Update lz4hc API : LZ4_compressHC_safe()

3 files changed, 68 insertions, 111 deletions

diff --git a/NEWS b/NEWS
index a1d452a..0f33388 100644
--- a/NEWS
+++ b/NEWS
@@ -1,6 +1,8 @@
 r129:
 Added  : LZ4_compress_fast()
+Changed: New compression functions LZ4_compress_safe() - Suggested by Evan Nemerson & Takayuki Matsuoka
 Added  : AppVeyor CI environment, for Visual tests - Suggested by Takayuki Matsuoka
+Fixed  : GCC 4.9+ optimization bug - Reported by Markus Trippelsdorf, Evan Nemerson and Greg Slazinski
 Updated: Documentation converted to MarkDown
 
 r128:
diff --git a/lib/lz4hc.c b/lib/lz4hc.c
index c7a94a0..234e1af 100644
--- a/lib/lz4hc.c
+++ b/lib/lz4hc.c
@@ -536,55 +536,24 @@ _Search3:
 }
 
 
-int LZ4_compressHC2(const char* source, char* dest, int inputSize, int compressionLevel)
-{
-    LZ4HC_Data_Structure ctx;
-    LZ4HC_init(&ctx, (const BYTE*)source);
-    return LZ4HC_compress_generic (&ctx, source, dest, inputSize, 0, compressionLevel, noLimit);
-}
-
-int LZ4_compressHC(const char* source, char* dest, int inputSize) { return LZ4_compressHC2(source, dest, inputSize, 0); }
-
-int LZ4_compressHC2_limitedOutput(const char* source, char* dest, int inputSize, int maxOutputSize, int compressionLevel)
-{
-    LZ4HC_Data_Structure ctx;
-    LZ4HC_init(&ctx, (const BYTE*)source);
-    return LZ4HC_compress_generic (&ctx, source, dest, inputSize, maxOutputSize, compressionLevel, limitedOutput);
-}
-
-int LZ4_compressHC_limitedOutput(const char* source, char* dest, int inputSize, int maxOutputSize)
-{
-    return LZ4_compressHC2_limitedOutput(source, dest, inputSize, maxOutputSize, 0);
-}
-
-
-/*****************************
- * Using external allocation
- * ***************************/
 int LZ4_sizeofStateHC(void) { return sizeof(LZ4HC_Data_Structure); }
 
-
-int LZ4_compressHC2_withStateHC (void* state, const char* source, char* dest, int inputSize, int compressionLevel)
+int LZ4_compressHC_safe_extStateHC (void* state, const char* source, char* dest, int inputSize, int maxOutputSize, int compressionLevel)
 {
     if (((size_t)(state)&(sizeof(void*)-1)) != 0) return 0;   /* Error : state is not aligned for pointers (32 or 64 bits) */
     LZ4HC_init ((LZ4HC_Data_Structure*)state, (const BYTE*)source);
-    return LZ4HC_compress_generic (state, source, dest, inputSize, 0, compressionLevel, noLimit);
+    if (maxOutputSize < LZ4_compressBound(inputSize))
+        return LZ4HC_compress_generic (state, source, dest, inputSize, maxOutputSize, compressionLevel, limitedOutput);
+    else
+        return LZ4HC_compress_generic (state, source, dest, inputSize, maxOutputSize, compressionLevel, noLimit);
 }
 
-int LZ4_compressHC_withStateHC (void* state, const char* source, char* dest, int inputSize)
-{ return LZ4_compressHC2_withStateHC (state, source, dest, inputSize, 0); }
-
-
-int LZ4_compressHC2_limitedOutput_withStateHC (void* state, const char* source, char* dest, int inputSize, int maxOutputSize, int compressionLevel)
+int LZ4_compressHC_safe(const char* source, char* dest, int inputSize, int maxOutputSize, int compressionLevel)
 {
-    if (((size_t)(state)&(sizeof(void*)-1)) != 0) return 0;   /* Error : state is not aligned for pointers (32 or 64 bits) */
-    LZ4HC_init ((LZ4HC_Data_Structure*)state, (const BYTE*)source);
-    return LZ4HC_compress_generic (state, source, dest, inputSize, maxOutputSize, compressionLevel, limitedOutput);
+    LZ4HC_Data_Structure state;
+    return LZ4_compressHC_safe_extStateHC(&state, source, dest, inputSize, maxOutputSize, compressionLevel);
 }
 
-int LZ4_compressHC_limitedOutput_withStateHC (void* state, const char* source, char* dest, int inputSize, int maxOutputSize)
-{ return LZ4_compressHC2_limitedOutput_withStateHC (state, source, dest, inputSize, maxOutputSize, 0); }
-
 
 
 /**************************************
@@ -592,7 +561,7 @@ int LZ4_compressHC_limitedOutput_withStateHC (void* state, const char* source, c
  * ************************************/
 /* allocation */
 LZ4_streamHC_t* LZ4_createStreamHC(void) { return (LZ4_streamHC_t*)malloc(sizeof(LZ4_streamHC_t)); }
-int LZ4_freeStreamHC (LZ4_streamHC_t* LZ4_streamHCPtr) { free(LZ4_streamHCPtr); return 0; }
+int             LZ4_freeStreamHC (LZ4_streamHC_t* LZ4_streamHCPtr) { free(LZ4_streamHCPtr); return 0; }
 
 
 /* initialization */
@@ -669,14 +638,12 @@ static int LZ4_compressHC_continue_generic (LZ4HC_Data_Structure* ctxPtr,
     return LZ4HC_compress_generic (ctxPtr, source, dest, inputSize, maxOutputSize, ctxPtr->compressionLevel, limit);
 }
 
-int LZ4_compressHC_continue (LZ4_streamHC_t* LZ4_streamHCPtr, const char* source, char* dest, int inputSize)
+int LZ4_compressHC_safe_continue (LZ4_streamHC_t* LZ4_streamHCPtr, const char* source, char* dest, int inputSize, int maxOutputSize)
 {
-    return LZ4_compressHC_continue_generic ((LZ4HC_Data_Structure*)LZ4_streamHCPtr, source, dest, inputSize, 0, noLimit);
-}
-
-int LZ4_compressHC_limitedOutput_continue (LZ4_streamHC_t* LZ4_streamHCPtr, const char* source, char* dest, int inputSize, int maxOutputSize)
-{
-    return LZ4_compressHC_continue_generic ((LZ4HC_Data_Structure*)LZ4_streamHCPtr, source, dest, inputSize, maxOutputSize, limitedOutput);
+    if (maxOutputSize < LZ4_compressBound(inputSize))
+        return LZ4_compressHC_continue_generic ((LZ4HC_Data_Structure*)LZ4_streamHCPtr, source, dest, inputSize, maxOutputSize, limitedOutput);
+    else
+        return LZ4_compressHC_continue_generic ((LZ4HC_Data_Structure*)LZ4_streamHCPtr, source, dest, inputSize, maxOutputSize, noLimit);
 }
 
 
@@ -705,6 +672,20 @@ int LZ4_saveDictHC (LZ4_streamHC_t* LZ4_streamHCPtr, char* safeBuffer, int dictS
 /***********************************
  * Deprecated Functions
  ***********************************/
+/* Deprecated compression functions */
+int LZ4_compressHC(const char* source, char* dest, int inputSize) { return LZ4_compressHC2(source, dest, inputSize, 0); }
+int LZ4_compressHC_limitedOutput(const char* src, char* dst, int srcSize, int maxDstSize) { return LZ4_compressHC_safe(src, dst, srcSize, maxDstSize, 0); }
+int LZ4_compressHC2(const char* src, char* dst, int srcSize, int cLevel) { return LZ4_compressHC_safe (src, dst, srcSize, LZ4_compressBound(srcSize), cLevel); }
+int LZ4_compressHC2_limitedOutput(const char* src, char* dst, int srcSize, int maxDstSize, int cLevel) { return LZ4_compressHC_safe(src, dst, srcSize, maxDstSize, cLevel); }
+int LZ4_compressHC_withStateHC (void* state, const char* src, char* dst, int srcSize) { return LZ4_compressHC_safe_extStateHC (state, src, dst, srcSize, LZ4_compressBound(srcSize), 0); }
+int LZ4_compressHC_limitedOutput_withStateHC (void* state, const char* src, char* dst, int srcSize, int maxDstSize) { return LZ4_compressHC_safe_extStateHC (state, src, dst, srcSize, maxDstSize, 0); }
+int LZ4_compressHC2_withStateHC (void* state, const char* src, char* dst, int srcSize, int cLevel) { return LZ4_compressHC_safe_extStateHC(state, src, dst, srcSize, LZ4_compressBound(srcSize), cLevel); }
+int LZ4_compressHC2_limitedOutput_withStateHC (void* state, const char* src, char* dst, int srcSize, int maxDstSize, int cLevel) { return LZ4_compressHC_safe_extStateHC(state, src, dst, srcSize, maxDstSize, cLevel); }
+int LZ4_compressHC_continue (LZ4_streamHC_t* ctx, const char* src, char* dst, int srcSize) { return LZ4_compressHC_safe_continue (ctx, src, dst, srcSize, LZ4_compressBound(srcSize)); }
+int LZ4_compressHC_limitedOutput_continue (LZ4_streamHC_t* ctx, const char* src, char* dst, int srcSize, int maxDstSize) { return LZ4_compressHC_safe_continue (ctx, src, dst, srcSize, maxDstSize); }
+
+
+/* Deprecated streaming functions */
 int LZ4_sizeofStreamStateHC(void) { return LZ4_STREAMHCSIZE; }
 
 int LZ4_resetStreamStateHC(void* state, const char* inputBuffer)
@@ -727,17 +708,6 @@ int LZ4_freeHC (void* LZ4HC_Data)
     return (0);
 }
 
-/*
-int LZ4_compressHC_continue (void* LZ4HC_Data, const char* source, char* dest, int inputSize)
-{
-return LZ4HC_compress_generic (LZ4HC_Data, source, dest, inputSize, 0, 0, noLimit);
-}
-int LZ4_compressHC_limitedOutput_continue (void* LZ4HC_Data, const char* source, char* dest, int inputSize, int maxOutputSize)
-{
-return LZ4HC_compress_generic (LZ4HC_Data, source, dest, inputSize, maxOutputSize, 0, limitedOutput);
-}
-*/
-
 int LZ4_compressHC2_continue (void* LZ4HC_Data, const char* source, char* dest, int inputSize, int compressionLevel)
 {
     return LZ4HC_compress_generic (LZ4HC_Data, source, dest, inputSize, 0, compressionLevel, noLimit);
diff --git a/lib/lz4hc.h b/lib/lz4hc.h
index 4a05845..c257dcc 100644
--- a/lib/lz4hc.h
+++ b/lib/lz4hc.h
@@ -38,78 +38,53 @@
 extern "C" {
 #endif
 
+/*****************************
+*  Includes
+*****************************/
+#include <stddef.h>   /* size_t */
+
 
-int LZ4_compressHC (const char* source, char* dest, int inputSize);
+/**************************************
+*  Block Compression
+**************************************/
+int LZ4_compressHC_safe (const char* source, char* dest, int inputSize, int maxOutputSize, int compressionLevel);
 /*
-LZ4_compressHC :
+LZ4_compressHC_safe :
     return : the number of bytes in compressed buffer dest
              or 0 if compression fails.
     note : destination buffer must be already allocated.
-        To avoid any problem, size it to handle worst cases situations (input data not compressible)
+        To guarantee compression completion, size it to handle worst cases situations (data not compressible)
         Worst case size evaluation is provided by function LZ4_compressBound() (see "lz4.h")
+    inputSize  : Max supported value is LZ4_MAX_INPUT_SIZE (see "lz4.h")
+    compressionLevel : Recommended values are between 4 and 9, although any value between 0 and 16 will work.
+                       0 means use default 'compressionLevel' value.
+                       Values >16 behave the same as 16.
 */
 
-int LZ4_compressHC_limitedOutput (const char* source, char* dest, int inputSize, int maxOutputSize);
-/*
-LZ4_compress_limitedOutput() :
-    Compress 'inputSize' bytes from 'source' into an output buffer 'dest' of maximum size 'maxOutputSize'.
-    If it cannot achieve it, compression will stop, and result of the function will be zero.
-    This function never writes outside of provided output buffer.
-
-    inputSize  : Max supported value is 1 GB
-    maxOutputSize : is maximum allowed size into the destination buffer (which must be already allocated)
-    return : the number of output bytes written in buffer 'dest'
-             or 0 if compression fails.
-*/
-
-
-int LZ4_compressHC2 (const char* source, char* dest, int inputSize, int compressionLevel);
-int LZ4_compressHC2_limitedOutput (const char* source, char* dest, int inputSize, int maxOutputSize, int compressionLevel);
-/*
-    Same functions as above, but with programmable 'compressionLevel'.
-    Recommended values are between 4 and 9, although any value between 0 and 16 will work.
-    'compressionLevel'==0 means use default 'compressionLevel' value.
-    Values above 16 behave the same as 16.
-    Equivalent variants exist for all other compression functions below.
-*/
 
 /* Note :
    Decompression functions are provided within LZ4 source code (see "lz4.h") (BSD license)
 */
 
 
-/**************************************
-*  Using an external allocation
-**************************************/
 int LZ4_sizeofStateHC(void);
-int LZ4_compressHC_withStateHC               (void* state, const char* source, char* dest, int inputSize);
-int LZ4_compressHC_limitedOutput_withStateHC (void* state, const char* source, char* dest, int inputSize, int maxOutputSize);
-
-int LZ4_compressHC2_withStateHC              (void* state, const char* source, char* dest, int inputSize, int compressionLevel);
-int LZ4_compressHC2_limitedOutput_withStateHC(void* state, const char* source, char* dest, int inputSize, int maxOutputSize, int compressionLevel);
+int LZ4_compressHC_safe_extStateHC(void* state, const char* source, char* dest, int inputSize, int maxOutputSize, int compressionLevel);
 
 /*
-These functions are provided should you prefer to allocate memory for compression tables with your own allocation methods.
+This function is provided should you prefer to allocate memory for compression tables with your own allocation methods.
 To know how much memory must be allocated for the compression tables, use :
 int LZ4_sizeofStateHC();
 
 Note that tables must be aligned for pointer (32 or 64 bits), otherwise compression will fail (return code 0).
 
 The allocated memory can be provided to the compression functions using 'void* state' parameter.
-LZ4_compress_withStateHC() and LZ4_compress_limitedOutput_withStateHC() are equivalent to previously described functions.
-They just use the externally allocated memory for state instead of allocating their own (on stack, or on heap).
+LZ4_compressHC_safe_extStateHC() is equivalent to previously described function.
+It just uses externally allocated memory for stateHC instead of allocating their own (on stack, or on heap).
 */
 
 
-
-/*****************************
-*  Includes
-*****************************/
-#include <stddef.h>   /* size_t */
-
-
 /**************************************
-*  Experimental Streaming Functions
+*  Streaming Compression
 **************************************/
 #define LZ4_STREAMHCSIZE        262192
 #define LZ4_STREAMHCSIZE_SIZET (LZ4_STREAMHCSIZE / sizeof(size_t))
@@ -137,8 +112,7 @@ to avoid size mismatch between different versions.
 void LZ4_resetStreamHC (LZ4_streamHC_t* LZ4_streamHCPtr, int compressionLevel);
 int  LZ4_loadDictHC (LZ4_streamHC_t* LZ4_streamHCPtr, const char* dictionary, int dictSize);
 
-int LZ4_compressHC_continue (LZ4_streamHC_t* LZ4_streamHCPtr, const char* source, char* dest, int inputSize);
-int LZ4_compressHC_limitedOutput_continue (LZ4_streamHC_t* LZ4_streamHCPtr, const char* source, char* dest, int inputSize, int maxOutputSize);
+int LZ4_compressHC_safe_continue (LZ4_streamHC_t* LZ4_streamHCPtr, const char* source, char* dest, int inputSize, int maxOutputSize);
 
 int LZ4_saveDictHC (LZ4_streamHC_t* LZ4_streamHCPtr, char* safeBuffer, int maxDictSize);
 
@@ -149,8 +123,8 @@ One key assumption is that each previous block will remain read-accessible while
 Before starting compression, state must be properly initialized, using LZ4_resetStreamHC().
 A first "fictional block" can then be designated as initial dictionary, using LZ4_loadDictHC() (Optional).
 
-Then, use LZ4_compressHC_continue() or LZ4_compressHC_limitedOutput_continue() to compress each successive block.
-They work like usual LZ4_compressHC() or LZ4_compressHC_limitedOutput(), but use previous memory blocks to improve compression.
+Then, use LZ4_compressHC_safe_continue() to compress each successive block.
+It works like LZ4_compressHC_safe(), but use previous memory blocks to improve compression.
 Previous memory blocks (including initial dictionary when present) must remain accessible and unmodified during compression.
 
 If, for any reason, previous data block can't be preserved in memory during next compression block,
@@ -161,16 +135,27 @@ using LZ4_saveDictHC().
 
 
 /**************************************
- * Deprecated Streaming Functions
+ * Deprecated Functions
  * ************************************/
-/* Note : these streaming functions follows the older model, and should no longer be used */
+
+/* compression functions */
+int LZ4_compressHC                (const char* source, char* dest, int inputSize);
+int LZ4_compressHC_limitedOutput  (const char* source, char* dest, int inputSize, int maxOutputSize);
+int LZ4_compressHC2               (const char* source, char* dest, int inputSize, int compressionLevel);
+int LZ4_compressHC2_limitedOutput (const char* source, char* dest, int inputSize, int maxOutputSize, int compressionLevel);
+int LZ4_compressHC_withStateHC               (void* state, const char* source, char* dest, int inputSize);
+int LZ4_compressHC_limitedOutput_withStateHC (void* state, const char* source, char* dest, int inputSize, int maxOutputSize);
+int LZ4_compressHC2_withStateHC              (void* state, const char* source, char* dest, int inputSize, int compressionLevel);
+int LZ4_compressHC2_limitedOutput_withStateHC(void* state, const char* source, char* dest, int inputSize, int maxOutputSize, int compressionLevel);
+int LZ4_compressHC_continue               (LZ4_streamHC_t* LZ4_streamHCPtr, const char* source, char* dest, int inputSize);
+int LZ4_compressHC_limitedOutput_continue (LZ4_streamHC_t* LZ4_streamHCPtr, const char* source, char* dest, int inputSize, int maxOutputSize);
+
+/* Streaming functions following the older model; should no longer be used */
 void* LZ4_createHC (const char* inputBuffer);
 char* LZ4_slideInputBufferHC (void* LZ4HC_Data);
 int   LZ4_freeHC (void* LZ4HC_Data);
-
 int   LZ4_compressHC2_continue (void* LZ4HC_Data, const char* source, char* dest, int inputSize, int compressionLevel);
 int   LZ4_compressHC2_limitedOutput_continue (void* LZ4HC_Data, const char* source, char* dest, int inputSize, int maxOutputSize, int compressionLevel);
-
 int   LZ4_sizeofStreamStateHC(void);
 int   LZ4_resetStreamStateHC(void* state, const char* inputBuffer);