1// SPDX-License-Identifier: GPL-2.0
2#include <fcntl.h>
3#include <stdio.h>
4#include <string.h>
5#include <unistd.h>
6#include <sys/stat.h>
7#include <sys/mman.h>
8#include <zlib.h>
9#include <linux/compiler.h>
10#include <internal/lib.h>
11
12#include "util/compress.h"
13
14#define CHUNK_SIZE  16384
15
16int gzip_decompress_to_file(const char *input, int output_fd)
17{
18	int ret = Z_STREAM_ERROR;
19	int input_fd;
20	void *ptr;
21	int len;
22	struct stat stbuf;
23	unsigned char buf[CHUNK_SIZE];
24	z_stream zs = {
25		.zalloc		= Z_NULL,
26		.zfree		= Z_NULL,
27		.opaque		= Z_NULL,
28		.avail_in	= 0,
29		.next_in	= Z_NULL,
30	};
31
32	input_fd = open(input, O_RDONLY);
33	if (input_fd < 0)
34		return -1;
35
36	if (fstat(input_fd, &stbuf) < 0)
37		goto out_close;
38
39	ptr = mmap(NULL, stbuf.st_size, PROT_READ, MAP_PRIVATE, input_fd, 0);
40	if (ptr == MAP_FAILED)
41		goto out_close;
42
43	if (inflateInit2(&zs, 16 + MAX_WBITS) != Z_OK)
44		goto out_unmap;
45
46	zs.next_in = ptr;
47	zs.avail_in = stbuf.st_size;
48
49	do {
50		zs.next_out = buf;
51		zs.avail_out = CHUNK_SIZE;
52
53		ret = inflate(&zs, Z_NO_FLUSH);
54		switch (ret) {
55		case Z_NEED_DICT:
56			ret = Z_DATA_ERROR;
57			/* fall through */
58		case Z_DATA_ERROR:
59		case Z_MEM_ERROR:
60			goto out;
61		default:
62			break;
63		}
64
65		len = CHUNK_SIZE - zs.avail_out;
66		if (writen(output_fd, buf, len) != len) {
67			ret = Z_DATA_ERROR;
68			goto out;
69		}
70
71	} while (ret != Z_STREAM_END);
72
73out:
74	inflateEnd(&zs);
75out_unmap:
76	munmap(ptr, stbuf.st_size);
77out_close:
78	close(input_fd);
79
80	return ret == Z_STREAM_END ? 0 : -1;
81}
82
83bool gzip_is_compressed(const char *input)
84{
85	int fd = open(input, O_RDONLY);
86	const uint8_t magic[2] = { 0x1f, 0x8b };
87	char buf[2] = { 0 };
88	ssize_t rc;
89
90	if (fd < 0)
91		return -1;
92
93	rc = read(fd, buf, sizeof(buf));
94	close(fd);
95	return rc == sizeof(buf) ?
96	       memcmp(buf, magic, sizeof(buf)) == 0 : false;
97}
98