1/*
2 * xz_pipe_decomp.c
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.
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 */
35int 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	lzma_end (&strm);
105	return ret;
106}
107
108int main ()
109{
110	int ret;
111
112	ret = xz_decompress (stdin, stdout);
113	return ret;
114}
115
116