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b28a10ae AS |
1 | // SPDX-License-Identifier: GPL-2.0-or-later |
2 | /* | |
3 | * Author: Aleksa Sarai <cyphar@cyphar.com> | |
4 | * Copyright (C) 2018-2019 SUSE LLC. | |
5 | */ | |
6 | ||
7 | #define _GNU_SOURCE | |
8 | #include <errno.h> | |
9 | #include <fcntl.h> | |
10 | #include <stdbool.h> | |
11 | #include <string.h> | |
12 | #include <syscall.h> | |
13 | #include <limits.h> | |
14 | ||
15 | #include "helpers.h" | |
16 | ||
17 | bool needs_openat2(const struct open_how *how) | |
18 | { | |
19 | return how->resolve != 0; | |
20 | } | |
21 | ||
22 | int raw_openat2(int dfd, const char *path, void *how, size_t size) | |
23 | { | |
24 | int ret = syscall(__NR_openat2, dfd, path, how, size); | |
25 | return ret >= 0 ? ret : -errno; | |
26 | } | |
27 | ||
28 | int sys_openat2(int dfd, const char *path, struct open_how *how) | |
29 | { | |
30 | return raw_openat2(dfd, path, how, sizeof(*how)); | |
31 | } | |
32 | ||
33 | int sys_openat(int dfd, const char *path, struct open_how *how) | |
34 | { | |
35 | int ret = openat(dfd, path, how->flags, how->mode); | |
36 | return ret >= 0 ? ret : -errno; | |
37 | } | |
38 | ||
39 | int sys_renameat2(int olddirfd, const char *oldpath, | |
40 | int newdirfd, const char *newpath, unsigned int flags) | |
41 | { | |
42 | int ret = syscall(__NR_renameat2, olddirfd, oldpath, | |
43 | newdirfd, newpath, flags); | |
44 | return ret >= 0 ? ret : -errno; | |
45 | } | |
46 | ||
47 | int touchat(int dfd, const char *path) | |
48 | { | |
9a0584f0 | 49 | int fd = openat(dfd, path, O_CREAT, 0700); |
b28a10ae AS |
50 | if (fd >= 0) |
51 | close(fd); | |
52 | return fd; | |
53 | } | |
54 | ||
55 | char *fdreadlink(int fd) | |
56 | { | |
57 | char *target, *tmp; | |
58 | ||
59 | E_asprintf(&tmp, "/proc/self/fd/%d", fd); | |
60 | ||
61 | target = malloc(PATH_MAX); | |
62 | if (!target) | |
63 | ksft_exit_fail_msg("fdreadlink: malloc failed\n"); | |
64 | memset(target, 0, PATH_MAX); | |
65 | ||
66 | E_readlink(tmp, target, PATH_MAX); | |
67 | free(tmp); | |
68 | return target; | |
69 | } | |
70 | ||
71 | bool fdequal(int fd, int dfd, const char *path) | |
72 | { | |
73 | char *fdpath, *dfdpath, *other; | |
74 | bool cmp; | |
75 | ||
76 | fdpath = fdreadlink(fd); | |
77 | dfdpath = fdreadlink(dfd); | |
78 | ||
79 | if (!path) | |
80 | E_asprintf(&other, "%s", dfdpath); | |
81 | else if (*path == '/') | |
82 | E_asprintf(&other, "%s", path); | |
83 | else | |
84 | E_asprintf(&other, "%s/%s", dfdpath, path); | |
85 | ||
86 | cmp = !strcmp(fdpath, other); | |
87 | ||
88 | free(fdpath); | |
89 | free(dfdpath); | |
90 | free(other); | |
91 | return cmp; | |
92 | } | |
93 | ||
94 | bool openat2_supported = false; | |
95 | ||
96 | void __attribute__((constructor)) init(void) | |
97 | { | |
98 | struct open_how how = {}; | |
99 | int fd; | |
100 | ||
101 | BUILD_BUG_ON(sizeof(struct open_how) != OPEN_HOW_SIZE_VER0); | |
102 | ||
103 | /* Check openat2(2) support. */ | |
104 | fd = sys_openat2(AT_FDCWD, ".", &how); | |
105 | openat2_supported = (fd >= 0); | |
106 | ||
107 | if (fd >= 0) | |
108 | close(fd); | |
109 | } |