зеркало из https://github.com/mozilla/pjs.git
137 строки
3.7 KiB
C++
137 строки
3.7 KiB
C++
/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this file,
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* You can obtain one at http://mozilla.org/MPL/2.0/. */
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#include <algorithm>
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#include <sys/stat.h>
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#include <cstring>
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#include <zlib.h>
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#include <fcntl.h>
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#include <errno.h>
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#include "mozilla/Assertions.h"
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#include "SeekableZStream.h"
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#include "Utils.h"
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#include "Logging.h"
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static const size_t CHUNK = 16384;
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/* Generate a seekable compressed stream. */
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int main(int argc, char* argv[])
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{
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if (argc != 3 || !argv[1] || !argv[2] || (strcmp(argv[1], argv[2]) == 0)) {
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log("usage: %s file_to_compress out_file", argv[0]);
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return 1;
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}
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AutoCloseFD origFd = open(argv[1], O_RDONLY);
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if (origFd == -1) {
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log("Couldn't open %s: %s", argv[1], strerror(errno));
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return 1;
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}
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struct stat st;
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int ret = fstat(origFd, &st);
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if (ret == -1) {
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log("Couldn't seek %s: %s", argv[1], strerror(errno));
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return 1;
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}
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size_t origSize = st.st_size;
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log("Size = %lu", origSize);
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if (origSize == 0) {
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log("Won't compress %s: it's empty", argv[1]);
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return 1;
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}
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/* Mmap the original file */
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MappedPtr origBuf;
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origBuf.Assign(mmap(NULL, origSize, PROT_READ, MAP_PRIVATE, origFd, 0), origSize);
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if (origBuf == MAP_FAILED) {
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log("Couldn't mmap %s: %s", argv[1], strerror(errno));
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return 1;
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}
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/* Create the compressed file */
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AutoCloseFD outFd = open(argv[2], O_RDWR | O_CREAT | O_TRUNC, 0666);
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if (outFd == -1) {
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log("Couldn't open %s: %s", argv[2], strerror(errno));
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return 1;
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}
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/* Expected total number of chunks */
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size_t nChunks = ((origSize + CHUNK - 1) / CHUNK);
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/* The first chunk is going to be stored after the header and the offset
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* table */
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size_t offset = sizeof(SeekableZStreamHeader) + nChunks * sizeof(uint32_t);
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/* Give enough room for the header and the offset table, and map them */
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ret = ftruncate(outFd, offset);
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MOZ_ASSERT(ret == 0);
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MappedPtr headerMap;
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headerMap.Assign(mmap(NULL, offset, PROT_READ | PROT_WRITE, MAP_SHARED,
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outFd, 0), offset);
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if (headerMap == MAP_FAILED) {
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log("Couldn't mmap %s: %s", argv[1], strerror(errno));
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return 1;
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}
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SeekableZStreamHeader *header = new (headerMap) SeekableZStreamHeader;
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le_uint32 *entry = reinterpret_cast<le_uint32 *>(&header[1]);
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/* Initialize header */
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header->chunkSize = CHUNK;
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header->totalSize = offset;
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/* Seek at the end of the output file, where we're going to append
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* compressed streams */
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lseek(outFd, offset, SEEK_SET);
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/* Initialize zlib structure */
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z_stream zStream;
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memset(&zStream, 0, sizeof(zStream));
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/* Compression buffer */
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AutoDeleteArray<Bytef> outBuf = new Bytef[CHUNK * 2];
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Bytef *origData = static_cast<Bytef*>(origBuf);
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size_t avail = 0;
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while (origSize) {
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avail = std::min(origSize, CHUNK);
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/* Compress chunk */
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ret = deflateInit(&zStream, 9);
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MOZ_ASSERT(ret == Z_OK);
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zStream.avail_in = avail;
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zStream.next_in = origData;
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zStream.avail_out = CHUNK * 2;
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zStream.next_out = outBuf;
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ret = deflate(&zStream, Z_FINISH);
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MOZ_ASSERT(ret == Z_STREAM_END);
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ret = deflateEnd(&zStream);
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MOZ_ASSERT(ret == Z_OK);
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MOZ_ASSERT(zStream.avail_out > 0);
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/* Write chunk */
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size_t len = write(outFd, outBuf, 2 * CHUNK - zStream.avail_out);
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MOZ_ASSERT(len == 2 * CHUNK - zStream.avail_out);
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/* Adjust headers */
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header->totalSize += len;
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*entry++ = offset;
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header->nChunks++;
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/* Prepare for next iteration */
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origSize -= avail;
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origData += avail;
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offset += len;
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}
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header->lastChunkSize = avail;
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MOZ_ASSERT(header->nChunks == nChunks);
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log("Compressed size is %lu", offset);
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return 0;
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}
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