--- /dev/null
+///////////////////////////////////////////////////////////////////////////////
+//
+/// \file block_decoder.c
+/// \brief Decodes .xz Blocks
+//
+// Author: Lasse Collin
+//
+// This file has been put into the public domain.
+// You can do whatever you want with this file.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#include "block_decoder.h"
+#include "filter_decoder.h"
+#include "check.h"
+
+
+struct lzma_coder_s {
+ enum {
+ SEQ_CODE,
+ SEQ_PADDING,
+ SEQ_CHECK,
+ } sequence;
+
+ /// The filters in the chain; initialized with lzma_raw_decoder_init().
+ lzma_next_coder next;
+
+ /// Decoding options; we also write Compressed Size and Uncompressed
+ /// Size back to this structure when the decoding has been finished.
+ lzma_block *block;
+
+ /// Compressed Size calculated while decoding
+ lzma_vli compressed_size;
+
+ /// Uncompressed Size calculated while decoding
+ lzma_vli uncompressed_size;
+
+ /// Maximum allowed Compressed Size; this takes into account the
+ /// size of the Block Header and Check fields when Compressed Size
+ /// is unknown.
+ lzma_vli compressed_limit;
+
+ /// Position when reading the Check field
+ size_t check_pos;
+
+ /// Check of the uncompressed data
+ lzma_check_state check;
+
+ /// True if the integrity check won't be calculated and verified.
+ bool ignore_check;
+};
+
+
+static inline bool
+update_size(lzma_vli *size, lzma_vli add, lzma_vli limit)
+{
+ if (limit > LZMA_VLI_MAX)
+ limit = LZMA_VLI_MAX;
+
+ if (limit < *size || limit - *size < add)
+ return true;
+
+ *size += add;
+
+ return false;
+}
+
+
+static inline bool
+is_size_valid(lzma_vli size, lzma_vli reference)
+{
+ return reference == LZMA_VLI_UNKNOWN || reference == size;
+}
+
+
+static lzma_ret
+block_decode(lzma_coder *coder, 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)
+{
+ switch (coder->sequence) {
+ case SEQ_CODE: {
+ const size_t in_start = *in_pos;
+ const size_t out_start = *out_pos;
+
+ const lzma_ret ret = coder->next.code(coder->next.coder,
+ allocator, in, in_pos, in_size,
+ out, out_pos, out_size, action);
+
+ const size_t in_used = *in_pos - in_start;
+ const size_t out_used = *out_pos - out_start;
+
+ // NOTE: We compare to compressed_limit here, which prevents
+ // the total size of the Block growing past LZMA_VLI_MAX.
+ if (update_size(&coder->compressed_size, in_used,
+ coder->compressed_limit)
+ || update_size(&coder->uncompressed_size,
+ out_used,
+ coder->block->uncompressed_size))
+ return LZMA_DATA_ERROR;
+
+ if (!coder->ignore_check)
+ lzma_check_update(&coder->check, coder->block->check,
+ out + out_start, out_used);
+
+ if (ret != LZMA_STREAM_END)
+ return ret;
+
+ // Compressed and Uncompressed Sizes are now at their final
+ // values. Verify that they match the values given to us.
+ if (!is_size_valid(coder->compressed_size,
+ coder->block->compressed_size)
+ || !is_size_valid(coder->uncompressed_size,
+ coder->block->uncompressed_size))
+ return LZMA_DATA_ERROR;
+
+ // Copy the values into coder->block. The caller
+ // may use this information to construct Index.
+ coder->block->compressed_size = coder->compressed_size;
+ coder->block->uncompressed_size = coder->uncompressed_size;
+
+ coder->sequence = SEQ_PADDING;
+ }
+
+ // Fall through
+
+ case SEQ_PADDING:
+ // Compressed Data is padded to a multiple of four bytes.
+ while (coder->compressed_size & 3) {
+ if (*in_pos >= in_size)
+ return LZMA_OK;
+
+ // We use compressed_size here just get the Padding
+ // right. The actual Compressed Size was stored to
+ // coder->block already, and won't be modified by
+ // us anymore.
+ ++coder->compressed_size;
+
+ if (in[(*in_pos)++] != 0x00)
+ return LZMA_DATA_ERROR;
+ }
+
+ if (coder->block->check == LZMA_CHECK_NONE)
+ return LZMA_STREAM_END;
+
+ if (!coder->ignore_check)
+ lzma_check_finish(&coder->check, coder->block->check);
+
+ coder->sequence = SEQ_CHECK;
+
+ // Fall through
+
+ case SEQ_CHECK: {
+ const size_t check_size = lzma_check_size(coder->block->check);
+ lzma_bufcpy(in, in_pos, in_size, coder->block->raw_check,
+ &coder->check_pos, check_size);
+ if (coder->check_pos < check_size)
+ return LZMA_OK;
+
+ // Validate the Check only if we support it.
+ // coder->check.buffer may be uninitialized
+ // when the Check ID is not supported.
+ if (!coder->ignore_check
+ && lzma_check_is_supported(coder->block->check)
+ && memcmp(coder->block->raw_check,
+ coder->check.buffer.u8,
+ check_size) != 0)
+ return LZMA_DATA_ERROR;
+
+ return LZMA_STREAM_END;
+ }
+ }
+
+ return LZMA_PROG_ERROR;
+}
+
+
+static void
+block_decoder_end(lzma_coder *coder, const lzma_allocator *allocator)
+{
+ lzma_next_end(&coder->next, allocator);
+ lzma_free(coder, allocator);
+ return;
+}
+
+
+extern lzma_ret
+lzma_block_decoder_init(lzma_next_coder *next, const lzma_allocator *allocator,
+ lzma_block *block)
+{
+ lzma_next_coder_init(&lzma_block_decoder_init, next, allocator);
+
+ // Validate the options. lzma_block_unpadded_size() does that for us
+ // except for Uncompressed Size and filters. Filters are validated
+ // by the raw decoder.
+ if (lzma_block_unpadded_size(block) == 0
+ || !lzma_vli_is_valid(block->uncompressed_size))
+ return LZMA_PROG_ERROR;
+
+ // Allocate and initialize *next->coder if needed.
+ if (next->coder == NULL) {
+ next->coder = lzma_alloc(sizeof(lzma_coder), allocator);
+ if (next->coder == NULL)
+ return LZMA_MEM_ERROR;
+
+ next->code = &block_decode;
+ next->end = &block_decoder_end;
+ next->coder->next = LZMA_NEXT_CODER_INIT;
+ }
+
+ // Basic initializations
+ next->coder->sequence = SEQ_CODE;
+ next->coder->block = block;
+ next->coder->compressed_size = 0;
+ next->coder->uncompressed_size = 0;
+
+ // If Compressed Size is not known, we calculate the maximum allowed
+ // value so that encoded size of the Block (including Block Padding)
+ // is still a valid VLI and a multiple of four.
+ next->coder->compressed_limit
+ = block->compressed_size == LZMA_VLI_UNKNOWN
+ ? (LZMA_VLI_MAX & ~LZMA_VLI_C(3))
+ - block->header_size
+ - lzma_check_size(block->check)
+ : block->compressed_size;
+
+ // Initialize the check. It's caller's problem if the Check ID is not
+ // supported, and the Block decoder cannot verify the Check field.
+ // Caller can test lzma_check_is_supported(block->check).
+ next->coder->check_pos = 0;
+ lzma_check_init(&next->coder->check, block->check);
+
+ next->coder->ignore_check = block->version >= 1
+ ? block->ignore_check : false;
+
+ // Initialize the filter chain.
+ return lzma_raw_decoder_init(&next->coder->next, allocator,
+ block->filters);
+}
+
+
+extern LZMA_API(lzma_ret)
+lzma_block_decoder(lzma_stream *strm, lzma_block *block)
+{
+ lzma_next_strm_init(lzma_block_decoder_init, strm, block);
+
+ strm->internal->supported_actions[LZMA_RUN] = true;
+ strm->internal->supported_actions[LZMA_FINISH] = true;
+
+ return LZMA_OK;
+}
projects / zpackage / blobdiff