regroup name creation logic into its own function

for a cleaner main file decompression loop

programs/fileio.c

@@ -1895,48 +1895,27 @@ int FIO_decompressFilename(const char* dstFileName, const char* srcFileName,
 }
 
 
-#define MAXSUFFIXSIZE 8
+/* FIO_determineDstName() :
-int FIO_decompressMultipleFilenames(const char** srcNamesTable, unsigned nbFiles,
+ * create a destination filename from a srcFileName.
-                                    const char* outFileName,
+ * @return a pointer to it.
-                                    const char* dictFileName)
+ * @return == NULL if there is an error */
+static const char*
+FIO_determineDstName(const char* srcFileName)
 {
-    int skippedFiles = 0;
+    static size_t dfnbCapacity = 0;
-    int missingFiles = 0;
+    static char* dstFileNameBuffer = NULL;   /* using static allocation : this function cannot be multi-threaded */
-    dRess_t ress = FIO_createDResources(dictFileName);
 
-    if (outFileName) {
-        unsigned u;
-        ress.dstFile = FIO_openDstFile(outFileName);
-        if (ress.dstFile == 0) EXM_THROW(71, "cannot open %s", outFileName);
-        for (u=0; u<nbFiles; u++)
-            missingFiles += FIO_decompressSrcFile(ress, outFileName, srcNamesTable[u]);
-        if (fclose(ress.dstFile))
-            EXM_THROW(72, "Write error : cannot properly close output file");
-    } else {
-        size_t suffixSize;
-        size_t dfnbCapacity = FNSPACE;
-        unsigned u;
-        char* dstFileName = (char*)malloc(dfnbCapacity);
-        if (dstFileName==NULL)
-            EXM_THROW(73, "not enough memory for dstFileName");
-        for (u=0; u<nbFiles; u++) {   /* create dstFileName */
-            const char* const srcFileName = srcNamesTable[u];
-            const char* const suffixPtr = strrchr(srcFileName, '.');
     size_t const sfnSize = strlen(srcFileName);
-            if (!suffixPtr) {
+    size_t suffixSize;
+    const char* const suffixPtr = strrchr(srcFileName, '.');
+    if (suffixPtr == NULL) {
         DISPLAYLEVEL(1, "zstd: %s: unknown suffix -- ignored \n",
                         srcFileName);
-                skippedFiles++;
+        return NULL;
-                continue;
     }
     suffixSize = strlen(suffixPtr);
-            if (dfnbCapacity+suffixSize <= sfnSize+1) {
+
-                free(dstFileName);
+    /* check suffix is authorized */
-                dfnbCapacity = sfnSize + 20;
-                dstFileName = (char*)malloc(dfnbCapacity);
-                if (dstFileName==NULL)
-                    EXM_THROW(74, "not enough memory for dstFileName");
-            }
     if (sfnSize <= suffixSize
         || (   strcmp(suffixPtr, ZSTD_EXTENSION)
         #ifdef ZSTD_GZDECOMPRESS
@@ -1963,15 +1942,52 @@ int FIO_decompressMultipleFilenames(const char** srcNamesTable, unsigned nbFiles
         ;
         DISPLAYLEVEL(1, "zstd: %s: unknown suffix (%s expected) -- ignored \n",
                      srcFileName, suffixlist);
-                skippedFiles++;
+        return NULL;
-                continue;
-            } else {
-                memcpy(dstFileName, srcFileName, sfnSize - suffixSize);
-                dstFileName[sfnSize-suffixSize] = '\0';
     }
+
+    /* allocate enough space to write dstFilename into it */
+    if (dfnbCapacity+suffixSize <= sfnSize+1) {
+        free(dstFileNameBuffer);
+        dfnbCapacity = sfnSize + 20;
+        dstFileNameBuffer = (char*)malloc(dfnbCapacity);
+        if (dstFileNameBuffer==NULL)
+            EXM_THROW(74, "not enough memory for dstFileName");
+    }
+
+    /* return dst name == src name truncated from suffix */
+    memcpy(dstFileNameBuffer, srcFileName, sfnSize - suffixSize);
+    dstFileNameBuffer[sfnSize-suffixSize] = '\0';
+    return dstFileNameBuffer;
+
+    /* note : dstFileNameBuffer memory is not going to be free */
+}
+
+
+int FIO_decompressMultipleFilenames(const char** srcNamesTable, unsigned nbFiles,
+                                    const char* outFileName,
+                                    const char* dictFileName)
+{
+    int skippedFiles = 0;
+    int missingFiles = 0;
+    dRess_t ress = FIO_createDResources(dictFileName);
+
+    if (outFileName) {
+        unsigned u;
+        ress.dstFile = FIO_openDstFile(outFileName);
+        if (ress.dstFile == 0) EXM_THROW(71, "cannot open %s", outFileName);
+        for (u=0; u<nbFiles; u++)
+            missingFiles += FIO_decompressSrcFile(ress, outFileName, srcNamesTable[u]);
+        if (fclose(ress.dstFile))
+            EXM_THROW(72, "Write error : cannot properly close output file");
+    } else {
+        unsigned u;
+        for (u=0; u<nbFiles; u++) {   /* create dstFileName */
+            const char* const srcFileName = srcNamesTable[u];
+            const char* const dstFileName = FIO_determineDstName(srcFileName);
+            if (dstFileName == NULL) { skippedFiles++; continue; }
+
             missingFiles += FIO_decompressDstFile(ress, dstFileName, srcFileName);
         }
-        free(dstFileName);
     }
 
     FIO_freeDResources(ress);