diplodocus.org Git - nmh/blob - sbr/escape_display_name.c

   1 /*
   2  * escape_display_name.c -- Escape a display name, hopefully per RFC 5322.
   3  *
   4  * This code is Copyright (c) 2012, by the authors of nmh.  See the
   5  * COPYRIGHT file in the root directory of the nmh distribution for
   6  * complete copyright information.
   7  */
   8
   9 #include <sys/types.h>
  10 #include <h/utils.h>
  11 #include <string.h>
  12 #include <stdlib.h>
  13
  14 /* Escape a display name, hopefully per RFC 5322.  Assumes one-byte
  15    characters.  The char array pointed to by the name argument is
  16    modified in place.  Its size is specified by the namesize
  17    argument. */
  18 void
  19 escape_display_name (char *name, size_t namesize) {
  20     /* Quote and escape name that contains any specials, as necessary. */
  21     if (strpbrk("\"(),.:;<>@[\\]", name)) {
  22         char *destp, *srcp;
  23         /* Maximum space requirement would be if each character had
  24            to be escaped, plus enclosing double quotes, plus null termintor.
  25            E.g., 2 characters, "", would require 7, "\"\""0, where that 0
  26            is '\0'. */
  27         char *tmp = mh_xmalloc (2*strlen(name) + 3);
  28
  29         for (destp = tmp, srcp = name; *srcp; ++srcp) {
  30             if (srcp == name) {
  31                 /* Insert initial double quote, if needed. */
  32                 if (*srcp != '"') {
  33                     *destp++ = '"';
  34                 }
  35             } else {
  36                 /* Escape embedded, unescaped double quote. */
  37                 if (*srcp == '"' && *(srcp+1) != '\0' && *(srcp-1) != '\\') {
  38                     *destp++ = '\\';
  39                 }
  40             }
  41
  42             *destp++ = *srcp;
  43
  44             /* End of name. */
  45             if (*(srcp+1) == '\0') {
  46                 /* Insert final double quote, if needed. */
  47                 if (*srcp != '"') {
  48                     *destp++ = '"';
  49                 }
  50
  51                 *destp++ = '\0';
  52             }
  53         }
  54
  55         if (strcmp (tmp, "\"")) {
  56             /* assert (strlen(tmp) + 1 == destp - tmp); */
  57             size_t len = destp - tmp;
  58             strncpy (name, tmp, len <= namesize  ?  len  :  namesize);
  59         } else {
  60             /* Handle just " as special case here instead of above. */
  61             strncpy (name, "\"\\\"\"", namesize);
  62         }
  63
  64         name[namesize - 1] = '\0';
  65
  66         free (tmp);
  67     }
  68 }