a special
* value indicating that the value is unknown.
*
* Experimental: vli_type can be defined to uint32_t to save a few bytes
* in code size (no effect on speed). Doing so limits the uncompressed and
* compressed size of the file to less than 256 MiB and may also weaken
* error detection slightly.
*/
typedef uint64_t vli_type;
#define VLI_MAX ((vli_type)-1 / 2)
#define VLI_UNKNOWN ((vli_type)-1)
/* Maximum encoded size of a VLI */
#define VLI_BYTES_MAX (sizeof(vli_type) * 8 / 7)
/* Integrity Check types */
enum xz_check {
XZ_CHECK_NONE = 0,
XZ_CHECK_CRC32 = 1,
XZ_CHECK_CRC64 = 4,
XZ_CHECK_SHA256 = 10
};
/* Maximum possible Check ID */
#define XZ_CHECK_MAX 15
// END xz_stream.h
#define IS_CRC64(check_type) ((check_type) == XZ_CHECK_CRC64)
/* Hash used to validate the Index field */
struct xz_dec_hash {
vli_type unpadded;
vli_type uncompressed;
uint32_t crc32;
};
struct xz_dec {
/* Position in dec_main() */
enum {
SEQ_STREAM_HEADER,
SEQ_BLOCK_START,
SEQ_BLOCK_HEADER,
SEQ_BLOCK_UNCOMPRESS,
SEQ_BLOCK_PADDING,
SEQ_BLOCK_CHECK,
SEQ_INDEX,
SEQ_INDEX_PADDING,
SEQ_INDEX_CRC32,
SEQ_STREAM_FOOTER
} sequence;
/* Position in variable-length integers and Check fields */
uint32_t pos;
/* Variable-length integer decoded by dec_vli() */
vli_type vli;
/* Saved in_pos and out_pos */
size_t in_start;
size_t out_start;
/* CRC32 or CRC64 value in Block or CRC32 value in Index */
uint64_t crc;
/* Type of the integrity check calculated from uncompressed data */
enum xz_check check_type;
/*
* True if the next call to xz_dec_run() is allowed to return
* XZ_BUF_ERROR.
*/
int allow_buf_error;
/* Information stored in Block Header */
struct {
/*
* Value stored in the Compressed Size field, or
* VLI_UNKNOWN if Compressed Size is not present.
*/
vli_type compressed;
/*
* Value stored in the Uncompressed Size field, or
* VLI_UNKNOWN if Uncompressed Size is not present.
*/
vli_type uncompressed;
/* Size of the Block Header field */
uint32_t size;
} block_header;
/* Information collected when decoding Blocks */
struct {
/* Observed compressed size of the current Block */
vli_type compressed;
/* Observed uncompressed size of the current Block */
vli_type uncompressed;
/* Number of Blocks decoded so far */
vli_type count;
/*
* Hash calculated from the Block sizes. This is used to
* validate the Index field.
*/
struct xz_dec_hash hash;
} block;
/* Variables needed when verifying the Index field */
struct {
/* Position in dec_index() */
enum {
SEQ_INDEX_COUNT,
SEQ_INDEX_UNPADDED,
SEQ_INDEX_UNCOMPRESSED
} sequence;
/* Size of the Index in bytes */
vli_type size;
/* Number of Records (matches block.count in valid files) */
vli_type count;
/*
* Hash calculated from the Records (matches block.hash in
* valid files).
*/
struct xz_dec_hash hash;
} index;
/*
* Temporary buffer needed to hold Stream Header, Block Header,
* and Stream Footer. The Block Header is the biggest (1 KiB)
* so we reserve space according to that. buf[] has to be aligned
* to a multiple of four bytes; the size_t variables before it
* should guarantee this.
*/
struct {
size_t pos;
size_t size;
uint8_t buf[1024];
} temp;
struct xz_dec_lzma2 *lzma2;
#ifdef XZ_DEC_BCJ
struct xz_dec_bcj *bcj;
int bcj_active;
#endif
};
/* Sizes of the Check field with different Check IDs */
static const uint8_t check_sizes[16] = {
0,
4, 4, 4,
8, 8, 8,
16, 16, 16,
32, 32, 32,
64, 64, 64
};
/*
* Fill s->temp by copying data starting from b->in[b->in_pos]. Caller
* must have set s->temp.pos to indicate how much data we are suppos |
 |