upgrade bundled lz4 to 1.9.4

src/borg/algorithms/lz4/lib/lz4.h

@@ -1,7 +1,7 @@
 /*
  *  LZ4 - Fast LZ compression algorithm
  *  Header File
- *  Copyright (C) 2011-present, Yann Collet.
+ *  Copyright (C) 2011-2020, Yann Collet.
 
    BSD 2-Clause License (http://www.opensource.org/licenses/bsd-license.php)
 
@@ -97,36 +97,77 @@ extern "C" {
 #  define LZ4LIB_API LZ4LIB_VISIBILITY
 #endif
 
+/*! LZ4_FREESTANDING :
+ *  When this macro is set to 1, it enables "freestanding mode" that is
+ *  suitable for typical freestanding environment which doesn't support
+ *  standard C library.
+ *
+ *  - LZ4_FREESTANDING is a compile-time switch.
+ *  - It requires the following macros to be defined:
+ *    LZ4_memcpy, LZ4_memmove, LZ4_memset.
+ *  - It only enables LZ4/HC functions which don't use heap.
+ *    All LZ4F_* functions are not supported.
+ *  - See tests/freestanding.c to check its basic setup.
+ */
+#if defined(LZ4_FREESTANDING) && (LZ4_FREESTANDING == 1)
+#  define LZ4_HEAPMODE 0
+#  define LZ4HC_HEAPMODE 0
+#  define LZ4_STATIC_LINKING_ONLY_DISABLE_MEMORY_ALLOCATION 1
+#  if !defined(LZ4_memcpy)
+#    error "LZ4_FREESTANDING requires macro 'LZ4_memcpy'."
+#  endif
+#  if !defined(LZ4_memset)
+#    error "LZ4_FREESTANDING requires macro 'LZ4_memset'."
+#  endif
+#  if !defined(LZ4_memmove)
+#    error "LZ4_FREESTANDING requires macro 'LZ4_memmove'."
+#  endif
+#elif ! defined(LZ4_FREESTANDING)
+#  define LZ4_FREESTANDING 0
+#endif
+
+
 /*------   Version   ------*/
 #define LZ4_VERSION_MAJOR    1    /* for breaking interface changes  */
 #define LZ4_VERSION_MINOR    9    /* for new (non-breaking) interface capabilities */
-#define LZ4_VERSION_RELEASE  2    /* for tweaks, bug-fixes, or development */
+#define LZ4_VERSION_RELEASE  4    /* for tweaks, bug-fixes, or development */
 
 #define LZ4_VERSION_NUMBER (LZ4_VERSION_MAJOR *100*100 + LZ4_VERSION_MINOR *100 + LZ4_VERSION_RELEASE)
 
 #define LZ4_LIB_VERSION LZ4_VERSION_MAJOR.LZ4_VERSION_MINOR.LZ4_VERSION_RELEASE
 #define LZ4_QUOTE(str) #str
 #define LZ4_EXPAND_AND_QUOTE(str) LZ4_QUOTE(str)
-#define LZ4_VERSION_STRING LZ4_EXPAND_AND_QUOTE(LZ4_LIB_VERSION)
+#define LZ4_VERSION_STRING LZ4_EXPAND_AND_QUOTE(LZ4_LIB_VERSION)  /* requires v1.7.3+ */
 
-LZ4LIB_API int LZ4_versionNumber (void);  /**< library version number; useful to check dll version */
-LZ4LIB_API const char* LZ4_versionString (void);   /**< library version string; useful to check dll version */
+LZ4LIB_API int LZ4_versionNumber (void);  /**< library version number; useful to check dll version; requires v1.3.0+ */
+LZ4LIB_API const char* LZ4_versionString (void);   /**< library version string; useful to check dll version; requires v1.7.5+ */
 
 
 /*-************************************
 *  Tuning parameter
 **************************************/
+#define LZ4_MEMORY_USAGE_MIN 10
+#define LZ4_MEMORY_USAGE_DEFAULT 14
+#define LZ4_MEMORY_USAGE_MAX 20
+
 /*!
  * LZ4_MEMORY_USAGE :
- * Memory usage formula : N->2^N Bytes (examples : 10 -> 1KB; 12 -> 4KB ; 16 -> 64KB; 20 -> 1MB; etc.)
- * Increasing memory usage improves compression ratio.
- * Reduced memory usage may improve speed, thanks to better cache locality.
+ * Memory usage formula : N->2^N Bytes (examples : 10 -> 1KB; 12 -> 4KB ; 16 -> 64KB; 20 -> 1MB; )
+ * Increasing memory usage improves compression ratio, at the cost of speed.
+ * Reduced memory usage may improve speed at the cost of ratio, thanks to better cache locality.
  * Default value is 14, for 16KB, which nicely fits into Intel x86 L1 cache
  */
 #ifndef LZ4_MEMORY_USAGE
-# define LZ4_MEMORY_USAGE 14
+# define LZ4_MEMORY_USAGE LZ4_MEMORY_USAGE_DEFAULT
 #endif
 
+#if (LZ4_MEMORY_USAGE < LZ4_MEMORY_USAGE_MIN)
+#  error "LZ4_MEMORY_USAGE is too small !"
+#endif
+
+#if (LZ4_MEMORY_USAGE > LZ4_MEMORY_USAGE_MAX)
+#  error "LZ4_MEMORY_USAGE is too large !"
+#endif
 
 /*-************************************
 *  Simple Functions
@@ -186,7 +227,8 @@ LZ4LIB_API int LZ4_compressBound(int inputSize);
     The larger the acceleration value, the faster the algorithm, but also the lesser the compression.
     It's a trade-off. It can be fine tuned, with each successive value providing roughly +~3% to speed.
     An acceleration value of "1" is the same as regular LZ4_compress_default()
-    Values <= 0 will be replaced by ACCELERATION_DEFAULT (currently == 1, see lz4.c).
+    Values <= 0 will be replaced by LZ4_ACCELERATION_DEFAULT (currently == 1, see lz4.c).
+    Values > LZ4_ACCELERATION_MAX will be replaced by LZ4_ACCELERATION_MAX (currently == 65537, see lz4.c).
 */
 LZ4LIB_API int LZ4_compress_fast (const char* src, char* dst, int srcSize, int dstCapacity, int acceleration);
 
@@ -212,7 +254,18 @@ LZ4LIB_API int LZ4_compress_fast_extState (void* state, const char* src, char* d
  *               New value is necessarily <= input value.
  * @return : Nb bytes written into 'dst' (necessarily <= targetDestSize)
  *           or 0 if compression fails.
-*/
+ *
+ * Note : from v1.8.2 to v1.9.1, this function had a bug (fixed un v1.9.2+):
+ *        the produced compressed content could, in specific circumstances,
+ *        require to be decompressed into a destination buffer larger
+ *        by at least 1 byte than the content to decompress.
+ *        If an application uses `LZ4_compress_destSize()`,
+ *        it's highly recommended to update liblz4 to v1.9.2 or better.
+ *        If this can't be done or ensured,
+ *        the receiving decompression function should provide
+ *        a dstCapacity which is > decompressedSize, by at least 1 byte.
+ *        See https://github.com/lz4/lz4/issues/859 for details
+ */
 LZ4LIB_API int LZ4_compress_destSize (const char* src, char* dst, int* srcSizePtr, int targetDstSize);
 
 
@@ -220,25 +273,35 @@ LZ4LIB_API int LZ4_compress_destSize (const char* src, char* dst, int* srcSizePt
  *  Decompress an LZ4 compressed block, of size 'srcSize' at position 'src',
  *  into destination buffer 'dst' of size 'dstCapacity'.
  *  Up to 'targetOutputSize' bytes will be decoded.
- *  The function stops decoding on reaching this objective,
- *  which can boost performance when only the beginning of a block is required.
+ *  The function stops decoding on reaching this objective.
+ *  This can be useful to boost performance
+ *  whenever only the beginning of a block is required.
  *
- * @return : the number of bytes decoded in `dst` (necessarily <= dstCapacity)
+ * @return : the number of bytes decoded in `dst` (necessarily <= targetOutputSize)
  *           If source stream is detected malformed, function returns a negative result.
  *
- *  Note : @return can be < targetOutputSize, if compressed block contains less data.
+ *  Note 1 : @return can be < targetOutputSize, if compressed block contains less data.
  *
- *  Note 2 : this function features 2 parameters, targetOutputSize and dstCapacity,
- *           and expects targetOutputSize <= dstCapacity.
- *           It effectively stops decoding on reaching targetOutputSize,
+ *  Note 2 : targetOutputSize must be <= dstCapacity
+ *
+ *  Note 3 : this function effectively stops decoding on reaching targetOutputSize,
  *           so dstCapacity is kind of redundant.
- *           This is because in a previous version of this function,
- *           decoding operation would not "break" a sequence in the middle.
- *           As a consequence, there was no guarantee that decoding would stop at exactly targetOutputSize,
+ *           This is because in older versions of this function,
+ *           decoding operation would still write complete sequences.
+ *           Therefore, there was no guarantee that it would stop writing at exactly targetOutputSize,
  *           it could write more bytes, though only up to dstCapacity.
  *           Some "margin" used to be required for this operation to work properly.
- *           This is no longer necessary.
- *           The function nonetheless keeps its signature, in an effort to not break API.
+ *           Thankfully, this is no longer necessary.
+ *           The function nonetheless keeps the same signature, in an effort to preserve API compatibility.
+ *
+ *  Note 4 : If srcSize is the exact size of the block,
+ *           then targetOutputSize can be any value,
+ *           including larger than the block's decompressed size.
+ *           The function will, at most, generate block's decompressed size.
+ *
+ *  Note 5 : If srcSize is _larger_ than block's compressed size,
+ *           then targetOutputSize **MUST** be <= block's decompressed size.
+ *           Otherwise, *silent corruption will occur*.
  */
 LZ4LIB_API int LZ4_decompress_safe_partial (const char* src, char* dst, int srcSize, int targetOutputSize, int dstCapacity);
 
@@ -248,8 +311,25 @@ LZ4LIB_API int LZ4_decompress_safe_partial (const char* src, char* dst, int srcS
 ***********************************************/
 typedef union LZ4_stream_u LZ4_stream_t;  /* incomplete type (defined later) */
 
+/**
+ Note about RC_INVOKED
+
+ - RC_INVOKED is predefined symbol of rc.exe (the resource compiler which is part of MSVC/Visual Studio).
+   https://docs.microsoft.com/en-us/windows/win32/menurc/predefined-macros
+
+ - Since rc.exe is a legacy compiler, it truncates long symbol (> 30 chars)
+   and reports warning "RC4011: identifier truncated".
+
+ - To eliminate the warning, we surround long preprocessor symbol with
+   "#if !defined(RC_INVOKED) ... #endif" block that means
+   "skip this block when rc.exe is trying to read it".
+*/
+#if !defined(RC_INVOKED) /* https://docs.microsoft.com/en-us/windows/win32/menurc/predefined-macros */
+#if !defined(LZ4_STATIC_LINKING_ONLY_DISABLE_MEMORY_ALLOCATION)
 LZ4LIB_API LZ4_stream_t* LZ4_createStream(void);
 LZ4LIB_API int           LZ4_freeStream (LZ4_stream_t* streamPtr);
+#endif /* !defined(LZ4_STATIC_LINKING_ONLY_DISABLE_MEMORY_ALLOCATION) */
+#endif
 
 /*! LZ4_resetStream_fast() : v1.9.0+
  *  Use this to prepare an LZ4_stream_t for a new chain of dependent blocks
@@ -333,8 +413,12 @@ typedef union LZ4_streamDecode_u LZ4_streamDecode_t;   /* tracking context */
  *  creation / destruction of streaming decompression tracking context.
  *  A tracking context can be re-used multiple times.
  */
+#if !defined(RC_INVOKED) /* https://docs.microsoft.com/en-us/windows/win32/menurc/predefined-macros */
+#if !defined(LZ4_STATIC_LINKING_ONLY_DISABLE_MEMORY_ALLOCATION)
 LZ4LIB_API LZ4_streamDecode_t* LZ4_createStreamDecode(void);
 LZ4LIB_API int                 LZ4_freeStreamDecode (LZ4_streamDecode_t* LZ4_stream);
+#endif /* !defined(LZ4_STATIC_LINKING_ONLY_DISABLE_MEMORY_ALLOCATION) */
+#endif
 
 /*! LZ4_setStreamDecode() :
  *  An LZ4_streamDecode_t context can be allocated once and re-used multiple times.
@@ -384,7 +468,10 @@ LZ4LIB_API int LZ4_decoderRingBufferSize(int maxBlockSize);
  *  save the last 64KB of decoded data into a safe buffer where it can't be modified during decompression,
  *  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_safe_continue (LZ4_streamDecode_t* LZ4_streamDecode,
+                        const char* src, char* dst,
+                        int srcSize, int dstCapacity);
 
 
 /*! LZ4_decompress_*_usingDict() :
@@ -395,7 +482,16 @@ LZ4LIB_API int LZ4_decompress_safe_continue (LZ4_streamDecode_t* LZ4_streamDecod
  *  Performance tip : Decompression speed can be substantially increased
  *                    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_safe_usingDict(const char* src, char* dst,
+                              int srcSize, int dstCapacity,
+                              const char* dictStart, int dictSize);
+
+LZ4LIB_API int
+LZ4_decompress_safe_partial_usingDict(const char* src, char* dst,
+                                      int compressedSize,
+                                      int targetOutputSize, int maxOutputSize,
+                                      const char* dictStart, int dictSize);
 
 #endif /* LZ4_H_2983827168210 */
 
@@ -474,13 +570,15 @@ LZ4LIB_STATIC_API int LZ4_compress_fast_extState_fastReset (void* state, const c
  *  stream (and source buffer) must remain in-place / accessible / unchanged
  *  through the completion of the first compression call on the stream.
  */
-LZ4LIB_STATIC_API void LZ4_attach_dictionary(LZ4_stream_t* workingStream, const LZ4_stream_t* dictionaryStream);
+LZ4LIB_STATIC_API void
+LZ4_attach_dictionary(LZ4_stream_t* workingStream,
+                const LZ4_stream_t* dictionaryStream);
 
 
 /*! In-place compression and decompression
  *
  * It's possible to have input and output sharing the same buffer,
- * for highly contrained memory environments.
+ * for highly constrained memory environments.
  * In both cases, it requires input to lay at the end of the buffer,
  * and decompression to start at beginning of the buffer.
  * Buffer size must feature some margin, hence be larger than final size.
@@ -547,74 +645,52 @@ LZ4LIB_STATIC_API void LZ4_attach_dictionary(LZ4_stream_t* workingStream, const
 #define LZ4_H_98237428734687
 
 /*-************************************************************
- *  PRIVATE DEFINITIONS
+ *  Private Definitions
  **************************************************************
  * Do not use these definitions directly.
  * They are only exposed to allow static allocation of `LZ4_stream_t` and `LZ4_streamDecode_t`.
- * Accessing members will expose code to API and/or ABI break in future versions of the library.
+ * Accessing members will expose user code to API and/or ABI break in future versions of the library.
  **************************************************************/
 #define LZ4_HASHLOG   (LZ4_MEMORY_USAGE-2)
 #define LZ4_HASHTABLESIZE (1 << LZ4_MEMORY_USAGE)
 #define LZ4_HASH_SIZE_U32 (1 << LZ4_HASHLOG)       /* required as macro for static allocation */
 
 #if defined(__cplusplus) || (defined (__STDC_VERSION__) && (__STDC_VERSION__ >= 199901L) /* C99 */)
-#include <stdint.h>
-
-typedef struct LZ4_stream_t_internal LZ4_stream_t_internal;
-struct LZ4_stream_t_internal {
-    uint32_t hashTable[LZ4_HASH_SIZE_U32];
-    uint32_t currentOffset;
-    uint16_t dirty;
-    uint16_t tableType;
-    const uint8_t* dictionary;
-    const LZ4_stream_t_internal* dictCtx;
-    uint32_t dictSize;
-};
-
-typedef struct {
-    const uint8_t* externalDict;
-    size_t extDictSize;
-    const uint8_t* prefixEnd;
-    size_t prefixSize;
-} LZ4_streamDecode_t_internal;
-
+# include <stdint.h>
+  typedef  int8_t  LZ4_i8;
+  typedef uint8_t  LZ4_byte;
+  typedef uint16_t LZ4_u16;
+  typedef uint32_t LZ4_u32;
 #else
+  typedef   signed char  LZ4_i8;
+  typedef unsigned char  LZ4_byte;
+  typedef unsigned short LZ4_u16;
+  typedef unsigned int   LZ4_u32;
+#endif
+
+/*! LZ4_stream_t :
+ *  Never ever use below internal definitions directly !
+ *  These definitions are not API/ABI safe, and may change in future versions.
+ *  If you need static allocation, declare or allocate an LZ4_stream_t object.
+**/
 
 typedef struct LZ4_stream_t_internal LZ4_stream_t_internal;
 struct LZ4_stream_t_internal {
-    unsigned int hashTable[LZ4_HASH_SIZE_U32];
-    unsigned int currentOffset;
-    unsigned short dirty;
-    unsigned short tableType;
-    const unsigned char* dictionary;
+    LZ4_u32 hashTable[LZ4_HASH_SIZE_U32];
+    const LZ4_byte* dictionary;
     const LZ4_stream_t_internal* dictCtx;
-    unsigned int dictSize;
+    LZ4_u32 currentOffset;
+    LZ4_u32 tableType;
+    LZ4_u32 dictSize;
+    /* Implicit padding to ensure structure is aligned */
 };
 
-typedef struct {
-    const unsigned char* externalDict;
-    const unsigned char* prefixEnd;
-    size_t extDictSize;
-    size_t prefixSize;
-} LZ4_streamDecode_t_internal;
-
-#endif
-
-/*! LZ4_stream_t :
- *  information structure to track an LZ4 stream.
- *  LZ4_stream_t can also be created using LZ4_createStream(), which is recommended.
- *  The structure definition can be convenient for static allocation
- *  (on stack, or as part of larger structure).
- *  Init this structure with LZ4_initStream() before first use.
- *  note : only use this definition in association with static linking !
- *    this definition is not API/ABI safe, and may change in a future version.
- */
-#define LZ4_STREAMSIZE_U64 ((1 << (LZ4_MEMORY_USAGE-3)) + 4 + ((sizeof(void*)==16) ? 4 : 0) /*AS-400*/ )
-#define LZ4_STREAMSIZE     (LZ4_STREAMSIZE_U64 * sizeof(unsigned long long))
+#define LZ4_STREAM_MINSIZE  ((1UL << LZ4_MEMORY_USAGE) + 32)  /* static size, for inter-version compatibility */
 union LZ4_stream_u {
-    unsigned long long table[LZ4_STREAMSIZE_U64];
+    char minStateSize[LZ4_STREAM_MINSIZE];
     LZ4_stream_t_internal internal_donotuse;
-} ;  /* previously typedef'd to LZ4_stream_t */
+}; /* previously typedef'd to LZ4_stream_t */
+
 
 /*! LZ4_initStream() : v1.9.0+
  *  An LZ4_stream_t structure must be initialized at least once.
@@ -629,21 +705,25 @@ union LZ4_stream_u {
  *         In which case, the function will @return NULL.
  *  Note2: An LZ4_stream_t structure guarantees correct alignment and size.
  *  Note3: Before v1.9.0, use LZ4_resetStream() instead
- */
+**/
 LZ4LIB_API LZ4_stream_t* LZ4_initStream (void* buffer, size_t size);
 
 
 /*! LZ4_streamDecode_t :
- *  information structure to track an LZ4 stream during decompression.
- *  init this structure  using LZ4_setStreamDecode() before first use.
- *  note : only use in association with static linking !
- *         this definition is not API/ABI safe,
- *         and may change in a future version !
- */
-#define LZ4_STREAMDECODESIZE_U64 (4 + ((sizeof(void*)==16) ? 2 : 0) /*AS-400*/ )
-#define LZ4_STREAMDECODESIZE     (LZ4_STREAMDECODESIZE_U64 * sizeof(unsigned long long))
+ *  Never ever use below internal definitions directly !
+ *  These definitions are not API/ABI safe, and may change in future versions.
+ *  If you need static allocation, declare or allocate an LZ4_streamDecode_t object.
+**/
+typedef struct {
+    const LZ4_byte* externalDict;
+    const LZ4_byte* prefixEnd;
+    size_t extDictSize;
+    size_t prefixSize;
+} LZ4_streamDecode_t_internal;
+
+#define LZ4_STREAMDECODE_MINSIZE 32
 union LZ4_streamDecode_u {
-    unsigned long long table[LZ4_STREAMDECODESIZE_U64];
+    char minStateSize[LZ4_STREAMDECODE_MINSIZE];
     LZ4_streamDecode_t_internal internal_donotuse;
 } ;   /* previously typedef'd to LZ4_streamDecode_t */
 
@@ -667,22 +747,21 @@ union LZ4_streamDecode_u {
 #ifdef LZ4_DISABLE_DEPRECATE_WARNINGS
 #  define LZ4_DEPRECATED(message)   /* disable deprecation warnings */
 #else
-#  define LZ4_GCC_VERSION (__GNUC__ * 100 + __GNUC_MINOR__)
 #  if defined (__cplusplus) && (__cplusplus >= 201402) /* C++14 or greater */
 #    define LZ4_DEPRECATED(message) [[deprecated(message)]]
-#  elif (LZ4_GCC_VERSION >= 405) || defined(__clang__)
-#    define LZ4_DEPRECATED(message) __attribute__((deprecated(message)))
-#  elif (LZ4_GCC_VERSION >= 301)
-#    define LZ4_DEPRECATED(message) __attribute__((deprecated))
 #  elif defined(_MSC_VER)
 #    define LZ4_DEPRECATED(message) __declspec(deprecated(message))
+#  elif defined(__clang__) || (defined(__GNUC__) && (__GNUC__ * 10 + __GNUC_MINOR__ >= 45))
+#    define LZ4_DEPRECATED(message) __attribute__((deprecated(message)))
+#  elif defined(__GNUC__) && (__GNUC__ * 10 + __GNUC_MINOR__ >= 31)
+#    define LZ4_DEPRECATED(message) __attribute__((deprecated))
 #  else
-#    pragma message("WARNING: You need to implement LZ4_DEPRECATED for this compiler")
-#    define LZ4_DEPRECATED(message)
+#    pragma message("WARNING: LZ4_DEPRECATED needs custom implementation for this compiler")
+#    define LZ4_DEPRECATED(message)   /* disabled */
 #  endif
 #endif /* LZ4_DISABLE_DEPRECATE_WARNINGS */
 
-/* Obsolete compression functions */
+/*! Obsolete compression functions (since v1.7.3) */
 LZ4_DEPRECATED("use LZ4_compress_default() instead")       LZ4LIB_API int LZ4_compress               (const char* src, char* dest, int srcSize);
 LZ4_DEPRECATED("use LZ4_compress_default() instead")       LZ4LIB_API int LZ4_compress_limitedOutput (const char* src, char* dest, int srcSize, int maxOutputSize);
 LZ4_DEPRECATED("use LZ4_compress_fast_extState() instead") LZ4LIB_API int LZ4_compress_withState               (void* state, const char* source, char* dest, int inputSize);
@@ -690,11 +769,12 @@ LZ4_DEPRECATED("use LZ4_compress_fast_extState() instead") LZ4LIB_API int LZ4_co
 LZ4_DEPRECATED("use LZ4_compress_fast_continue() instead") LZ4LIB_API int LZ4_compress_continue                (LZ4_stream_t* LZ4_streamPtr, const char* source, char* dest, int inputSize);
 LZ4_DEPRECATED("use LZ4_compress_fast_continue() instead") LZ4LIB_API int LZ4_compress_limitedOutput_continue  (LZ4_stream_t* LZ4_streamPtr, const char* source, char* dest, int inputSize, int maxOutputSize);
 
-/* Obsolete decompression functions */
+/*! Obsolete decompression functions (since v1.8.0) */
 LZ4_DEPRECATED("use LZ4_decompress_fast() instead") LZ4LIB_API int LZ4_uncompress (const char* source, char* dest, int outputSize);
 LZ4_DEPRECATED("use LZ4_decompress_safe() instead") LZ4LIB_API int LZ4_uncompress_unknownOutputSize (const char* source, char* dest, int isize, int maxOutputSize);
 
-/* Obsolete streaming functions; degraded functionality; do not use!
+/* Obsolete streaming functions (since v1.7.0)
+ * degraded functionality; do not use!
  *
  * In order to perform streaming compression, these functions depended on data
  * that is no longer tracked in the state. They have been preserved as well as
@@ -708,23 +788,22 @@ LZ4_DEPRECATED("Use LZ4_createStream() instead") LZ4LIB_API int   LZ4_sizeofStre
 LZ4_DEPRECATED("Use LZ4_resetStream() instead")  LZ4LIB_API int   LZ4_resetStreamState(void* state, char* inputBuffer);
 LZ4_DEPRECATED("Use LZ4_saveDict() instead")     LZ4LIB_API char* LZ4_slideInputBuffer (void* state);
 
-/* Obsolete streaming decoding functions */
+/*! Obsolete streaming decoding functions (since v1.7.0) */
 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!**
+/*! Obsolete LZ4_decompress_fast variants (since v1.9.0) :
  *  These functions used to be faster than LZ4_decompress_safe(),
- *  but it has changed, and they are now slower than LZ4_decompress_safe().
+ *  but this is no longer the case. They are now slower.
  *  This is because LZ4_decompress_fast() doesn't know the input size,
- *  and therefore must progress more cautiously in the input buffer to not read beyond the end of block.
+ *  and therefore must progress more cautiously into the input buffer to not read beyond the end of block.
  *  On top of that `LZ4_decompress_fast()` is not protected vs malformed or malicious inputs, making it a security liability.
  *  As a consequence, LZ4_decompress_fast() is strongly discouraged, and deprecated.
  *
  *  The last remaining LZ4_decompress_fast() specificity is that
  *  it can decompress a block without knowing its compressed size.
- *  Such functionality could be achieved in a more secure manner,
- *  by also providing the maximum size of input buffer,
- *  but it would require new prototypes, and adaptation of the implementation to this new use case.
+ *  Such functionality can be achieved in a more secure manner
+ *  by employing LZ4_decompress_safe_partial().
  *
  *  Parameters:
  *  originalSize : is the uncompressed size to regenerate.
@@ -739,7 +818,6 @@ 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**.
  */
-
 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")