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/////////////////////////////////////////////////////////////////////////////// // /// \file 03_compress_custom.c /// \brief Compress in multi-call mode using x86 BCJ and LZMA2 /// /// Usage: ./03_compress_custom < INFILE > OUTFILE /// /// Example: ./03_compress_custom < foo > foo.xz // // Author: Lasse Collin // // This file has been put into the public domain. // You can do whatever you want with this file. // /////////////////////////////////////////////////////////////////////////////// #include <stdbool.h> #include <stdlib.h> #include <stdio.h> #include <string.h> #include <errno.h> #include <lzma.h> static bool init_encoder(lzma_stream *strm) { // Use the default preset (6) for LZMA2. // // The lzma_options_lzma structure and the lzma_lzma_preset() function // are declared in lzma/lzma12.h (src/liblzma/api/lzma/lzma12.h in the // source package or e.g. /usr/include/lzma/lzma12.h depending on // the install prefix). lzma_options_lzma opt_lzma2; if (lzma_lzma_preset(&opt_lzma2, LZMA_PRESET_DEFAULT)) { // It should never fail because the default preset // (and presets 0-9 optionally with LZMA_PRESET_EXTREME) // are supported by all stable liblzma versions. // // (The encoder initialization later in this function may // still fail due to unsupported preset *if* the features // required by the preset have been disabled at build time, // but no-one does such things except on embedded systems.) fprintf(stderr, "Unsupported preset, possibly a bug\n"); return false; } // Now we could customize the LZMA2 options if we wanted. For example, // we could set the the dictionary size (opt_lzma2.dict_size) to // something else than the default (8 MiB) of the default preset. // See lzma/lzma12.h for details of all LZMA2 options. // // The x86 BCJ filter will try to modify the x86 instruction stream so // that LZMA2 can compress it better. The x86 BCJ filter doesn't need // any options so it will be set to NULL below. // // Construct the filter chain. The uncompressed data goes first to // the first filter in the array, in this case the x86 BCJ filter. // The array is always terminated by setting .id = LZMA_VLI_UNKNOWN. // // See lzma/filter.h for more information about the lzma_filter // structure. lzma_filter filters[] = { { .id = LZMA_FILTER_X86, .options = NULL }, { .id = LZMA_FILTER_LZMA2, .options = &opt_lzma2 }, { .id = LZMA_VLI_UNKNOWN, .options = NULL }, }; // Initialize the encoder using the custom filter chain. lzma_ret ret = lzma_stream_encoder(strm, filters, LZMA_CHECK_CRC64); if (ret == LZMA_OK) return true; const char *msg; switch (ret) { case LZMA_MEM_ERROR: msg = "Memory allocation failed"; break; case LZMA_OPTIONS_ERROR: // We are no longer using a plain preset so this error // message has been edited accordingly compared to // 01_compress_easy.c. msg = "Specified filter chain is not supported"; break; case LZMA_UNSUPPORTED_CHECK: msg = "Specified integrity check is not supported"; break; default: msg = "Unknown error, possibly a bug"; break; } fprintf(stderr, "Error initializing the encoder: %s (error code %u)\n", msg, ret); return false; } // This function is identical to the one in 01_compress_easy.c. static bool compress(lzma_stream *strm, FILE *infile, FILE *outfile) { lzma_action action = LZMA_RUN; uint8_t inbuf[BUFSIZ]; uint8_t outbuf[BUFSIZ]; strm->next_in = NULL; strm->avail_in = 0; strm->next_out = outbuf; strm->avail_out = sizeof(outbuf); while (true) { if (strm->avail_in == 0 && !feof(infile)) { strm->next_in = inbuf; strm->avail_in = fread(inbuf, 1, sizeof(inbuf), infile); if (ferror(infile)) { fprintf(stderr, "Read error: %s\n", strerror(errno)); return false; } if (feof(infile)) action = LZMA_FINISH; } lzma_ret ret = lzma_code(strm, action); if (strm->avail_out == 0 || ret == LZMA_STREAM_END) { size_t write_size = sizeof(outbuf) - strm->avail_out; if (fwrite(outbuf, 1, write_size, outfile) != write_size) { fprintf(stderr, "Write error: %s\n", strerror(errno)); return false; } strm->next_out = outbuf; strm->avail_out = sizeof(outbuf); } if (ret != LZMA_OK) { if (ret == LZMA_STREAM_END) return true; const char *msg; switch (ret) { case LZMA_MEM_ERROR: msg = "Memory allocation failed"; break; case LZMA_DATA_ERROR: msg = "File size limits exceeded"; break; default: msg = "Unknown error, possibly a bug"; break; } fprintf(stderr, "Encoder error: %s (error code %u)\n", msg, ret); return false; } } } extern int main(void) { lzma_stream strm = LZMA_STREAM_INIT; bool success = init_encoder(&strm); if (success) success = compress(&strm, stdin, stdout); lzma_end(&strm); if (fclose(stdout)) { fprintf(stderr, "Write error: %s\n", strerror(errno)); success = false; } return success ? EXIT_SUCCESS : EXIT_FAILURE; }
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