1 | // SPDX-License-Identifier: GPL-2.0-or-later |
2 | /* fd-based mount test. |
3 | * |
4 | * Copyright (C) 2017 Red Hat, Inc. All Rights Reserved. |
5 | * Written by David Howells (dhowells@redhat.com) |
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: fd, buf: buf, nbytes: sizeof(buf)); |
29 | if (n < 0) |
30 | break; |
31 | n -= 2; |
32 | |
33 | switch (buf[0]) { |
34 | case 'e': |
35 | fprintf(stderr, format: "Error: %*.*s\n" , n, n, buf + 2); |
36 | break; |
37 | case 'w': |
38 | fprintf(stderr, format: "Warning: %*.*s\n" , n, n, buf + 2); |
39 | break; |
40 | case 'i': |
41 | fprintf(stderr, format: "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, format: "%s: %m\n" , s); |
54 | exit(status: 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(fs_name: "afs" , flags: 0); |
109 | if (fsfd == -1) { |
110 | perror(s: "fsopen" ); |
111 | exit(status: 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, flags: 0, MOUNT_ATTR_RDONLY); |
118 | if (mfd < 0) |
119 | mount_error(fd: fsfd, s: "fsmount" ); |
120 | E(close(fsfd)); |
121 | |
122 | if (move_mount(from_dfd: mfd, from_pathname: "" , AT_FDCWD, to_pathname: "/mnt" , MOVE_MOUNT_F_EMPTY_PATH) < 0) { |
123 | perror(s: "move_mount" ); |
124 | exit(status: 1); |
125 | } |
126 | |
127 | E(close(mfd)); |
128 | exit(status: 0); |
129 | } |
130 | |