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Diffstat (limited to 'src/liblzma/common/auto_decoder.c')
| -rw-r--r-- | src/liblzma/common/auto_decoder.c | 206 |
1 files changed, 206 insertions, 0 deletions
diff --git a/src/liblzma/common/auto_decoder.c b/src/liblzma/common/auto_decoder.c new file mode 100644 index 0000000..2a5c089 --- /dev/null +++ b/src/liblzma/common/auto_decoder.c @@ -0,0 +1,206 @@ +/////////////////////////////////////////////////////////////////////////////// +// +/// \file auto_decoder.c +/// \brief Autodetect between .xz, .lzma (LZMA_Alone), and .lz (lzip) +// +// Author: Lasse Collin +// +// This file has been put into the public domain. +// You can do whatever you want with this file. +// +/////////////////////////////////////////////////////////////////////////////// + +#include "stream_decoder.h" +#include "alone_decoder.h" +#ifdef HAVE_LZIP_DECODER +# include "lzip_decoder.h" +#endif + + +typedef struct { + /// .xz Stream decoder, LZMA_Alone decoder, or lzip decoder + lzma_next_coder next; + + uint64_t memlimit; + uint32_t flags; + + enum { + SEQ_INIT, + SEQ_CODE, + SEQ_FINISH, + } sequence; +} lzma_auto_coder; + + +static lzma_ret +auto_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_auto_coder *coder = coder_ptr; + + switch (coder->sequence) { + case SEQ_INIT: + if (*in_pos >= in_size) + return LZMA_OK; + + // Update the sequence now, because we want to continue from + // SEQ_CODE even if we return some LZMA_*_CHECK. + coder->sequence = SEQ_CODE; + + // Detect the file format. .xz files start with 0xFD which + // cannot be the first byte of .lzma (LZMA_Alone) format. + // The .lz format starts with 0x4C which could be the + // first byte of a .lzma file but luckily it would mean + // lc/lp/pb being 4/3/1 which liblzma doesn't support because + // lc + lp > 4. So using just 0x4C to detect .lz is OK here. + if (in[*in_pos] == 0xFD) { + return_if_error(lzma_stream_decoder_init( + &coder->next, allocator, + coder->memlimit, coder->flags)); +#ifdef HAVE_LZIP_DECODER + } else if (in[*in_pos] == 0x4C) { + return_if_error(lzma_lzip_decoder_init( + &coder->next, allocator, + coder->memlimit, coder->flags)); +#endif + } else { + return_if_error(lzma_alone_decoder_init(&coder->next, + allocator, coder->memlimit, true)); + + // If the application wants to know about missing + // integrity check or about the check in general, we + // need to handle it here, because LZMA_Alone decoder + // doesn't accept any flags. + if (coder->flags & LZMA_TELL_NO_CHECK) + return LZMA_NO_CHECK; + + if (coder->flags & LZMA_TELL_ANY_CHECK) + return LZMA_GET_CHECK; + } + + // Fall through + + case SEQ_CODE: { + const lzma_ret ret = coder->next.code( + coder->next.coder, allocator, + in, in_pos, in_size, + out, out_pos, out_size, action); + if (ret != LZMA_STREAM_END + || (coder->flags & LZMA_CONCATENATED) == 0) + return ret; + + coder->sequence = SEQ_FINISH; + } + + // Fall through + + case SEQ_FINISH: + // When LZMA_CONCATENATED was used and we were decoding + // a LZMA_Alone file, we need to check that there is no + // trailing garbage and wait for LZMA_FINISH. + if (*in_pos < in_size) + return LZMA_DATA_ERROR; + + return action == LZMA_FINISH ? LZMA_STREAM_END : LZMA_OK; + + default: + assert(0); + return LZMA_PROG_ERROR; + } +} + + +static void +auto_decoder_end(void *coder_ptr, const lzma_allocator *allocator) +{ + lzma_auto_coder *coder = coder_ptr; + lzma_next_end(&coder->next, allocator); + lzma_free(coder, allocator); + return; +} + + +static lzma_check +auto_decoder_get_check(const void *coder_ptr) +{ + const lzma_auto_coder *coder = coder_ptr; + + // It is LZMA_Alone if get_check is NULL. + return coder->next.get_check == NULL ? LZMA_CHECK_NONE + : coder->next.get_check(coder->next.coder); +} + + +static lzma_ret +auto_decoder_memconfig(void *coder_ptr, uint64_t *memusage, + uint64_t *old_memlimit, uint64_t new_memlimit) +{ + lzma_auto_coder *coder = coder_ptr; + + lzma_ret ret; + + if (coder->next.memconfig != NULL) { + ret = coder->next.memconfig(coder->next.coder, + memusage, old_memlimit, new_memlimit); + assert(*old_memlimit == coder->memlimit); + } else { + // No coder is configured yet. Use the base value as + // the current memory usage. + *memusage = LZMA_MEMUSAGE_BASE; + *old_memlimit = coder->memlimit; + + ret = LZMA_OK; + if (new_memlimit != 0 && new_memlimit < *memusage) + ret = LZMA_MEMLIMIT_ERROR; + } + + if (ret == LZMA_OK && new_memlimit != 0) + coder->memlimit = new_memlimit; + + return ret; +} + + +static lzma_ret +auto_decoder_init(lzma_next_coder *next, const lzma_allocator *allocator, + uint64_t memlimit, uint32_t flags) +{ + lzma_next_coder_init(&auto_decoder_init, next, allocator); + + if (flags & ~LZMA_SUPPORTED_FLAGS) + return LZMA_OPTIONS_ERROR; + + lzma_auto_coder *coder = next->coder; + if (coder == NULL) { + coder = lzma_alloc(sizeof(lzma_auto_coder), allocator); + if (coder == NULL) + return LZMA_MEM_ERROR; + + next->coder = coder; + next->code = &auto_decode; + next->end = &auto_decoder_end; + next->get_check = &auto_decoder_get_check; + next->memconfig = &auto_decoder_memconfig; + coder->next = LZMA_NEXT_CODER_INIT; + } + + coder->memlimit = my_max(1, memlimit); + coder->flags = flags; + coder->sequence = SEQ_INIT; + + return LZMA_OK; +} + + +extern LZMA_API(lzma_ret) +lzma_auto_decoder(lzma_stream *strm, uint64_t memlimit, uint32_t flags) +{ + lzma_next_strm_init(auto_decoder_init, strm, memlimit, flags); + + strm->internal->supported_actions[LZMA_RUN] = true; + strm->internal->supported_actions[LZMA_FINISH] = true; + + return LZMA_OK; +} |