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Subblock decoder: Don't exit the main loop in decode_buffer()
too early if we hit End of Input while decoding a Subblock of type Repeating Data. To keep the loop termination condition elegant, the order of enumerations in coder->sequence were changed. To keep the case-labels in roughly the same order as the enumerations in coder->sequence, large chunks of code was moved around. This made the diff big and ugly compared to the amount of the actual changes made.
This commit is contained in:
Lasse Collin
parent
b254bd97b1
commit
33be3c0e24
1 changed files with 139 additions and 133 deletions
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@ -30,20 +30,24 @@ struct lzma_coder_s {
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lzma_next_coder next;
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enum {
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// These require that there is at least one input
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// byte available.
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SEQ_FLAGS,
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SEQ_SIZE_1,
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SEQ_SIZE_2,
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SEQ_SIZE_3,
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SEQ_DATA,
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SEQ_FILTER_FLAGS,
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SEQ_FILTER_END,
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SEQ_REPEAT_COUNT_1,
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SEQ_REPEAT_COUNT_2,
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SEQ_REPEAT_COUNT_3,
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SEQ_REPEAT_SIZE,
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SEQ_REPEAT_READ_DATA,
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SEQ_SIZE_1,
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SEQ_SIZE_2,
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SEQ_SIZE_3, // This must be right before SEQ_DATA.
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// These don't require any input to be available.
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SEQ_DATA,
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SEQ_REPEAT_FAST,
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SEQ_REPEAT_NORMAL,
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SEQ_FILTER_FLAGS,
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SEQ_FILTER_END,
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} sequence;
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/// Number of bytes left in the current Subblock Data field.
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@ -167,7 +171,7 @@ decode_buffer(lzma_coder *coder, lzma_allocator *allocator,
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size_t *restrict out_pos, size_t out_size, lzma_action action)
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{
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while (*out_pos < out_size && (*in_pos < in_size
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|| coder->sequence == SEQ_DATA))
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|| coder->sequence >= SEQ_DATA))
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switch (coder->sequence) {
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case SEQ_FLAGS: {
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if ((in[*in_pos] >> 4) != FLAG_PADDING)
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@ -284,8 +288,68 @@ decode_buffer(lzma_coder *coder, lzma_allocator *allocator,
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break;
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}
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case SEQ_SIZE_1:
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case SEQ_FILTER_FLAGS: {
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const lzma_ret ret = coder->filter_flags_decoder.code(
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coder->filter_flags_decoder.coder, allocator,
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in, in_pos, in_size, NULL, NULL, 0, LZMA_RUN);
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if (ret != LZMA_STREAM_END)
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return ret == LZMA_HEADER_ERROR
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? LZMA_DATA_ERROR : ret;
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// Don't free the filter_flags_decoder. It doesn't take much
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// memory and we may need it again.
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// Initialize the Subfilter. Subblock and Copy filters are
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// not allowed.
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if (coder->filter_flags.id == LZMA_FILTER_COPY
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|| coder->filter_flags.id
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== LZMA_FILTER_SUBBLOCK)
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return LZMA_DATA_ERROR;
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coder->helper.end_was_reached = false;
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lzma_options_filter filters[3] = {
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{
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.id = coder->filter_flags.id,
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.options = coder->filter_flags.options,
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}, {
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.id = LZMA_FILTER_SUBBLOCK_HELPER,
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.options = &coder->helper,
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}, {
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.id = LZMA_VLI_VALUE_UNKNOWN,
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.options = NULL,
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}
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};
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// Optimization: We know that LZMA uses End of Payload Marker
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// (not End of Input), so we can omit the helper filter.
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if (filters[0].id == LZMA_FILTER_LZMA)
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filters[1].id = LZMA_VLI_VALUE_UNKNOWN;
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return_if_error(lzma_raw_decoder_init(
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&coder->subfilter, allocator,
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filters, LZMA_VLI_VALUE_UNKNOWN, false));
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coder->sequence = SEQ_FLAGS;
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break;
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}
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case SEQ_FILTER_END:
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// We are in the beginning of a Subblock. The next Subblock
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// whose type is not Padding, must indicate end of Subfilter.
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if (in[*in_pos] == (FLAG_PADDING << 4)) {
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++*in_pos;
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break;
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}
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if (in[*in_pos] != (FLAG_END_SUBFILTER << 4))
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return LZMA_DATA_ERROR;
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coder->sequence = SEQ_FLAGS;
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break;
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case SEQ_REPEAT_COUNT_1:
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case SEQ_SIZE_1:
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// We use the same code to parse
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// - the Size (28 bits) in Subblocks of type Data; and
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// - the Repeat count (28 bits) in Subblocks of type
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@ -295,21 +359,23 @@ decode_buffer(lzma_coder *coder, lzma_allocator *allocator,
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++coder->sequence;
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break;
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case SEQ_SIZE_2:
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case SEQ_REPEAT_COUNT_2:
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case SEQ_SIZE_2:
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coder->size |= (size_t)(in[*in_pos]) << 12;
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++*in_pos;
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++coder->sequence;
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break;
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case SEQ_SIZE_3:
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case SEQ_REPEAT_COUNT_3:
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case SEQ_SIZE_3:
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coder->size |= (size_t)(in[*in_pos]) << 20;
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++*in_pos;
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// The real value is the stored value plus one.
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++coder->size;
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++*in_pos;
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// This moves to SEQ_REPEAT_SIZE or SEQ_DATA. That's why
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// SEQ_DATA must be right after SEQ_SIZE_3 in coder->sequence.
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++coder->sequence;
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break;
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@ -348,6 +414,68 @@ decode_buffer(lzma_coder *coder, lzma_allocator *allocator,
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break;
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}
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case SEQ_DATA: {
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// Limit the amount of input to match the available
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// Subblock Data size.
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size_t in_limit;
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if (in_size - *in_pos > coder->size)
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in_limit = *in_pos + coder->size;
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else
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in_limit = in_size;
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if (coder->subfilter.code == NULL) {
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const size_t copy_size = bufcpy(
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in, in_pos, in_limit,
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out, out_pos, out_size);
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coder->size -= copy_size;
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if (update_uncompressed_size(coder, copy_size))
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return LZMA_DATA_ERROR;
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} else {
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const size_t in_start = *in_pos;
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const lzma_ret ret = subfilter_decode(
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coder, allocator,
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in, in_pos, in_limit,
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out, out_pos, out_size,
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action);
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// Update the number of unprocessed bytes left in
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// this Subblock. This assert() is true because
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// in_limit prevents *in_pos getting too big.
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assert(*in_pos - in_start <= coder->size);
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coder->size -= *in_pos - in_start;
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if (ret == LZMA_STREAM_END) {
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// End of Subfilter can occur only at
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// a Subblock boundary.
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if (coder->size != 0)
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return LZMA_DATA_ERROR;
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// We need a Subblock with Unset
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// Subfilter before more data.
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coder->sequence = SEQ_FILTER_END;
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break;
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}
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if (ret != LZMA_OK)
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return ret;
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}
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// If we couldn't process the whole Subblock Data yet, return.
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if (coder->size > 0)
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return LZMA_OK;
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// Check if we have decoded all the data.
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if (coder->uncompressed_size == 0
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&& coder->subfilter.code == NULL)
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return LZMA_STREAM_END;
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coder->sequence = SEQ_FLAGS;
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break;
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}
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case SEQ_REPEAT_FAST: {
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// Optimization for cases when there is only one byte to
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// repeat and no Subfilter.
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@ -432,128 +560,6 @@ decode_buffer(lzma_coder *coder, lzma_allocator *allocator,
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break;
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case SEQ_DATA: {
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// Limit the amount of input to match the available
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// Subblock Data size.
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size_t in_limit;
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if (in_size - *in_pos > coder->size)
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in_limit = *in_pos + coder->size;
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else
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in_limit = in_size;
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if (coder->subfilter.code == NULL) {
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const size_t copy_size = bufcpy(
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in, in_pos, in_limit,
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out, out_pos, out_size);
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coder->size -= copy_size;
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if (update_uncompressed_size(coder, copy_size))
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return LZMA_DATA_ERROR;
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} else {
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const size_t in_start = *in_pos;
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const lzma_ret ret = subfilter_decode(
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coder, allocator,
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in, in_pos, in_limit,
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out, out_pos, out_size,
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action);
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// Update the number of unprocessed bytes left in
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// this Subblock. This assert() is true because
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// in_limit prevents *in_pos getting too big.
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assert(*in_pos - in_start <= coder->size);
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coder->size -= *in_pos - in_start;
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if (ret == LZMA_STREAM_END) {
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// End of Subfilter can occur only at
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// a Subblock boundary.
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if (coder->size != 0)
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return LZMA_DATA_ERROR;
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// We need a Subblock with Unset
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// Subfilter before more data.
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coder->sequence = SEQ_FILTER_END;
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break;
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}
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if (ret != LZMA_OK)
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return ret;
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}
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// If we couldn't process the whole Subblock Data yet, return.
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if (coder->size > 0)
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return LZMA_OK;
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// Check if we have decoded all the data.
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if (coder->uncompressed_size == 0
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&& coder->subfilter.code == NULL)
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return LZMA_STREAM_END;
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coder->sequence = SEQ_FLAGS;
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break;
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}
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case SEQ_FILTER_FLAGS: {
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const lzma_ret ret = coder->filter_flags_decoder.code(
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coder->filter_flags_decoder.coder, allocator,
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in, in_pos, in_size, NULL, NULL, 0, LZMA_RUN);
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if (ret != LZMA_STREAM_END)
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return ret == LZMA_HEADER_ERROR
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? LZMA_DATA_ERROR : ret;
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// Don't free the filter_flags_decoder. It doesn't take much
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// memory and we may need it again.
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// Initialize the Subfilter. Subblock and Copy filters are
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// not allowed.
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if (coder->filter_flags.id == LZMA_FILTER_COPY
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|| coder->filter_flags.id
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== LZMA_FILTER_SUBBLOCK)
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return LZMA_DATA_ERROR;
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coder->helper.end_was_reached = false;
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lzma_options_filter filters[3] = {
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{
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.id = coder->filter_flags.id,
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.options = coder->filter_flags.options,
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}, {
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.id = LZMA_FILTER_SUBBLOCK_HELPER,
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.options = &coder->helper,
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}, {
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.id = LZMA_VLI_VALUE_UNKNOWN,
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.options = NULL,
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}
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};
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// Optimization: We know that LZMA uses End of Payload Marker
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// (not End of Input), so we can omit the helper filter.
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if (filters[0].id == LZMA_FILTER_LZMA)
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filters[1].id = LZMA_VLI_VALUE_UNKNOWN;
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return_if_error(lzma_raw_decoder_init(
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&coder->subfilter, allocator,
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filters, LZMA_VLI_VALUE_UNKNOWN, false));
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coder->sequence = SEQ_FLAGS;
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break;
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}
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case SEQ_FILTER_END:
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// We are in the beginning of a Subblock. The next Subblock
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// whose type is not Padding, must indicate end of Subfilter.
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if (in[*in_pos] == (FLAG_PADDING << 4)) {
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++*in_pos;
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break;
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}
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if (in[*in_pos] != (FLAG_END_SUBFILTER << 4))
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return LZMA_DATA_ERROR;
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coder->sequence = SEQ_FLAGS;
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break;
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default:
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return LZMA_PROG_ERROR;
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}
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