make `_fast*()` decoder generate a deprecation warning

updated modification

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.
 </p></pre><BR>
 
-<pre><b>int LZ4_decompress_fast (const char* src, char* dst, int originalSize);
-</b><p>  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**.
- 
-</p></pre><BR>
-
 <pre><b>int LZ4_decompress_safe_partial (const char* src, char* dst, int srcSize, int targetOutputSize, int dstCapacity);
 </b><p>  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);
 </p></pre><BR>
 
 <pre><b>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);
 </b><p>  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
 </p></pre><BR>
 
 <pre><b>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);
 </b><p>  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 </b>/* LZ4_DISABLE_DEPRECATE_WARNINGS */<b>
-</b><p>  Should deprecation warnings be a problem,
-  it is generally possible to disable them,
+</b><p>
+  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.
+ 
+</p></pre><BR>
+
+<pre><b>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);
+</b><p>  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**.
+ 
 </p></pre><BR>
 
 </html>
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 @@
 <html>
 <head>
 <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
-<title>1.8.3 Manual</title>
+<title>1.9.0 Manual</title>
 </head>
 <body>
-<h1>1.8.3 Manual</h1>
+<h1>1.9.0 Manual</h1>
 <hr>
 <a name="Contents"></a><h2>Contents</h2>
 <ol>
diff --git a/examples/compress_functions.c b/examples/compress_functions.c
index 41d3c8c..7fd6775 100644
--- a/examples/compress_functions.c
+++ b/examples/compress_functions.c
@@ -60,6 +60,7 @@
 #define _POSIX_C_SOURCE 199309L
 
 /* Includes, for Power! */
+#define LZ4_DISABLE_DEPRECATE_WARNINGS   /* LZ4_decompress_fast */
 #include "lz4.h"
 #include <stdio.h>    /* for printf() */
 #include <stdlib.h>   /* 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 <string.h>      /* strcmp */
 #include <time.h>        /* 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 <sys/mman.h>   /* 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