doc/examples_old/xz_pipe_decomp.c

   1 /*
   2  * xz_pipe_decomp.c
   3  * A simple example of pipe-only xz decompressor implementation.
   4  * version: 2012-06-14 - 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_decomp.c -o xz_pipe_decomp
  10  *
  11  * Usage example:
  12  * $ cat some_file.xz | ./xz_pipe_decomp > some_file
  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 /* read/write buffer sizes */
  23 #define IN_BUF_MAX      4096
  24 #define OUT_BUF_MAX     4096
  25
  26 /* error codes */
  27 #define RET_OK                  0
  28 #define RET_ERROR_INIT          1
  29 #define RET_ERROR_INPUT         2
  30 #define RET_ERROR_OUTPUT        3
  31 #define RET_ERROR_DECOMPRESSION 4
  32
  33
  34 /* note: in_file and out_file must be open already */
  35 int xz_decompress (FILE *in_file, FILE *out_file)
  36 {
  37         lzma_stream strm = LZMA_STREAM_INIT; /* alloc and init lzma_stream struct */
  38         const uint32_t flags = LZMA_TELL_UNSUPPORTED_CHECK | LZMA_CONCATENATED;
  39         const uint64_t memory_limit = UINT64_MAX; /* no memory limit */
  40         uint8_t in_buf [IN_BUF_MAX];
  41         uint8_t out_buf [OUT_BUF_MAX];
  42         size_t in_len;  /* length of useful data in in_buf */
  43         size_t out_len; /* length of useful data in out_buf */
  44         bool in_finished = false;
  45         bool out_finished = false;
  46         lzma_action action;
  47         lzma_ret ret_xz;
  48         int ret;
  49
  50         ret = RET_OK;
  51
  52         /* initialize xz decoder */
  53         ret_xz = lzma_stream_decoder (&strm, memory_limit, flags);
  54         if (ret_xz != LZMA_OK) {
  55                 fprintf (stderr, "lzma_stream_decoder error: %d\n", (int) ret_xz);
  56                 return RET_ERROR_INIT;
  57         }
  58
  59         while ((! in_finished) && (! out_finished)) {
  60                 /* read incoming data */
  61                 in_len = fread (in_buf, 1, IN_BUF_MAX, in_file);
  62
  63                 if (feof (in_file)) {
  64                         in_finished = true;
  65                 }
  66                 if (ferror (in_file)) {
  67                         in_finished = true;
  68                         ret = RET_ERROR_INPUT;
  69                 }
  70
  71                 strm.next_in = in_buf;
  72                 strm.avail_in = in_len;
  73
  74                 /* if no more data from in_buf, flushes the
  75                    internal xz buffers and closes the decompressed data
  76                    with LZMA_FINISH */
  77                 action = in_finished ? LZMA_FINISH : LZMA_RUN;
  78
  79                 /* loop until there's no pending decompressed output */
  80                 do {
  81                         /* out_buf is clean at this point */
  82                         strm.next_out = out_buf;
  83                         strm.avail_out = OUT_BUF_MAX;
  84
  85                         /* decompress data */
  86                         ret_xz = lzma_code (&strm, action);
  87
  88                         if ((ret_xz != LZMA_OK) && (ret_xz != LZMA_STREAM_END)) {
  89                                 fprintf (stderr, "lzma_code error: %d\n", (int) ret_xz);
  90                                 out_finished = true;
  91                                 ret = RET_ERROR_DECOMPRESSION;
  92                         } else {
  93                                 /* write decompressed data */
  94                                 out_len = OUT_BUF_MAX - strm.avail_out;
  95                                 fwrite (out_buf, 1, out_len, out_file);
  96                                 if (ferror (out_file)) {
  97                                         out_finished = true;
  98                                         ret = RET_ERROR_OUTPUT;
  99                                 }
 100                         }
 101                 } while (strm.avail_out == 0);
 102         }
 103
 104         /* Bug fix (2012-06-14): If no errors were detected, check
 105            that the last lzma_code() call returned LZMA_STREAM_END.
 106            If not, the file is probably truncated. */
 107         if ((ret == RET_OK) && (ret_xz != LZMA_STREAM_END)) {
 108                 fprintf (stderr, "Input truncated or corrupt\n");
 109                 ret = RET_ERROR_DECOMPRESSION;
 110         }
 111
 112         lzma_end (&strm);
 113         return ret;
 114 }
 115
 116 int main ()
 117 {
 118         int ret;
 119
 120         ret = xz_decompress (stdin, stdout);
 121         return ret;
 122 }
 123