util: new function checkfilename

checkfilename checks for restrictions on filenames imposed by Mercurial
itself, irrespective of on what platform it is run.

mercurial/dirstate.py

@@ -269,9 +269,7 b' class dirstate(object):'
     def _addpath(self, f, check=False):
         oldstate = self[f]
         if check or oldstate == "r":
-            if '\r' in f or '\n' in f:
-                raise util.Abort(
-                    _("'\\n' and '\\r' disallowed in filenames: %r") % f)
+            util.checkfilename(f)
             if f in self._dirs:
                 raise util.Abort(_('directory %r already in dirstate') % f)
             # shadows

mercurial/util.py

@@ -493,6 +493,11 b' def copyfiles(src, dst, hardlink=None):'
 
     return hardlink, num
 
+def checkfilename(f):
+    '''Check that the filename f is an acceptable filename for a tracked file'''
+    if '\r' in f or '\n' in f:
+        raise Abort(_("'\\n' and '\\r' disallowed in filenames: %r") % f)
+
 _windows_reserved_filenames = '''con prn aux nul
     com1 com2 com3 com4 com5 com6 com7 com8 com9
     lpt1 lpt2 lpt3 lpt4 lpt5 lpt6 lpt7 lpt8 lpt9'''.split()