dwmblocks/sigdwmblocks/sigdwmblocks.c
2021-08-03 16:58:21 +05:30

105 lines
2.8 KiB
C

#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#define NILL INT_MIN
#define LOCKFILE "/var/local/dwmblocks/dwmblocks.pid"
int
parsesignal(char *arg)
{
int i = 0;
for (; *arg != '\0'; arg++)
if (*arg >= '0' && *arg <= '9')
i = 10 * i + *arg - '0';
else {
fputs("Usage: sigdwmblocks <signal> [<sigval>]\n", stderr);
exit(2);
}
if ((i += SIGRTMIN) > SIGRTMAX) {
fputs("Error: <signal> out of range.\n", stderr);
exit(2);
}
return i;
}
int
parsesigval(char *arg)
{
int s = 1, i = 0;
if (*arg == '-') {
s = -1;
arg++;
} else if (*arg == '+')
arg++;
for (; *arg != '\0'; arg++)
if (*arg >= '0' && *arg <= '9')
i = 10 * i + *arg - '0';
else {
fputs("Usage: sigdwmblocks <signal> [<sigval>]\n", stderr);
exit(2);
}
return s * i;
}
void
sendsignal(int sig, union sigval sv)
{
int fd;
struct flock fl;
if ((fd = open(LOCKFILE, O_RDONLY)) == -1) {
if (errno == ENOENT) {
fputs("Error: no running instance of dwmblocks.\n", stderr);
exit(3);
}
perror("sendsignal - open");
exit(1);
}
fl.l_type = F_WRLCK;
fl.l_whence = SEEK_SET;
fl.l_start = 0;
fl.l_len = 0;
if (fcntl(fd, F_GETLK, &fl) == -1) {
perror("sendsignal - fcntl");
close(fd);
exit(1);
}
close(fd);
if (fl.l_type != F_WRLCK) {
fputs("Error: no running instance of dwmblocks.\n", stderr);
exit(3);
}
if (sigqueue(fl.l_pid, sig, sv) == -1) {
if (errno == ESRCH) {
fputs("Error: no running instance of dwmblocks.\n", stderr);
exit(3);
} else {
perror("sendsignal - sigqueue");
exit(1);
}
}
}
int
main(int argc, char *argv[])
{
int sig;
union sigval sv;
if (argc < 2 || argc > 3) {
fputs("Usage: sigdwmblocks <signal> [<sigval>]\n", stderr);
return 2;
}
sig = parsesignal(argv[1]);
sv.sival_int = argc == 2 ? NILL : parsesigval(argv[2]);
sendsignal(sig, sv);
return 0;
}