release/src/router/busybox/libbb/process_escape_sequence.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * Utility routines.
   4  *
   5  * Copyright (C) Manuel Novoa III <mjn3@codepoet.org>
   6  * and Vladimir Oleynik <dzo@simtreas.ru>
   7  *
   8  * Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
   9  */
  10
  11 #include "libbb.h"
  12
  13 #define WANT_HEX_ESCAPES 1
  14
  15 /* Usual "this only works for ascii compatible encodings" disclaimer. */
  16 #undef _tolower
  17 #define _tolower(X) ((X)|((char) 0x20))
  18
  19 char FAST_FUNC bb_process_escape_sequence(const char **ptr)
  20 {
  21         /* bash builtin "echo -e '\ec'" interprets \e as ESC,
  22          * but coreutils "/bin/echo -e '\ec'" does not.
  23          * manpages tend to support coreutils way. */
  24         static const char charmap[] ALIGN1 = {
  25                 'a',  'b', /*'e',*/ 'f',  'n',  'r',  't',  'v',  '\\', 0,
  26                 '\a', '\b', /*27,*/ '\f', '\n', '\r', '\t', '\v', '\\', '\\' };
  27
  28         const char *p;
  29         const char *q;
  30         unsigned num_digits;
  31         unsigned r;
  32         unsigned n;
  33         unsigned d;
  34         unsigned base;
  35
  36         num_digits = n = 0;
  37         base = 8;
  38         q = *ptr;
  39
  40 #ifdef WANT_HEX_ESCAPES
  41         if (*q == 'x') {
  42                 ++q;
  43                 base = 16;
  44                 ++num_digits;
  45         }
  46 #endif
  47
  48         do {
  49                 d = (unsigned char)(*q) - '0';
  50 #ifdef WANT_HEX_ESCAPES
  51                 if (d >= 10) {
  52                         d = (unsigned char)(_tolower(*q)) - 'a' + 10;
  53                 }
  54 #endif
  55
  56                 if (d >= base) {
  57 #ifdef WANT_HEX_ESCAPES
  58                         if ((base == 16) && (!--num_digits)) {
  59 /*                              return '\\'; */
  60                                 --q;
  61                         }
  62 #endif
  63                         break;
  64                 }
  65
  66                 r = n * base + d;
  67                 if (r > UCHAR_MAX) {
  68                         break;
  69                 }
  70
  71                 n = r;
  72                 ++q;
  73         } while (++num_digits < 3);
  74
  75         if (num_digits == 0) {  /* mnemonic escape sequence? */
  76                 p = charmap;
  77                 do {
  78                         if (*p == *q) {
  79                                 q++;
  80                                 break;
  81                         }
  82                 } while (*++p);
  83                 n = *(p + (sizeof(charmap)/2));
  84         }
  85
  86         *ptr = q;
  87
  88         return (char) n;
  89 }