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 <sys/types.h> 17 #include <sys/stat.h> 18 #include <fcntl.h> 19 #include <errno.h> 20 #include <unistd.h> 21 22 int main(void) 23 { 24 char buf[64]; 25 int fd; 26 27 fd = open("/proc/self/wchan", O_RDONLY); 28 if (fd == -1) { 29 if (errno == ENOENT) 30 return 4; 31 return 1; 32 } 33 34 buf[0] = '\0'; 35 if (read(fd, buf, sizeof(buf)) != 1) 36 return 1; 37 if (buf[0] != '0') 38 return 1; 39 return 0; 40 } 41