sigdwmblocks.c (2345B)
1 #include <errno.h> 2 #include <fcntl.h> 3 #include <limits.h> 4 #include <signal.h> 5 #include <stdio.h> 6 #include <stdlib.h> 7 #include <string.h> 8 #include <unistd.h> 9 10 #define LOCKFILE "/tmp/dwmblocks.pid" 11 12 void 13 sendsignal(int signum, union sigval sv) 14 { 15 int fd; 16 struct flock fl; 17 18 fd = open(LOCKFILE, O_RDONLY); 19 if (fd == -1) { 20 if (errno == ENOENT) { 21 fputs("Error: no running instance of dwmblocks.\n", stderr); 22 exit(2); 23 } 24 perror("sendsignal - open"); 25 exit(1); 26 } 27 fl.l_type = F_WRLCK; 28 fl.l_start = 0; 29 fl.l_whence = SEEK_SET; 30 fl.l_len = 0; 31 if (fcntl(fd, F_GETLK, &fl) == -1) { 32 perror("sendsignal - fcntl"); 33 exit(1); 34 } 35 if (fl.l_type == F_UNLCK) { 36 fputs("Error: no running instance of dwmblocks.\n", stderr); 37 exit(2); 38 } 39 if (sigqueue(fl.l_pid, signum, sv) == -1) { 40 if (errno == EINVAL) { 41 fputs("Error: invalid signal provided in argument.\n", stderr); 42 exit(3); 43 } else if (errno == ESRCH) { 44 fputs("Error: no running instance of dwmblocks.\n", stderr); 45 exit(2); 46 } else { 47 perror("sendsignal - sigqueue"); 48 exit(1); 49 } 50 } 51 } 52 53 int 54 main(int argc, char *argv[]) 55 { 56 if (argc > 1) { 57 int signal; 58 union sigval sv; 59 60 if (sscanf(argv[1], "%d", &signal) == 1 && 61 signal > 0 && (signal += SIGRTMIN) <= SIGRTMAX) { 62 if (argc == 2) { 63 sv.sival_int = INT_MIN; 64 sendsignal(signal, sv); 65 return 0; 66 } else if (argc == 3 && 67 sscanf(argv[2], "%d", &(sv.sival_int)) == 1) { 68 sendsignal(signal, sv); 69 return 0; 70 } 71 } 72 } 73 fprintf(stderr, "Usage: %s <signal> [<sigval>]\n", argv[0]); 74 return 3; 75 }