1 files changed, 131 insertions, 0 deletions
diff --git a/src/zstd/examples/dictionary_decompression.c b/src/zstd/examples/dictionary_decompression.c
new file mode 100644
index 00000000..07e6e24c
--- /dev/null
+++ b/src/zstd/examples/dictionary_decompression.c
@@ -0,0 +1,131 @@
+/*
+ * Copyright (c) 2016-present, Yann Collet, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under both the BSD-style license (found in the
+ * LICENSE file in the root directory of this source tree) and the GPLv2 (found
+ * in the COPYING file in the root directory of this source tree).
+ * You may select, at your option, one of the above-listed licenses.
+ */
+
+
+
+#include <stdlib.h>    // malloc, exit
+#include <stdio.h>     // printf
+#include <string.h>    // strerror
+#include <errno.h>     // errno
+#include <sys/stat.h>  // stat
+#define ZSTD_STATIC_LINKING_ONLY   // ZSTD_findDecompressedSize
+#include <zstd.h>      // presumes zstd library is installed
+
+
+static off_t fsize_orDie(const char *filename)
+{
+    struct stat st;
+    if (stat(filename, &st) == 0) return st.st_size;
+    /* error */
+    perror(filename);
+    exit(1);
+}
+
+static FILE* fopen_orDie(const char *filename, const char *instruction)
+{
+    FILE* const inFile = fopen(filename, instruction);
+    if (inFile) return inFile;
+    /* error */
+    perror(filename);
+    exit(2);
+}
+
+static void* malloc_orDie(size_t size)
+{
+    void* const buff = malloc(size);
+    if (buff) return buff;
+    /* error */
+    perror("malloc");
+    exit(3);
+}
+
+static void* loadFile_orDie(const char* fileName, size_t* size)
+{
+    off_t const buffSize = fsize_orDie(fileName);
+    FILE* const inFile = fopen_orDie(fileName, "rb");
+    void* const buffer = malloc_orDie(buffSize);
+    size_t const readSize = fread(buffer, 1, buffSize, inFile);
+    if (readSize != (size_t)buffSize) {
+        fprintf(stderr, "fread: %s : %s \n", fileName, strerror(errno));
+        exit(4);
+    }
+    fclose(inFile);
+    *size = buffSize;
+    return buffer;
+}
+
+/* createDict() :
+   `dictFileName` is supposed to have been created using `zstd --train` */
+static ZSTD_DDict* createDict_orDie(const char* dictFileName)
+{
+    size_t dictSize;
+    printf("loading dictionary %s \n", dictFileName);
+    void* const dictBuffer = loadFile_orDie(dictFileName, &dictSize);
+    ZSTD_DDict* const ddict = ZSTD_createDDict(dictBuffer, dictSize);
+    if (ddict==NULL) { fprintf(stderr, "ZSTD_createDDict error \n"); exit(5); }
+    free(dictBuffer);
+    return ddict;
+}
+
+
+static void decompress(const char* fname, const ZSTD_DDict* ddict)
+{
+    size_t cSize;
+    void* const cBuff = loadFile_orDie(fname, &cSize);
+    unsigned long long const rSize = ZSTD_findDecompressedSize(cBuff, cSize);
+    if (rSize==ZSTD_CONTENTSIZE_ERROR) {
+        fprintf(stderr, "%s : it was not compressed by zstd.\n", fname);
+        exit(5);
+    } else if (rSize==ZSTD_CONTENTSIZE_UNKNOWN) {
+        fprintf(stderr, "%s : original size unknown \n", fname);
+        exit(6);
+    }
+
+    void* const rBuff = malloc_orDie((size_t)rSize);
+
+    ZSTD_DCtx* const dctx = ZSTD_createDCtx();
+    if (dctx==NULL) { fprintf(stderr, "ZSTD_createDCtx() error \n"); exit(10); }
+    size_t const dSize = ZSTD_decompress_usingDDict(dctx, rBuff, rSize, cBuff, cSize, ddict);
+    if (dSize != rSize) {
+        fprintf(stderr, "error decoding %s : %s \n", fname, ZSTD_getErrorName(dSize));
+        exit(7);
+    }
+
+    /* success */
+    printf("%25s : %6u -> %7u \n", fname, (unsigned)cSize, (unsigned)rSize);
+
+    ZSTD_freeDCtx(dctx);
+    free(rBuff);
+    free(cBuff);
+}
+
+
+int main(int argc, const char** argv)
+{
+    const char* const exeName = argv[0];
+
+    if (argc<3) {
+        printf("wrong arguments\n");
+        printf("usage:\n");
+        printf("%s [FILES] dictionary\n", exeName);
+        return 1;
+    }
+
+    /* load dictionary only once */
+    const char* const dictName = argv[argc-1];
+    ZSTD_DDict* const dictPtr = createDict_orDie(dictName);
+
+    int u;
+    for (u=1; u<argc-1; u++) decompress(argv[u], dictPtr);
+
+    ZSTD_freeDDict(dictPtr);
+    printf("All %u files correctly decoded (in memory) \n", argc-2);
+    return 0;
+}