sys/boot/common/interp_backslash.c

   1 /*-
   2  * Redistribution and use in source and binary forms, with or without
   3  * modification, are permitted provided that the following conditions
   4  * are met:
   5  * 1. Redistributions of source code must retain the above copyright
   6  *    notice, this list of conditions and the following disclaimer.
   7  * 2. Redistributions in binary form must reproduce the above copyright
   8  *    notice, this list of conditions and the following disclaimer in the
   9  *    documentation and/or other materials provided with the distribution.
  10  *
  11  * Jordan K. Hubbard
  12  * 29 August 1998
  13  *
  14  * Routine for doing backslash elimination.
  15  *
  16  * $FreeBSD: src/sys/boot/common/interp_backslash.c,v 1.6 2003/08/25 23:30:41 obrien Exp $
  17  * $DragonFly: src/sys/boot/common/interp_backslash.c,v 1.3 2003/11/10 06:08:31 dillon Exp $
  18  */
  19
  20 #include <stand.h>
  21 #include <string.h>
  22 #include "bootstrap.h"
  23
  24 #define DIGIT(x) (isdigit(x) ? (x) - '0' : islower(x) ? (x) + 10 - 'a' : (x) + 10 - 'A')
  25
  26 /*
  27  * backslash: Return malloc'd copy of str with all standard "backslash
  28  * processing" done on it.  Original can be free'd if desired.
  29  */
  30 char *
  31 backslash(char *str)
  32 {
  33     /*
  34      * Remove backslashes from the strings. Turn \040 etc. into a single
  35      * character (we allow eight bit values). Currently NUL is not
  36      * allowed.  Also escape as needed.
  37      *
  38      * Turn "\n" and "\t" into '\n' and '\t' characters. Etc.
  39      *
  40      */
  41     char *new_str;
  42     int seenbs = 0;
  43     int i = 0;
  44     int j = 0;
  45
  46     for (i = 0; str[i]; ++i) {
  47         if (str[i] == '\'' ||
  48             str[i] == '"' ||
  49             str[i] == '$') {
  50                 ++j;
  51         }
  52     }
  53     j += i + 2; /* terminator + possible final backslash */
  54
  55     new_str = malloc(j);
  56
  57     i = 0;
  58     while (*str) {
  59         if (seenbs) {
  60             seenbs = 0;
  61             switch (*str) {
  62             case '\\':
  63                 new_str[i++] = '\\';
  64                 str++;
  65                 break;
  66
  67             /* preserve backslashed quotes, dollar signs */
  68             case '\'':
  69             case '"':
  70             case '$':
  71                 new_str[i++] = '\\';
  72                 new_str[i++] = *str++;
  73                 break;
  74
  75             case 'b':
  76                 new_str[i++] = '\b';
  77                 str++;
  78                 break;
  79
  80             case 'f':
  81                 new_str[i++] = '\f';
  82                 str++;
  83                 break;
  84
  85             case 'r':
  86                 new_str[i++] = '\r';
  87                 str++;
  88                 break;
  89
  90             case 'n':
  91                 new_str[i++] = '\n';
  92                 str++;
  93                 break;
  94
  95             case 's':
  96                 new_str[i++] = ' ';
  97                 str++;
  98                 break;
  99
 100             case 't':
 101                 new_str[i++] = '\t';
 102                 str++;
 103                 break;
 104
 105             case 'v':
 106                 new_str[i++] = '\13';
 107                 str++;
 108                 break;
 109
 110             case 'z':
 111                 str++;
 112                 break;
 113
 114             case '0': case '1': case '2': case '3': case '4':
 115             case '5': case '6': case '7': case '8': case '9': {
 116                 char val;
 117
 118                 /* Three digit octal constant? */
 119                 if (*str >= '0' && *str <= '3' &&
 120                     *(str + 1) >= '0' && *(str + 1) <= '7' &&
 121                     *(str + 2) >= '0' && *(str + 2) <= '7') {
 122
 123                     val = (DIGIT(*str) << 6) + (DIGIT(*(str + 1)) << 3) +
 124                         DIGIT(*(str + 2));
 125
 126                     /* Allow null value if user really wants to shoot
 127                        at feet, but beware! */
 128                     new_str[i++] = val;
 129                     str += 3;
 130                     break;
 131                 }
 132
 133                 /* One or two digit hex constant?
 134                  * If two are there they will both be taken.
 135                  * Use \z to split them up if this is not wanted.
 136                  */
 137                 if (*str == '0' &&
 138                     (*(str + 1) == 'x' || *(str + 1) == 'X') &&
 139                     isxdigit(*(str + 2))) {
 140                     val = DIGIT(*(str + 2));
 141                     if (isxdigit(*(str + 3))) {
 142                         val = (val << 4) + DIGIT(*(str + 3));
 143                         str += 4;
 144                     }
 145                     else
 146                         str += 3;
 147                     /* Yep, allow null value here too */
 148                     new_str[i++] = val;
 149                     break;
 150                 }
 151             }
 152             break;
 153
 154             default:
 155                 new_str[i++] = *str++;
 156                 break;
 157             }
 158         }
 159         else {
 160             if (*str == '\\') {
 161                 seenbs = 1;
 162                 str++;
 163             } else {
 164                 new_str[i++] = *str++;
 165             }
 166         }
 167     }
 168
 169     if (seenbs) {
 170         /*
 171          * The final character was a '\'. Put it in as a single backslash.
 172          */
 173         new_str[i++] = '\\';
 174     }
 175     new_str[i] = 0;
 176     if (i >= j)
 177         panic("bls");
 178
 179     return new_str;
 180 }