Function filename_unescape

src/cksum.c:731–777

   than "n" or another backslash, return NULL.  */

static char *
filename_unescape (char *s, idx_t s_len)
{
  char *dst = s;

  for (idx_t i = 0; i < s_len; i++)
    {
      switch (s[i])
        {
        case '\\':
          if (i == s_len - 1)
            {
              /* File name ends with an unescaped backslash: invalid.  */
              return NULL;
            }
          ++i;
          switch (s[i])
            {
            case 'n':
              *dst++ = '\n';
              break;
            case 'r':
              *dst++ = '\r';
              break;
            case '\\':
              *dst++ = '\\';
              break;
            default:
              /* Only '\', 'n' or 'r' may follow a backslash.  */
              return NULL;
            }
          break;

        case '\0':
          /* The file name may not contain a NUL.  */
          return NULL;

        default:
          *dst++ = s[i];
          break;
        }
    }
  if (dst < s + s_len)
    *dst = '\0';

  return s;
}

/* Return true if S is a LEN-byte NUL-terminated string of hex or base64
   digits and has the expected length.  Otherwise, return false.  */