src/basic/bus-label.c

   1 /* SPDX-License-Identifier: LGPL-2.1-or-later */
   2
   3 #include <stdlib.h>
   4
   5 #include "alloc-util.h"
   6 #include "bus-label.h"
   7 #include "hexdecoct.h"
   8 #include "macro.h"
   9
  10 char *bus_label_escape(const char *s) {
  11         char *r, *t;
  12         const char *f;
  13
  14         assert_return(s, NULL);
  15
  16         /* Escapes all chars that D-Bus' object path cannot deal
  17          * with. Can be reversed with bus_path_unescape(). We special
  18          * case the empty string. */
  19
  20         if (*s == 0)
  21                 return strdup("_");
  22
  23         r = new(char, strlen(s)*3 + 1);
  24         if (!r)
  25                 return NULL;
  26
  27         for (f = s, t = r; *f; f++) {
  28
  29                 /* Escape everything that is not a-zA-Z0-9. We also
  30                  * escape 0-9 if it's the first character */
  31
  32                 if (!(*f >= 'A' && *f <= 'Z') &&
  33                     !(*f >= 'a' && *f <= 'z') &&
  34                     !(f > s && *f >= '0' && *f <= '9')) {
  35                         *(t++) = '_';
  36                         *(t++) = hexchar(*f >> 4);
  37                         *(t++) = hexchar(*f);
  38                 } else
  39                         *(t++) = *f;
  40         }
  41
  42         *t = 0;
  43
  44         return r;
  45 }
  46
  47 char *bus_label_unescape_n(const char *f, size_t l) {
  48         char *r, *t;
  49         size_t i;
  50
  51         assert_return(f, NULL);
  52
  53         /* Special case for the empty string */
  54         if (l == 1 && *f == '_')
  55                 return strdup("");
  56
  57         r = new(char, l + 1);
  58         if (!r)
  59                 return NULL;
  60
  61         for (i = 0, t = r; i < l; ++i) {
  62                 if (f[i] == '_') {
  63                         int a, b;
  64
  65                         if (l - i < 3 ||
  66                             (a = unhexchar(f[i + 1])) < 0 ||
  67                             (b = unhexchar(f[i + 2])) < 0) {
  68                                 /* Invalid escape code, let's take it literal then */
  69                                 *(t++) = '_';
  70                         } else {
  71                                 *(t++) = (char) ((a << 4) | b);
  72                                 i += 2;
  73                         }
  74                 } else
  75                         *(t++) = f[i];
  76         }
  77
  78         *t = 0;
  79
  80         return r;
  81 }