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/*
* a program to listen for X bell events and run a user defined program
* when it is caught.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>
#include <signal.h>
#include <X11/Xlib.h>
#include <sys/types.h>
#include <X11/XKBlib.h>
/*
* maximum number of arguments we will try and call when
* launching the user defined program
*/
#define ARG_LIMIT 20
#define BUFF_SIZE 512
char *program = "sh -c /home/daniel_j/programming/bash/beep.sh";
Display *display;
XEvent xevent;
XkbEvent *xkbevent;
int xkbeventcode; /* stores the event code for the xkb extension */
int
forkexecute()
{
pid_t pid = fork();
if (pid == 0)
{
// child process, we don't want to ignore signals
signal(SIGCHLD, SIG_DFL);
/*
* we don't want std{out,err} to be associated with the terminal,
* but we also don't want to close it to avoid the file descriptors
* being re-used potentially leading to problems, so reopen them to /dev/null
*/
freopen("/dev/null", "w", stdout);
freopen("/dev/null", "w", stderr);
char *args[ARG_LIMIT];
char *buff = malloc(BUFF_SIZE);
if (buff == NULL)
{
perror("malloc");
return -1;
}
/*
* the program we're calling might have arguments,
* so we tokenise the string and add each part to an array
* that we will use in execvp
*/
strncpy(buff, program, BUFF_SIZE-1);
char *t = strtok(buff, " ");
int z = 0;
while (t != NULL && z < ARG_LIMIT-1) // save a position for NULL
{
args[z] = t;
t = strtok(NULL, " ");
z++;
}
args[z] = (char *)0;
execvp(args[0], args);
_exit(1);
}
else if (pid == -1)
{
perror("fork");
return -1;
}
return 1;
}
void
bellevent(void)
{
/*
* a bell event was caught, execute the user defined program
*/
int ret = forkexecute();
if (ret != 1)
fprintf(stderr, "forkexecute() failed");
}
int
main(void)
{
// ignore child processes
signal(SIGCHLD, SIG_IGN);
// ignore return values for now
display = XkbOpenDisplay(NULL, &xkbeventcode, NULL, NULL, NULL, NULL);
if (!display)
{
fprintf(stderr, "Cannot open display.\n");
exit(1);
}
XkbSelectEvents(display, XkbUseCoreKbd, XkbBellNotifyMask, XkbBellNotifyMask);
while (1)
{
XNextEvent(display, &xevent);
if (xevent.type == xkbeventcode)
{
xkbevent = (XkbEvent *)&xevent;
if (xkbevent->any.xkb_type == XkbBellNotify)
{
bellevent();
}
}
}
return 0;
}
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