1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0-or-later
2*4882a593Smuzhiyun /* fd-based mount test.
3*4882a593Smuzhiyun *
4*4882a593Smuzhiyun * Copyright (C) 2017 Red Hat, Inc. All Rights Reserved.
5*4882a593Smuzhiyun * Written by David Howells (dhowells@redhat.com)
6*4882a593Smuzhiyun */
7*4882a593Smuzhiyun
8*4882a593Smuzhiyun #include <stdio.h>
9*4882a593Smuzhiyun #include <stdlib.h>
10*4882a593Smuzhiyun #include <unistd.h>
11*4882a593Smuzhiyun #include <errno.h>
12*4882a593Smuzhiyun #include <fcntl.h>
13*4882a593Smuzhiyun #include <sys/prctl.h>
14*4882a593Smuzhiyun #include <sys/wait.h>
15*4882a593Smuzhiyun #include <linux/mount.h>
16*4882a593Smuzhiyun #include <linux/unistd.h>
17*4882a593Smuzhiyun
18*4882a593Smuzhiyun #define E(x) do { if ((x) == -1) { perror(#x); exit(1); } } while(0)
19*4882a593Smuzhiyun
check_messages(int fd)20*4882a593Smuzhiyun static void check_messages(int fd)
21*4882a593Smuzhiyun {
22*4882a593Smuzhiyun char buf[4096];
23*4882a593Smuzhiyun int err, n;
24*4882a593Smuzhiyun
25*4882a593Smuzhiyun err = errno;
26*4882a593Smuzhiyun
27*4882a593Smuzhiyun for (;;) {
28*4882a593Smuzhiyun n = read(fd, buf, sizeof(buf));
29*4882a593Smuzhiyun if (n < 0)
30*4882a593Smuzhiyun break;
31*4882a593Smuzhiyun n -= 2;
32*4882a593Smuzhiyun
33*4882a593Smuzhiyun switch (buf[0]) {
34*4882a593Smuzhiyun case 'e':
35*4882a593Smuzhiyun fprintf(stderr, "Error: %*.*s\n", n, n, buf + 2);
36*4882a593Smuzhiyun break;
37*4882a593Smuzhiyun case 'w':
38*4882a593Smuzhiyun fprintf(stderr, "Warning: %*.*s\n", n, n, buf + 2);
39*4882a593Smuzhiyun break;
40*4882a593Smuzhiyun case 'i':
41*4882a593Smuzhiyun fprintf(stderr, "Info: %*.*s\n", n, n, buf + 2);
42*4882a593Smuzhiyun break;
43*4882a593Smuzhiyun }
44*4882a593Smuzhiyun }
45*4882a593Smuzhiyun
46*4882a593Smuzhiyun errno = err;
47*4882a593Smuzhiyun }
48*4882a593Smuzhiyun
49*4882a593Smuzhiyun static __attribute__((noreturn))
mount_error(int fd,const char * s)50*4882a593Smuzhiyun void mount_error(int fd, const char *s)
51*4882a593Smuzhiyun {
52*4882a593Smuzhiyun check_messages(fd);
53*4882a593Smuzhiyun fprintf(stderr, "%s: %m\n", s);
54*4882a593Smuzhiyun exit(1);
55*4882a593Smuzhiyun }
56*4882a593Smuzhiyun
57*4882a593Smuzhiyun /* Hope -1 isn't a syscall */
58*4882a593Smuzhiyun #ifndef __NR_fsopen
59*4882a593Smuzhiyun #define __NR_fsopen -1
60*4882a593Smuzhiyun #endif
61*4882a593Smuzhiyun #ifndef __NR_fsmount
62*4882a593Smuzhiyun #define __NR_fsmount -1
63*4882a593Smuzhiyun #endif
64*4882a593Smuzhiyun #ifndef __NR_fsconfig
65*4882a593Smuzhiyun #define __NR_fsconfig -1
66*4882a593Smuzhiyun #endif
67*4882a593Smuzhiyun #ifndef __NR_move_mount
68*4882a593Smuzhiyun #define __NR_move_mount -1
69*4882a593Smuzhiyun #endif
70*4882a593Smuzhiyun
71*4882a593Smuzhiyun
fsopen(const char * fs_name,unsigned int flags)72*4882a593Smuzhiyun static inline int fsopen(const char *fs_name, unsigned int flags)
73*4882a593Smuzhiyun {
74*4882a593Smuzhiyun return syscall(__NR_fsopen, fs_name, flags);
75*4882a593Smuzhiyun }
76*4882a593Smuzhiyun
fsmount(int fsfd,unsigned int flags,unsigned int ms_flags)77*4882a593Smuzhiyun static inline int fsmount(int fsfd, unsigned int flags, unsigned int ms_flags)
78*4882a593Smuzhiyun {
79*4882a593Smuzhiyun return syscall(__NR_fsmount, fsfd, flags, ms_flags);
80*4882a593Smuzhiyun }
81*4882a593Smuzhiyun
fsconfig(int fsfd,unsigned int cmd,const char * key,const void * val,int aux)82*4882a593Smuzhiyun static inline int fsconfig(int fsfd, unsigned int cmd,
83*4882a593Smuzhiyun const char *key, const void *val, int aux)
84*4882a593Smuzhiyun {
85*4882a593Smuzhiyun return syscall(__NR_fsconfig, fsfd, cmd, key, val, aux);
86*4882a593Smuzhiyun }
87*4882a593Smuzhiyun
move_mount(int from_dfd,const char * from_pathname,int to_dfd,const char * to_pathname,unsigned int flags)88*4882a593Smuzhiyun static inline int move_mount(int from_dfd, const char *from_pathname,
89*4882a593Smuzhiyun int to_dfd, const char *to_pathname,
90*4882a593Smuzhiyun unsigned int flags)
91*4882a593Smuzhiyun {
92*4882a593Smuzhiyun return syscall(__NR_move_mount,
93*4882a593Smuzhiyun from_dfd, from_pathname,
94*4882a593Smuzhiyun to_dfd, to_pathname, flags);
95*4882a593Smuzhiyun }
96*4882a593Smuzhiyun
97*4882a593Smuzhiyun #define E_fsconfig(fd, cmd, key, val, aux) \
98*4882a593Smuzhiyun do { \
99*4882a593Smuzhiyun if (fsconfig(fd, cmd, key, val, aux) == -1) \
100*4882a593Smuzhiyun mount_error(fd, key ?: "create"); \
101*4882a593Smuzhiyun } while (0)
102*4882a593Smuzhiyun
main(int argc,char * argv[])103*4882a593Smuzhiyun int main(int argc, char *argv[])
104*4882a593Smuzhiyun {
105*4882a593Smuzhiyun int fsfd, mfd;
106*4882a593Smuzhiyun
107*4882a593Smuzhiyun /* Mount a publically available AFS filesystem */
108*4882a593Smuzhiyun fsfd = fsopen("afs", 0);
109*4882a593Smuzhiyun if (fsfd == -1) {
110*4882a593Smuzhiyun perror("fsopen");
111*4882a593Smuzhiyun exit(1);
112*4882a593Smuzhiyun }
113*4882a593Smuzhiyun
114*4882a593Smuzhiyun E_fsconfig(fsfd, FSCONFIG_SET_STRING, "source", "#grand.central.org:root.cell.", 0);
115*4882a593Smuzhiyun E_fsconfig(fsfd, FSCONFIG_CMD_CREATE, NULL, NULL, 0);
116*4882a593Smuzhiyun
117*4882a593Smuzhiyun mfd = fsmount(fsfd, 0, MOUNT_ATTR_RDONLY);
118*4882a593Smuzhiyun if (mfd < 0)
119*4882a593Smuzhiyun mount_error(fsfd, "fsmount");
120*4882a593Smuzhiyun E(close(fsfd));
121*4882a593Smuzhiyun
122*4882a593Smuzhiyun if (move_mount(mfd, "", AT_FDCWD, "/mnt", MOVE_MOUNT_F_EMPTY_PATH) < 0) {
123*4882a593Smuzhiyun perror("move_mount");
124*4882a593Smuzhiyun exit(1);
125*4882a593Smuzhiyun }
126*4882a593Smuzhiyun
127*4882a593Smuzhiyun E(close(mfd));
128*4882a593Smuzhiyun exit(0);
129*4882a593Smuzhiyun }
130