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