use same path validation process for fgcommands "load", "save",

"loadxml", ans "savexml" as is used for io.open(). This is still
Nasal based for now. See $FG_ROOT/Nasal/io.nas.

src/Main/fg_commands.cxx

@@ -320,16 +320,23 @@ do_resume (const SGPropertyNode * arg)
 static bool
 do_load (const SGPropertyNode * arg)
 {
-  const string &file = arg->getStringValue("file", "fgfs.sav");
-  ifstream input(file.c_str());
-  if (input.good() && fgLoadFlight(input)) {
-    input.close();
-    SG_LOG(SG_INPUT, SG_INFO, "Restored flight from " << file);
-    return true;
-  } else {
-    SG_LOG(SG_INPUT, SG_WARN, "Cannot load flight from " << file);
-    return false;
-  }
+    const string &file = arg->getStringValue("file", "fgfs.sav");
+
+    if (!fgValidatePath(file.c_str(), false)) {
+        SG_LOG(SG_IO, SG_ALERT, "load: reading '" << file << "' denied "
+                "(unauthorized access)");
+        return false;
+    }
+
+    ifstream input(file.c_str());
+    if (input.good() && fgLoadFlight(input)) {
+        input.close();
+        SG_LOG(SG_INPUT, SG_INFO, "Restored flight from " << file);
+        return true;
+    } else {
+        SG_LOG(SG_INPUT, SG_WARN, "Cannot load flight from " << file);
+        return false;
+    }
 }
 
 
@@ -342,18 +349,25 @@ do_load (const SGPropertyNode * arg)
 static bool
 do_save (const SGPropertyNode * arg)
 {
-  const string &file = arg->getStringValue("file", "fgfs.sav");
-  bool write_all = arg->getBoolValue("write-all", false);
-  SG_LOG(SG_INPUT, SG_INFO, "Saving flight");
-  ofstream output(file.c_str());
-  if (output.good() && fgSaveFlight(output, write_all)) {
-    output.close();
-    SG_LOG(SG_INPUT, SG_INFO, "Saved flight to " << file);
-    return true;
-  } else {
-    SG_LOG(SG_INPUT, SG_ALERT, "Cannot save flight to " << file);
-    return false;
-  }
+    const string &file = arg->getStringValue("file", "fgfs.sav");
+
+    if (!fgValidatePath(file.c_str(), false)) {
+        SG_LOG(SG_IO, SG_ALERT, "save: reading '" << file << "' denied "
+                "(unauthorized access)");
+        return false;
+    }
+
+    bool write_all = arg->getBoolValue("write-all", false);
+    SG_LOG(SG_INPUT, SG_INFO, "Saving flight");
+    ofstream output(file.c_str());
+    if (output.good() && fgSaveFlight(output, write_all)) {
+        output.close();
+        SG_LOG(SG_INPUT, SG_INFO, "Saved flight to " << file);
+        return true;
+    } else {
+        SG_LOG(SG_INPUT, SG_ALERT, "Cannot save flight to " << file);
+        return false;
+    }
 }
 
 
@@ -1336,6 +1350,12 @@ do_load_xml_to_proptree(const SGPropertyNode * arg)
     if (file.extension() != "xml")
         file.concat(".xml");
 
+    if (!fgValidatePath(file.c_str(), false)) {
+        SG_LOG(SG_IO, SG_ALERT, "loadxml: reading '" << file.str() << "' denied "
+                "(unauthorized access)");
+        return false;
+    }
+
     SGPropertyNode *targetnode;
     if (arg->hasValue("targetnode"))
         targetnode = fgGetNode(arg->getStringValue("targetnode"), true);
@@ -1349,7 +1369,7 @@ do_load_xml_to_proptree(const SGPropertyNode * arg)
         return false;
     }
 
-    return  true;
+    return true;
 }
 
 
@@ -1376,6 +1396,12 @@ do_save_xml_from_proptree(const SGPropertyNode * arg)
     if (file.extension() != "xml")
         file.concat(".xml");
 
+    if (!fgValidatePath(file.c_str(), true)) {
+        SG_LOG(SG_IO, SG_ALERT, "savexml: writing to '" << file.str() << "' denied "
+                "(unauthorized access)");
+        return false;
+    }
+
     SGPropertyNode *sourcenode;
     if (arg->hasValue("sourcenode"))
         sourcenode = fgGetNode(arg->getStringValue("sourcenode"), true);

src/Main/main.cxx

@@ -81,6 +81,7 @@
 #include "renderer.hxx"
 #include "splash.hxx"
 #include "main.hxx"
+#include "util.hxx"
 
 
 static double real_delta_time_sec = 0.0;
@@ -984,6 +985,7 @@ bool fgMainInit( int argc, char **argv ) {
     string_list *col = new string_list;
     globals->set_channel_options_list( col );
 
+    fgValidatePath("", false);  // initialize static variables
     upper_case_property("/sim/presets/airport-id");
     upper_case_property("/sim/presets/runway");
     upper_case_property("/sim/tower/airport-id");

src/Main/util.cxx

@@ -147,7 +147,7 @@ fgGetLowPass (double current, double target, double timeratio)
 
 
 string
-fgUnescape(const char *s)
+fgUnescape (const char *s)
 {
     string r;
     while (*s) {
@@ -197,5 +197,19 @@ fgUnescape(const char *s)
     return r;
 }
 
+
+const char *fgValidatePath (const char *str, bool write)
+{
+    static SGPropertyNode_ptr r, w;
+    if (!r) {
+        r = fgGetNode("/sim/paths/validate/read", true);
+        w = fgGetNode("/sim/paths/validate/write", true);
+    }
+    SGPropertyNode *prop = write ? w : r;
+    prop->setStringValue(str);
+    const char *result = prop->getStringValue();
+    return result[0] ? result : 0;
+}
+
 // end of util.cxx
 

src/Main/util.hxx

@@ -83,4 +83,12 @@ extern double fgGetLowPass (double current, double target, double timeratio);
 extern std::string fgUnescape (const char *str);
 
 
+/**
+ * Validation listener interface for io.nas, used by fgcommands.
+ * @param path Path to be validated
+ * @param write True for write operations and false for read operations.
+ * @return The validated path on success or 0 if access denied.
+ */
+extern const char *fgValidatePath (const char *path, bool write);
+
 #endif // __UTIL_HXX