Bug 3603

If your icon themes have circular inheritance, XcursorScanTheme recurses  
infinitely (until it eventually stack-overflows).   
    
We noticed this bug because the KDE mouse control panel dies when you try to  
launch it (if you have circular icon theme inheritence) -- the rest of KDE  
works fine.   
   
I hacked up a little patch that checks for circular Inherits. A quick overview  
of my patch:   
   
 ~ renamed XcursorScanTheme to XcursorScanThemeAccum and added a third  
parameter, seen, which is a list of all the themes that have already been  
checked.   
   
 ~ Added a new XcursorScanTheme that is a wrapper around XcursorScanThemeAccum  
so that the existing calls to XcursorScanTheme do not have to be changed. (To  
keep the patch simple).   
   
 ~ Only recursively call XcursorScanThemeAccum if the inherited theme has not  
already been checked.   
   
 ~ Note that I prepend new themes to the list, rather than append them, because  
it flows naturally with the recursion that way.   
  
This is the patch that we use internally, I am sure a few changes would be  
needed if it was applied to the official source. Please feel free to email if 
you have questions or flames. 
    
$ tla changes --diffs    
* looking for tos@lindows.com--2004/xcursor--circular-inherits--1.1.3--base-0    
to compare with    
* comparing to tos@lindows.com--2004/xcursor--circular-inherits--1.1.3--base-0    
M  library.c    
M  xcursorint.h    
    
* modified files    
    
--- orig/library.c    
+++ mod/library.c    
@@ -196,10 +196,26 @@    
     return result;    
 }    
     
+int ListMem(StringList *seen, const char *theme)    
+{    
+    if (!seen)    
+	return 0;    
+    
+    while (seen->next != 0) {    
+	printf("(%s,%s)\n",seen->theme,theme);    
+	if (strcmp(seen->theme, theme) == 0)    
+	    return 1;    
+	seen=seen->next;    
+    }    
+    if (strcmp(seen->theme, theme) == 0)    
+	return 1;    
+    return 0;    
+}    
+    
 #define XCURSOR_SCAN_CORE   ((FILE *) 1)    
     
 static FILE *    
-XcursorScanTheme (const char *theme, const char *name)    
+XcursorScanThemeAccum (const char *theme, const char *name, StringList *seen)    
 {    
     FILE	*f = 0;    
     char	*full;    
@@ -248,12 +264,28 @@    
      * Recurse to scan inherited themes    
      */    
     for (i = inherits; i && f == 0; i = _XcursorNextPath (i))    
-	f = XcursorScanTheme (i, name);    
+    {    
+	if (!ListMem(seen, i))    
+	{    
+	    StringList *newSeen = (struct list_struct    
*)malloc(sizeof(StringList));    
+	    newSeen->next  = seen;    
+	    newSeen->theme = i;    
+	    f = XcursorScanThemeAccum (i, name, newSeen);    
+	    free(newSeen);    
+	}    
+    }    
+    
     if (inherits)    
 	free (inherits);    
     return f;    
 }    
     
+static FILE *    
+XcursorScanTheme (const char *theme, const char *name)    
+{    
+    return (XcursorScanThemeAccum (theme, name, 0));    
+}    
+    
 XcursorImage *    
 XcursorLibraryLoadImage (const char *file, const char *theme, int size)    
 {    
    
    
--- orig/xcursorint.h    
+++ mod/xcursorint.h    
@@ -104,5 +104,12 @@    
     
 Cursor    
 _XcursorCreateFontCursor (Display *dpy, unsigned int shape);    
+    
+typedef struct _StringList    
+{    
+    const char *theme;    
+    struct _StringList *next;    
+} StringList;    
+    
         
 #endif /* _XCURSORINT_H_ */