Added automonitor.

Automonitor is a program that calls a bash script to configure displays
when it detects a change in the drm subsystem.

It's experimental and is not set up by default. It would need to be set
up explicitly somewhere for it to work.

1 files changed, 91 insertions, 0 deletions

diff --git a/extras/util/automonitor/automonitor.c b/extras/util/automonitor/automonitor.c
new file mode 100644
index 0000000..f55e2f4
--- /dev/null
+++ b/extras/util/automonitor/automonitor.c
@@ -0,0 +1,91 @@
+#include <libudev.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/select.h>
+#include <sys/wait.h>
+#include <unistd.h>
+
+#define BLOCK_SIZE 512
+#define STRNCMP(s, cs) strncmp(s, cs, strlen(cs))
+
+int execute_shell_script() {
+  char *home = getenv("HOME");
+
+  if (!home) {
+    fprintf(stderr, "No home environment variable.");
+    return 1;
+  }
+
+  char script_path[4096];
+
+  snprintf(script_path, sizeof(script_path) - 1,
+           "%s/.xmonad/configure-displays", home);
+
+  int f = fork();
+  if (f == 0) {
+    // child process.
+    execl(script_path, script_path, "change", NULL);
+    perror("Exec failed");
+    exit(1);
+  } else {
+    if (f == -1) {
+      perror("Forking failed");
+      return 1;
+    } else {
+      waitpid(f, NULL, 0);
+    }
+  }
+
+  return 0;
+}
+
+int main() {
+  struct udev *udev;
+  struct udev_device *dev;
+  struct udev_monitor *mon;
+  int fd;
+
+  udev = udev_new();
+  if (!udev) {
+    fprintf(stderr, "Cannot create new udev context\n");
+    return 1;
+  }
+
+  mon = udev_monitor_new_from_netlink(udev, "udev");
+  udev_monitor_filter_add_match_subsystem_devtype(mon, "drm", NULL);
+  udev_monitor_enable_receiving(mon);
+  fd = udev_monitor_get_fd(mon);
+
+  int found_event = 0;
+  while (1) {
+    fd_set fds;
+    struct timeval to = {0};
+    if (found_event) {
+      to.tv_usec = 100000;
+    }
+    int ret;
+
+    FD_ZERO(&fds);
+    FD_SET(fd, &fds);
+
+    ret = select(fd + 1, &fds, NULL, NULL, found_event ? &to : NULL);
+    if (ret > 0 && FD_ISSET(fd, &fds)) {
+      dev = udev_monitor_receive_device(mon);
+      if (dev) {
+        if (STRNCMP(udev_device_get_action(dev), "change") == 0) {
+          printf("I: Change detected.\n");
+          found_event = 1;
+          // Still need to clean up some trailing detected changes.
+        }
+      }
+    } else if (ret == 0 && found_event) {
+      printf("Executing shell script hook.\n");
+      if (execute_shell_script()) {
+        fprintf(stderr, "Unable to execute shell script.");
+      };
+      found_event = 0;
+    }
+  }
+}