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-rw-r--r--src/zstd/examples/streaming_compression.c123
1 files changed, 123 insertions, 0 deletions
diff --git a/src/zstd/examples/streaming_compression.c b/src/zstd/examples/streaming_compression.c
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+++ b/src/zstd/examples/streaming_compression.c
@@ -0,0 +1,123 @@
+/*
+ * 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 <string.h> // memset, strcat, strlen
+#include <zstd.h> // presumes zstd library is installed
+#include "common.h" // Helper functions, CHECK(), and CHECK_ZSTD()
+
+
+static void compressFile_orDie(const char* fname, const char* outName, int cLevel)
+{
+ /* Open the input and output files. */
+ FILE* const fin = fopen_orDie(fname, "rb");
+ FILE* const fout = fopen_orDie(outName, "wb");
+ /* Create the input and output buffers.
+ * They may be any size, but we recommend using these functions to size them.
+ * Performance will only suffer significantly for very tiny buffers.
+ */
+ size_t const buffInSize = ZSTD_CStreamInSize();
+ void* const buffIn = malloc_orDie(buffInSize);
+ size_t const buffOutSize = ZSTD_CStreamOutSize();
+ void* const buffOut = malloc_orDie(buffOutSize);
+
+ /* Create the context. */
+ ZSTD_CCtx* const cctx = ZSTD_createCCtx();
+ CHECK(cctx != NULL, "ZSTD_createCCtx() failed!");
+
+ /* Set any parameters you want.
+ * Here we set the compression level, and enable the checksum.
+ */
+ CHECK_ZSTD( ZSTD_CCtx_setParameter(cctx, ZSTD_c_compressionLevel, cLevel) );
+ CHECK_ZSTD( ZSTD_CCtx_setParameter(cctx, ZSTD_c_checksumFlag, 1) );
+
+ /* This loop read from the input file, compresses that entire chunk,
+ * and writes all output produced to the output file.
+ */
+ size_t const toRead = buffInSize;
+ for (;;) {
+ size_t read = fread_orDie(buffIn, toRead, fin);
+ /* Select the flush mode.
+ * If the read may not be finished (read == toRead) we use
+ * ZSTD_e_continue. If this is the last chunk, we use ZSTD_e_end.
+ * Zstd optimizes the case where the first flush mode is ZSTD_e_end,
+ * since it knows it is compressing the entire source in one pass.
+ */
+ int const lastChunk = (read < toRead);
+ ZSTD_EndDirective const mode = lastChunk ? ZSTD_e_end : ZSTD_e_continue;
+ /* Set the input buffer to what we just read.
+ * We compress until the input buffer is empty, each time flushing the
+ * output.
+ */
+ ZSTD_inBuffer input = { buffIn, read, 0 };
+ int finished;
+ do {
+ /* Compress into the output buffer and write all of the output to
+ * the file so we can reuse the buffer next iteration.
+ */
+ ZSTD_outBuffer output = { buffOut, buffOutSize, 0 };
+ size_t const remaining = ZSTD_compressStream2(cctx, &output , &input, mode);
+ CHECK_ZSTD(remaining);
+ fwrite_orDie(buffOut, output.pos, fout);
+ /* If we're on the last chunk we're finished when zstd returns 0,
+ * which means its consumed all the input AND finished the frame.
+ * Otherwise, we're finished when we've consumed all the input.
+ */
+ finished = lastChunk ? (remaining == 0) : (input.pos == input.size);
+ } while (!finished);
+ CHECK(input.pos == input.size,
+ "Impossible: zstd only returns 0 when the input is completely consumed!");
+
+ if (lastChunk) {
+ break;
+ }
+ }
+
+ ZSTD_freeCCtx(cctx);
+ fclose_orDie(fout);
+ fclose_orDie(fin);
+ free(buffIn);
+ free(buffOut);
+}
+
+
+static char* createOutFilename_orDie(const char* filename)
+{
+ size_t const inL = strlen(filename);
+ size_t const outL = inL + 5;
+ void* const outSpace = malloc_orDie(outL);
+ memset(outSpace, 0, outL);
+ strcat(outSpace, filename);
+ strcat(outSpace, ".zst");
+ return (char*)outSpace;
+}
+
+int main(int argc, const char** argv)
+{
+ const char* const exeName = argv[0];
+
+ if (argc!=2) {
+ printf("wrong arguments\n");
+ printf("usage:\n");
+ printf("%s FILE\n", exeName);
+ return 1;
+ }
+
+ const char* const inFilename = argv[1];
+
+ char* const outFilename = createOutFilename_orDie(inFilename);
+ compressFile_orDie(inFilename, outFilename, 1);
+
+ free(outFilename); /* not strictly required, since program execution stops there,
+ * but some static analyzer main complain otherwise */
+ return 0;
+}