Add xrdp-waitforx to wait for X to start with RandR outputs

For some window managers (fvwm2 and fvwm3) if the X server isn't running and has output it's possible for the window manager to fail or reconfigure randr incorrectly. With xrdp-waitfox: - Install xrdp-waitfox to the BIN dir. - sesman will run xrdp-waitfox as the logged in user. - Set an alarm to exit after 30 seconds. - Try to open env DISPLAY value's display (10 seconds). - Test for RandR extension. - Wait for outputs to appear (10 seconds).
2022-11-19 21:43:00 -05:00
parent 9bab8e0da5
commit 829378bba8
8 changed files with 173 additions and 71 deletions
@@ -0,0 +1,96 @@
+#include <X11/extensions/Xrandr.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/signal.h>
+#include <unistd.h>
+
+#define ATTEMPTS 10
+#define ALARM_WAIT 30
+
+void
+alarm_handler(int signal_num)
+{
+    printf("Unable to find RandR outputs after %d seconds\n", ALARM_WAIT);
+    exit(1);
+}
+
+int
+main(int argc, char **argv)
+{
+    char *display = NULL;
+    int error_base = 0;
+    int event_base = 0;
+    int n = 0;
+    int outputs = 0;
+    int wait = ATTEMPTS;
+
+    Display *dpy = NULL;
+    XRRScreenResources *res = NULL;
+
+    display = getenv("DISPLAY");
+
+    signal(SIGALRM, alarm_handler);
+    alarm(ALARM_WAIT);
+
+    if (!display)
+    {
+        printf("DISPLAY is null");
+        exit(1);
+    }
+
+    for (n = 1; n <= wait; ++n)
+    {
+        dpy = XOpenDisplay(display);
+        printf("Opening display %s. Attempt %d of %d\n", display, n, wait);
+        if (dpy != NULL)
+        {
+            printf("Opened display %s\n", display);
+            break;
+        }
+        sleep(1);
+    }
+
+    if (!dpy)
+    {
+        printf("Unable to open display %s\n", display);
+        exit(1);
+    }
+
+    if (!XRRQueryExtension(dpy, &event_base, &error_base))
+    {
+        printf("RandR not supported on display %s", display);
+    }
+    else
+    {
+        for (n = 1; n <= wait; ++n)
+        {
+            res = XRRGetScreenResources(dpy, DefaultRootWindow(dpy));
+            printf("Waiting for outputs. Attempt %d of %d\n", n, wait);
+            if (res != NULL)
+            {
+                if (res->noutput > 0)
+                {
+                    outputs = res->noutput;
+                    XRRFreeScreenResources(res);
+                    printf("Found %d output[s]\n", outputs);
+                    break;
+                }
+                XRRFreeScreenResources(res);
+            }
+            sleep(1);
+        }
+
+        if (outputs > 0)
+        {
+            printf("display %s ready with %d outputs\n", display, res->noutput);
+        }
+        else
+        {
+            printf("Unable to find any outputs\n");
+            exit(1);
+        }
+    }
+
+    exit(0);
+}