From 5a1ff0323cf3a64358c65c01e69f3ecb9fac8ccd Mon Sep 17 00:00:00 2001
From: Daniel Jones <admin@danieljon.es>
Date: Tue, 26 Mar 2019 18:23:40 +1030
Subject: first code commit

---
 xbell.c | 114 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 114 insertions(+)
 create mode 100644 xbell.c

(limited to 'xbell.c')

diff --git a/xbell.c b/xbell.c
new file mode 100644
index 0000000..70ca37a
--- /dev/null
+++ b/xbell.c
@@ -0,0 +1,114 @@
+#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 arguemnts we will try and call when
+ * launching the usder 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+1] = (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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