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 sys_read(int fd,void * buf,size_t len)25 static inline ssize_t sys_read(int fd, void *buf, size_t len) 26 { 27 return syscall(SYS_read, fd, buf, len); 28 } 29 main(void)30 int 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