From 7a39fb8fb69a47486b91810708bbe796331b26a2 Mon Sep 17 00:00:00 2001 From: Yann Collet Date: Thu, 4 Apr 2019 12:47:36 -0700 Subject: make `_fast*()` decoder generate a deprecation warning updated modification --- doc/lz4_manual.html | 65 ++++++++++++++++++++++++++----------------- doc/lz4frame_manual.html | 4 +-- examples/compress_functions.c | 1 + lib/README.md | 14 ++++++++-- lib/lz4.h | 20 +++++++++---- tests/fullbench.c | 1 + tests/fuzzer.c | 4 +-- 7 files changed, 70 insertions(+), 39 deletions(-) diff --git a/doc/lz4_manual.html b/doc/lz4_manual.html index f25aa79..b738c8d 100644 --- a/doc/lz4_manual.html +++ b/doc/lz4_manual.html @@ -127,27 +127,6 @@ int LZ4_compress_fast_extState (void* state, const char* src, char* dst, int src or 0 if compression fails.

int LZ4_decompress_fast (const char* src, char* dst, int originalSize);
-  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**.
- 
-

int LZ4_decompress_safe_partial (const char* src, char* dst, int srcSize, int targetOutputSize, int dstCapacity);
   Decompress an LZ4 compressed block, of size 'srcSize' at position 'src',
   into destination buffer 'dst' of size 'dstCapacity'.
@@ -258,7 +237,6 @@ int                 LZ4_freeStreamDecode (LZ4_streamDecode_t* LZ4_stream);

int LZ4_decompress_safe_continue (LZ4_streamDecode_t* LZ4_streamDecode, const char* src, char* dst, int srcSize, int dstCapacity);
-int LZ4_decompress_fast_continue (LZ4_streamDecode_t* LZ4_streamDecode, const char* src, char* dst, int originalSize);
   These decoding functions allow decompression of consecutive blocks in "streaming" mode.
   A block is an unsplittable entity, it must be presented entirely to a decompression function.
   Decompression functions only accepts one block at a time.
@@ -285,7 +263,6 @@ int LZ4_decompress_fast_continue (LZ4_streamDecode_t* LZ4_streamDecode, const ch

int LZ4_decompress_safe_usingDict (const char* src, char* dst, int srcSize, int dstCapcity, const char* dictStart, int dictSize);
-int LZ4_decompress_fast_usingDict (const char* src, char* dst, int originalSize, const char* dictStart, int dictSize);
   These decoding functions work the same as
   a combination of LZ4_setStreamDecode() followed by LZ4_decompress_*_continue()
   They are stand-alone, and don't need an LZ4_streamDecode_t structure.
@@ -457,11 +434,47 @@ union LZ4_streamDecode_u {
 #    define LZ4_DEPRECATED(message)
 #  endif
 #endif /* LZ4_DISABLE_DEPRECATE_WARNINGS */
-
  Should deprecation warnings be a problem,
-  it is generally possible to disable them,
+

+  Deprecated functions make the compiler generate a warning when invoked.
+  This is meant to invite users to update their source code.
+  Should deprecation warnings be a problem, it is generally possible to disable them,
   typically with -Wno-deprecated-declarations for gcc
   or _CRT_SECURE_NO_WARNINGS in Visual.
-  Otherwise, it's also possible to define LZ4_DISABLE_DEPRECATE_WARNINGS 
+
+  Another method is to define LZ4_DISABLE_DEPRECATE_WARNINGS
+  before including the header file.
+ 
+

+ +

LZ4_DEPRECATED("This function is deprecated and unsafe. Consider using LZ4_decompress_safe() instead") LZ4LIB_API
+int LZ4_decompress_fast (const char* src, char* dst, int originalSize);
+LZ4_DEPRECATED("This function is deprecated and unsafe. Consider using LZ4_decompress_safe_continue() instead") LZ4LIB_API
+int LZ4_decompress_fast_continue (LZ4_streamDecode_t* LZ4_streamDecode, const char* src, char* dst, int originalSize);
+LZ4_DEPRECATED("This function is deprecated and unsafe. Consider using LZ4_decompress_safe_usingDict() instead") LZ4LIB_API
+int LZ4_decompress_fast_usingDict (const char* src, char* dst, int originalSize, const char* dictStart, int dictSize);
+  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**.
+

diff --git a/doc/lz4frame_manual.html b/doc/lz4frame_manual.html index 2b16045..4277c3c 100644 --- a/doc/lz4frame_manual.html +++ b/doc/lz4frame_manual.html @@ -1,10 +1,10 @@ -1.8.3 Manual +1.9.0 Manual -

1.8.3 Manual

1.9.0 Manual

/* for printf() */ #include /* for exit() */ diff --git a/lib/README.md b/lib/README.md index e9b221f..be8eba0 100644 --- a/lib/README.md +++ b/lib/README.md @@ -7,8 +7,8 @@ not all of them are necessary. #### Minimal LZ4 build The minimum required is **`lz4.c`** and **`lz4.h`**, -which provides the fast compression and decompression algorithm. -They generate and decode data using [LZ4 block format]. +which provides the fast compression and decompression algorithms. +They generate and decode data using the [LZ4 block format]. #### High Compression variant @@ -49,9 +49,17 @@ The following build macro can be determined at compilation time : - `LZ4_FAST_DEC_LOOP` : this triggers the optimized decompression loop. This loops works great on x86/x64 cpus, and is automatically enabled on this platform. It's possible to enable or disable it manually, by passing `LZ4_FAST_DEC_LOOP=1` or `0` to the preprocessor. - Typically with `gcc` : `-DLZ4_FAST_DEC_LOOP=1`, + For example, with `gcc` : `-DLZ4_FAST_DEC_LOOP=1`, and with `make` : `CPPFLAGS+=-DLZ4_FAST_DEC_LOOP=1 make lz4`. +- `LZ4_DISABLE_DEPRECATE_WARNINGS` : invoking a deprecated function will make the compiler generate a warning. + This is meant to invite users to update their source code. + Should this be a problem, it's generally to make the compiler ignore these warnings, + for example with `-Wno-deprecated-declarations` on `gcc`, + or `_CRT_SECURE_NO_WARNINGS` for Visual Studio. + Another method is to define `LZ4_DISABLE_DEPRECATE_WARNINGS` + before including the LZ4 header files. + #### Amalgamation diff --git a/lib/lz4.h b/lib/lz4.h index c848f5f..1dc8e00 100644 --- a/lib/lz4.h +++ b/lib/lz4.h @@ -563,11 +563,16 @@ union LZ4_streamDecode_u { **************************************/ /*! Deprecation warnings - * Should deprecation warnings be a problem, - * it is generally possible to disable them, + * + * Deprecated functions make the compiler generate a warning when invoked. + * This is meant to invite users to update their source code. + * Should deprecation warnings be a problem, it is generally possible to disable them, * typically with -Wno-deprecated-declarations for gcc * or _CRT_SECURE_NO_WARNINGS in Visual. - * Otherwise, it's also possible to define LZ4_DISABLE_DEPRECATE_WARNINGS */ + * + * Another method is to define LZ4_DISABLE_DEPRECATE_WARNINGS + * before including the header file. + */ #ifdef LZ4_DISABLE_DEPRECATE_WARNINGS # define LZ4_DEPRECATED(message) /* disable deprecation warnings */ #else @@ -640,9 +645,12 @@ LZ4_DEPRECATED("use LZ4_decompress_fast_usingDict() instead") LZ4LIB_API int LZ4 * 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); +LZ4_DEPRECATED("This function is deprecated and unsafe. Consider using LZ4_decompress_safe() instead") LZ4LIB_API +int LZ4_decompress_fast (const char* src, char* dst, int originalSize); +LZ4_DEPRECATED("This function is deprecated and unsafe. Consider using LZ4_decompress_safe_continue() instead") LZ4LIB_API +int LZ4_decompress_fast_continue (LZ4_streamDecode_t* LZ4_streamDecode, const char* src, char* dst, int originalSize); +LZ4_DEPRECATED("This function is deprecated and unsafe. Consider using LZ4_decompress_safe_usingDict() instead") 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/tests/fullbench.c b/tests/fullbench.c index 4b4e921..e08947d 100644 --- a/tests/fullbench.c +++ b/tests/fullbench.c @@ -42,6 +42,7 @@ #include /* strcmp */ #include /* clock_t, clock(), CLOCKS_PER_SEC */ +#define LZ4_DISABLE_DEPRECATE_WARNINGS /* LZ4_decompress_fast */ #include "lz4.h" #include "lz4hc.h" #include "lz4frame.h" diff --git a/tests/fuzzer.c b/tests/fuzzer.c index 893ffc1..69c763b 100644 --- a/tests/fuzzer.c +++ b/tests/fuzzer.c @@ -32,8 +32,6 @@ # pragma warning(disable : 4310) /* disable: C4310: constant char value > 127 */ #endif -#define LZ4_DISABLE_DEPRECATE_WARNINGS - /*-************************************ * Dependencies @@ -53,7 +51,9 @@ # include /* mmap */ #endif +#define LZ4_DISABLE_DEPRECATE_WARNINGS /* LZ4_decompress_fast */ #define LZ4_STATIC_LINKING_ONLY +#include "lz4.h" #define LZ4_HC_STATIC_LINKING_ONLY #include "lz4hc.h" #define XXH_STATIC_LINKING_ONLY -- cgit v0.12

1.8.3 Manual

1.9.0 Manual

Contents