1/* 2 * xz_pipe_comp.c 3 * A simple example of pipe-only xz compressor implementation. 4 * version: 2010-07-12 - by Daniel Mealha Cabrita 5 * Not copyrighted -- provided to the public domain. 6 * 7 * Compiling: 8 * Link with liblzma. GCC example: 9 * $ gcc -llzma xz_pipe_comp.c -o xz_pipe_comp 10 * 11 * Usage example: 12 * $ cat some_file | ./xz_pipe_comp > some_file.xz 13 */ 14 15#include <stdio.h> 16#include <stdint.h> 17#include <inttypes.h> 18#include <stdbool.h> 19#include <lzma.h> 20 21 22/* COMPRESSION SETTINGS */ 23 24/* analogous to xz CLI options: -0 to -9 */ 25#define COMPRESSION_LEVEL 6 26 27/* boolean setting, analogous to xz CLI option: -e */ 28#define COMPRESSION_EXTREME true 29 30/* see: /usr/include/lzma/check.h LZMA_CHECK_* */ 31#define INTEGRITY_CHECK LZMA_CHECK_CRC64 32 33 34/* read/write buffer sizes */ 35#define IN_BUF_MAX 4096 36#define OUT_BUF_MAX 4096 37 38/* error codes */ 39#define RET_OK 0 40#define RET_ERROR_INIT 1 41#define RET_ERROR_INPUT 2 42#define RET_ERROR_OUTPUT 3 43#define RET_ERROR_COMPRESSION 4 44 45 46/* note: in_file and out_file must be open already */ 47int xz_compress (FILE *in_file, FILE *out_file) 48{ 49 uint32_t preset = COMPRESSION_LEVEL | (COMPRESSION_EXTREME ? LZMA_PRESET_EXTREME : 0); 50 lzma_check check = INTEGRITY_CHECK; 51 lzma_stream strm = LZMA_STREAM_INIT; /* alloc and init lzma_stream struct */ 52 uint8_t in_buf [IN_BUF_MAX]; 53 uint8_t out_buf [OUT_BUF_MAX]; 54 size_t in_len; /* length of useful data in in_buf */ 55 size_t out_len; /* length of useful data in out_buf */ 56 bool in_finished = false; 57 bool out_finished = false; 58 lzma_action action; 59 lzma_ret ret_xz; 60 int ret; 61 62 ret = RET_OK; 63 64 /* initialize xz encoder */ 65 ret_xz = lzma_easy_encoder (&strm, preset, check); 66 if (ret_xz != LZMA_OK) { 67 fprintf (stderr, "lzma_easy_encoder error: %d\n", (int) ret_xz); 68 return RET_ERROR_INIT; 69 } 70 71 while ((! in_finished) && (! out_finished)) { 72 /* read incoming data */ 73 in_len = fread (in_buf, 1, IN_BUF_MAX, in_file); 74 75 if (feof (in_file)) { 76 in_finished = true; 77 } 78 if (ferror (in_file)) { 79 in_finished = true; 80 ret = RET_ERROR_INPUT; 81 } 82 83 strm.next_in = in_buf; 84 strm.avail_in = in_len; 85 86 /* if no more data from in_buf, flushes the 87 internal xz buffers and closes the xz data 88 with LZMA_FINISH */ 89 action = in_finished ? LZMA_FINISH : LZMA_RUN; 90 91 /* loop until there's no pending compressed output */ 92 do { 93 /* out_buf is clean at this point */ 94 strm.next_out = out_buf; 95 strm.avail_out = OUT_BUF_MAX; 96 97 /* compress data */ 98 ret_xz = lzma_code (&strm, action); 99 100 if ((ret_xz != LZMA_OK) && (ret_xz != LZMA_STREAM_END)) { 101 fprintf (stderr, "lzma_code error: %d\n", (int) ret_xz); 102 out_finished = true; 103 ret = RET_ERROR_COMPRESSION; 104 } else { 105 /* write compressed data */ 106 out_len = OUT_BUF_MAX - strm.avail_out; 107 fwrite (out_buf, 1, out_len, out_file); 108 if (ferror (out_file)) { 109 out_finished = true; 110 ret = RET_ERROR_OUTPUT; 111 } 112 } 113 } while (strm.avail_out == 0); 114 } 115 116 lzma_end (&strm); 117 return ret; 118} 119 120int main () 121{ 122 int ret; 123 124 ret = xz_compress (stdin, stdout); 125 return ret; 126} 127 128