| /* |
| * .xz Stream decoder |
| * |
| * Author: Lasse Collin <lasse.collin@tukaani.org> |
| * |
| * This file has been put into the public domain. |
| * You can do whatever you want with this file. |
| */ |
| |
| #include "xz_private.h" |
| #include "xz_stream.h" |
| |
| /* Hash used to validate the Index field */ |
| struct xz_dec_hash { |
| vli_type unpadded; |
| vli_type uncompressed; |
| uint32_t crc32; |
| }; |
| |
| struct xz_dec { |
| /* Position in dec_main() */ |
| enum { |
| SEQ_STREAM_HEADER, |
| SEQ_BLOCK_START, |
| SEQ_BLOCK_HEADER, |
| SEQ_BLOCK_UNCOMPRESS, |
| SEQ_BLOCK_PADDING, |
| SEQ_BLOCK_CHECK, |
| SEQ_INDEX, |
| SEQ_INDEX_PADDING, |
| SEQ_INDEX_CRC32, |
| SEQ_STREAM_FOOTER |
| } sequence; |
| |
| /* Position in variable-length integers and Check fields */ |
| uint32_t pos; |
| |
| /* Variable-length integer decoded by dec_vli() */ |
| vli_type vli; |
| |
| /* Saved in_pos and out_pos */ |
| size_t in_start; |
| size_t out_start; |
| |
| /* CRC32 value in Block or Index */ |
| uint32_t crc32; |
| |
| /* Type of the integrity check calculated from uncompressed data */ |
| enum xz_check check_type; |
| |
| /* Operation mode */ |
| enum xz_mode mode; |
| |
| /* |
| * True if the next call to xz_dec_run() is allowed to return |
| * XZ_BUF_ERROR. |
| */ |
| bool allow_buf_error; |
| |
| /* Information stored in Block Header */ |
| struct { |
| /* |
| * Value stored in the Compressed Size field, or |
| * VLI_UNKNOWN if Compressed Size is not present. |
| */ |
| vli_type compressed; |
| |
| /* |
| * Value stored in the Uncompressed Size field, or |
| * VLI_UNKNOWN if Uncompressed Size is not present. |
| */ |
| vli_type uncompressed; |
| |
| /* Size of the Block Header field */ |
| uint32_t size; |
| } block_header; |
| |
| /* Information collected when decoding Blocks */ |
| struct { |
| /* Observed compressed size of the current Block */ |
| vli_type compressed; |
| |
| /* Observed uncompressed size of the current Block */ |
| vli_type uncompressed; |
| |
| /* Number of Blocks decoded so far */ |
| vli_type count; |
| |
| /* |
| * Hash calculated from the Block sizes. This is used to |
| * validate the Index field. |
| */ |
| struct xz_dec_hash hash; |
| } block; |
| |
| /* Variables needed when verifying the Index field */ |
| struct { |
| /* Position in dec_index() */ |
| enum { |
| SEQ_INDEX_COUNT, |
| SEQ_INDEX_UNPADDED, |
| SEQ_INDEX_UNCOMPRESSED |
| } sequence; |
| |
| /* Size of the Index in bytes */ |
| vli_type size; |
| |
| /* Number of Records (matches block.count in valid files) */ |
| vli_type count; |
| |
| /* |
| * Hash calculated from the Records (matches block.hash in |
| * valid files). |
| */ |
| struct xz_dec_hash hash; |
| } index; |
| |
| /* |
| * Temporary buffer needed to hold Stream Header, Block Header, |
| * and Stream Footer. The Block Header is the biggest (1 KiB) |
| * so we reserve space according to that. buf[] has to be aligned |
| * to a multiple of four bytes; the size_t variables before it |
| * should guarantee this. |
| */ |
| struct { |
| size_t pos; |
| size_t size; |
| uint8_t buf[1024]; |
| } temp; |
| |
| struct xz_dec_lzma2 *lzma2; |
| |
| #ifdef XZ_DEC_BCJ |
| struct xz_dec_bcj *bcj; |
| bool bcj_active; |
| #endif |
| }; |
| |
| #ifdef XZ_DEC_ANY_CHECK |
| /* Sizes of the Check field with different Check IDs */ |
| static const uint8_t check_sizes[16] = { |
| 0, |
| 4, 4, 4, |
| 8, 8, 8, |
| 16, 16, 16, |
| 32, 32, 32, |
| 64, 64, 64 |
| }; |
| #endif |
| |
| /* |
| * Fill s->temp by copying data starting from b->in[b->in_pos]. Caller |
| * must have set s->temp.pos to indicate how much data we are supposed |
| * to copy into s->temp.buf. Return true once s->temp.pos has reached |
| * s->temp.size. |
| */ |
| static bool fill_temp(struct xz_dec *s, struct xz_buf *b) |
| { |
| size_t copy_size = min_t(size_t, |
| b->in_size - b->in_pos, s->temp.size - s->temp.pos); |
| |
| memcpy(s->temp.buf + s->temp.pos, b->in + b->in_pos, copy_size); |
| b->in_pos += copy_size; |
| s->temp.pos += copy_size; |
| |
| if (s->temp.pos == s->temp.size) { |
| s->temp.pos = 0; |
| return true; |
| } |
| |
| return false; |
| } |
| |
| /* Decode a variable-length integer (little-endian base-128 encoding) */ |
| static enum xz_ret dec_vli(struct xz_dec *s, const uint8_t *in, |
| size_t *in_pos, size_t in_size) |
| { |
| uint8_t byte; |
| |
| if (s->pos == 0) |
| s->vli = 0; |
| |
| while (*in_pos < in_size) { |
| byte = in[*in_pos]; |
| ++*in_pos; |
| |
| s->vli |= (vli_type)(byte & 0x7F) << s->pos; |
| |
| if ((byte & 0x80) == 0) { |
| /* Don't allow non-minimal encodings. */ |
| if (byte == 0 && s->pos != 0) |
| return XZ_DATA_ERROR; |
| |
| s->pos = 0; |
| return XZ_STREAM_END; |
| } |
| |
| s->pos += 7; |
| if (s->pos == 7 * VLI_BYTES_MAX) |
| return XZ_DATA_ERROR; |
| } |
| |
| return XZ_OK; |
| } |
| |
| /* |
| * Decode the Compressed Data field from a Block. Update and validate |
| * the observed compressed and uncompressed sizes of the Block so that |
| * they don't exceed the values possibly stored in the Block Header |
| * (validation assumes that no integer overflow occurs, since vli_type |
| * is normally uint64_t). Update the CRC32 if presence of the CRC32 |
| * field was indicated in Stream Header. |
| * |
| * Once the decoding is finished, validate that the observed sizes match |
| * the sizes possibly stored in the Block Header. Update the hash and |
| * Block count, which are later used to validate the Index field. |
| */ |
| static enum xz_ret dec_block(struct xz_dec *s, struct xz_buf *b) |
| { |
| enum xz_ret ret; |
| |
| s->in_start = b->in_pos; |
| s->out_start = b->out_pos; |
| |
| #ifdef XZ_DEC_BCJ |
| if (s->bcj_active) |
| ret = xz_dec_bcj_run(s->bcj, s->lzma2, b); |
| else |
| #endif |
| ret = xz_dec_lzma2_run(s->lzma2, b); |
| |
| s->block.compressed += b->in_pos - s->in_start; |
| s->block.uncompressed += b->out_pos - s->out_start; |
| |
| /* |
| * There is no need to separately check for VLI_UNKNOWN, since |
| * the observed sizes are always smaller than VLI_UNKNOWN. |
| */ |
| if (s->block.compressed > s->block_header.compressed |
| || s->block.uncompressed |
| > s->block_header.uncompressed) |
| return XZ_DATA_ERROR; |
| |
| if (s->check_type == XZ_CHECK_CRC32) |
| s->crc32 = xz_crc32(b->out + s->out_start, |
| b->out_pos - s->out_start, s->crc32); |
| |
| if (ret == XZ_STREAM_END) { |
| if (s->block_header.compressed != VLI_UNKNOWN |
| && s->block_header.compressed |
| != s->block.compressed) |
| return XZ_DATA_ERROR; |
| |
| if (s->block_header.uncompressed != VLI_UNKNOWN |
| && s->block_header.uncompressed |
| != s->block.uncompressed) |
| return XZ_DATA_ERROR; |
| |
| s->block.hash.unpadded += s->block_header.size |
| + s->block.compressed; |
| |
| #ifdef XZ_DEC_ANY_CHECK |
| s->block.hash.unpadded += check_sizes[s->check_type]; |
| #else |
| if (s->check_type == XZ_CHECK_CRC32) |
| s->block.hash.unpadded += 4; |
| #endif |
| |
| s->block.hash.uncompressed += s->block.uncompressed; |
| s->block.hash.crc32 = xz_crc32( |
| (const uint8_t *)&s->block.hash, |
| sizeof(s->block.hash), s->block.hash.crc32); |
| |
| ++s->block.count; |
| } |
| |
| return ret; |
| } |
| |
| /* Update the Index size and the CRC32 value. */ |
| static void index_update(struct xz_dec *s, const struct xz_buf *b) |
| { |
| size_t in_used = b->in_pos - s->in_start; |
| s->index.size += in_used; |
| s->crc32 = xz_crc32(b->in + s->in_start, in_used, s->crc32); |
| } |
| |
| /* |
| * Decode the Number of Records, Unpadded Size, and Uncompressed Size |
| * fields from the Index field. That is, Index Padding and CRC32 are not |
| * decoded by this function. |
| * |
| * This can return XZ_OK (more input needed), XZ_STREAM_END (everything |
| * successfully decoded), or XZ_DATA_ERROR (input is corrupt). |
| */ |
| static enum xz_ret dec_index(struct xz_dec *s, struct xz_buf *b) |
| { |
| enum xz_ret ret; |
| |
| do { |
| ret = dec_vli(s, b->in, &b->in_pos, b->in_size); |
| if (ret != XZ_STREAM_END) { |
| index_update(s, b); |
| return ret; |
| } |
| |
| switch (s->index.sequence) { |
| case SEQ_INDEX_COUNT: |
| s->index.count = s->vli; |
| |
| /* |
| * Validate that the Number of Records field |
| * indicates the same number of Records as |
| * there were Blocks in the Stream. |
| */ |
| if (s->index.count != s->block.count) |
| return XZ_DATA_ERROR; |
| |
| s->index.sequence = SEQ_INDEX_UNPADDED; |
| break; |
| |
| case SEQ_INDEX_UNPADDED: |
| s->index.hash.unpadded += s->vli; |
| s->index.sequence = SEQ_INDEX_UNCOMPRESSED; |
| break; |
| |
| case SEQ_INDEX_UNCOMPRESSED: |
| s->index.hash.uncompressed += s->vli; |
| s->index.hash.crc32 = xz_crc32( |
| (const uint8_t *)&s->index.hash, |
| sizeof(s->index.hash), |
| s->index.hash.crc32); |
| --s->index.count; |
| s->index.sequence = SEQ_INDEX_UNPADDED; |
| break; |
| } |
| } while (s->index.count > 0); |
| |
| return XZ_STREAM_END; |
| } |
| |
| /* |
| * Validate that the next four input bytes match the value of s->crc32. |
| * s->pos must be zero when starting to validate the first byte. |
| */ |
| static enum xz_ret crc32_validate(struct xz_dec *s, struct xz_buf *b) |
| { |
| do { |
| if (b->in_pos == b->in_size) |
| return XZ_OK; |
| |
| if (((s->crc32 >> s->pos) & 0xFF) != b->in[b->in_pos++]) |
| return XZ_DATA_ERROR; |
| |
| s->pos += 8; |
| |
| } while (s->pos < 32); |
| |
| s->crc32 = 0; |
| s->pos = 0; |
| |
| return XZ_STREAM_END; |
| } |
| |
| #ifdef XZ_DEC_ANY_CHECK |
| /* |
| * Skip over the Check field when the Check ID is not supported. |
| * Returns true once the whole Check field has been skipped over. |
| */ |
| static bool check_skip(struct xz_dec *s, struct xz_buf *b) |
| { |
| while (s->pos < check_sizes[s->check_type]) { |
| if (b->in_pos == b->in_size) |
| return false; |
| |
| ++b->in_pos; |
| ++s->pos; |
| } |
| |
| s->pos = 0; |
| |
| return true; |
| } |
| #endif |
| |
| /* Decode the Stream Header field (the first 12 bytes of the .xz Stream). */ |
| static enum xz_ret dec_stream_header(struct xz_dec *s) |
| { |
| if (!memeq(s->temp.buf, HEADER_MAGIC, HEADER_MAGIC_SIZE)) |
| return XZ_FORMAT_ERROR; |
| |
| if (xz_crc32(s->temp.buf + HEADER_MAGIC_SIZE, 2, 0) |
| != get_le32(s->temp.buf + HEADER_MAGIC_SIZE + 2)) |
| return XZ_DATA_ERROR; |
| |
| if (s->temp.buf[HEADER_MAGIC_SIZE] != 0) |
| return XZ_OPTIONS_ERROR; |
| |
| /* |
| * Of integrity checks, we support only none (Check ID = 0) and |
| * CRC32 (Check ID = 1). However, if XZ_DEC_ANY_CHECK is defined, |
| * we will accept other check types too, but then the check won't |
| * be verified and a warning (XZ_UNSUPPORTED_CHECK) will be given. |
| */ |
| if (s->temp.buf[HEADER_MAGIC_SIZE + 1] > XZ_CHECK_MAX) |
| return XZ_OPTIONS_ERROR; |
| |
| s->check_type = s->temp.buf[HEADER_MAGIC_SIZE + 1]; |
| |
| #ifdef XZ_DEC_ANY_CHECK |
| if (s->check_type > XZ_CHECK_CRC32) |
| return XZ_UNSUPPORTED_CHECK; |
| #else |
| if (s->check_type > XZ_CHECK_CRC32) |
| return XZ_OPTIONS_ERROR; |
| #endif |
| |
| return XZ_OK; |
| } |
| |
| /* Decode the Stream Footer field (the last 12 bytes of the .xz Stream) */ |
| static enum xz_ret dec_stream_footer(struct xz_dec *s) |
| { |
| if (!memeq(s->temp.buf + 10, FOOTER_MAGIC, FOOTER_MAGIC_SIZE)) |
| return XZ_DATA_ERROR; |
| |
| if (xz_crc32(s->temp.buf + 4, 6, 0) != get_le32(s->temp.buf)) |
| return XZ_DATA_ERROR; |
| |
| /* |
| * Validate Backward Size. Note that we never added the size of the |
| * Index CRC32 field to s->index.size, thus we use s->index.size / 4 |
| * instead of s->index.size / 4 - 1. |
| */ |
| if ((s->index.size >> 2) != get_le32(s->temp.buf + 4)) |
| return XZ_DATA_ERROR; |
| |
| if (s->temp.buf[8] != 0 || s->temp.buf[9] != s->check_type) |
| return XZ_DATA_ERROR; |
| |
| /* |
| * Use XZ_STREAM_END instead of XZ_OK to be more convenient |
| * for the caller. |
| */ |
| return XZ_STREAM_END; |
| } |
| |
| /* Decode the Block Header and initialize the filter chain. */ |
| static enum xz_ret dec_block_header(struct xz_dec *s) |
| { |
| enum xz_ret ret; |
| |
| /* |
| * Validate the CRC32. We know that the temp buffer is at least |
| * eight bytes so this is safe. |
| */ |
| s->temp.size -= 4; |
| if (xz_crc32(s->temp.buf, s->temp.size, 0) |
| != get_le32(s->temp.buf + s->temp.size)) |
| return XZ_DATA_ERROR; |
| |
| s->temp.pos = 2; |
| |
| /* |
| * Catch unsupported Block Flags. We support only one or two filters |
| * in the chain, so we catch that with the same test. |
| */ |
| #ifdef XZ_DEC_BCJ |
| if (s->temp.buf[1] & 0x3E) |
| #else |
| if (s->temp.buf[1] & 0x3F) |
| #endif |
| return XZ_OPTIONS_ERROR; |
| |
| /* Compressed Size */ |
| if (s->temp.buf[1] & 0x40) { |
| if (dec_vli(s, s->temp.buf, &s->temp.pos, s->temp.size) |
| != XZ_STREAM_END) |
| return XZ_DATA_ERROR; |
| |
| s->block_header.compressed = s->vli; |
| } else { |
| s->block_header.compressed = VLI_UNKNOWN; |
| } |
| |
| /* Uncompressed Size */ |
| if (s->temp.buf[1] & 0x80) { |
| if (dec_vli(s, s->temp.buf, &s->temp.pos, s->temp.size) |
| != XZ_STREAM_END) |
| return XZ_DATA_ERROR; |
| |
| s->block_header.uncompressed = s->vli; |
| } else { |
| s->block_header.uncompressed = VLI_UNKNOWN; |
| } |
| |
| #ifdef XZ_DEC_BCJ |
| /* If there are two filters, the first one must be a BCJ filter. */ |
| s->bcj_active = s->temp.buf[1] & 0x01; |
| if (s->bcj_active) { |
| if (s->temp.size - s->temp.pos < 2) |
| return XZ_OPTIONS_ERROR; |
| |
| ret = xz_dec_bcj_reset(s->bcj, s->temp.buf[s->temp.pos++]); |
| if (ret != XZ_OK) |
| return ret; |
| |
| /* |
| * We don't support custom start offset, |
| * so Size of Properties must be zero. |
| */ |
| if (s->temp.buf[s->temp.pos++] != 0x00) |
| return XZ_OPTIONS_ERROR; |
| } |
| #endif |
| |
| /* Valid Filter Flags always take at least two bytes. */ |
| if (s->temp.size - s->temp.pos < 2) |
| return XZ_DATA_ERROR; |
| |
| /* Filter ID = LZMA2 */ |
| if (s->temp.buf[s->temp.pos++] != 0x21) |
| return XZ_OPTIONS_ERROR; |
| |
| /* Size of Properties = 1-byte Filter Properties */ |
| if (s->temp.buf[s->temp.pos++] != 0x01) |
| return XZ_OPTIONS_ERROR; |
| |
| /* Filter Properties contains LZMA2 dictionary size. */ |
| if (s->temp.size - s->temp.pos < 1) |
| return XZ_DATA_ERROR; |
| |
| ret = xz_dec_lzma2_reset(s->lzma2, s->temp.buf[s->temp.pos++]); |
| if (ret != XZ_OK) |
| return ret; |
| |
| /* The rest must be Header Padding. */ |
| while (s->temp.pos < s->temp.size) |
| if (s->temp.buf[s->temp.pos++] != 0x00) |
| return XZ_OPTIONS_ERROR; |
| |
| s->temp.pos = 0; |
| s->block.compressed = 0; |
| s->block.uncompressed = 0; |
| |
| return XZ_OK; |
| } |
| |
| static enum xz_ret dec_main(struct xz_dec *s, struct xz_buf *b) |
| { |
| enum xz_ret ret; |
| |
| /* |
| * Store the start position for the case when we are in the middle |
| * of the Index field. |
| */ |
| s->in_start = b->in_pos; |
| |
| while (true) { |
| switch (s->sequence) { |
| case SEQ_STREAM_HEADER: |
| /* |
| * Stream Header is copied to s->temp, and then |
| * decoded from there. This way if the caller |
| * gives us only little input at a time, we can |
| * still keep the Stream Header decoding code |
| * simple. Similar approach is used in many places |
| * in this file. |
| */ |
| if (!fill_temp(s, b)) |
| return XZ_OK; |
| |
| /* |
| * If dec_stream_header() returns |
| * XZ_UNSUPPORTED_CHECK, it is still possible |
| * to continue decoding if working in multi-call |
| * mode. Thus, update s->sequence before calling |
| * dec_stream_header(). |
| */ |
| s->sequence = SEQ_BLOCK_START; |
| |
| ret = dec_stream_header(s); |
| if (ret != XZ_OK) |
| return ret; |
| |
| /* Fall through */ |
| |
| case SEQ_BLOCK_START: |
| /* We need one byte of input to continue. */ |
| if (b->in_pos == b->in_size) |
| return XZ_OK; |
| |
| /* See if this is the beginning of the Index field. */ |
| if (b->in[b->in_pos] == 0) { |
| s->in_start = b->in_pos++; |
| s->sequence = SEQ_INDEX; |
| break; |
| } |
| |
| /* |
| * Calculate the size of the Block Header and |
| * prepare to decode it. |
| */ |
| s->block_header.size |
| = ((uint32_t)b->in[b->in_pos] + 1) * 4; |
| |
| s->temp.size = s->block_header.size; |
| s->temp.pos = 0; |
| s->sequence = SEQ_BLOCK_HEADER; |
| |
| /* Fall through */ |
| |
| case SEQ_BLOCK_HEADER: |
| if (!fill_temp(s, b)) |
| return XZ_OK; |
| |
| ret = dec_block_header(s); |
| if (ret != XZ_OK) |
| return ret; |
| |
| s->sequence = SEQ_BLOCK_UNCOMPRESS; |
| |
| /* Fall through */ |
| |
| case SEQ_BLOCK_UNCOMPRESS: |
| ret = dec_block(s, b); |
| if (ret != XZ_STREAM_END) |
| return ret; |
| |
| s->sequence = SEQ_BLOCK_PADDING; |
| |
| /* Fall through */ |
| |
| case SEQ_BLOCK_PADDING: |
| /* |
| * Size of Compressed Data + Block Padding |
| * must be a multiple of four. We don't need |
| * s->block.compressed for anything else |
| * anymore, so we use it here to test the size |
| * of the Block Padding field. |
| */ |
| while (s->block.compressed & 3) { |
| if (b->in_pos == b->in_size) |
| return XZ_OK; |
| |
| if (b->in[b->in_pos++] != 0) |
| return XZ_DATA_ERROR; |
| |
| ++s->block.compressed; |
| } |
| |
| s->sequence = SEQ_BLOCK_CHECK; |
| |
| /* Fall through */ |
| |
| case SEQ_BLOCK_CHECK: |
| if (s->check_type == XZ_CHECK_CRC32) { |
| ret = crc32_validate(s, b); |
| if (ret != XZ_STREAM_END) |
| return ret; |
| } |
| #ifdef XZ_DEC_ANY_CHECK |
| else if (!check_skip(s, b)) { |
| return XZ_OK; |
| } |
| #endif |
| |
| s->sequence = SEQ_BLOCK_START; |
| break; |
| |
| case SEQ_INDEX: |
| ret = dec_index(s, b); |
| if (ret != XZ_STREAM_END) |
| return ret; |
| |
| s->sequence = SEQ_INDEX_PADDING; |
| |
| /* Fall through */ |
| |
| case SEQ_INDEX_PADDING: |
| while ((s->index.size + (b->in_pos - s->in_start)) |
| & 3) { |
| if (b->in_pos == b->in_size) { |
| index_update(s, b); |
| return XZ_OK; |
| } |
| |
| if (b->in[b->in_pos++] != 0) |
| return XZ_DATA_ERROR; |
| } |
| |
| /* Finish the CRC32 value and Index size. */ |
| index_update(s, b); |
| |
| /* Compare the hashes to validate the Index field. */ |
| if (!memeq(&s->block.hash, &s->index.hash, |
| sizeof(s->block.hash))) |
| return XZ_DATA_ERROR; |
| |
| s->sequence = SEQ_INDEX_CRC32; |
| |
| /* Fall through */ |
| |
| case SEQ_INDEX_CRC32: |
| ret = crc32_validate(s, b); |
| if (ret != XZ_STREAM_END) |
| return ret; |
| |
| s->temp.size = STREAM_HEADER_SIZE; |
| s->sequence = SEQ_STREAM_FOOTER; |
| |
| /* Fall through */ |
| |
| case SEQ_STREAM_FOOTER: |
| if (!fill_temp(s, b)) |
| return XZ_OK; |
| |
| return dec_stream_footer(s); |
| } |
| } |
| |
| /* Never reached */ |
| } |
| |
| /* |
| * xz_dec_run() is a wrapper for dec_main() to handle some special cases in |
| * multi-call and single-call decoding. |
| * |
| * In multi-call mode, we must return XZ_BUF_ERROR when it seems clear that we |
| * are not going to make any progress anymore. This is to prevent the caller |
| * from calling us infinitely when the input file is truncated or otherwise |
| * corrupt. Since zlib-style API allows that the caller fills the input buffer |
| * only when the decoder doesn't produce any new output, we have to be careful |
| * to avoid returning XZ_BUF_ERROR too easily: XZ_BUF_ERROR is returned only |
| * after the second consecutive call to xz_dec_run() that makes no progress. |
| * |
| * In single-call mode, if we couldn't decode everything and no error |
| * occurred, either the input is truncated or the output buffer is too small. |
| * Since we know that the last input byte never produces any output, we know |
| * that if all the input was consumed and decoding wasn't finished, the file |
| * must be corrupt. Otherwise the output buffer has to be too small or the |
| * file is corrupt in a way that decoding it produces too big output. |
| * |
| * If single-call decoding fails, we reset b->in_pos and b->out_pos back to |
| * their original values. This is because with some filter chains there won't |
| * be any valid uncompressed data in the output buffer unless the decoding |
| * actually succeeds (that's the price to pay of using the output buffer as |
| * the workspace). |
| */ |
| XZ_EXTERN enum xz_ret xz_dec_run(struct xz_dec *s, struct xz_buf *b) |
| { |
| size_t in_start; |
| size_t out_start; |
| enum xz_ret ret; |
| |
| if (DEC_IS_SINGLE(s->mode)) |
| xz_dec_reset(s); |
| |
| in_start = b->in_pos; |
| out_start = b->out_pos; |
| ret = dec_main(s, b); |
| |
| if (DEC_IS_SINGLE(s->mode)) { |
| if (ret == XZ_OK) |
| ret = b->in_pos == b->in_size |
| ? XZ_DATA_ERROR : XZ_BUF_ERROR; |
| |
| if (ret != XZ_STREAM_END) { |
| b->in_pos = in_start; |
| b->out_pos = out_start; |
| } |
| |
| } else if (ret == XZ_OK && in_start == b->in_pos |
| && out_start == b->out_pos) { |
| if (s->allow_buf_error) |
| ret = XZ_BUF_ERROR; |
| |
| s->allow_buf_error = true; |
| } else { |
| s->allow_buf_error = false; |
| } |
| |
| return ret; |
| } |
| |
| XZ_EXTERN struct xz_dec *xz_dec_init(enum xz_mode mode, uint32_t dict_max) |
| { |
| struct xz_dec *s = kmalloc(sizeof(*s), GFP_KERNEL); |
| if (s == NULL) |
| return NULL; |
| |
| s->mode = mode; |
| |
| #ifdef XZ_DEC_BCJ |
| s->bcj = xz_dec_bcj_create(DEC_IS_SINGLE(mode)); |
| if (s->bcj == NULL) |
| goto error_bcj; |
| #endif |
| |
| s->lzma2 = xz_dec_lzma2_create(mode, dict_max); |
| if (s->lzma2 == NULL) |
| goto error_lzma2; |
| |
| xz_dec_reset(s); |
| return s; |
| |
| error_lzma2: |
| #ifdef XZ_DEC_BCJ |
| xz_dec_bcj_end(s->bcj); |
| error_bcj: |
| #endif |
| kfree(s); |
| return NULL; |
| } |
| |
| XZ_EXTERN void xz_dec_reset(struct xz_dec *s) |
| { |
| s->sequence = SEQ_STREAM_HEADER; |
| s->allow_buf_error = false; |
| s->pos = 0; |
| s->crc32 = 0; |
| memzero(&s->block, sizeof(s->block)); |
| memzero(&s->index, sizeof(s->index)); |
| s->temp.pos = 0; |
| s->temp.size = STREAM_HEADER_SIZE; |
| } |
| |
| XZ_EXTERN void xz_dec_end(struct xz_dec *s) |
| { |
| if (s != NULL) { |
| xz_dec_lzma2_end(s->lzma2); |
| #ifdef XZ_DEC_BCJ |
| xz_dec_bcj_end(s->bcj); |
| #endif |
| kfree(s); |
| } |
| } |