1 | /* vi: set sw=4 ts=4: */
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2 | /*
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3 | * Utility routines.
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4 | *
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5 | * Copyright (C) Manuel Novoa III <mjn3@codepoet.org>
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6 | * and Vladimir Oleynik <dzo@simtreas.ru>
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7 | *
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8 | * Licensed under GPLv2 or later, see file LICENSE in this source tree.
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9 | */
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10 |
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11 | #include "libbb.h"
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12 |
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13 | #define WANT_HEX_ESCAPES 1
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14 |
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15 | /* Usual "this only works for ascii compatible encodings" disclaimer. */
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16 | #undef _tolower
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17 | #define _tolower(X) ((X)|((char) 0x20))
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18 |
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19 | char FAST_FUNC bb_process_escape_sequence(const char **ptr)
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20 | {
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21 | const char *q;
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22 | unsigned num_digits;
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23 | unsigned n;
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24 | unsigned base;
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25 |
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26 | num_digits = n = 0;
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27 | base = 8;
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28 | q = *ptr;
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29 |
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30 | if (WANT_HEX_ESCAPES && *q == 'x') {
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31 | ++q;
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32 | base = 16;
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33 | ++num_digits;
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34 | }
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35 |
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36 | /* bash requires leading 0 in octal escapes:
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37 | * \02 works, \2 does not (prints \ and 2).
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38 | * We treat \2 as a valid octal escape sequence. */
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39 | do {
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40 | unsigned r;
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41 | #if !WANT_HEX_ESCAPES
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42 | unsigned d = (unsigned char)(*q) - '0';
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43 | #else
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44 | unsigned d = (unsigned char)_tolower(*q) - '0';
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45 | if (d >= 10)
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46 | d += ('0' - 'a' + 10);
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47 | #endif
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48 | if (d >= base) {
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49 | if (WANT_HEX_ESCAPES && base == 16) {
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50 | --num_digits;
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51 | if (num_digits == 0) {
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52 | /* \x<bad_char>: return '\',
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53 | * leave ptr pointing to x */
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54 | return '\\';
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55 | }
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56 | }
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57 | break;
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58 | }
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59 |
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60 | r = n * base + d;
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61 | if (r > UCHAR_MAX) {
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62 | break;
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63 | }
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64 |
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65 | n = r;
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66 | ++q;
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67 | } while (++num_digits < 3);
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68 |
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69 | if (num_digits == 0) {
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70 | /* Not octal or hex escape sequence.
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71 | * Is it one-letter one? */
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72 |
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73 | /* bash builtin "echo -e '\ec'" interprets \e as ESC,
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74 | * but coreutils "/bin/echo -e '\ec'" does not.
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75 | * Manpages tend to support coreutils way.
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76 | * Update: coreutils added support for \e on 28 Oct 2009. */
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77 | static const char charmap[] ALIGN1 = {
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78 | 'a', 'b', 'e', 'f', 'n', 'r', 't', 'v', '\\', '\0',
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79 | '\a', '\b', 27, '\f', '\n', '\r', '\t', '\v', '\\', '\\',
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80 | };
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81 | const char *p = charmap;
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82 | do {
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83 | if (*p == *q) {
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84 | q++;
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85 | break;
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86 | }
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87 | } while (*++p != '\0');
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88 | /* p points to found escape char or NUL,
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89 | * advance it and find what it translates to.
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90 | * Note that \NUL and unrecognized sequence \z return '\'
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91 | * and leave ptr pointing to NUL or z. */
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92 | n = p[sizeof(charmap) / 2];
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93 | }
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94 |
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95 | *ptr = q;
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96 |
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97 | return (char) n;
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98 | }
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99 |
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100 | char* FAST_FUNC strcpy_and_process_escape_sequences(char *dst, const char *src)
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101 | {
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102 | while (1) {
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103 | char c, c1;
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104 | c = c1 = *src++;
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105 | if (c1 == '\\')
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106 | c1 = bb_process_escape_sequence(&src);
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107 | *dst = c1;
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108 | if (c == '\0')
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109 | return dst;
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110 | dst++;
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111 | }
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112 | }
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