diff options
Diffstat (limited to 'src/liblzma/common/copy_coder.c')
| -rw-r--r-- | src/liblzma/common/copy_coder.c | 143 |
1 files changed, 143 insertions, 0 deletions
diff --git a/src/liblzma/common/copy_coder.c b/src/liblzma/common/copy_coder.c new file mode 100644 index 00000000..64864f60 --- /dev/null +++ b/src/liblzma/common/copy_coder.c @@ -0,0 +1,143 @@ +/////////////////////////////////////////////////////////////////////////////// +// +/// \file copy_coder.c +/// \brief The Copy filter encoder and decoder +// +// Copyright (C) 2007 Lasse Collin +// +// This library is free software; you can redistribute it and/or +// modify it under the terms of the GNU Lesser General Public +// License as published by the Free Software Foundation; either +// version 2.1 of the License, or (at your option) any later version. +// +// This library is distributed in the hope that it will be useful, +// but WITHOUT ANY WARRANTY; without even the implied warranty of +// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +// Lesser General Public License for more details. +// +/////////////////////////////////////////////////////////////////////////////// + +#include "copy_coder.h" + + +struct lzma_coder_s { + lzma_next_coder next; + lzma_vli uncompressed_size; + bool is_encoder; +}; + + +static lzma_ret +copy_code(lzma_coder *coder, 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) +{ + // If we aren't the last filter in the chain, the Copy filter + // is totally useless. Note that it is job of the next coder to + // take care of Uncompressed Size, so we don't need to update our + // coder->uncompressed_size at all. + if (coder->next.code != NULL) + return coder->next.code(coder->next.coder, allocator, + in, in_pos, in_size, out, out_pos, out_size, + action); + + // If we get here, we are the last filter in the chain. + + const size_t in_avail = in_size - *in_pos; + + if (coder->is_encoder) { + // Check that we don't have too much input. + if ((lzma_vli)(in_avail) > coder->uncompressed_size) + return LZMA_DATA_ERROR; + + // Check that once LZMA_FINISH has been given, the + // amount of input matches uncompressed_size if it + // is known. + if (action == LZMA_FINISH && coder->uncompressed_size + != LZMA_VLI_VALUE_UNKNOWN + && coder->uncompressed_size + != (lzma_vli)(in_avail)) + return LZMA_DATA_ERROR; + + } else { + // Limit in_size so that we don't copy too much. + if ((lzma_vli)(in_avail) > coder->uncompressed_size) + in_size = *in_pos + (size_t)(coder->uncompressed_size); + } + + // Store the old input position, which is needed to update + // coder->uncompressed_size. + const size_t in_start = *in_pos; + + // We are the last coder in the chain. + // Just copy as much data as possible. + bufcpy(in, in_pos, in_size, out, out_pos, out_size); + + // Update uncompressed_size if it is known. + if (coder->uncompressed_size != LZMA_VLI_VALUE_UNKNOWN) + coder->uncompressed_size -= *in_pos - in_start; + + // action can be LZMA_FINISH only in the encoder. + if ((action == LZMA_FINISH && *in_pos == in_size) + || coder->uncompressed_size == 0) + return LZMA_STREAM_END; + + return LZMA_OK; +} + + +static void +copy_coder_end(lzma_coder *coder, lzma_allocator *allocator) +{ + lzma_next_coder_end(&coder->next, allocator); + lzma_free(coder, allocator); + return; +} + + +static lzma_ret +copy_coder_init(lzma_next_coder *next, lzma_allocator *allocator, + const lzma_filter_info *filters, bool is_encoder) +{ + // Allocate memory for the decoder if needed. + if (next->coder == NULL) { + next->coder = lzma_alloc(sizeof(lzma_coder), allocator); + if (next->coder == NULL) + return LZMA_MEM_ERROR; + + next->code = ©_code; + next->end = ©_coder_end; + next->coder->next = LZMA_NEXT_CODER_INIT; + } + + // Copy Uncompressed Size which is used to limit the output size. + next->coder->uncompressed_size = filters[0].uncompressed_size; + + // The coder acts slightly differently as encoder and decoder. + next->coder->is_encoder = is_encoder; + + // Initialize the next decoder in the chain, if any. + return lzma_next_filter_init( + &next->coder->next, allocator, filters + 1); +} + + +#ifdef HAVE_ENCODER +extern lzma_ret +lzma_copy_encoder_init(lzma_next_coder *next, lzma_allocator *allocator, + const lzma_filter_info *filters) +{ + lzma_next_coder_init(copy_coder_init, next, allocator, filters, true); +} +#endif + + +#ifdef HAVE_DECODER +extern lzma_ret +lzma_copy_decoder_init(lzma_next_coder *next, lzma_allocator *allocator, + const lzma_filter_info *filters) +{ + lzma_next_coder_init(copy_coder_init, next, allocator, filters, false); +} +#endif |