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
16 int 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
73 out:
74 inflateEnd(&zs);
75 out_unmap:
76 munmap(ptr, stbuf.st_size);
77 out_close:
78 close(input_fd);
79
80 return ret == Z_STREAM_END ? 0 : -1;
81 }
82
83 bool 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
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