Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
1// SPDX-License-Identifier: GPL-2.0
2#include <fcntl.h>
3#include <stdio.h>
4#include <unistd.h>
5#include <sys/stat.h>
6#include <sys/mman.h>
7#include <zlib.h>
8#include <linux/compiler.h>
9#include <unistd.h>
10
11#include "util/compress.h"
12#include "util/util.h"
13#include "util/debug.h"
14
15
16#define CHUNK_SIZE 16384
17
18int gzip_decompress_to_file(const char *input, int output_fd)
19{
20 int ret = Z_STREAM_ERROR;
21 int input_fd;
22 void *ptr;
23 int len;
24 struct stat stbuf;
25 unsigned char buf[CHUNK_SIZE];
26 z_stream zs = {
27 .zalloc = Z_NULL,
28 .zfree = Z_NULL,
29 .opaque = Z_NULL,
30 .avail_in = 0,
31 .next_in = Z_NULL,
32 };
33
34 input_fd = open(input, O_RDONLY);
35 if (input_fd < 0)
36 return -1;
37
38 if (fstat(input_fd, &stbuf) < 0)
39 goto out_close;
40
41 ptr = mmap(NULL, stbuf.st_size, PROT_READ, MAP_PRIVATE, input_fd, 0);
42 if (ptr == MAP_FAILED)
43 goto out_close;
44
45 if (inflateInit2(&zs, 16 + MAX_WBITS) != Z_OK)
46 goto out_unmap;
47
48 zs.next_in = ptr;
49 zs.avail_in = stbuf.st_size;
50
51 do {
52 zs.next_out = buf;
53 zs.avail_out = CHUNK_SIZE;
54
55 ret = inflate(&zs, Z_NO_FLUSH);
56 switch (ret) {
57 case Z_NEED_DICT:
58 ret = Z_DATA_ERROR;
59 /* fall through */
60 case Z_DATA_ERROR:
61 case Z_MEM_ERROR:
62 goto out;
63 default:
64 break;
65 }
66
67 len = CHUNK_SIZE - zs.avail_out;
68 if (writen(output_fd, buf, len) != len) {
69 ret = Z_DATA_ERROR;
70 goto out;
71 }
72
73 } while (ret != Z_STREAM_END);
74
75out:
76 inflateEnd(&zs);
77out_unmap:
78 munmap(ptr, stbuf.st_size);
79out_close:
80 close(input_fd);
81
82 return ret == Z_STREAM_END ? 0 : -1;
83}
84
85bool gzip_is_compressed(const char *input)
86{
87 int fd = open(input, O_RDONLY);
88 const uint8_t magic[2] = { 0x1f, 0x8b };
89 char buf[2] = { 0 };
90 ssize_t rc;
91
92 if (fd < 0)
93 return -1;
94
95 rc = read(fd, buf, sizeof(buf));
96 close(fd);
97 return rc == sizeof(buf) ?
98 memcmp(buf, magic, sizeof(buf)) == 0 : false;
99}