1#include <stdio.h>
 2#include <unistd.h>
 3#include <sys/stat.h>
 4#include <sys/mman.h>
 5#include <zlib.h>
 6
 7#include "util/util.h"
 8#include "util/debug.h"
 9
10
11#define CHUNK_SIZE  16384
12
13int gzip_decompress_to_file(const char *input, int output_fd)
14{
15	int ret = Z_STREAM_ERROR;
16	int input_fd;
17	void *ptr;
18	int len;
19	struct stat stbuf;
20	unsigned char buf[CHUNK_SIZE];
21	z_stream zs = {
22		.zalloc		= Z_NULL,
23		.zfree		= Z_NULL,
24		.opaque		= Z_NULL,
25		.avail_in	= 0,
26		.next_in	= Z_NULL,
27	};
28
29	input_fd = open(input, O_RDONLY);
30	if (input_fd < 0)
31		return -1;
32
33	if (fstat(input_fd, &stbuf) < 0)
34		goto out_close;
35
36	ptr = mmap(NULL, stbuf.st_size, PROT_READ, MAP_PRIVATE, input_fd, 0);
37	if (ptr == MAP_FAILED)
38		goto out_close;
39
40	if (inflateInit2(&zs, 16 + MAX_WBITS) != Z_OK)
41		goto out_unmap;
42
43	zs.next_in = ptr;
44	zs.avail_in = stbuf.st_size;
45
46	do {
47		zs.next_out = buf;
48		zs.avail_out = CHUNK_SIZE;
49
50		ret = inflate(&zs, Z_NO_FLUSH);
51		switch (ret) {
52		case Z_NEED_DICT:
53			ret = Z_DATA_ERROR;
54			/* fall through */
55		case Z_DATA_ERROR:
56		case Z_MEM_ERROR:
57			goto out;
58		default:
59			break;
60		}
61
62		len = CHUNK_SIZE - zs.avail_out;
63		if (writen(output_fd, buf, len) != len) {
64			ret = Z_DATA_ERROR;
65			goto out;
66		}
67
68	} while (ret != Z_STREAM_END);
69
70out:
71	inflateEnd(&zs);
72out_unmap:
73	munmap(ptr, stbuf.st_size);
74out_close:
75	close(input_fd);
76
77	return ret == Z_STREAM_END ? 0 : -1;
78}