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-rw-r--r--src/zstd/examples/dictionary_decompression.c99
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diff --git a/src/zstd/examples/dictionary_decompression.c b/src/zstd/examples/dictionary_decompression.c
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+++ b/src/zstd/examples/dictionary_decompression.c
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+/*
+ * Copyright (c) 2016-2020, 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 <stdio.h> // printf
+#include <stdlib.h> // free
+#include <zstd.h> // presumes zstd library is installed
+#include "common.h" // Helper functions, CHECK(), and CHECK_ZSTD()
+
+/* 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 = mallocAndLoadFile_orDie(dictFileName, &dictSize);
+ ZSTD_DDict* const ddict = ZSTD_createDDict(dictBuffer, dictSize);
+ CHECK(ddict != NULL, "ZSTD_createDDict() failed!");
+ free(dictBuffer);
+ return ddict;
+}
+
+static void decompress(const char* fname, const ZSTD_DDict* ddict)
+{
+ size_t cSize;
+ void* const cBuff = mallocAndLoadFile_orDie(fname, &cSize);
+ /* Read the content size from the frame header. For simplicity we require
+ * that it is always present. By default, zstd will write the content size
+ * in the header when it is known. If you can't guarantee that the frame
+ * content size is always written into the header, either use streaming
+ * decompression, or ZSTD_decompressBound().
+ */
+ unsigned long long const rSize = ZSTD_getFrameContentSize(cBuff, cSize);
+ CHECK(rSize != ZSTD_CONTENTSIZE_ERROR, "%s: not compressed by zstd!", fname);
+ CHECK(rSize != ZSTD_CONTENTSIZE_UNKNOWN, "%s: original size unknown!", fname);
+ void* const rBuff = malloc_orDie((size_t)rSize);
+
+ /* Check that the dictionary ID matches.
+ * If a non-zstd dictionary is used, then both will be zero.
+ * By default zstd always writes the dictionary ID into the frame.
+ * Zstd will check if there is a dictionary ID mismatch as well.
+ */
+ unsigned const expectedDictID = ZSTD_getDictID_fromDDict(ddict);
+ unsigned const actualDictID = ZSTD_getDictID_fromFrame(cBuff, cSize);
+ CHECK(actualDictID == expectedDictID,
+ "DictID mismatch: expected %u got %u",
+ expectedDictID,
+ actualDictID);
+
+ /* Decompress using the dictionary.
+ * If you need to control the decompression parameters, then use the
+ * advanced API: ZSTD_DCtx_setParameter(), ZSTD_DCtx_refDDict(), and
+ * ZSTD_decompressDCtx().
+ */
+ ZSTD_DCtx* const dctx = ZSTD_createDCtx();
+ CHECK(dctx != NULL, "ZSTD_createDCtx() failed!");
+ size_t const dSize = ZSTD_decompress_usingDDict(dctx, rBuff, rSize, cBuff, cSize, ddict);
+ CHECK_ZSTD(dSize);
+ /* When zstd knows the content size, it will error if it doesn't match. */
+ CHECK(dSize == rSize, "Impossible because zstd will check this condition!");
+
+ /* 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;
+}