src/basic/bus-label.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2 /***
   3   Copyright 2013 Lennart Poettering
   4 ***/
   5
   6 #include <stdlib.h>
   7
   8 #include "alloc-util.h"
   9 #include "bus-label.h"
  10 #include "hexdecoct.h"
  11 #include "macro.h"
  12
  13 char *bus_label_escape(const char *s) {
  14         char *r, *t;
  15         const char *f;
  16
  17         assert_return(s, NULL);
  18
  19         /* Escapes all chars that D-Bus' object path cannot deal
  20          * with. Can be reversed with bus_path_unescape(). We special
  21          * case the empty string. */
  22
  23         if (*s == 0)
  24                 return strdup("_");
  25
  26         r = new(char, strlen(s)*3 + 1);
  27         if (!r)
  28                 return NULL;
  29
  30         for (f = s, t = r; *f; f++) {
  31
  32                 /* Escape everything that is not a-zA-Z0-9. We also
  33                  * escape 0-9 if it's the first character */
  34
  35                 if (!(*f >= 'A' && *f <= 'Z') &&
  36                     !(*f >= 'a' && *f <= 'z') &&
  37                     !(f > s && *f >= '0' && *f <= '9')) {
  38                         *(t++) = '_';
  39                         *(t++) = hexchar(*f >> 4);
  40                         *(t++) = hexchar(*f);
  41                 } else
  42                         *(t++) = *f;
  43         }
  44
  45         *t = 0;
  46
  47         return r;
  48 }
  49
  50 char *bus_label_unescape_n(const char *f, size_t l) {
  51         char *r, *t;
  52         size_t i;
  53
  54         assert_return(f, NULL);
  55
  56         /* Special case for the empty string */
  57         if (l == 1 && *f == '_')
  58                 return strdup("");
  59
  60         r = new(char, l + 1);
  61         if (!r)
  62                 return NULL;
  63
  64         for (i = 0, t = r; i < l; ++i) {
  65                 if (f[i] == '_') {
  66                         int a, b;
  67
  68                         if (l - i < 3 ||
  69                             (a = unhexchar(f[i + 1])) < 0 ||
  70                             (b = unhexchar(f[i + 2])) < 0) {
  71                                 /* Invalid escape code, let's take it literal then */
  72                                 *(t++) = '_';
  73                         } else {
  74                                 *(t++) = (char) ((a << 4) | b);
  75                                 i += 2;
  76                         }
  77                 } else
  78                         *(t++) = f[i];
  79         }
  80
  81         *t = 0;
  82
  83         return r;
  84 }