Allow defining monitordirs variable: subset/dir of topdirs which will get monitored for updates

src/utils/pathut.cpp

@@ -353,6 +353,29 @@ bool path_isroot(const string& path)
     return false;
 }
 
+bool path_isdesc(const string& _top, const string& _sub)
+{
+    string top = path_canon(_top);
+    string sub = path_canon(_sub);
+    path_catslash(top);
+    path_catslash(sub);
+    for (;;) {
+        if (sub == top) {
+            return true;
+        }
+        string::size_type l = sub.size();
+        sub = path_getfather(sub);
+        if (sub.size() == l || sub.size() < top.size()) {
+            // At root or sub shorter than top: done
+            if (sub == top) {
+                return true;
+            } else {
+                return false;
+            }
+        }
+    }
+}
+
 bool path_isabsolute(const string& path)
 {
     if (!path.empty() && (path[0] == '/'

src/utils/pathut.h

@@ -113,6 +113,10 @@ extern bool path_isabsolute(const std::string& s);
 /// Test if path is root (x:/). root is defined by root/.. == root
 extern bool path_isroot(const std::string& p);
 
+/// Test if sub is a subdirectory of top. This is a textual test,
+/// links not allowed
+extern bool path_isdesc(const std::string& top, const std::string& sub);
+
 /// Turn absolute path into file:// url
 extern std::string path_pathtofileurl(const std::string& path);