doc/examples_old/xz_pipe_comp.c

   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 */
  47 int 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
 120 int main ()
 121 {
 122         int ret;
 123
 124         ret = xz_compress (stdin, stdout);
 125         return ret;
 126 }
 127