Bug#656844: apt: support #clear directive in CommandLine parser

[Daniel Hartwig <mandyke@gmail.com>]

Package: apt
Severity: wishlist
Usertags: push


Patch to add support for clearing configuration items from the command-line:

 $ apt-config -o Foo::Bar=1 -o "#clear Foo::Bar" dump | grep ^Foo
 Foo "";
 Foo::Bar "";

=== modified file 'apt-pkg/contrib/cmndline.cc'
--- apt-pkg/contrib/cmndline.cc	2011-09-21 16:42:08 +0000
+++ apt-pkg/contrib/cmndline.cc	2012-01-22 08:49:03 +0000
@@ -192,6 +192,24 @@
       // Arbitrary item specification
       if ((A->Flags & ArbItem) == ArbItem)
       {
+         // Specials
+         if (strlen(Argument) >= 1 && Argument[0] == '#')
+         {
+            const char *I = strchrnul(Argument, ' ');
+            const string Dir(Argument+1,I);
+
+            if (Dir == "clear")
+            {
+               if (*I != ' ' || *(I+1) == 0)
+                  return _error->Error(_("Syntax error %s:%u: clear directive requires an option tree as argument"),"",0);
+               Conf->Clear(string(I+1));
+            }
+            else
+               return _error->Error(_("Syntax error %s:%u: Unsupported directive '%s'"),"",0,Dir.c_str());
+
+            return true;
+         }
+
 	 const char *J = strchr(Argument, '=');
 	 if (J == NULL)
 	    return _error->Error(_("Option %s: Configuration item specification must have an =<val>."),argv[I]);