summaryrefslogtreecommitdiffstats
path: root/src/liblzma/common/lzip_decoder.c
diff options
context:
space:
mode:
Diffstat (limited to 'src/liblzma/common/lzip_decoder.c')
-rw-r--r--src/liblzma/common/lzip_decoder.c418
1 files changed, 418 insertions, 0 deletions
diff --git a/src/liblzma/common/lzip_decoder.c b/src/liblzma/common/lzip_decoder.c
new file mode 100644
index 0000000..88cc7ff
--- /dev/null
+++ b/src/liblzma/common/lzip_decoder.c
@@ -0,0 +1,418 @@
+///////////////////////////////////////////////////////////////////////////////
+//
+/// \file lzip_decoder.c
+/// \brief Decodes .lz (lzip) files
+//
+// Author: Michał Górny
+// Lasse Collin
+//
+// This file has been put into the public domain.
+// You can do whatever you want with this file.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#include "lzip_decoder.h"
+#include "lzma_decoder.h"
+#include "check.h"
+
+
+// .lz format version 0 lacks the 64-bit Member size field in the footer.
+#define LZIP_V0_FOOTER_SIZE 12
+#define LZIP_V1_FOOTER_SIZE 20
+#define LZIP_FOOTER_SIZE_MAX LZIP_V1_FOOTER_SIZE
+
+// lc/lp/pb are hardcoded in the .lz format.
+#define LZIP_LC 3
+#define LZIP_LP 0
+#define LZIP_PB 2
+
+
+typedef struct {
+ enum {
+ SEQ_ID_STRING,
+ SEQ_VERSION,
+ SEQ_DICT_SIZE,
+ SEQ_CODER_INIT,
+ SEQ_LZMA_STREAM,
+ SEQ_MEMBER_FOOTER,
+ } sequence;
+
+ /// .lz member format version
+ uint32_t version;
+
+ /// CRC32 of the uncompressed data in the .lz member
+ uint32_t crc32;
+
+ /// Uncompressed size of the .lz member
+ uint64_t uncompressed_size;
+
+ /// Compressed size of the .lz member
+ uint64_t member_size;
+
+ /// Memory usage limit
+ uint64_t memlimit;
+
+ /// Amount of memory actually needed
+ uint64_t memusage;
+
+ /// If true, LZMA_GET_CHECK is returned after decoding the header
+ /// fields. As all files use CRC32 this is redundant but it's
+ /// implemented anyway since the initialization functions supports
+ /// all other flags in addition to LZMA_TELL_ANY_CHECK.
+ bool tell_any_check;
+
+ /// If true, we won't calculate or verify the CRC32 of
+ /// the uncompressed data.
+ bool ignore_check;
+
+ /// If true, we will decode concatenated .lz members and stop if
+ /// non-.lz data is seen after at least one member has been
+ /// successfully decoded.
+ bool concatenated;
+
+ /// When decoding concatenated .lz members, this is true as long as
+ /// we are decoding the first .lz member. This is needed to avoid
+ /// incorrect LZMA_FORMAT_ERROR in case there is non-.lz data at
+ /// the end of the file.
+ bool first_member;
+
+ /// Reading position in the header and footer fields
+ size_t pos;
+
+ /// Buffer to hold the .lz footer fields
+ uint8_t buffer[LZIP_FOOTER_SIZE_MAX];
+
+ /// Options decoded from the .lz header that needed to initialize
+ /// the LZMA1 decoder.
+ lzma_options_lzma options;
+
+ /// LZMA1 decoder
+ lzma_next_coder lzma_decoder;
+
+} lzma_lzip_coder;
+
+
+static lzma_ret
+lzip_decode(void *coder_ptr, const lzma_allocator *allocator,
+ const uint8_t *restrict in, size_t *restrict in_pos,
+ size_t in_size, uint8_t *restrict out,
+ size_t *restrict out_pos, size_t out_size, lzma_action action)
+{
+ lzma_lzip_coder *coder = coder_ptr;
+
+ while (true)
+ switch (coder->sequence) {
+ case SEQ_ID_STRING: {
+ // The "ID string" or magic bytes are "LZIP" in US-ASCII.
+ const uint8_t lzip_id_string[4] = { 0x4C, 0x5A, 0x49, 0x50 };
+
+ while (coder->pos < sizeof(lzip_id_string)) {
+ if (*in_pos >= in_size) {
+ // If we are on the 2nd+ concatenated member
+ // and the input ends before we can read
+ // the magic bytes, we discard the bytes that
+ // were already read (up to 3) and finish.
+ // See the reasoning below.
+ return !coder->first_member
+ && action == LZMA_FINISH
+ ? LZMA_STREAM_END : LZMA_OK;
+ }
+
+ if (in[*in_pos] != lzip_id_string[coder->pos]) {
+ // The .lz format allows putting non-.lz data
+ // at the end of the file. If we have seen
+ // at least one valid .lz member already,
+ // then we won't consume the byte at *in_pos
+ // and will return LZMA_STREAM_END. This way
+ // apps can easily locate and read the non-.lz
+ // data after the .lz member(s).
+ //
+ // NOTE: If the first 1-3 bytes of the non-.lz
+ // data match the .lz ID string then the first
+ // 1-3 bytes of the junk will get ignored by
+ // us. If apps want to properly locate the
+ // trailing data they must ensure that the
+ // first byte of their custom data isn't the
+ // same as the first byte of .lz ID string.
+ // With the liblzma API we cannot rewind the
+ // input position across calls to lzma_code().
+ return !coder->first_member
+ ? LZMA_STREAM_END : LZMA_FORMAT_ERROR;
+ }
+
+ ++*in_pos;
+ ++coder->pos;
+ }
+
+ coder->pos = 0;
+
+ coder->crc32 = 0;
+ coder->uncompressed_size = 0;
+ coder->member_size = sizeof(lzip_id_string);
+
+ coder->sequence = SEQ_VERSION;
+ }
+
+ // Fall through
+
+ case SEQ_VERSION:
+ if (*in_pos >= in_size)
+ return LZMA_OK;
+
+ coder->version = in[(*in_pos)++];
+
+ // We support version 0 and unextended version 1.
+ if (coder->version > 1)
+ return LZMA_OPTIONS_ERROR;
+
+ ++coder->member_size;
+ coder->sequence = SEQ_DICT_SIZE;
+
+ // .lz versions 0 and 1 use CRC32 as the integrity check
+ // so if the application wanted to know that
+ // (LZMA_TELL_ANY_CHECK) we can tell it now.
+ if (coder->tell_any_check)
+ return LZMA_GET_CHECK;
+
+ // Fall through
+
+ case SEQ_DICT_SIZE: {
+ if (*in_pos >= in_size)
+ return LZMA_OK;
+
+ const uint32_t ds = in[(*in_pos)++];
+ ++coder->member_size;
+
+ // The five lowest bits are for the base-2 logarithm of
+ // the dictionary size and the highest three bits are
+ // the fractional part (0/16 to 7/16) that will be
+ // subtracted to get the final value.
+ //
+ // For example, with 0xB5:
+ // b2log = 21
+ // fracnum = 5
+ // dict_size = 2^21 - 2^21 * 5 / 16 = 1408 KiB
+ const uint32_t b2log = ds & 0x1F;
+ const uint32_t fracnum = ds >> 5;
+
+ // The format versions 0 and 1 allow dictionary size in the
+ // range [4 KiB, 512 MiB].
+ if (b2log < 12 || b2log > 29 || (b2log == 12 && fracnum > 0))
+ return LZMA_DATA_ERROR;
+
+ // 2^[b2log] - 2^[b2log] * [fracnum] / 16
+ // = 2^[b2log] - [fracnum] * 2^([b2log] - 4)
+ coder->options.dict_size = (UINT32_C(1) << b2log)
+ - (fracnum << (b2log - 4));
+
+ assert(coder->options.dict_size >= 4096);
+ assert(coder->options.dict_size <= (UINT32_C(512) << 20));
+
+ coder->options.preset_dict = NULL;
+ coder->options.lc = LZIP_LC;
+ coder->options.lp = LZIP_LP;
+ coder->options.pb = LZIP_PB;
+
+ // Calculate the memory usage.
+ coder->memusage = lzma_lzma_decoder_memusage(&coder->options)
+ + LZMA_MEMUSAGE_BASE;
+
+ // Initialization is a separate step because if we return
+ // LZMA_MEMLIMIT_ERROR we need to be able to restart after
+ // the memlimit has been increased.
+ coder->sequence = SEQ_CODER_INIT;
+ }
+
+ // Fall through
+
+ case SEQ_CODER_INIT: {
+ if (coder->memusage > coder->memlimit)
+ return LZMA_MEMLIMIT_ERROR;
+
+ const lzma_filter_info filters[2] = {
+ {
+ .id = LZMA_FILTER_LZMA1,
+ .init = &lzma_lzma_decoder_init,
+ .options = &coder->options,
+ }, {
+ .init = NULL,
+ }
+ };
+
+ return_if_error(lzma_next_filter_init(&coder->lzma_decoder,
+ allocator, filters));
+
+ coder->crc32 = 0;
+ coder->sequence = SEQ_LZMA_STREAM;
+ }
+
+ // Fall through
+
+ case SEQ_LZMA_STREAM: {
+ const size_t in_start = *in_pos;
+ const size_t out_start = *out_pos;
+
+ const lzma_ret ret = coder->lzma_decoder.code(
+ coder->lzma_decoder.coder, allocator,
+ in, in_pos, in_size, out, out_pos, out_size,
+ action);
+
+ const size_t out_used = *out_pos - out_start;
+
+ coder->member_size += *in_pos - in_start;
+ coder->uncompressed_size += out_used;
+
+ // Don't update the CRC32 if the integrity check will be
+ // ignored or if there was no new output. The latter is
+ // important in case out == NULL to avoid null pointer + 0
+ // which is undefined behavior.
+ if (!coder->ignore_check && out_used > 0)
+ coder->crc32 = lzma_crc32(out + out_start, out_used,
+ coder->crc32);
+
+ if (ret != LZMA_STREAM_END)
+ return ret;
+
+ coder->sequence = SEQ_MEMBER_FOOTER;
+ }
+
+ // Fall through
+
+ case SEQ_MEMBER_FOOTER: {
+ // The footer of .lz version 0 lacks the Member size field.
+ // This is the only difference between version 0 and
+ // unextended version 1 formats.
+ const size_t footer_size = coder->version == 0
+ ? LZIP_V0_FOOTER_SIZE
+ : LZIP_V1_FOOTER_SIZE;
+
+ // Copy the CRC32, Data size, and Member size fields to
+ // the internal buffer.
+ lzma_bufcpy(in, in_pos, in_size, coder->buffer, &coder->pos,
+ footer_size);
+
+ // Return if we didn't get the whole footer yet.
+ if (coder->pos < footer_size)
+ return LZMA_OK;
+
+ coder->pos = 0;
+ coder->member_size += footer_size;
+
+ // Check that the footer fields match the observed data.
+ if (!coder->ignore_check
+ && coder->crc32 != read32le(&coder->buffer[0]))
+ return LZMA_DATA_ERROR;
+
+ if (coder->uncompressed_size != read64le(&coder->buffer[4]))
+ return LZMA_DATA_ERROR;
+
+ if (coder->version > 0) {
+ // .lz version 0 has no Member size field.
+ if (coder->member_size != read64le(&coder->buffer[12]))
+ return LZMA_DATA_ERROR;
+ }
+
+ // Decoding is finished if we weren't requested to decode
+ // more than one .lz member.
+ if (!coder->concatenated)
+ return LZMA_STREAM_END;
+
+ coder->first_member = false;
+ coder->sequence = SEQ_ID_STRING;
+ break;
+ }
+
+ default:
+ assert(0);
+ return LZMA_PROG_ERROR;
+ }
+
+ // Never reached
+}
+
+
+static void
+lzip_decoder_end(void *coder_ptr, const lzma_allocator *allocator)
+{
+ lzma_lzip_coder *coder = coder_ptr;
+ lzma_next_end(&coder->lzma_decoder, allocator);
+ lzma_free(coder, allocator);
+ return;
+}
+
+
+static lzma_check
+lzip_decoder_get_check(const void *coder_ptr lzma_attribute((__unused__)))
+{
+ return LZMA_CHECK_CRC32;
+}
+
+
+static lzma_ret
+lzip_decoder_memconfig(void *coder_ptr, uint64_t *memusage,
+ uint64_t *old_memlimit, uint64_t new_memlimit)
+{
+ lzma_lzip_coder *coder = coder_ptr;
+
+ *memusage = coder->memusage;
+ *old_memlimit = coder->memlimit;
+
+ if (new_memlimit != 0) {
+ if (new_memlimit < coder->memusage)
+ return LZMA_MEMLIMIT_ERROR;
+
+ coder->memlimit = new_memlimit;
+ }
+
+ return LZMA_OK;
+}
+
+
+extern lzma_ret
+lzma_lzip_decoder_init(
+ lzma_next_coder *next, const lzma_allocator *allocator,
+ uint64_t memlimit, uint32_t flags)
+{
+ lzma_next_coder_init(&lzma_lzip_decoder_init, next, allocator);
+
+ if (flags & ~LZMA_SUPPORTED_FLAGS)
+ return LZMA_OPTIONS_ERROR;
+
+ lzma_lzip_coder *coder = next->coder;
+ if (coder == NULL) {
+ coder = lzma_alloc(sizeof(lzma_lzip_coder), allocator);
+ if (coder == NULL)
+ return LZMA_MEM_ERROR;
+
+ next->coder = coder;
+ next->code = &lzip_decode;
+ next->end = &lzip_decoder_end;
+ next->get_check = &lzip_decoder_get_check;
+ next->memconfig = &lzip_decoder_memconfig;
+
+ coder->lzma_decoder = LZMA_NEXT_CODER_INIT;
+ }
+
+ coder->sequence = SEQ_ID_STRING;
+ coder->memlimit = my_max(1, memlimit);
+ coder->memusage = LZMA_MEMUSAGE_BASE;
+ coder->tell_any_check = (flags & LZMA_TELL_ANY_CHECK) != 0;
+ coder->ignore_check = (flags & LZMA_IGNORE_CHECK) != 0;
+ coder->concatenated = (flags & LZMA_CONCATENATED) != 0;
+ coder->first_member = true;
+ coder->pos = 0;
+
+ return LZMA_OK;
+}
+
+
+extern LZMA_API(lzma_ret)
+lzma_lzip_decoder(lzma_stream *strm, uint64_t memlimit, uint32_t flags)
+{
+ lzma_next_strm_init(lzma_lzip_decoder_init, strm, memlimit, flags);
+
+ strm->internal->supported_actions[LZMA_RUN] = true;
+ strm->internal->supported_actions[LZMA_FINISH] = true;
+
+ return LZMA_OK;
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-16 20:03:33 +0000