Fix handling of URIs in custom XSL loader

There was an error how URIs were handled in our custom XSL loader
that rewrites include URIs to point to admin dir if the include
is not found in the current dir.

The check for the file would not work if the path contains chars
that are usually escaped in URIs, like a space (%20), as we get
a already encoded version of that URI in the loader and did not
decode it before checking the existence of the file.

(Fix #2249)

Author: ePirat

src/xslt.c

@@ -204,18 +204,27 @@ static xmlDocPtr custom_loader(const        xmlChar *URI,
 {
     xmlDocPtr ret;
     xmlChar *rel_path, *fn, *final_URI = NULL;
+    char *path_URI = NULL;
     xsltStylesheet *c;
     ice_config_t *config;
 
     switch (type) {
         /* In case an include is loaded */
         case XSLT_LOAD_STYLESHEET:
+            /* URI is an escaped URI, make an unescaped version */
+            path_URI = util_url_unescape((const char*)URI);
+            /* Error if we can't unescape */
+            if (path_URI == NULL)
+                return NULL;
+
             /* Not look in admindir if the include file exists */
-            if (access((const char *)URI, F_OK) == 0)
+            if (access(path_URI, F_OK) == 0) {
+                free(path_URI);
                 break;
+            }
+            free(path_URI);
 
             c = (xsltStylesheet *) ctxt;
-
             /* Check if we actually have context/path */
             if (ctxt == NULL || c->doc->URL == NULL)
                 break;
@@ -238,7 +247,11 @@ static xmlDocPtr custom_loader(const        xmlChar *URI,
         /* In case a top stylesheet is loaded */
         case XSLT_LOAD_START:
             config = config_get_config();
-            /* Check if admin path actually changed. If so clear it. */
+            /* Admin path is cached, so that we don't need to get it from
+             * the config every time we load a xsl include.
+             * Whenever a new top stylesheet is loaded, we check here
+             * if the path in the config has changed and adjust it, if needed.
+             */
             if (admin_path != NULL &&
                 strcmp(config->adminroot_dir, (char *)admin_path) != 0) {
                 xmlFree(admin_path);