[gnome-desktop/randr-assignment-errors] Accumulate errors in the recursive real_assign_crtcs()

[Federico Mena Quintero <federico src gnome org>]

commit adde41e2a4ee87f764150343cbfa39b2c59cb4e4
Author: Federico Mena Quintero <federico novell com>
Date:   Thu Apr 8 13:35:28 2010 -0500

    Accumulate errors in the recursive real_assign_crtcs()
    
    When we need to debug why a CRTC assignment didn't succeed, we need the full
    log of what the algorithm tried to do.  This accumulates the errors that
    happen along the process inside real_assign_crtcs().  Before we could
    silently leak the innermost errors, and we were ignoring them in the end.
    
    Signed-off-by: Federico Mena Quintero <federico novell com>

 libgnome-desktop/gnome-rr-config.c |   90 +++++++++++++++++++++++++++++------
 1 files changed, 74 insertions(+), 16 deletions(-)
---
diff --git a/libgnome-desktop/gnome-rr-config.c b/libgnome-desktop/gnome-rr-config.c
index 85387ce..6db57dd 100644
--- a/libgnome-desktop/gnome-rr-config.c
+++ b/libgnome-desktop/gnome-rr-config.c
@@ -1427,11 +1427,11 @@ crtc_assignment_assign (CrtcAssignment   *assign,
     if (!gnome_rr_output_supports_mode (output, mode))
     {
 	g_set_error (error, GNOME_RR_ERROR, GNOME_RR_ERROR_CRTC_ASSIGNMENT,
-		     _("output %s does not support mode %dx%d %fHz"),
+		     _("output %s does not support mode %dx%d %dHz"),
 		     output_name,
 		     gnome_rr_mode_get_width (mode),
 		     gnome_rr_mode_get_height (mode),
-		     gnome_rr_mode_get_freq (mode) / 1000000.0);
+		     gnome_rr_mode_get_freq (mode));
 	return FALSE;
     }
 
@@ -1587,6 +1587,13 @@ crtc_is_rotated (GnomeRRCrtc *crtc)
     return FALSE;
 }
 
+static void
+accumulate_error (GString *accumulated_error, GError *error)
+{
+    g_string_append_printf (accumulated_error, "    %s\n", error->message);
+    g_error_free (error);
+}
+
 /* Check whether the given set of settings can be used
  * at the same time -- ie. whether there is an assignment
  * of CRTC's to outputs.
@@ -1603,6 +1610,10 @@ real_assign_crtcs (GnomeRRScreen *screen,
     GnomeRRCrtc **crtcs = gnome_rr_screen_list_crtcs (screen);
     GnomeOutputInfo *output;
     int i;
+    gboolean tried_mode;
+    GError *my_error;
+    GString *accumulated_error;
+    gboolean success;
 
     output = *outputs;
     if (!output)
@@ -1614,48 +1625,95 @@ real_assign_crtcs (GnomeRRScreen *screen,
 	return real_assign_crtcs (screen, outputs + 1, assignment, error);
     }
 
+    success = FALSE;
+    tried_mode = FALSE;
+    accumulated_error = g_string_new (NULL);
+
     for (i = 0; crtcs[i] != NULL; ++i)
     {
 	int pass;
 
-	/* Make two passses, one where frequencies must match, then
+	/* Make two passes, one where frequencies must match, then
 	 * one where they don't have to
 	 */
 	for (pass = 0; pass < 2; ++pass)
 	{
 	    GnomeRRCrtc *crtc = crtcs[i];
-	    GnomeRROutput *gnome_rr_output =
-		gnome_rr_screen_get_output_by_name (screen, output->name);
+	    int crtc_id = gnome_rr_crtc_get_id (crtc);
+	    GnomeRROutput *gnome_rr_output = gnome_rr_screen_get_output_by_name (screen, output->name);
 	    GnomeRRMode **modes = gnome_rr_output_list_modes (gnome_rr_output);
 	    int j;
-	
+
 	    for (j = 0; modes[j] != NULL; ++j)
 	    {
 		GnomeRRMode *mode = modes[j];
-		
-		if (gnome_rr_mode_get_width (mode) == output->width	&&
-		    gnome_rr_mode_get_height (mode) == output->height &&
-		    (pass == 1 || gnome_rr_mode_get_freq (mode) == output->rate))
+		int mode_width;
+		int mode_height;
+		int mode_freq;
+
+		mode_width = gnome_rr_mode_get_width (mode);
+		mode_height = gnome_rr_mode_get_height (mode);
+		mode_freq = gnome_rr_mode_get_freq (mode);
+
+		g_string_append_printf (accumulated_error,
+					_("CRTC %d: trying mode %dx%d %dHz with output at %dx%d %dHz (pass %d)\n"),
+					crtc_id,
+					mode_width, mode_height, mode_freq,
+					output->width, output->height, output->rate,
+					pass);
+
+		if (mode_width == output->width	&&
+		    mode_height == output->height &&
+		    (pass == 1 || mode_freq == output->rate))
 		{
+		    tried_mode = TRUE;
+
+		    my_error = NULL;
 		    if (crtc_assignment_assign (
 			    assignment, crtc, modes[j],
 			    output->x, output->y,
 			    output->rotation,
                             output->primary,
 			    gnome_rr_output,
-			    error))
+			    &my_error))
 		    {
-			if (real_assign_crtcs (screen, outputs + 1, assignment, error))
-			    return TRUE;
-			
+			my_error = NULL;
+			if (real_assign_crtcs (screen, outputs + 1, assignment, &my_error)) {
+			    success = TRUE;
+			    goto out;
+			} else
+			    accumulate_error (accumulated_error, my_error);
+
 			crtc_assignment_unassign (assignment, crtc, gnome_rr_output);
-		    }
+		    } else
+			accumulate_error (accumulated_error, my_error);
 		}
 	    }
 	}
     }
 
-    return FALSE;
+out:
+
+    if (success)
+	g_string_free (accumulated_error, TRUE);
+    else {
+	char *str;
+
+	str = g_string_free (accumulated_error, FALSE);
+
+	if (tried_mode)
+	    g_set_error (error, GNOME_RR_ERROR, GNOME_RR_ERROR_CRTC_ASSIGNMENT,
+			 _("could not assign CRTCs to outputs:\n%s"),
+			 str);
+	else
+	    g_set_error (error, GNOME_RR_ERROR, GNOME_RR_ERROR_CRTC_ASSIGNMENT,
+			 _("none of the selected modes were compatible with the possible modes:\n%s"),
+			 str);
+
+	g_free (str);
+    }
+
+    return success;
 }
 
 static void