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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 18:45:59 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-04-07 18:45:59 +0000 |
commit | 19fcec84d8d7d21e796c7624e521b60d28ee21ed (patch) | |
tree | 42d26aa27d1e3f7c0b8bd3fd14e7d7082f5008dc /src/zstd/examples/streaming_decompression.c | |
parent | Initial commit. (diff) | |
download | ceph-upstream.tar.xz ceph-upstream.zip |
Adding upstream version 16.2.11+ds.upstream/16.2.11+dsupstream
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to '')
-rw-r--r-- | src/zstd/examples/streaming_decompression.c | 100 |
1 files changed, 100 insertions, 0 deletions
diff --git a/src/zstd/examples/streaming_decompression.c b/src/zstd/examples/streaming_decompression.c new file mode 100644 index 000000000..26eda3441 --- /dev/null +++ b/src/zstd/examples/streaming_decompression.c @@ -0,0 +1,100 @@ +/* + * 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> // fprintf +#include <stdlib.h> // free +#include <zstd.h> // presumes zstd library is installed +#include "common.h" // Helper functions, CHECK(), and CHECK_ZSTD() + +static void decompressFile_orDie(const char* fname) +{ + FILE* const fin = fopen_orDie(fname, "rb"); + size_t const buffInSize = ZSTD_DStreamInSize(); + void* const buffIn = malloc_orDie(buffInSize); + FILE* const fout = stdout; + size_t const buffOutSize = ZSTD_DStreamOutSize(); /* Guarantee to successfully flush at least one complete compressed block in all circumstances. */ + void* const buffOut = malloc_orDie(buffOutSize); + + ZSTD_DCtx* const dctx = ZSTD_createDCtx(); + CHECK(dctx != NULL, "ZSTD_createDCtx() failed!"); + + /* This loop assumes that the input file is one or more concatenated zstd + * streams. This example won't work if there is trailing non-zstd data at + * the end, but streaming decompression in general handles this case. + * ZSTD_decompressStream() returns 0 exactly when the frame is completed, + * and doesn't consume input after the frame. + */ + size_t const toRead = buffInSize; + size_t read; + size_t lastRet = 0; + int isEmpty = 1; + while ( (read = fread_orDie(buffIn, toRead, fin)) ) { + isEmpty = 0; + ZSTD_inBuffer input = { buffIn, read, 0 }; + /* Given a valid frame, zstd won't consume the last byte of the frame + * until it has flushed all of the decompressed data of the frame. + * Therefore, instead of checking if the return code is 0, we can + * decompress just check if input.pos < input.size. + */ + while (input.pos < input.size) { + ZSTD_outBuffer output = { buffOut, buffOutSize, 0 }; + /* The return code is zero if the frame is complete, but there may + * be multiple frames concatenated together. Zstd will automatically + * reset the context when a frame is complete. Still, calling + * ZSTD_DCtx_reset() can be useful to reset the context to a clean + * state, for instance if the last decompression call returned an + * error. + */ + size_t const ret = ZSTD_decompressStream(dctx, &output , &input); + CHECK_ZSTD(ret); + fwrite_orDie(buffOut, output.pos, fout); + lastRet = ret; + } + } + + if (isEmpty) { + fprintf(stderr, "input is empty\n"); + exit(1); + } + + if (lastRet != 0) { + /* The last return value from ZSTD_decompressStream did not end on a + * frame, but we reached the end of the file! We assume this is an + * error, and the input was truncated. + */ + fprintf(stderr, "EOF before end of stream: %zu\n", lastRet); + exit(1); + } + + ZSTD_freeDCtx(dctx); + fclose_orDie(fin); + fclose_orDie(fout); + free(buffIn); + free(buffOut); +} + + +int main(int argc, const char** argv) +{ + const char* const exeName = argv[0]; + + if (argc!=2) { + fprintf(stderr, "wrong arguments\n"); + fprintf(stderr, "usage:\n"); + fprintf(stderr, "%s FILE\n", exeName); + return 1; + } + + const char* const inFilename = argv[1]; + + decompressFile_orDie(inFilename); + return 0; +} |