From: Yann Collet <cyan@fb.com>
Date: Sun, 28 Aug 2016 15:19:47 +0000 (-0700)
Subject: legacy contexts can be re-used
X-Git-Tag: v1.0.0^2~19
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=767d8f66fa115d93729badc7f83edc40eb29c6bd;p=thirdparty%2Fzstd.git

legacy contexts can be re-used
---

diff --git a/lib/decompress/zstd_decompress.c b/lib/decompress/zstd_decompress.c
index 5b95de96f..97adec205 100644
--- a/lib/decompress/zstd_decompress.c
+++ b/lib/decompress/zstd_decompress.c
@@ -1341,6 +1341,7 @@ struct ZSTD_DStream_s {
     size_t dictSize;
     const void* dictSource;
     void* legacyContext;
+    U32 previousLegacyVersion;
     U32 legacyVersion;
 };   /* typedef'd to ZSTD_DStream within "zstd.h" */
 
@@ -1380,7 +1381,7 @@ size_t ZSTD_freeDStream(ZSTD_DStream* zds)
     if (zds->dictContent) zds->customMem.customFree(zds->customMem.opaque, zds->dictContent);
 #if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT >= 1)
     if (zds->legacyContext) {
-        ZSTD_freeLegacyStreamContext(zds->legacyContext, zds->legacyVersion);
+        ZSTD_freeLegacyStreamContext(zds->legacyContext, zds->previousLegacyVersion);
         zds->legacyContext = NULL;
     }
 #endif
@@ -1407,7 +1408,6 @@ size_t ZSTD_initDStream_usingDict(ZSTD_DStream* zds, const void* dict, size_t di
         memcpy(zds->dictContent, dict, dictSize);
         zds->dictSize = dictSize;
     }
-    if (zds->legacyContext) zds->customMem.customFree(zds->customMem.opaque, zds->dictContent);   /* legacy restarts from scratch on each call, to detect restart */
     zds->legacyVersion = 0;
     return 0;
 }
@@ -1470,10 +1470,14 @@ size_t ZSTD_decompressStream(ZSTD_DStream* zds, ZSTD_outBuffer* output, ZSTD_inB
             {   size_t const hSize = ZSTD_getFrameParams(&zds->fParams, zds->headerBuffer, zds->lhSize);
                 if (ZSTD_isError(hSize))
 #if defined(ZSTD_LEGACY_SUPPORT) && (ZSTD_LEGACY_SUPPORT>=1)
-                {   U32 const legacyVersion = ZSTD_isLegacy(istart, iend-istart)
+                {   U32 const legacyVersion = ZSTD_isLegacy(istart, iend-istart);
                     if (legacyVersion) {
-                        zds->legacyVersion = legacyVersion;
-                        return ZSTD_decompressLegacyStream(&zds->legacyContext, zds->legacyVersion, output, input);
+                        size_t initResult;
+                        initResult = ZSTD_initLegacyStream(&zds->legacyContext, zds->previousLegacyVersion, legacyVersion,
+                                                           zds->dictContent, zds->dictSize);
+                        if (ZSTD_isError(initResult)) return initResult;
+                        zds->legacyVersion = zds->previousLegacyVersion = legacyVersion;
+                        return ZSTD_decompressLegacyStream(zds->legacyContext, zds->legacyVersion, output, input);
                     } else {
                         return hSize; /* error */
                 }   }
diff --git a/lib/legacy/zstd_legacy.h b/lib/legacy/zstd_legacy.h
index a5a767e49..589852335 100644
--- a/lib/legacy/zstd_legacy.h
+++ b/lib/legacy/zstd_legacy.h
@@ -147,22 +147,6 @@ MEM_STATIC size_t ZSTD_decompressLegacy(
 }
 
 
-MEM_STATIC void* ZSTD_createLegacyStreamContext(U32 version)
-{
-    switch(version)
-    {
-        default :
-        case 1 :
-        case 2 :
-        case 3 :
-            return NULL;
-        case 4 : return ZBUFFv04_createDCtx();
-        case 5 : return ZBUFFv05_createDCtx();
-        case 6 : return ZBUFFv06_createDCtx();
-        case 7 : return ZBUFFv07_createDCtx();
-    }
-}
-
 MEM_STATIC size_t ZSTD_freeLegacyStreamContext(void* legacyContext, U32 version)
 {
     switch(version)
@@ -180,56 +164,58 @@ MEM_STATIC size_t ZSTD_freeLegacyStreamContext(void* legacyContext, U32 version)
 }
 
 
-MEM_STATIC void ZSTD_initLegacyStream(void* legacyContext, U32 version,
-                                      const void* dict, size_t dictSize)
+MEM_STATIC size_t ZSTD_initLegacyStream(void** legacyContext, U32 prevVersion, U32 newVersion,
+                                        const void* dict, size_t dictSize)
 {
-    switch(version)
+    if (prevVersion != newVersion) ZSTD_freeLegacyStreamContext(*legacyContext, prevVersion);
+    switch(newVersion)
     {
         default :
         case 1 :
         case 2 :
         case 3 :
-            return;
+            return 0;
         case 4 :
         {
-            ZBUFFv04_DCtx* dctx = (ZBUFFv04_DCtx*) legacyContext;
+            ZBUFFv04_DCtx* dctx = (prevVersion != newVersion) ? ZBUFFv04_createDCtx() : (ZBUFFv04_DCtx*)*legacyContext;
+            if (dctx==NULL) return ERROR(memory_allocation);
             ZBUFFv04_decompressInit(dctx);
             ZBUFFv04_decompressWithDictionary(dctx, dict, dictSize);
-            return;
+            *legacyContext = dctx;
+            return 0;
         }
         case 5 :
         {
-            ZBUFFv05_DCtx* dctx = (ZBUFFv05_DCtx*) legacyContext;
+            ZBUFFv05_DCtx* dctx = (prevVersion != newVersion) ? ZBUFFv05_createDCtx() : (ZBUFFv05_DCtx*)*legacyContext;
+            if (dctx==NULL) return ERROR(memory_allocation);
             ZBUFFv05_decompressInitDictionary(dctx, dict, dictSize);
-            return;
+            *legacyContext = dctx;
+            return 0;
         }
         case 6 :
         {
-            ZBUFFv06_DCtx* dctx = (ZBUFFv06_DCtx*) legacyContext;
+            ZBUFFv06_DCtx* dctx = (prevVersion != newVersion) ? ZBUFFv06_createDCtx() : (ZBUFFv06_DCtx*)*legacyContext;
+            if (dctx==NULL) return ERROR(memory_allocation);
             ZBUFFv06_decompressInitDictionary(dctx, dict, dictSize);
-            return;
+            *legacyContext = dctx;
+            return 0;
         }
         case 7 :
         {
-            ZBUFFv07_DCtx* dctx = (ZBUFFv07_DCtx*) legacyContext;
+            ZBUFFv07_DCtx* dctx = (prevVersion != newVersion) ? ZBUFFv07_createDCtx() : (ZBUFFv07_DCtx*)*legacyContext;
+            if (dctx==NULL) return ERROR(memory_allocation);
             ZBUFFv07_decompressInitDictionary(dctx, dict, dictSize);
-            return;
+            *legacyContext = dctx;
+            return 0;
         }
     }
 }
 
 
 
-MEM_STATIC size_t ZSTD_decompressLegacyStream(void** legacyContext, U32 version,
-                                              ZSTD_outBuffer* output, ZSTD_inBuffer* input,
-                                              const void* dict, size_t dictSize)
+MEM_STATIC size_t ZSTD_decompressLegacyStream(void* legacyContext, U32 version,
+                                              ZSTD_outBuffer* output, ZSTD_inBuffer* input)
 {
-    if (*legacyContext == NULL) {
-        *legacyContext = ZSTD_createLegacyStreamContext(version);
-        if (*legacyContext==NULL) return ERROR(memory_allocation);
-        ZSTD_initLegacyStream(*legacyContext, version, dict, dictSize);
-    }
-
     switch(version)
     {
         default :
@@ -239,7 +225,7 @@ MEM_STATIC size_t ZSTD_decompressLegacyStream(void** legacyContext, U32 version,
             return ERROR(version_unsupported);
         case 4 :
             {
-                ZBUFFv04_DCtx* dctx = (ZBUFFv04_DCtx*) (*legacyContext);
+                ZBUFFv04_DCtx* dctx = (ZBUFFv04_DCtx*) legacyContext;
                 const void* src = (const char*)input->src + input->pos;
                 size_t readSize = input->size - input->pos;
                 void* dst = (char*)output->dst + output->pos;
@@ -251,7 +237,7 @@ MEM_STATIC size_t ZSTD_decompressLegacyStream(void** legacyContext, U32 version,
             }
         case 5 :
             {
-                ZBUFFv05_DCtx* dctx = (ZBUFFv05_DCtx*) (*legacyContext);
+                ZBUFFv05_DCtx* dctx = (ZBUFFv05_DCtx*) legacyContext;
                 const void* src = (const char*)input->src + input->pos;
                 size_t readSize = input->size - input->pos;
                 void* dst = (char*)output->dst + output->pos;
@@ -263,7 +249,7 @@ MEM_STATIC size_t ZSTD_decompressLegacyStream(void** legacyContext, U32 version,
             }
         case 6 :
             {
-                ZBUFFv06_DCtx* dctx = (ZBUFFv06_DCtx*) (*legacyContext);
+                ZBUFFv06_DCtx* dctx = (ZBUFFv06_DCtx*) legacyContext;
                 const void* src = (const char*)input->src + input->pos;
                 size_t readSize = input->size - input->pos;
                 void* dst = (char*)output->dst + output->pos;
@@ -275,7 +261,7 @@ MEM_STATIC size_t ZSTD_decompressLegacyStream(void** legacyContext, U32 version,
             }
         case 7 :
             {
-                ZBUFFv07_DCtx* dctx = (ZBUFFv07_DCtx*) (*legacyContext);
+                ZBUFFv07_DCtx* dctx = (ZBUFFv07_DCtx*) legacyContext;
                 const void* src = (const char*)input->src + input->pos;
                 size_t readSize = input->size - input->pos;
                 void* dst = (char*)output->dst + output->pos;