added ZSTD_createDDict_byReference()

diff --git a/NEWS b/NEWS
index 9a341781e978032908d9c6d2c6fd645714aa44d8..5e92718175bc859d7c51f8bb0540cf9867c5f8d7 100644 (file)
--- a/NEWS
+++ b/NEWS
@@ -1,6 +1,7 @@
 v1.1.3
 cli : new : commands for advanced parameters, by Przemyslaw Skibinski
 API : fix : all symbols properly exposed in libzstd, by Nick Terrell
+API : new : ZSTD_create?Dict_byReference(), requested by Bartosz Taudul
 
 v1.1.2
 API : streaming : decompression : changed : automatic implicit reset when chain-decoding new frames without init

diff --git a/lib/compress/zstd_compress.c b/lib/compress/zstd_compress.c
index 2a9ddd6695b0a46804bd371f84edcda26e9723ea..afac869c8307def293cf435d49310b5006d994a3 100644 (file)
--- a/lib/compress/zstd_compress.c
+++ b/lib/compress/zstd_compress.c
@@ -2736,7 +2736,6 @@ struct ZSTD_CDict_s {
     void* dictBuffer;
     const void* dictContent;
     size_t dictContentSize;
-    unsigned byReference;
     ZSTD_CCtx* refContext;
 };  /* typedef'd tp ZSTD_CDict within "zstd.h" */
 
@@ -2764,14 +2763,12 @@ ZSTD_CDict* ZSTD_createCDict_advanced(const void* dictBuffer, size_t dictSize, u
         if ((byReference) || (!dictBuffer) || (!dictSize)) {
             cdict->dictBuffer = NULL;
             cdict->dictContent = dictBuffer;
-            cdict->byReference = 1;
         } else {
             void* const internalBuffer = ZSTD_malloc(dictSize, customMem);
-            if (!internalBuffer) return NULL;
+            if (!internalBuffer) { ZSTD_free(cctx, customMem); ZSTD_free(cdict, customMem); return NULL; }
             memcpy(internalBuffer, dictBuffer, dictSize);
             cdict->dictBuffer = internalBuffer;
             cdict->dictContent = internalBuffer;
-            cdict->byReference = 0;
         }
 
         {   size_t const errorCode = ZSTD_compressBegin_advanced(cctx, cdict->dictContent, dictSize, params, 0);
@@ -2809,7 +2806,7 @@ size_t ZSTD_freeCDict(ZSTD_CDict* cdict)
     if (cdict==NULL) return 0;   /* support free on NULL */
     {   ZSTD_customMem const cMem = cdict->refContext->customMem;
         ZSTD_freeCCtx(cdict->refContext);
-        if (!cdict->byReference) ZSTD_free(cdict->dictBuffer, cMem);
+        ZSTD_free(cdict->dictBuffer, cMem);
         ZSTD_free(cdict, cMem);
         return 0;
     }

diff --git a/lib/decompress/zstd_decompress.c b/lib/decompress/zstd_decompress.c
index 7addff8d0f37790f14e12586c4fad555ecf02672..19e8287e222532d11bfb73d344e81e20bb2364b0 100644 (file)
--- a/lib/decompress/zstd_decompress.c
+++ b/lib/decompress/zstd_decompress.c
@@ -1713,39 +1713,44 @@ size_t ZSTD_decompressBegin_usingDict(ZSTD_DCtx* dctx, const void* dict, size_t
 /* ======   ZSTD_DDict   ====== */
 
 struct ZSTD_DDict_s {
-    void* dict;
+    void* dictBuffer;
+    const void* dictContent;
     size_t dictSize;
     ZSTD_DCtx* refContext;
 };  /* typedef'd to ZSTD_DDict within "zstd.h" */
 
-ZSTD_DDict* ZSTD_createDDict_advanced(const void* dict, size_t dictSize, ZSTD_customMem customMem)
+ZSTD_DDict* ZSTD_createDDict_advanced(const void* dict, size_t dictSize, unsigned byReference, ZSTD_customMem customMem)
 {
     if (!customMem.customAlloc && !customMem.customFree) customMem = defaultCustomMem;
     if (!customMem.customAlloc || !customMem.customFree) return NULL;
 
     {   ZSTD_DDict* const ddict = (ZSTD_DDict*) ZSTD_malloc(sizeof(ZSTD_DDict), customMem);
-        void* const dictContent = ZSTD_malloc(dictSize, customMem);
         ZSTD_DCtx* const dctx = ZSTD_createDCtx_advanced(customMem);
 
-        if (!dictContent || !ddict || !dctx) {
-            ZSTD_free(dictContent, customMem);
+        if (!ddict || !dctx) {
             ZSTD_free(ddict, customMem);
             ZSTD_free(dctx, customMem);
             return NULL;
         }
 
-        if (dictSize) {
-            memcpy(dictContent, dict, dictSize);
+        if ((byReference) || (!dict) || (!dictSize)) {
+            ddict->dictBuffer = NULL;
+            ddict->dictContent = dict;
+        } else {
+            void* const internalBuffer = ZSTD_malloc(dictSize, customMem);
+            if (!internalBuffer) { ZSTD_free(dctx, customMem); ZSTD_free(ddict, customMem); return NULL; }
+            memcpy(internalBuffer, dict, dictSize);
+            ddict->dictBuffer = internalBuffer;
+            ddict->dictContent = internalBuffer;
         }
-        {   size_t const errorCode = ZSTD_decompressBegin_usingDict(dctx, dictContent, dictSize);
+        {   size_t const errorCode = ZSTD_decompressBegin_usingDict(dctx, ddict->dictContent, dictSize);
             if (ZSTD_isError(errorCode)) {
-                ZSTD_free(dictContent, customMem);
+                ZSTD_free(ddict->dictBuffer, customMem);
                 ZSTD_free(ddict, customMem);
                 ZSTD_free(dctx, customMem);
                 return NULL;
         }   }
 
-        ddict->dict = dictContent;
         ddict->dictSize = dictSize;
         ddict->refContext = dctx;
         return ddict;
@@ -1758,7 +1763,7 @@ ZSTD_DDict* ZSTD_createDDict_advanced(const void* dict, size_t dictSize, ZSTD_cu
 ZSTD_DDict* ZSTD_createDDict(const void* dict, size_t dictSize)
 {
     ZSTD_customMem const allocator = { NULL, NULL, NULL };
-    return ZSTD_createDDict_advanced(dict, dictSize, allocator);
+    return ZSTD_createDDict_advanced(dict, dictSize, 0, allocator);
 }
 
 size_t ZSTD_freeDDict(ZSTD_DDict* ddict)
@@ -1766,7 +1771,7 @@ size_t ZSTD_freeDDict(ZSTD_DDict* ddict)
     if (ddict==NULL) return 0;   /* support free on NULL */
     {   ZSTD_customMem const cMem = ddict->refContext->customMem;
         ZSTD_freeDCtx(ddict->refContext);
-        ZSTD_free(ddict->dict, cMem);
+        ZSTD_free(ddict->dictBuffer, cMem);
         ZSTD_free(ddict, cMem);
         return 0;
     }
@@ -1796,7 +1801,7 @@ unsigned ZSTD_getDictID_fromDict(const void* dict, size_t dictSize)
 unsigned ZSTD_getDictID_fromDDict(const ZSTD_DDict* ddict)
 {
     if (ddict==NULL) return 0;
-    return ZSTD_getDictID_fromDict(ddict->dict, ddict->dictSize);
+    return ZSTD_getDictID_fromDict(ddict->dictContent, ddict->dictSize);
 }
 
 /*! ZSTD_getDictID_fromFrame() :
@@ -1827,7 +1832,7 @@ size_t ZSTD_decompress_usingDDict(ZSTD_DCtx* dctx,
                             const ZSTD_DDict* ddict)
 {
 #if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT==1)
-    if (ZSTD_isLegacy(src, srcSize)) return ZSTD_decompressLegacy(dst, dstCapacity, src, srcSize, ddict->dict, ddict->dictSize);
+    if (ZSTD_isLegacy(src, srcSize)) return ZSTD_decompressLegacy(dst, dstCapacity, src, srcSize, ddict->dictContent, ddict->dictSize);
 #endif
     ZSTD_refDCtx(dctx, ddict->refContext);
     ZSTD_checkContinuity(dctx, dst);
@@ -2007,7 +2012,7 @@ size_t ZSTD_decompressStream(ZSTD_DStream* zds, ZSTD_outBuffer* output, ZSTD_inB
 #if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT>=1)
                 {   U32 const legacyVersion = ZSTD_isLegacy(istart, iend-istart);
                     if (legacyVersion) {
-                        const void* const dict = zds->ddict ? zds->ddict->dict : NULL;
+                        const void* const dict = zds->ddict ? zds->ddict->dictContent : NULL;
                         size_t const dictSize = zds->ddict ? zds->ddict->dictSize : 0;
                         CHECK_F(ZSTD_initLegacyStream(&zds->legacyContext, zds->previousLegacyVersion, legacyVersion,
                                                        dict, dictSize));

diff --git a/lib/zstd.h b/lib/zstd.h
index 20682b494acd2dd44d190ea957050bc7132ffffc..187ee5c28669cb3b18fde84729c82336a55e9845 100644 (file)
--- a/lib/zstd.h
+++ b/lib/zstd.h
@@ -194,8 +194,8 @@ typedef struct ZSTD_DDict_s ZSTD_DDict;
 
 /*! ZSTD_createDDict() :
 *   Create a digested dictionary, ready to start decompression operation without startup delay.
-*   `dict` can be released after creation. */
-ZSTDLIB_API ZSTD_DDict* ZSTD_createDDict(const void* dict, size_t dictSize);
+*   dictBuffer can be released after DDict creation, as its content is copied inside DDict */
+ZSTDLIB_API ZSTD_DDict* ZSTD_createDDict(const void* dictBuffer, size_t dictSize);
 
 /*! ZSTD_freeDDict() :
 *   Function frees memory allocated with ZSTD_createDDict() */
@@ -328,7 +328,7 @@ ZSTDLIB_API size_t ZSTD_DStreamOutSize(void);   /*!< recommended size for output
  * ***************************************************************************************/
 
 /* --- Constants ---*/
-#define ZSTD_MAGICNUMBER            0xFD2FB528   /* v0.8 */
+#define ZSTD_MAGICNUMBER            0xFD2FB528   /* >= v0.8.0 */
 #define ZSTD_MAGIC_SKIPPABLE_START  0x184D2A50U
 
 #define ZSTD_WINDOWLOG_MAX_32  25
@@ -464,6 +464,15 @@ ZSTDLIB_API ZSTD_DCtx* ZSTD_createDCtx_advanced(ZSTD_customMem customMem);
  *  Gives the amount of memory used by a given ZSTD_DCtx */
 ZSTDLIB_API size_t ZSTD_sizeof_DCtx(const ZSTD_DCtx* dctx);
 
+/*! ZSTD_createDDict_byReference() :
+ *  Create a digested dictionary, ready to start decompression operation without startup delay.
+ *  Dictionary content is simply referenced, and therefore stays in dictBuffer.
+ *  It is important that dictBuffer outlives DDict, it must remain read accessible throughout the lifetime of DDict */
+ZSTDLIB_API ZSTD_DDict* ZSTD_createDDict_byReference(const void* dictBuffer, size_t dictSize);
+
+ZSTDLIB_API ZSTD_DDict* ZSTD_createDDict_advanced(const void* dict, size_t dictSize,
+                                                  unsigned byReference, ZSTD_customMem customMem);
+
 /*! ZSTD_sizeof_DDict() :
  *  Gives the amount of memory used by a given ZSTD_DDict */
 ZSTDLIB_API size_t ZSTD_sizeof_DDict(const ZSTD_DDict* ddict);