1 /*
2 * Copyright © 2018 Alexey Dobriyan <adobriyan@gmail.com>
3 *
4 * Permission to use, copy, modify, and distribute this software for any
5 * purpose with or without fee is hereby granted, provided that the above
6 * copyright notice and this permission notice appear in all copies.
7 *
8 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15 */
16 #define _GNU_SOURCE
17 #include <unistd.h>
18 #include <sys/syscall.h>
19 #include <sys/types.h>
20 #include <sys/stat.h>
21 #include <fcntl.h>
22 #include <errno.h>
23 #include <unistd.h>
24 #include <string.h>
25 #include <stdio.h>
26
sys_read(int fd,void * buf,size_t len)27 static inline ssize_t sys_read(int fd, void *buf, size_t len)
28 {
29 return syscall(SYS_read, fd, buf, len);
30 }
31
main(void)32 int main(void)
33 {
34 char buf1[64];
35 char buf2[64];
36 int fd;
37 ssize_t rv;
38
39 fd = open("/proc/self/syscall", O_RDONLY);
40 if (fd == -1) {
41 if (errno == ENOENT)
42 return 2;
43 return 1;
44 }
45
46 /* Do direct system call as libc can wrap anything. */
47 snprintf(buf1, sizeof(buf1), "%ld 0x%lx 0x%lx 0x%lx",
48 (long)SYS_read, (long)fd, (long)buf2, (long)sizeof(buf2));
49
50 memset(buf2, 0, sizeof(buf2));
51 rv = sys_read(fd, buf2, sizeof(buf2));
52 if (rv < 0)
53 return 1;
54 if (rv < strlen(buf1))
55 return 1;
56 if (strncmp(buf1, buf2, strlen(buf1)) != 0)
57 return 1;
58
59 return 0;
60 }
61