Initial commit.

caffeine.c

@@ -0,0 +1,119 @@
+#include <unistd.h> /* access */
+#include <stdlib.h> /* exit */
+#include <syslog.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <errno.h>
+
+#include <X11/extensions/scrnsaver.h>
+
+#define TEMP_FILE "/tmp/caffeine"
+
+char file_exists(const char *filename)
+{
+    return access(filename, F_OK) != -1;
+}
+
+void daemonize()
+{
+    close(0);
+    close(1);
+    close(2);
+    open("/dev/null", O_RDONLY); /* stdin */
+    open("/dev/null", O_WRONLY); /* stdout */
+    open("/dev/null", O_WRONLY); /* stderr */
+    chdir("/");
+    int pid = fork();
+    if(pid > 0)
+        exit(0);
+    setsid();
+    pid = fork();
+    if(pid > 0)
+        exit(0);
+}
+
+#if 1
+static volatile sig_atomic_t n = 0;
+
+void usr1hdl(int sig)
+{
+    int save_errno = errno;
+    signal(SIGUSR1, usr1hdl);
+    n = 1;
+    errno = save_errno;
+}
+
+void termhdl(int sig)
+{
+    int save_errno = errno;
+    signal(SIGTERM, termhdl);
+    n = 2;
+    errno = save_errno;
+}
+#endif
+
+int main(int argc, char *argv[])
+{
+    Display *dpy;
+    int event_base, error_base, major, minor;
+    int is_on;
+
+    /*daemonize();*/
+
+    signal(SIGUSR1, usr1hdl);
+    signal(SIGTERM, termhdl);
+
+    openlog("caffeine", 0, LOG_USER);
+    syslog(LOG_INFO, "Daemon started, pid == %d", getpid());
+
+    dpy = XOpenDisplay(0);
+    if(!dpy) {
+        syslog(LOG_ERR, "Failed to open display.");
+        return 1;
+    }
+
+    if(!XScreenSaverQueryExtension(dpy, &event_base, &error_base)) {
+        syslog(LOG_ERR, "XScreenSaver extension does not exist.");
+        return 2;
+    }
+
+    XScreenSaverQueryVersion(dpy, &major, &minor);
+    if(!(major > 1 || (major == 1 && minor >= 1))) {
+        syslog(LOG_ERR, "XScreenSaver extension is too old, need >=1.1.");
+        return 3;
+    }
+
+    is_on = 0;
+    for(;;) {
+        pause();
+        if(n == 0) {
+            /* do nothing */
+        } else if(n == 1) {
+            is_on = !is_on;
+            if(is_on) {
+                syslog(LOG_INFO, "Enabling...");
+                creat(TEMP_FILE, 0644);
+                XScreenSaverSuspend(dpy, True);
+            } else {
+                syslog(LOG_INFO, "Disabling...");
+                unlink(TEMP_FILE);
+                XScreenSaverSuspend(dpy, False);
+            }
+            XSync(dpy, False);
+        } else if(n == 2) {
+            syslog(LOG_INFO, "Shutting down...");
+            unlink(TEMP_FILE);
+            XScreenSaverSuspend(dpy, False);
+            XSync(dpy, False);
+            break;
+        } else {
+            /* unknown state */
+        }
+
+        n = 0;
+    }
+
+    closelog();
+
+    return 0;
+}