Added sanity checks to user and system file paths in case they don't exist.

src/binwalk/core/parser.py

@@ -145,10 +145,11 @@ class MagicParser(object):
             files = [file_name]
 
         for fname in files:
-            if os.path.exists(fname):
-                self.parse_file(fname)
-            else:
-                sys.stdout.write("WARNING: Magic file '%s' does not exist!\n" % fname)
+            if fname:
+                if os.path.exists(fname):
+                    self.parse_file(fname)
+                else:
+                    sys.stdout.write("WARNING: Magic file '%s' does not exist!\n" % fname)
 
         self.fd.seek(0)
         return self.fd.name

src/binwalk/core/settings.py

@@ -41,7 +41,7 @@ class Settings:
 
         # Dictionary of all absolute user/system file paths
         self.paths = {
-            'user'        : {},
+            'user'      : {},
             'system'    : {},
         }
 
@@ -59,6 +59,19 @@ class Settings:
         self.paths['system'][self.EXTRACT_FILE] = self._system_path(self.BINWALK_CONFIG_DIR, self.EXTRACT_FILE)
         self.paths['system'][self.PLUGINS] = self._system_path(self.BINWALK_PLUGINS_DIR)
 
+    def get_file_path(self, usersys, fname):
+        '''
+        Retrieves the specified file path from self.paths.
+
+        @usersys - One of: 'user', 'system'.
+        @fname   - The file name (e.g., self.BINWALK_MAGIC_FILE, self.PLUGINS, etc)
+
+        Returns the path, if it exists; returns None otherwise.
+        '''
+        if self.paths.has_key(usersys) and has_key(self.paths[usersys], fname) and self.paths[usersys][fname]:
+            return self.paths[usersys][fname]
+        return None
+
     def find_magic_file(self, fname, system_only=False, user_only=False):
         '''
         Finds the specified magic file name in the system / user magic file directories.
@@ -149,7 +162,12 @@ class Settings:
 
         Returns the full path to the 'subdir/basename' file.
         '''
-        return self._file_path(os.path.join(self.user_dir, self.BINWALK_USER_DIR, subdir), basename)
+        try:
+            return self._file_path(os.path.join(self.user_dir, self.BINWALK_USER_DIR, subdir), basename)
+        except KeyboardInterrupt as e :
+            raise e
+        except Exception:
+            return None
 
     def _system_path(self, subdir, basename=''):
         '''
@@ -160,5 +178,10 @@ class Settings:
         
         Returns the full path to the 'subdir/basename' file.
         '''
-        return self._file_path(os.path.join(self.system_dir, subdir), basename)
+        try:
+            return self._file_path(os.path.join(self.system_dir, subdir), basename)
+        except KeyboardInterrupt as e :
+            raise e
+        except Exception:
+            return None
 

src/binwalk/modules/extractor.py

@@ -258,18 +258,19 @@ class Extractor(Module):
         '''
         # Load the user extract file first to ensure its rules take precedence.
         extract_files = [
-            self.config.settings.paths['user'][self.config.settings.EXTRACT_FILE],
-            self.config.settings.paths['system'][self.config.settings.EXTRACT_FILE],
+            self.config.settings.get_file_path('user', self.config.settings.EXTRACT_FILE),
+            self.config.settings.get_file_path('system', self.config.settings.EXTRACT_FILE),
         ]
 
         for extract_file in extract_files:
-            try:
-                self.load_from_file(extract_file)
-            except KeyboardInterrupt as e:
-                raise e
-            except Exception as e:
-                if self.config.verbose:
-                    raise Exception("Extractor.load_defaults failed to load file '%s': %s" % (extract_file, str(e)))
+            if extract_file:
+                try:
+                    self.load_from_file(extract_file)
+                except KeyboardInterrupt as e:
+                    raise e
+                except Exception as e:
+                    if self.config.verbose:
+                        raise Exception("Extractor.load_defaults failed to load file '%s': %s" % (extract_file, str(e)))
 
     def build_output_directory(self, path):
         '''

src/binwalk/modules/signature.py

@@ -62,21 +62,21 @@ class Signature(Module):
         # Append the user's magic file first so that those signatures take precedence
         if self.search_for_opcodes:
             self.magic_files += [
-                    self.config.settings.paths['user'][self.config.settings.BINARCH_MAGIC_FILE],
-                    self.config.settings.paths['system'][self.config.settings.BINARCH_MAGIC_FILE],
+                    self.config.settings.get_file_path('user', self.config.settings.BINARCH_MAGIC_FILE),
+                    self.config.settings.get_file_path('system', self.config.settings.BINARCH_MAGIC_FILE),
             ]
 
         if self.cast_data_types:
             self.magic_files += [
-                    self.config.settings.paths['user'][self.config.settings.BINCAST_MAGIC_FILE],
-                    self.config.settings.paths['system'][self.config.settings.BINCAST_MAGIC_FILE],
+                    self.config.settings.get_file_path('user', self.config.settings.BINCAST_MAGIC_FILE),
+                    self.config.settings.get_file_path('system', self.config.settings.BINCAST_MAGIC_FILE),
             ]
 
         # Use the system default magic file if no other was specified, or if -B was explicitly specified
         if not self.magic_files or self.force_default_scan:
             self.magic_files += [
-                    self.config.settings.paths['user'][self.config.settings.BINWALK_MAGIC_FILE],
-                    self.config.settings.paths['system'][self.config.settings.BINWALK_MAGIC_FILE],
+                    self.config.settings.get_file_path('user', self.config.settings.BINWALK_MAGIC_FILE),
+                    self.config.settings.get_file_path('system', self.config.settings.BINWALK_MAGIC_FILE),
             ]
 
         # Parse the magic file(s) and initialize libmagic