3 * A simple example of pipe-only xz decompressor implementation.
4 * version: 2010-07-12 - by Daniel Mealha Cabrita
5 * Not copyrighted -- provided to the public domain.
8 * Link with liblzma. GCC example:
9 * $ gcc -llzma xz_pipe_decomp.c -o xz_pipe_decomp
12 * $ cat some_file.xz | ./xz_pipe_decomp > some_file
22 /* read/write buffer sizes */
23 #define IN_BUF_MAX 4096
24 #define OUT_BUF_MAX 4096
28 #define RET_ERROR_INIT 1
29 #define RET_ERROR_INPUT 2
30 #define RET_ERROR_OUTPUT 3
31 #define RET_ERROR_DECOMPRESSION 4
34 /* note: in_file and out_file must be open already */
35 int xz_decompress (FILE *in_file, FILE *out_file)
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;
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;
59 while ((! in_finished) && (! out_finished)) {
60 /* read incoming data */
61 in_len = fread (in_buf, 1, IN_BUF_MAX, in_file);
66 if (ferror (in_file)) {
68 ret = RET_ERROR_INPUT;
71 strm.next_in = in_buf;
72 strm.avail_in = in_len;
74 /* if no more data from in_buf, flushes the
75 internal xz buffers and closes the decompressed data
77 action = in_finished ? LZMA_FINISH : LZMA_RUN;
79 /* loop until there's no pending decompressed output */
81 /* out_buf is clean at this point */
82 strm.next_out = out_buf;
83 strm.avail_out = OUT_BUF_MAX;
86 ret_xz = lzma_code (&strm, action);
88 if ((ret_xz != LZMA_OK) && (ret_xz != LZMA_STREAM_END)) {
89 fprintf (stderr, "lzma_code error: %d\n", (int) ret_xz);
91 ret = RET_ERROR_DECOMPRESSION;
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)) {
98 ret = RET_ERROR_OUTPUT;
101 } while (strm.avail_out == 0);
112 ret = xz_decompress (stdin, stdout);