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b4d0d230 | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
f1b5618e DH |
2 | /* fd-based mount test. |
3 | * | |
4 | * Copyright (C) 2017 Red Hat, Inc. All Rights Reserved. | |
5 | * Written by David Howells (dhowells@redhat.com) | |
f1b5618e DH |
6 | */ |
7 | ||
8 | #include <stdio.h> | |
9 | #include <stdlib.h> | |
10 | #include <unistd.h> | |
11 | #include <errno.h> | |
12 | #include <fcntl.h> | |
13 | #include <sys/prctl.h> | |
14 | #include <sys/wait.h> | |
15 | #include <linux/mount.h> | |
16 | #include <linux/unistd.h> | |
17 | ||
18 | #define E(x) do { if ((x) == -1) { perror(#x); exit(1); } } while(0) | |
19 | ||
20 | static void check_messages(int fd) | |
21 | { | |
22 | char buf[4096]; | |
23 | int err, n; | |
24 | ||
25 | err = errno; | |
26 | ||
27 | for (;;) { | |
28 | n = read(fd, buf, sizeof(buf)); | |
29 | if (n < 0) | |
30 | break; | |
31 | n -= 2; | |
32 | ||
33 | switch (buf[0]) { | |
34 | case 'e': | |
35 | fprintf(stderr, "Error: %*.*s\n", n, n, buf + 2); | |
36 | break; | |
37 | case 'w': | |
38 | fprintf(stderr, "Warning: %*.*s\n", n, n, buf + 2); | |
39 | break; | |
40 | case 'i': | |
41 | fprintf(stderr, "Info: %*.*s\n", n, n, buf + 2); | |
42 | break; | |
43 | } | |
44 | } | |
45 | ||
46 | errno = err; | |
47 | } | |
48 | ||
49 | static __attribute__((noreturn)) | |
50 | void mount_error(int fd, const char *s) | |
51 | { | |
52 | check_messages(fd); | |
53 | fprintf(stderr, "%s: %m\n", s); | |
54 | exit(1); | |
55 | } | |
56 | ||
57 | /* Hope -1 isn't a syscall */ | |
58 | #ifndef __NR_fsopen | |
59 | #define __NR_fsopen -1 | |
60 | #endif | |
61 | #ifndef __NR_fsmount | |
62 | #define __NR_fsmount -1 | |
63 | #endif | |
64 | #ifndef __NR_fsconfig | |
65 | #define __NR_fsconfig -1 | |
66 | #endif | |
67 | #ifndef __NR_move_mount | |
68 | #define __NR_move_mount -1 | |
69 | #endif | |
70 | ||
71 | ||
72 | static inline int fsopen(const char *fs_name, unsigned int flags) | |
73 | { | |
74 | return syscall(__NR_fsopen, fs_name, flags); | |
75 | } | |
76 | ||
77 | static inline int fsmount(int fsfd, unsigned int flags, unsigned int ms_flags) | |
78 | { | |
79 | return syscall(__NR_fsmount, fsfd, flags, ms_flags); | |
80 | } | |
81 | ||
82 | static inline int fsconfig(int fsfd, unsigned int cmd, | |
83 | const char *key, const void *val, int aux) | |
84 | { | |
85 | return syscall(__NR_fsconfig, fsfd, cmd, key, val, aux); | |
86 | } | |
87 | ||
88 | static inline int move_mount(int from_dfd, const char *from_pathname, | |
89 | int to_dfd, const char *to_pathname, | |
90 | unsigned int flags) | |
91 | { | |
92 | return syscall(__NR_move_mount, | |
93 | from_dfd, from_pathname, | |
94 | to_dfd, to_pathname, flags); | |
95 | } | |
96 | ||
97 | #define E_fsconfig(fd, cmd, key, val, aux) \ | |
98 | do { \ | |
99 | if (fsconfig(fd, cmd, key, val, aux) == -1) \ | |
100 | mount_error(fd, key ?: "create"); \ | |
101 | } while (0) | |
102 | ||
103 | int main(int argc, char *argv[]) | |
104 | { | |
105 | int fsfd, mfd; | |
106 | ||
107 | /* Mount a publically available AFS filesystem */ | |
108 | fsfd = fsopen("afs", 0); | |
109 | if (fsfd == -1) { | |
110 | perror("fsopen"); | |
111 | exit(1); | |
112 | } | |
113 | ||
114 | E_fsconfig(fsfd, FSCONFIG_SET_STRING, "source", "#grand.central.org:root.cell.", 0); | |
115 | E_fsconfig(fsfd, FSCONFIG_CMD_CREATE, NULL, NULL, 0); | |
116 | ||
117 | mfd = fsmount(fsfd, 0, MOUNT_ATTR_RDONLY); | |
118 | if (mfd < 0) | |
119 | mount_error(fsfd, "fsmount"); | |
120 | E(close(fsfd)); | |
121 | ||
122 | if (move_mount(mfd, "", AT_FDCWD, "/mnt", MOVE_MOUNT_F_EMPTY_PATH) < 0) { | |
123 | perror("move_mount"); | |
124 | exit(1); | |
125 | } | |
126 | ||
127 | E(close(mfd)); | |
128 | exit(0); | |
129 | } |