added test for LZ4F_resetDecompressionContext()

5 files changed, 79 insertions, 59 deletions

diff --git a/doc/lz4frame_manual.html b/doc/lz4frame_manual.html
index fa2c0b9..87750a1 100644
--- a/doc/lz4frame_manual.html
+++ b/doc/lz4frame_manual.html
@@ -255,14 +255,11 @@ LZ4F_errorCode_t LZ4F_freeDecompressionContext(LZ4F_dctx* dctx);
  
 </p></pre><BR>
 
-<pre><b>LZ4F_errorCode_t LZ4F_resetDecompressionContext(LZ4F_dctx* dctx);
-</b><p>  When decompression ends successfully,
-  it's possible to start a new decompression immediately
-  re-using the same context.
-  However, in case of an error, the context is left in "undefined" state.
+<pre><b>void LZ4F_resetDecompressionContext(LZ4F_dctx* dctx);   </b>/* always successful */<b>
+</b><p>  In case of an error, the context is left in "undefined" state.
   In which case, it's necessary to reset it, before re-using it.
   This method can also be used to abruptly stop an unfinished decompression,
-  and start a new on the same context. 
+  and start a new with the same context. 
 </p></pre><BR>
 
 </html>
diff --git a/lib/lz4frame.c b/lib/lz4frame.c
index 7422638..fb37789 100644
--- a/lib/lz4frame.c
+++ b/lib/lz4frame.c
@@ -798,10 +798,9 @@ typedef enum {
     dstage_skipSkippable
 } dStage_t;
 
-LZ4F_errorCode_t LZ4F_resetDecompressionContext(LZ4F_dctx* dctx)
+void LZ4F_resetDecompressionContext(LZ4F_dctx* dctx)
 {
     dctx->dStage = dstage_getHeader;
-    return 0;
 }
 
 
@@ -939,7 +938,8 @@ LZ4F_errorCode_t LZ4F_getFrameInfo(LZ4F_dctx* dctxPtr, LZ4F_frameInfo_t* frameIn
         size_t o=0, i=0;
         *srcSizePtr = 0;
         *frameInfoPtr = dctxPtr->frameInfo;
-        return LZ4F_decompress(dctxPtr, NULL, &o, NULL, &i, NULL);  /* returns : recommended nb of bytes for LZ4F_decompress() */
+        /* returns : recommended nb of bytes for LZ4F_decompress() */
+        return LZ4F_decompress(dctxPtr, NULL, &o, NULL, &i, NULL);
     } else {
         if (dctxPtr->dStage == dstage_storeHeader) {
             /* frame decoding already started, in the middle of header => automatic fail */
@@ -949,7 +949,10 @@ LZ4F_errorCode_t LZ4F_getFrameInfo(LZ4F_dctx* dctxPtr, LZ4F_frameInfo_t* frameIn
             size_t decodeResult;
             size_t const hSize = LZ4F_headerSize(srcBuffer, *srcSizePtr);
             if (LZ4F_isError(hSize)) { *srcSizePtr=0; return hSize; }
-            if (*srcSizePtr < hSize) { *srcSizePtr=0; return err0r(LZ4F_ERROR_frameHeader_incomplete); }
+            if (*srcSizePtr < hSize) {
+                *srcSizePtr=0;
+                return err0r(LZ4F_ERROR_frameHeader_incomplete);
+            }
 
             decodeResult = LZ4F_decodeHeader(dctxPtr, srcBuffer, hSize);
             if (LZ4F_isError(decodeResult)) {
@@ -965,10 +968,15 @@ LZ4F_errorCode_t LZ4F_getFrameInfo(LZ4F_dctx* dctxPtr, LZ4F_frameInfo_t* frameIn
 
 
 /* trivial redirector, for common prototype */
-static int LZ4F_decompress_safe (const char* source, char* dest, int compressedSize, int maxDecompressedSize, const char* dictStart, int dictSize)
+static int LZ4F_decompress_safe (const char* src,
+                                 char* dst,
+                                 int compressedSize,
+                                 int dstCapacity,
+                                 const char* dictStart,
+                                 int dictSize)
 {
     (void)dictStart; (void)dictSize;
-    return LZ4_decompress_safe (source, dest, compressedSize, maxDecompressedSize);
+    return LZ4_decompress_safe (src, dst, compressedSize, dstCapacity);
 }
 
 
@@ -1101,7 +1109,7 @@ size_t LZ4F_decompress(LZ4F_dctx* dctxPtr,
                     doAnotherStage = 0;   /* not enough src data, ask for some more */
                     break;
                 }
-                {   LZ4F_errorCode_t const hSize = LZ4F_decodeHeader(dctxPtr, dctxPtr->header, dctxPtr->tmpInTarget);
+                {   LZ4F_errorCode_t const hSize = LZ4F_decodeHeader(dctxPtr, dctxPtr->header, dctxPtr->tmpInTarget);  /* will change dStage appropriately */
                     if (LZ4F_isError(hSize)) return hSize;
                 }
                 break;
@@ -1149,7 +1157,7 @@ size_t LZ4F_decompress(LZ4F_dctx* dctxPtr,
                 memcpy(dctxPtr->tmpIn + dctxPtr->tmpInSize, srcPtr, sizeToCopy);
                 srcPtr += sizeToCopy;
                 dctxPtr->tmpInSize += sizeToCopy;
-                if (dctxPtr->tmpInSize < BHSize) {   /* not enough input to get full cBlockSize; wait for more */
+                if (dctxPtr->tmpInSize < BHSize) {   /* not enough input for cBlockSize */
                     nextSrcSizeHint = BHSize - dctxPtr->tmpInSize;
                     doAnotherStage  = 0;
                     break;
@@ -1157,13 +1165,14 @@ size_t LZ4F_decompress(LZ4F_dctx* dctxPtr,
                 selectedIn = dctxPtr->tmpIn;
             }
 
-        /* case dstage_decodeCBlockSize: */   /* no more direct access, to prevent scan-build warning */
+        /* case dstage_decodeCBlockSize: */   /* no more direct access, to remove scan-build warning */
             {   size_t const nextCBlockSize = LZ4F_readLE32(selectedIn) & 0x7FFFFFFFU;
                 if (nextCBlockSize==0) {  /* frameEnd signal, no more CBlock */
                     dctxPtr->dStage = dstage_getSuffix;
                     break;
                 }
-                if (nextCBlockSize > dctxPtr->maxBlockSize) return err0r(LZ4F_ERROR_GENERIC);   /* invalid cBlockSize */
+                if (nextCBlockSize > dctxPtr->maxBlockSize)
+                    return err0r(LZ4F_ERROR_maxBlockSize_invalid);
                 dctxPtr->tmpInTarget = nextCBlockSize;
                 if (LZ4F_readLE32(selectedIn) & LZ4F_BLOCKUNCOMPRESSED_FLAG) {
                     dctxPtr->dStage = dstage_copyDirect;
@@ -1179,11 +1188,13 @@ size_t LZ4F_decompress(LZ4F_dctx* dctxPtr,
 
         case dstage_copyDirect:   /* uncompressed block */
             {   size_t sizeToCopy = dctxPtr->tmpInTarget;
-                if ((size_t)(srcEnd-srcPtr) < sizeToCopy) sizeToCopy = srcEnd - srcPtr;  /* not enough input to read full block */
+                if ((size_t)(srcEnd-srcPtr) < sizeToCopy) sizeToCopy = srcEnd - srcPtr;
                 if ((size_t)(dstEnd-dstPtr) < sizeToCopy) sizeToCopy = dstEnd - dstPtr;
                 memcpy(dstPtr, srcPtr, sizeToCopy);
-                if (dctxPtr->frameInfo.contentChecksumFlag) XXH32_update(&(dctxPtr->xxh), srcPtr, sizeToCopy);
-                if (dctxPtr->frameInfo.contentSize) dctxPtr->frameRemainingSize -= sizeToCopy;
+                if (dctxPtr->frameInfo.contentChecksumFlag)
+                    XXH32_update(&(dctxPtr->xxh), srcPtr, sizeToCopy);
+                if (dctxPtr->frameInfo.contentSize)
+                    dctxPtr->frameRemainingSize -= sizeToCopy;
 
                 /* dictionary management */
                 if (dctxPtr->frameInfo.blockMode==LZ4F_blockLinked)
@@ -1244,10 +1255,14 @@ size_t LZ4F_decompress(LZ4F_dctx* dctxPtr,
                 else
                     decoder = LZ4F_decompress_safe;
 
-                decodedSize = decoder((const char*)selectedIn, (char*)dstPtr, (int)dctxPtr->tmpInTarget, (int)dctxPtr->maxBlockSize, (const char*)dctxPtr->dict, (int)dctxPtr->dictSize);
+                decodedSize = decoder((const char*)selectedIn, (char*)dstPtr,
+                        (int)dctxPtr->tmpInTarget, (int)dctxPtr->maxBlockSize,
+                        (const char*)dctxPtr->dict, (int)dctxPtr->dictSize);
                 if (decodedSize < 0) return err0r(LZ4F_ERROR_GENERIC);   /* decompression failed */
-                if (dctxPtr->frameInfo.contentChecksumFlag) XXH32_update(&(dctxPtr->xxh), dstPtr, decodedSize);
-                if (dctxPtr->frameInfo.contentSize) dctxPtr->frameRemainingSize -= decodedSize;
+                if (dctxPtr->frameInfo.contentChecksumFlag)
+                    XXH32_update(&(dctxPtr->xxh), dstPtr, decodedSize);
+                if (dctxPtr->frameInfo.contentSize)
+                    dctxPtr->frameRemainingSize -= decodedSize;
 
                 /* dictionary management */
                 if (dctxPtr->frameInfo.blockMode==LZ4F_blockLinked)
@@ -1284,10 +1299,15 @@ size_t LZ4F_decompress(LZ4F_dctx* dctxPtr,
                 }
 
                 /* Decode */
-                decodedSize = decoder((const char*)selectedIn, (char*)dctxPtr->tmpOut, (int)dctxPtr->tmpInTarget, (int)dctxPtr->maxBlockSize, (const char*)dctxPtr->dict, (int)dctxPtr->dictSize);
-                if (decodedSize < 0) return err0r(LZ4F_ERROR_decompressionFailed);   /* decompression failed */
-                if (dctxPtr->frameInfo.contentChecksumFlag) XXH32_update(&(dctxPtr->xxh), dctxPtr->tmpOut, decodedSize);
-                if (dctxPtr->frameInfo.contentSize) dctxPtr->frameRemainingSize -= decodedSize;
+                decodedSize = decoder((const char*)selectedIn, (char*)dctxPtr->tmpOut,
+                        (int)dctxPtr->tmpInTarget, (int)dctxPtr->maxBlockSize,
+                        (const char*)dctxPtr->dict, (int)dctxPtr->dictSize);
+                if (decodedSize < 0)
+                    return err0r(LZ4F_ERROR_decompressionFailed);   /* decompression failed */
+                if (dctxPtr->frameInfo.contentChecksumFlag)
+                    XXH32_update(&(dctxPtr->xxh), dctxPtr->tmpOut, decodedSize);
+                if (dctxPtr->frameInfo.contentSize)
+                    dctxPtr->frameRemainingSize -= decodedSize;
                 dctxPtr->tmpOutSize = decodedSize;
                 dctxPtr->tmpOutStart = 0;
                 dctxPtr->dStage = dstage_flushOut;
@@ -1318,7 +1338,8 @@ size_t LZ4F_decompress(LZ4F_dctx* dctxPtr,
 
         case dstage_getSuffix:
             {   size_t const suffixSize = dctxPtr->frameInfo.contentChecksumFlag * 4;
-                if (dctxPtr->frameRemainingSize) return err0r(LZ4F_ERROR_frameSize_wrong);   /* incorrect frame size decoded */
+                if (dctxPtr->frameRemainingSize)
+                    return err0r(LZ4F_ERROR_frameSize_wrong);   /* incorrect frame size decoded */
                 if (suffixSize == 0) {  /* frame completed */
                     nextSrcSizeHint = 0;
                     dctxPtr->dStage = dstage_getHeader;
@@ -1379,7 +1400,8 @@ size_t LZ4F_decompress(LZ4F_dctx* dctxPtr,
                 memcpy(dctxPtr->header + dctxPtr->tmpInSize, srcPtr, sizeToCopy);
                 srcPtr += sizeToCopy;
                 dctxPtr->tmpInSize += sizeToCopy;
-                if (dctxPtr->tmpInSize < dctxPtr->tmpInTarget) { /* not enough input to get full sBlockSize; wait for more */
+                if (dctxPtr->tmpInSize < dctxPtr->tmpInTarget) {
+                    /* not enough input to get full sBlockSize; wait for more */
                     nextSrcSizeHint = dctxPtr->tmpInTarget - dctxPtr->tmpInSize;
                     doAnotherStage = 0;
                     break;
diff --git a/lib/lz4frame.h b/lib/lz4frame.h
index 9a2130a..b1719e2 100644
--- a/lib/lz4frame.h
+++ b/lib/lz4frame.h
@@ -364,14 +364,11 @@ LZ4FLIB_API size_t LZ4F_decompress(LZ4F_dctx* dctx,
 
 
 /*! LZ4F_resetDecompressionContext() : v1.8.0
- *  When decompression ends successfully,
- *  it's possible to start a new decompression immediately
- *  re-using the same context.
- *  However, in case of an error, the context is left in "undefined" state.
+ *  In case of an error, the context is left in "undefined" state.
  *  In which case, it's necessary to reset it, before re-using it.
  *  This method can also be used to abruptly stop an unfinished decompression,
- *  and start a new on the same context. */
-LZ4FLIB_API LZ4F_errorCode_t LZ4F_resetDecompressionContext(LZ4F_dctx* dctx);
+ *  and start a new with the same context. */
+LZ4FLIB_API void LZ4F_resetDecompressionContext(LZ4F_dctx* dctx);   /* always successful */
 
 
 
diff --git a/lib/lz4frame_static.h b/lib/lz4frame_static.h
index 8ea496d..d3bae82 100644
--- a/lib/lz4frame_static.h
+++ b/lib/lz4frame_static.h
@@ -50,15 +50,6 @@ extern "C" {
 #include "lz4frame.h"
 
 
-/* ---   Experimental functions   --- */
-/* LZ4F_resetDecompressionContext() :
- * LZ4F_decompress() does not guarantee to leave dctx in clean state in case of errors.
- * In order to re-use a dctx after a decompression error,
- * use LZ4F_resetDecompressionContext() first.
- * dctx will be able to start decompression on a new frame */
-LZ4FLIB_API LZ4F_errorCode_t LZ4F_resetDecompressionContext(LZ4F_dctx* dctx);
-
-
 /* ---   Error List   --- */
 #define LZ4F_LIST_ERRORS(ITEM) \
         ITEM(OK_NoError) \
diff --git a/tests/frametest.c b/tests/frametest.c
index 04597a4..538bedc 100644
--- a/tests/frametest.c
+++ b/tests/frametest.c
@@ -40,6 +40,7 @@
 #include <stdio.h>      /* fprintf */
 #include <string.h>     /* strcmp */
 #include <time.h>       /* clock_t, clock(), CLOCKS_PER_SEC */
+#include <assert.h>
 #include "lz4frame_static.h"
 #include "lz4.h"        /* LZ4_VERSION_STRING */
 #define XXH_STATIC_LINKING_ONLY
@@ -67,7 +68,6 @@ static void FUZ_writeLE32 (void* dstVoidPtr, U32 value32)
 #define GB *(1U<<30)
 
 static const U32 nbTestsDefault = 256 KB;
-#define COMPRESSIBLE_NOISE_LENGTH (2 MB)
 #define FUZ_COMPRESSIBILITY_DEFAULT 50
 static const U32 prime1 = 2654435761U;
 static const U32 prime2 = 2246822519U;
@@ -166,7 +166,7 @@ static unsigned FUZ_highbit(U32 v32)
 *********************************************************/
 int basicTests(U32 seed, double compressibility)
 {
-    int testResult = 0;
+#define COMPRESSIBLE_NOISE_LENGTH (2 MB)
     void* const CNBuffer = malloc(COMPRESSIBLE_NOISE_LENGTH);
     size_t const cBuffSize = LZ4F_compressFrameBound(COMPRESSIBLE_NOISE_LENGTH, NULL);
     void* const compressedBuffer = malloc(cBuffSize);
@@ -176,9 +176,10 @@ int basicTests(U32 seed, double compressibility)
     LZ4F_decompressionContext_t dCtx = NULL;
     LZ4F_compressionContext_t cctx = NULL;
     U64 crcOrig;
-
+    int basicTests_error = 0;
     LZ4F_preferences_t prefs;
     memset(&prefs, 0, sizeof(prefs));
+
     if (!CNBuffer || !compressedBuffer || !decodedBuffer) {
         DISPLAY("allocation error, not enough memory to start fuzzer tests \n");
         goto _output_error;
@@ -198,7 +199,7 @@ int basicTests(U32 seed, double compressibility)
     DISPLAYLEVEL(3, "LZ4F_compressFrame, compress null content : ");
     cSize = LZ4F_compressFrame(compressedBuffer, LZ4F_compressFrameBound(testSize, NULL), CNBuffer, testSize, NULL);
     if (LZ4F_isError(cSize)) goto _output_error;
-    DISPLAYLEVEL(3, "Compressed null content into a %i bytes frame \n", (int)cSize);
+    DISPLAYLEVEL(3, "null content encoded into a %u bytes frame \n", (unsigned)cSize);
 
     DISPLAYLEVEL(3, "LZ4F_createDecompressionContext \n");
     { LZ4F_errorCode_t const errorCode = LZ4F_createDecompressionContext(&dCtx, LZ4F_VERSION);
@@ -236,8 +237,6 @@ int basicTests(U32 seed, double compressibility)
     DISPLAYLEVEL(3, "Decompression test : \n");
     {   size_t decodedBufferSize = COMPRESSIBLE_NOISE_LENGTH;
         size_t compressedBufferSize = cSize;
-        BYTE* ip = (BYTE*)compressedBuffer;
-        BYTE* const iend = (BYTE*)compressedBuffer + cSize;
 
         LZ4F_errorCode_t errorCode = LZ4F_createDecompressionContext(&dCtx, LZ4F_VERSION);
         if (LZ4F_isError(errorCode)) goto _output_error;
@@ -280,6 +279,7 @@ int basicTests(U32 seed, double compressibility)
         {   size_t oSize = 0;
             size_t iSize = 0;
             LZ4F_frameInfo_t fi;
+            const BYTE* ip = (BYTE*)compressedBuffer;
 
             DISPLAYLEVEL(3, "Start by feeding 0 bytes, to get next input size : ");
             errorCode = LZ4F_decompress(dCtx, NULL, &oSize, ip, &iSize, NULL);
@@ -315,10 +315,30 @@ int basicTests(U32 seed, double compressibility)
             ip += iSize;
         }
 
+        DISPLAYLEVEL(3, "Decode a buggy input : ");
+        assert(COMPRESSIBLE_NOISE_LENGTH > 64);
+        assert(cSize > 48);
+        memcpy(decodedBuffer, (char*)compressedBuffer+16, 32);  /* save correct data */
+        memcpy((char*)compressedBuffer+16, (const char*)decodedBuffer+32, 32);  /* insert noise */
+        {   size_t dbSize = COMPRESSIBLE_NOISE_LENGTH;
+            size_t cbSize = cSize;
+            size_t const decompressError = LZ4F_decompress(dCtx, decodedBuffer, &dbSize,
+                                                               compressedBuffer, &cbSize,
+                                                               NULL);
+            if (!LZ4F_isError(decompressError)) goto _output_error;
+            DISPLAYLEVEL(3, "error detected : %s \n", LZ4F_getErrorName(decompressError));
+        }
+        memcpy((char*)compressedBuffer+16, decodedBuffer, 32);  /* restore correct data */
+
+        DISPLAYLEVEL(3, "Reset decompression context, since it's left in error state \n");
+        LZ4F_resetDecompressionContext(dCtx);   /* always successful */
+
         DISPLAYLEVEL(3, "Byte after byte : ");
         {   BYTE* const ostart = (BYTE*)decodedBuffer;
             BYTE* op = ostart;
             BYTE* const oend = (BYTE*)decodedBuffer + COMPRESSIBLE_NOISE_LENGTH;
+            const BYTE* ip = compressedBuffer;
+            const BYTE* const iend = ip + cSize;
             while (ip < iend) {
                 size_t oSize = oend-op;
                 size_t iSize = 1;
@@ -330,11 +350,7 @@ int basicTests(U32 seed, double compressibility)
             { U64 const crcDest = XXH64(decodedBuffer, COMPRESSIBLE_NOISE_LENGTH, 1);
               if (crcDest != crcOrig) goto _output_error; }
             DISPLAYLEVEL(3, "Regenerated %u/%u bytes \n", (unsigned)(op-ostart), COMPRESSIBLE_NOISE_LENGTH);
-            }
-
-        errorCode = LZ4F_freeDecompressionContext(dCtx);
-        if (LZ4F_isError(errorCode)) goto _output_error;
-        dCtx = NULL;
+        }
     }
 
     DISPLAYLEVEL(3, "Using 64 KB block : ");
@@ -366,9 +382,6 @@ int basicTests(U32 seed, double compressibility)
         const BYTE* ip = (const BYTE*)compressedBuffer;
         const BYTE* const iend = (const BYTE*)compressedBuffer + cSize;
 
-        { LZ4F_errorCode_t const createError = LZ4F_createDecompressionContext(&dCtx, LZ4F_VERSION);
-          if (LZ4F_isError(createError)) goto _output_error; }
-
         DISPLAYLEVEL(3, "random segment sizes : ");
         while (ip < iend) {
             unsigned const nbBits = FUZ_rand(&randState) % maxBits;
@@ -552,10 +565,10 @@ _end:
     free(decodedBuffer);
     LZ4F_freeDecompressionContext(dCtx); dCtx = NULL;
     LZ4F_freeCompressionContext(cctx); cctx = NULL;
-    return testResult;
+    return basicTests_error;
 
 _output_error:
-    testResult = 1;
+    basicTests_error = 1;
     DISPLAY("Error detected ! \n");
     goto _end;
 }