1 files changed, 123 insertions, 0 deletions
diff --git a/src/zstd/examples/streaming_compression.c b/src/zstd/examples/streaming_compression.c
new file mode 100644
index 000000000..f0f1065b1
--- /dev/null
+++ 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;
+}