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Linux kernel mirror (for testing) git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
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123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150// SPDX-License-Identifier: GPL-2.0
#include <string.h>#include <linux/perf_event.h>
#include "util/compress.h"#include "util/debug.h"
int zstd_init(struct zstd_data *data, int level){ data->comp_level = level; data->dstream = NULL; data->cstream = NULL; return 0;}
int zstd_fini(struct zstd_data *data){ if (data->dstream) { ZSTD_freeDStream(data->dstream); data->dstream = NULL; }
if (data->cstream) { ZSTD_freeCStream(data->cstream); data->cstream = NULL; }
return 0;}
ssize_t zstd_compress_stream_to_records(struct zstd_data *data, void *dst, size_t dst_size, void *src, size_t src_size, size_t max_record_size, size_t process_header(void *record, size_t increment)){ size_t ret, size, compressed = 0; ZSTD_inBuffer input = { src, src_size, 0 }; ZSTD_outBuffer output; void *record;
if (!data->cstream) { data->cstream = ZSTD_createCStream(); if (data->cstream == NULL) { pr_err("Couldn't create compression stream.\n"); return -1; }
ret = ZSTD_initCStream(data->cstream, data->comp_level); if (ZSTD_isError(ret)) { pr_err("Failed to initialize compression stream: %s\n", ZSTD_getErrorName(ret)); return -1; } }
while (input.pos < input.size) { record = dst; /* process_header writes the event header into record */ if (dst_size < sizeof(struct perf_event_header)) goto reset; size = process_header(record, 0); /* Output buffer full — cannot fit even the record header */ if (size > dst_size) goto reset; compressed += size; dst += size; dst_size -= size; output = (ZSTD_outBuffer){ dst, (dst_size > max_record_size) ? max_record_size : dst_size, 0 }; ret = ZSTD_compressStream(data->cstream, &output, &input); ZSTD_flushStream(data->cstream, &output); if (ZSTD_isError(ret)) { pr_err("failed to compress %ld bytes: %s\n", (long)src_size, ZSTD_getErrorName(ret)); goto reset; } size = output.pos; /* * No progress: ZSTD couldn't emit any bytes into the * remaining output buffer. Calling process_header * with size=0 would re-trigger header initialization, * double-subtracting the header size from dst_size and * underflowing the unsigned counter. */ if (size == 0) goto reset; size = process_header(record, size); compressed += size; dst += size; dst_size -= size; }
return compressed;
reset: /* Reset so the context is usable if the caller retries */ ret = ZSTD_initCStream(data->cstream, data->comp_level); if (ZSTD_isError(ret)) pr_err("failed to reset compression context: %s\n", ZSTD_getErrorName(ret)); return -1;}
size_t zstd_decompress_stream(struct zstd_data *data, void *src, size_t src_size, void *dst, size_t dst_size){ size_t ret; ZSTD_inBuffer input = { src, src_size, 0 }; ZSTD_outBuffer output = { dst, dst_size, 0 };
if (!data->dstream) { data->dstream = ZSTD_createDStream(); if (data->dstream == NULL) { pr_err("Couldn't create decompression stream.\n"); return 0; }
ret = ZSTD_initDStream(data->dstream); if (ZSTD_isError(ret)) { pr_err("Failed to initialize decompression stream: %s\n", ZSTD_getErrorName(ret)); return 0; } } while (input.pos < input.size) { size_t prev_in = input.pos; size_t prev_out = output.pos;
ret = ZSTD_decompressStream(data->dstream, &output, &input); if (ZSTD_isError(ret)) { pr_err("failed to decompress (B): %zd -> %zd, dst_size %zd : %s\n", src_size, output.pos, dst_size, ZSTD_getErrorName(ret)); return 0; } /* * Neither stream advanced — decompression is stuck. * Return 0 (error) rather than partial output: perf * uses ZSTD_flushStream (not ZSTD_endStream), so the * stream is continuous across compressed events. * Discarding unconsumed input would desynchronize the * decompressor, causing the next call to produce * garbage that could be misinterpreted as valid events. */ if (input.pos == prev_in && output.pos == prev_out) return 0; }
return output.pos;}