diff options
| -rw-r--r-- | lib/lz4.h | 52 | ||||
| -rw-r--r-- | lib/lz4hc.h | 2 |
2 files changed, 30 insertions, 24 deletions
@@ -203,27 +203,6 @@ LZ4LIB_API int LZ4_compress_fast_extState (void* state, const char* src, char* d LZ4LIB_API int LZ4_compress_destSize (const char* src, char* dst, int* srcSizePtr, int targetDstSize); -/*! LZ4_decompress_fast() : **unsafe!** - * This function used to be a bit faster than LZ4_decompress_safe(), - * though situation has changed in recent versions, - * and now `LZ4_decompress_safe()` can be as fast and sometimes faster than `LZ4_decompress_fast()`. - * Moreover, LZ4_decompress_fast() is not protected vs malformed input, as it doesn't perform full validation of compressed data. - * As a consequence, this function is no longer recommended, and may be deprecated in future versions. - * It's last remaining specificity is that it can decompress data without knowing its compressed size. - * - * originalSize : is the uncompressed size to regenerate. - * `dst` must be already allocated, its size must be >= 'originalSize' bytes. - * @return : number of bytes read from source buffer (== compressed size). - * If the source stream is detected malformed, the function stops decoding and returns a negative result. - * note : This function requires uncompressed originalSize to be known in advance. - * The function never writes past the output buffer. - * However, since it doesn't know its 'src' size, it may read past the intended input. - * Also, because match offsets are not validated during decoding, - * reads from 'src' may underflow. - * Use this function in trusted environment **only**. - */ -LZ4LIB_API int LZ4_decompress_fast (const char* src, char* dst, int originalSize); - /*! LZ4_decompress_safe_partial() : * Decompress an LZ4 compressed block, of size 'srcSize' at position 'src', * into destination buffer 'dst' of size 'dstCapacity'. @@ -370,7 +349,6 @@ LZ4LIB_API int LZ4_decoderRingBufferSize(int maxBlockSize); * then indicate where this data is saved using LZ4_setStreamDecode(), before decompressing next block. */ LZ4LIB_API int LZ4_decompress_safe_continue (LZ4_streamDecode_t* LZ4_streamDecode, const char* src, char* dst, int srcSize, int dstCapacity); -LZ4LIB_API int LZ4_decompress_fast_continue (LZ4_streamDecode_t* LZ4_streamDecode, const char* src, char* dst, int originalSize); /*! LZ4_decompress_*_usingDict() : @@ -382,7 +360,6 @@ LZ4LIB_API int LZ4_decompress_fast_continue (LZ4_streamDecode_t* LZ4_streamDecod * when dst == dictStart + dictSize. */ LZ4LIB_API int LZ4_decompress_safe_usingDict (const char* src, char* dst, int srcSize, int dstCapcity, const char* dictStart, int dictSize); -LZ4LIB_API int LZ4_decompress_fast_usingDict (const char* src, char* dst, int originalSize, const char* dictStart, int dictSize); /*^************************************* @@ -639,6 +616,35 @@ LZ4_DEPRECATED("Use LZ4_saveDict() instead") LZ4LIB_API char* LZ4_slideInput LZ4_DEPRECATED("use LZ4_decompress_safe_usingDict() instead") LZ4LIB_API int LZ4_decompress_safe_withPrefix64k (const char* src, char* dst, int compressedSize, int maxDstSize); LZ4_DEPRECATED("use LZ4_decompress_fast_usingDict() instead") LZ4LIB_API int LZ4_decompress_fast_withPrefix64k (const char* src, char* dst, int originalSize); +/*! LZ4_decompress_fast() : **unsafe!** + * These functions used to be a bit faster than LZ4_decompress_safe(), + * but situation has changed in recent versions. + * Now, `LZ4_decompress_safe()` is as fast and sometimes even faster than `LZ4_decompress_fast()`. + * Moreover, LZ4_decompress_safe() is protected vs malformed input, while `LZ4_decompress_fast()` is not, making it a security liability. + * As a consequence, LZ4_decompress_fast() is strongly discouraged, and deprecated. + * + * Last LZ4_decompress_fast() specificity is that it can decompress a block without knowing its compressed size. + * Note that even that functionality could be achieved in a more secure manner if need be, + * though it would require new prototypes, and adaptation of the implementation to this new use case. + * + * Parameters: + * originalSize : is the uncompressed size to regenerate. + * `dst` must be already allocated, its size must be >= 'originalSize' bytes. + * @return : number of bytes read from source buffer (== compressed size). + * The function expects to finish at block's end exactly. + * If the source stream is detected malformed, the function stops decoding and returns a negative result. + * note : LZ4_decompress_fast*() requires originalSize. Thanks to this information, it never writes past the output buffer. + * However, since it doesn't know its 'src' size, it may read an unknown amount of input, and overflow input buffer. + * Also, since match offsets are not validated, match reads from 'src' may underflow. + * These issues never happen if input data is correct. + * But they may happen if input data is invalid (error or intentional tampering). + * As a consequence, use these functions in trusted environments with trusted data **only**. + */ +LZ4LIB_API int LZ4_decompress_fast (const char* src, char* dst, int originalSize); +LZ4LIB_API int LZ4_decompress_fast_continue (LZ4_streamDecode_t* LZ4_streamDecode, const char* src, char* dst, int originalSize); +LZ4LIB_API int LZ4_decompress_fast_usingDict (const char* src, char* dst, int originalSize, const char* dictStart, int dictSize); + + #endif /* LZ4_H_2983827168210 */ diff --git a/lib/lz4hc.h b/lib/lz4hc.h index 5e7cb11..d1772f3 100644 --- a/lib/lz4hc.h +++ b/lib/lz4hc.h @@ -145,7 +145,7 @@ LZ4LIB_API int LZ4_freeStreamHC (LZ4_streamHC_t* streamHCPtr); Return value of LZ4_saveDictHC() is the size of dictionary effectively saved into 'safeBuffer' (<= 64 KB) After completing a streaming compression, - it's possible to start a new stream and re-use the LZ4_streamHC_t state + it's possible to start a new stream of blocks, and re-use the same LZ4_streamHC_t state by resetting it, using LZ4_resetStreamHC_fast(). */ |