/* * Copyright © 2018 Alexey Dobriyan <adobriyan@gmail.com> * * Permission to use, copy, modify, and distribute this software for any * purpose with or without fee is hereby granted, provided that the above * copyright notice and this permission notice appear in all copies. * * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */#include <unistd.h>#include <sys/syscall.h>#include <sys/types.h>#include <sys/stat.h>#include <fcntl.h>#include <errno.h>#include <string.h>#include <stdio.h> static inline ssize_t sys_read(int fd, void *buf, size_t len){	return syscall(SYS_read, fd, buf, len);} int main(void){	char buf1[64];	char buf2[64];	int fd;	ssize_t rv; 	fd = open("/proc/self/syscall", O_RDONLY);	if (fd == -1) {		if (errno == ENOENT)			return 4;		return 1;	} 	/* Do direct system call as libc can wrap anything. */	snprintf(buf1, sizeof(buf1), "%ld 0x%lx 0x%lx 0x%lx",		 (long)SYS_read, (long)fd, (long)buf2, (long)sizeof(buf2)); 	memset(buf2, 0, sizeof(buf2));	rv = sys_read(fd, buf2, sizeof(buf2));	if (rv < 0)		return 1;	if (rv < strlen(buf1))		return 1;	if (strncmp(buf1, buf2, strlen(buf1)) != 0)		return 1; 	return 0;}