[Pkg-libvirt-commits] [libguestfs] 28/65: v2v: test-harness: Don't send key to wake up guest from blank unless the display is black.

[Hilko Bengen]

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bengen pushed a commit to branch experimental
in repository libguestfs.

commit 7260b0fc089c4fc61ac6ad0a816ca0f025aa5107
Author: Richard W.M. Jones <rjones at redhat.com>
Date:   Fri Apr 10 09:43:41 2015 +0100

    v2v: test-harness: Don't send key to wake up guest from blank unless the display is black.
    
    Grub2 in RHEL 6 responds to any key including shift keys by entering
    the grub menu (and thus waiting for the 'user' to press Enter).  This
    means our previous strategy of always hitting the shift key before
    taking a screenshot didn't work well.
    
    Instead, take a screenshot, if it's all (or mostly) black, hit a shift
    key and take another screenshot.
---
 v2v/test-harness/v2v_test_harness.ml | 71 +++++++++++++++++++++++++++---------
 1 file changed, 54 insertions(+), 17 deletions(-)

diff --git a/v2v/test-harness/v2v_test_harness.ml b/v2v/test-harness/v2v_test_harness.ml
index a992680..9ab2de7 100644
--- a/v2v/test-harness/v2v_test_harness.ml
+++ b/v2v/test-harness/v2v_test_harness.ml
@@ -176,33 +176,70 @@ let run ~test ?input_disk ?input_xml ?(test_plan = default_plan) () =
       sprintf "%04d%02d%02d-%02d%02d%02d" y mo d h m s
     in
 
+    let display_is_black display =
+      let cmd =
+        sprintf "convert %s -format '%%[mean]' info:" (quote display) in
+      printf "%s\n%!" cmd;
+      let chan = open_process_in cmd in
+      let lines = ref [] in
+      (try while true do lines := input_line chan :: !lines done
+       with End_of_file -> ());
+      let lines = List.rev !lines in
+      let stat = close_process_in chan in
+      match stat with
+      | WEXITED 0 ->
+         let mean = Scanf.sscanf (List.hd lines) "%f" (fun f -> f) in
+         mean < 60.0            (* mostly or completely black *)
+      | WEXITED i ->
+         failwithf "external command '%s' exited with error %d" cmd 2;
+      | WSIGNALED i ->
+         failwithf "external command '%s' killed by signal %d" cmd i
+      | WSTOPPED i ->
+         failwithf "external command '%s' stopped by signal %d" cmd i
+    in
+
     let keys = [| "KEY_LEFTSHIFT"; "KEY_LEFTALT"; "KEY_LEFTCTRL" |] in
     let next_key = ref 0 in
 
     let take_screenshot t =
-      (* Send a key to wake up the screen from blanking.  But don't
-       * keep on hitting the shift key as that causes Windows to get in
-       * a muddle.
-       * https://rwmj.wordpress.com/2015/03/30/tip-wake-up-a-guest-from-screen-blank/ *)
-      let key = keys.(!next_key) in
-      next_key := !next_key+1;
-      if !next_key >= Array.length keys then next_key := 0;
-
-      let cmd = sprintf "virsh send-key %s %s" (quote domname) key in
-      printf "%s\n%!" cmd;
-      ignore (Sys.command cmd);
-      sleep 2;
-
-      (* Use 'virsh screenshot' command because our libvirt bindings
-       * don't include virDomainScreenshot, and in any case that API
-       * is complicated to use.  Returns the filename.
-       *)
       let filename = sprintf "%s-%s.scrn" test (timestamp t) in
       let cmd =
         sprintf "virsh screenshot %s %s" (quote domname) (quote filename) in
       printf "%s\n%!" cmd;
+
+      let do_virsh_screenshot () =
+        (* Use 'virsh screenshot' command because our libvirt bindings
+         * don't include virDomainScreenshot, and in any case that API
+         * is complicated to use.
+         *)
       if Sys.command cmd <> 0 then
         failwith "virsh screenshot command failed";
+      in
+
+      (* Take a screenshot. *)
+      do_virsh_screenshot ();
+
+      (* If the screenshot is completely black, send a key to wake up
+       * the screen from blanking.  But don't keep on hitting the shift
+       * key as that causes Windows to get in a muddle.  And don't send
+       * a key unnecessarily since grub responds to shift keys by going
+       * into a menu(!)
+       * https://rwmj.wordpress.com/2015/03/30/tip-wake-up-a-guest-from-screen-blank/
+       *)
+      if display_is_black filename then (
+        let key = keys.(!next_key) in
+        next_key := !next_key+1;
+        if !next_key >= Array.length keys then next_key := 0;
+
+        let cmd = sprintf "virsh send-key %s %s" (quote domname) key in
+        printf "%s\n%!" cmd;
+        ignore (Sys.command cmd);
+        sleep 2;
+
+        do_virsh_screenshot ()
+      );
+
+      (* Return the screenshot filename. *)
       filename
     in
 

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