1 // Copyright (c) 2012 The Chromium OS Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style license that can be 3 // found in the LICENSE file. 4 5 #include <fcntl.h> 6 #include <stdio.h> 7 #include <stdlib.h> 8 #include <unistd.h> 9 #include <asm/unistd.h> 10 11 void usage(const char *comm) { 12 fprintf(stderr, "Usage: %s <access mode>\n", comm); 13 fprintf(stderr, "\tAccess mode: 0-O_RDONLY, 1-O_WRONLY, 2-O_RDWR\n"); 14 return; 15 } 16 17 int main(int argc, char **argv) { 18 if (argc < 2) { 19 usage(argv[0]); 20 return 1; 21 } 22 23 unsigned int access_mode = strtoul(argv[1], NULL, 0); 24 if (access_mode < 0 || access_mode > 2) { 25 usage(argv[0]); 26 return 1; 27 } 28 29 char *path; 30 int flags; 31 32 switch (access_mode) { 33 case 0: 34 path = "/dev/zero"; 35 flags = O_RDONLY; 36 break; 37 case 1: 38 path = "/dev/null"; 39 flags = O_WRONLY; 40 break; 41 case 2: 42 path = "/dev/null"; 43 flags = O_RDWR; 44 break; 45 default: 46 usage(argv[0]); 47 return 1; 48 } 49 50 int fd = syscall(__NR_open, path, flags); 51 syscall(__NR_close, fd); 52 syscall(__NR_exit, 0); 53 } 54
