Implement white-/blacklisting

README.md

@@ -314,11 +314,10 @@ or in any directory above it in the hierarchy (recursively); when the file is
 found, it is loaded (only once!) as a Python module. YCM calls a `FlagsForFile`
 method in that module which should provide it with the information necessary to
 compile the current file. (You can also provide a path to a global
-`.ycm_extra_conf.py` file, which will be used as a fallback. See the Options
-section for more details.)
-To prevent the execution of malicious code from a file you didn't write
-YCM will ask once per module if it is safe to be loaded.
-(This can be disabled. See the Options section.)
+`.ycm_extra_conf.py` file, which will be used as a fallback.)
+To prevent the execution of malicious code from a file you didn't write YCM
+will ask once per module if it is safe to be loaded. This can be disabled and
+you can white-/blacklist files. See the Options section for more details.
 
 
 This system was designed this way so that the user can perform any arbitrary
@@ -665,6 +664,38 @@ Default: `1`
 
     let g:ycm_confirm_extra_conf = 1
 
+### The `g:ycm_extra_conf_globlist` option
+
+This option is a list that may contain several globbing patterns. If a pattern
+starts with a `!` all `.ycm_extra_conf.py` files matching that pattern will be
+blacklisted, that is they won't be loaded and no confirmation dialog will be
+shown. If a pattern does not start with a `!` all files matching that pattern
+will be whitelisted. Note that this option is not used when confirmation is
+disabled using `g:ycm_confirm_extra_conf` and that items earlier in the list
+will take precedence over the later ones.
+
+Rules:
+
+* `*`       matches everything
+* `?`       matches any single character
+* `[seq]`   matches any character in seq
+* `[!seq]`  matches any char not in seq
+
+Example:
+
+    let g:ycm_extra_conf_globlist = ['~/dev/*','!~/*']
+
+* The first rule will match everything contained in the `~/dev` directory so
+  `.ycm_extra_conf.py` files from there will be loaded.
+* The second rule will match everything in the home directory so a
+  `.ycm_extra_conf.py` file from there won't be loaded.
+* As the first rule takes precedence everything in the home directory excluding
+  the `~/dev` directory will be blacklisted.
+
+Default: `[]`
+
+    let g:ycm_extra_conf_globlist = []
+
 ### The `g:ycm_semantic_triggers` option
 
 This option controls the character-based triggers for the various semantic

plugin/youcompleteme.vim

@@ -106,6 +106,9 @@ let g:ycm_global_ycm_extra_conf =
 let g:ycm_confirm_extra_conf =
       \ get( g:, 'ycm_confirm_extra_conf', 1 )
 
+let g:ycm_extra_conf_globlist =
+      \ get( g:, 'ycm_extra_conf_globlist', [] )
+
 let g:ycm_semantic_triggers =
       \ get( g:, 'ycm_semantic_triggers', {
       \   'c' : ['->', '.'],

python/completers/cpp/flags.py

@@ -24,6 +24,7 @@ import random
 import string
 import sys
 import vimsupport
+from fnmatch import fnmatch
 
 YCM_EXTRA_CONF_FILENAME = '.ycm_extra_conf.py'
 NO_EXTRA_CONF_FILENAME_MESSAGE = ('No {0} file detected, so no compile flags '
@@ -108,15 +109,24 @@ class FlagsModules( object ):
 
   @staticmethod
   def ShouldLoad( module_file ):
-    """Checks if a module is safe to be loaded.
-    By default this will ask the user for confirmation."""
-    if module_file == GLOBAL_YCM_EXTRA_CONF_FILE:
+    """Checks if a module is safe to be loaded. By default this will try to
+    decide using a white-/blacklist and ask the user for confirmation as a
+    fallback."""
+
+    if ( module_file == GLOBAL_YCM_EXTRA_CONF_FILE or
+         not vimsupport.GetBoolValue( 'g:ycm_confirm_extra_conf' ) ):
       return True
-    if ( vimsupport.GetBoolValue( 'g:ycm_confirm_extra_conf' ) and
-         not vimsupport.Confirm(
-           CONFIRM_CONF_FILE_MESSAGE.format( module_file ) ) ):
+
+    globlist = vimsupport.GetVariableValue( 'g:ycm_extra_conf_globlist' )
+    for glob in globlist:
+      is_blacklisted = glob[0] == '!'
+      if MatchesGlobPattern( module_file, glob.lstrip('!') ):
+        return not is_blacklisted
+
+    if vimsupport.Confirm( CONFIRM_CONF_FILE_MESSAGE.format( module_file ) ):
+      return True
+    else:
       return False
-    return True
 
   def Load( self, module_file, force = False ):
     """Load and return the module contained in a file.
@@ -211,3 +221,12 @@ def _SpecialClangIncludes():
 
 def _DirectoryOfThisScript():
   return os.path.dirname( os.path.abspath( __file__ ) )
+
+
+def MatchesGlobPattern( filename, glob ):
+  """Returns true if a filename matches a given pattern. A '~' in glob will be
+  expanded to the home directory and checking will be performed using absolute
+  paths. See the documentation of fnmatch for the supported patterns."""
+
+  abspath = os.path.abspath( filename )
+  return fnmatch( abspath, os.path.abspath( os.path.expanduser( glob ) ) )