Number: 1269
Title: graphviz does not check cairo error status
Submitter: Adrian Johnson
Date: 2008-01-10
Subsys: cairo
Version: cvs (2008-01-10)
System: Linux
Severity: minor
Problem:
Graphviz is not checking the cairo surface status after creating a PS or PDF file. cairo_surface_destroy() will call cairo_surface_finish() if it hasn't already been called however the surface status will be lost.

The way to get the surface status is to call cairo_surface_finish() to finish writing the PS or PDF file. Then cairo_surface_status() can be called to obtain the final status before calling cairo_surface_destroy() to release the surface object.

If cairo detects an error while writing a PS/PDF file it will set the surface status to something other than CAIRO_STATUS_SUCCESS and abort writing the file or stream. In this case the PS/PDF file will almost certainly be in a broken state and the error should be reported to the user.
Comments:
[ellson] Thanks for this. Its in CVS

[adrian] I just checked out CVS and it appears to be missing this one line from the patch:

+ status = cairo_surface_status(surface);

[ellson] Got it. Thx.
Fix:
This is the patch that I used to get the cairo status. 


Index: plugin/pango/gvrender_pango.c
===================================================================
RCS file: /home/cvsroot/graphviz2/plugin/pango/gvrender_pango.c,v
retrieving revision 1.55
diff -u -p -r1.55 gvrender_pango.c
--- plugin/pango/gvrender_pango.c	24 Dec 2007 04:26:41 -0000	1.55
+++ plugin/pango/gvrender_pango.c	10 Jan 2008 07:41:03 -0000
@@ -187,6 +187,7 @@ static void cairogen_end_page(GVJ_t * jo
 {
     cairo_t *cr = (cairo_t *) job->context;
     cairo_surface_t *surface;
+    cairo_status_t status;


     switch (job->render.id) {


@@ -201,8 +202,14 @@ static void cairogen_end_page(GVJ_t * jo
     case FORMAT_PDF:
     case FORMAT_SVG:
 	cairo_show_page(cr);
+        surface = cairo_surface_reference(cairo_get_target(cr));
 	cairo_destroy(cr);
 	job->context = NULL;
+	cairo_surface_finish(surface);
+	status = cairo_surface_status(surface);
+	cairo_surface_destroy(surface);
+	if (status != CAIRO_STATUS_SUCCESS)
+	    fprintf(stderr, "cairo: %sn", cairo_status_to_string(status));
 	break;


     case FORMAT_CAIRO:

Owner: ellson
Status: Fixed (10 Jan 2007)