src/acl.sml

   1 (* HCoop Domtool (http://hcoop.sourceforge.net/)
   2  * Copyright (c) 2006, Adam Chlipala
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public License
   6  * as published by the Free Software Foundation; either version 2
   7  * of the License, or (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
  17  *)
  18
  19 (* Per-user access control lists for resources various *)
  20
  21 structure Acl :> ACL = struct
  22
  23 type acl = {user : string,
  24             class : string,
  25             value : string}
  26
  27 structure SM = DataStructures.StringMap
  28 structure SS = DataStructures.StringSet
  29
  30 val acl : SS.set SM.map SM.map ref = ref SM.empty
  31
  32 fun query {user, class, value} =
  33     case SM.find (!acl, user) of
  34         NONE => false
  35       | SOME classes =>
  36         case SM.find (classes, class) of
  37             NONE => false
  38           | SOME values => SS.member (values, value)
  39
  40 fun queryAll user =
  41     case SM.find (!acl, user) of
  42         NONE => []
  43       | SOME classes => SM.foldri (fn (class, values, out) =>
  44                                       (class, SS.foldr (op::) [] values) :: out)
  45                                   [] classes
  46
  47 fun users () = SM.foldri (fn (user, _, ls) => user :: ls) [] (!acl)
  48
  49 fun whoHas {class, value} =
  50     SM.foldri (fn (user, classes, users) =>
  51                   case SM.find (classes, class) of
  52                       NONE => users
  53                     | SOME values =>
  54                       if SS.member (values, value) then
  55                           user :: users
  56                       else
  57                           users) [] (!acl)
  58
  59 fun class {user, class} =
  60     case SM.find (!acl, user) of
  61         NONE => SS.empty
  62       | SOME classes =>
  63         case SM.find (classes, class) of
  64             NONE => SS.empty
  65           | SOME values => values
  66
  67 fun rmuser user =
  68     (acl := #1 (SM.remove (!acl, user)))
  69     handle NotFound => ()
  70
  71 fun grant {user, class, value} =
  72     let
  73         val classes = Option.getOpt (SM.find (!acl, user), SM.empty)
  74         val values = Option.getOpt (SM.find (classes, class), SS.empty)
  75     in
  76         acl := SM.insert (!acl, user,
  77                           SM.insert (classes, class,
  78                                      SS.add (values, value)))
  79     end
  80
  81 fun revoke {user, class, value} =
  82     let
  83         val classes = Option.getOpt (SM.find (!acl, user), SM.empty)
  84         val values = Option.getOpt (SM.find (classes, class), SS.empty)
  85
  86         val values = if SS.member (values, value) then
  87                          SS.delete (values, value)
  88                      else
  89                          values
  90     in
  91         acl := SM.insert (!acl, user,
  92                           SM.insert (classes, class,
  93                                      values))
  94     end
  95
  96 fun revokeFromAll {class, value} =
  97     acl := SM.map (fn classes =>
  98                       case SM.find (classes, class) of
  99                           NONE => classes
 100                         | SOME values =>
 101                           ((SM.insert (classes, class, SS.delete (values, value)))
 102                            handle NotFound => classes)) (!acl)
 103
 104 fun read fname =
 105     let
 106         val inf = TextIO.openIn fname
 107
 108         fun users usrs =
 109             case TextIO.inputLine inf of
 110                 NONE => usrs
 111               | SOME line =>
 112                 case String.tokens Char.isSpace line of
 113                     [user] =>
 114                     let
 115                         fun classes clss =
 116                             case TextIO.inputLine inf of
 117                                 NONE => clss
 118                               | SOME line =>
 119                                 case String.tokens Char.isSpace line of
 120                                     [] => clss
 121                                   | class :: values =>
 122                                     classes (SM.insert (clss, class,
 123                                                         foldl SS.add' SS.empty values))
 124                     in
 125                         users (SM.insert (usrs, user, classes SM.empty))
 126                     end
 127                   | _ => raise Fail "Unexpected ACL file format"
 128     in
 129         acl := users SM.empty
 130         before TextIO.closeIn inf
 131     end
 132
 133 fun write fname =
 134     let
 135         val outf = TextIO.openOut fname
 136
 137         val writeValues = SS.app (fn value =>
 138                                      (TextIO.output (outf, " ");
 139                                       TextIO.output (outf, value)))
 140
 141         val writeClasses = SM.appi (fn (class, values) =>
 142                                        if SS.isEmpty values then
 143                                            ()
 144                                        else
 145                                            (TextIO.output (outf, class);
 146                                             writeValues values;
 147                                             TextIO.output (outf, "\n")))
 148
 149         val writeUsers = SM.appi (fn (user, classes) =>
 150                                      if SM.numItems classes = 0 then
 151                                          ()
 152                                      else
 153                                          (TextIO.output (outf, user);
 154                                           TextIO.output (outf, "\n");
 155                                           writeClasses classes;
 156                                           TextIO.output (outf, "\n")))
 157     in
 158         writeUsers (!acl);
 159         TextIO.closeOut outf
 160     end
 161
 162 end