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/* * xz_pipe_comp.c * A simple example of pipe-only xz compressor implementation. * version: 2010-07-12 - by Daniel Mealha Cabrita * Not copyrighted -- provided to the public domain. * * Compiling: * Link with liblzma. GCC example: * $ gcc -llzma xz_pipe_comp.c -o xz_pipe_comp * * Usage example: * $ cat some_file \| ./xz_pipe_comp > some_file.xz / #include <stdio.h> #include <stdint.h> #include <inttypes.h> #include <stdbool.h> #include <lzma.h> / COMPRESSION SETTINGS / / analogous to xz CLI options: -0 to -9 / #define COMPRESSION_LEVEL 6 / boolean setting, analogous to xz CLI option: -e / #define COMPRESSION_EXTREME true / see: /usr/include/lzma/check.h LZMA_CHECK_* / #define INTEGRITY_CHECK LZMA_CHECK_CRC64 / read/write buffer sizes / #define IN_BUF_MAX 4096 #define OUT_BUF_MAX 4096 / error codes / #define RET_OK 0 #define RET_ERROR_INIT 1 #define RET_ERROR_INPUT 2 #define RET_ERROR_OUTPUT 3 #define RET_ERROR_COMPRESSION 4 / note: in_file and out_file must be open already / int xz_compress (FILE in_file, FILE out_file) { uint32_t preset = COMPRESSION_LEVEL \| (COMPRESSION_EXTREME ? LZMA_PRESET_EXTREME : 0); lzma_check check = INTEGRITY_CHECK; lzma_stream strm = LZMA_STREAM_INIT; / alloc and init lzma_stream struct / uint8_t in_buf [IN_BUF_MAX]; uint8_t out_buf [OUT_BUF_MAX]; size_t in_len; / length of useful data in in_buf / size_t out_len; / length of useful data in out_buf / bool in_finished = false; bool out_finished = false; lzma_action action; lzma_ret ret_xz; int ret; ret = RET_OK; / initialize xz encoder / ret_xz = lzma_easy_encoder (&strm, preset, check); if (ret_xz != LZMA_OK) { fprintf (stderr, "lzma_easy_encoder error: %d\n", (int) ret_xz); return RET_ERROR_INIT; } while ((! in_finished) && (! out_finished)) { / read incoming data / in_len = fread (in_buf, 1, IN_BUF_MAX, in_file); if (feof (in_file)) { in_finished = true; } if (ferror (in_file)) { in_finished = true; ret = RET_ERROR_INPUT; } strm.next_in = in_buf; strm.avail_in = in_len; / if no more data from in_buf, flushes the internal xz buffers and closes the xz data with LZMA_FINISH / action = in_finished ? LZMA_FINISH : LZMA_RUN; / loop until there's no pending compressed output / do { / out_buf is clean at this point / strm.next_out = out_buf; strm.avail_out = OUT_BUF_MAX; / compress data / ret_xz = lzma_code (&strm, action); if ((ret_xz != LZMA_OK) && (ret_xz != LZMA_STREAM_END)) { fprintf (stderr, "lzma_code error: %d\n", (int) ret_xz); out_finished = true; ret = RET_ERROR_COMPRESSION; } else { / write compressed data */ out_len = OUT_BUF_MAX - strm.avail_out; fwrite (out_buf, 1, out_len, out_file); if (ferror (out_file)) { out_finished = true; ret = RET_ERROR_OUTPUT; } } } while (strm.avail_out == 0); } lzma_end (&strm); return ret; } int main () { int ret; ret = xz_compress (stdin, stdout); return ret; }

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