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-rw-r--r--src/liblzma/common/copy_coder.c143
1 files changed, 143 insertions, 0 deletions
diff --git a/src/liblzma/common/copy_coder.c b/src/liblzma/common/copy_coder.c
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+++ b/src/liblzma/common/copy_coder.c
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+///////////////////////////////////////////////////////////////////////////////
+//
+/// \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 = &copy_code;
+ next->end = &copy_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