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 <string.h>
24 #include <stdio.h>
25
26 static inline ssize_t sys_read(int fd, void *buf, size_t len)
27 {
28 return syscall(SYS_read, fd, buf, len);
29 }
30
31 int main(void)
32 {
33 char buf1[64];
34 char buf2[64];
35 int fd;
36 ssize_t rv;
37
38 fd = open("/proc/self/syscall", O_RDONLY);
39 if (fd == -1) {
40 if (errno == ENOENT)
41 return 4;
42 return 1;
43 }
44
45 /* Do direct system call as libc can wrap anything. */
46 snprintf(buf1, sizeof(buf1), "%ld 0x%lx 0x%lx 0x%lx",
47 (long)SYS_read, (long)fd, (long)buf2, (long)sizeof(buf2));
48
49 memset(buf2, 0, sizeof(buf2));
50 rv = sys_read(fd, buf2, sizeof(buf2));
51 if (rv < 0)
52 return 1;
53 if (rv < strlen(buf1))
54 return 1;
55 if (strncmp(buf1, buf2, strlen(buf1)) != 0)
56 return 1;
57
58 return 0;
59 }