src/basic/bus-label.c

   1 /***
   2   This file is part of systemd.
   3
   4   Copyright 2013 Lennart Poettering
   5
   6   systemd is free software; you can redistribute it and/or modify it
   7   under the terms of the GNU Lesser General Public License as published by
   8   the Free Software Foundation; either version 2.1 of the License, or
   9   (at your option) any later version.
  10
  11   systemd is distributed in the hope that it will be useful, but
  12   WITHOUT ANY WARRANTY; without even the implied warranty of
  13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14   Lesser General Public License for more details.
  15
  16   You should have received a copy of the GNU Lesser General Public License
  17   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  18 ***/
  19
  20 #include <stdlib.h>
  21
  22 #include "alloc-util.h"
  23 #include "bus-label.h"
  24 #include "hexdecoct.h"
  25 #include "macro.h"
  26
  27 char *bus_label_escape(const char *s) {
  28         char *r, *t;
  29         const char *f;
  30
  31         assert_return(s, NULL);
  32
  33         /* Escapes all chars that D-Bus' object path cannot deal
  34          * with. Can be reversed with bus_path_unescape(). We special
  35          * case the empty string. */
  36
  37         if (*s == 0)
  38                 return strdup("_");
  39
  40         r = new(char, strlen(s)*3 + 1);
  41         if (!r)
  42                 return NULL;
  43
  44         for (f = s, t = r; *f; f++) {
  45
  46                 /* Escape everything that is not a-zA-Z0-9. We also
  47                  * escape 0-9 if it's the first character */
  48
  49                 if (!(*f >= 'A' && *f <= 'Z') &&
  50                     !(*f >= 'a' && *f <= 'z') &&
  51                     !(f > s && *f >= '0' && *f <= '9')) {
  52                         *(t++) = '_';
  53                         *(t++) = hexchar(*f >> 4);
  54                         *(t++) = hexchar(*f);
  55                 } else
  56                         *(t++) = *f;
  57         }
  58
  59         *t = 0;
  60
  61         return r;
  62 }
  63
  64 char *bus_label_unescape_n(const char *f, size_t l) {
  65         char *r, *t;
  66         size_t i;
  67
  68         assert_return(f, NULL);
  69
  70         /* Special case for the empty string */
  71         if (l == 1 && *f == '_')
  72                 return strdup("");
  73
  74         r = new(char, l + 1);
  75         if (!r)
  76                 return NULL;
  77
  78         for (i = 0, t = r; i < l; ++i) {
  79                 if (f[i] == '_') {
  80                         int a, b;
  81
  82                         if (l - i < 3 ||
  83                             (a = unhexchar(f[i + 1])) < 0 ||
  84                             (b = unhexchar(f[i + 2])) < 0) {
  85                                 /* Invalid escape code, let's take it literal then */
  86                                 *(t++) = '_';
  87                         } else {
  88                                 *(t++) = (char) ((a << 4) | b);
  89                                 i += 2;
  90                         }
  91                 } else
  92                         *(t++) = f[i];
  93         }
  94
  95         *t = 0;
  96
  97         return r;
  98 }