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 */
xz_decompress(FILE * in_file,FILE * out_file)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
main()116 int main ()
117 {
118 int ret;
119
120 ret = xz_decompress (stdin, stdout);
121 return ret;
122 }
123
124