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