usr/src/boot/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
  17 #include <sys/cdefs.h>
  18 __FBSDID("$FreeBSD$");
  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.
  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
  45     if ((new_str = strdup(str)) == NULL)
  46         return NULL;
  47
  48     while (*str) {
  49         if (seenbs) {
  50             seenbs = 0;
  51             switch (*str) {
  52             case '\\':
  53                 new_str[i++] = '\\';
  54                 str++;
  55                 break;
  56
  57             /* preserve backslashed quotes, dollar signs */
  58             case '\'':
  59             case '"':
  60             case '$':
  61                 new_str[i++] = '\\';
  62                 new_str[i++] = *str++;
  63                 break;
  64
  65             case 'b':
  66                 new_str[i++] = '\b';
  67                 str++;
  68                 break;
  69
  70             case 'f':
  71                 new_str[i++] = '\f';
  72                 str++;
  73                 break;
  74
  75             case 'r':
  76                 new_str[i++] = '\r';
  77                 str++;
  78                 break;
  79
  80             case 'n':
  81                 new_str[i++] = '\n';
  82                 str++;
  83                 break;
  84
  85             case 's':
  86                 new_str[i++] = ' ';
  87                 str++;
  88                 break;
  89
  90             case 't':
  91                 new_str[i++] = '\t';
  92                 str++;
  93                 break;
  94
  95             case 'v':
  96                 new_str[i++] = '\13';
  97                 str++;
  98                 break;
  99
 100             case 'z':
 101                 str++;
 102                 break;
 103
 104             case '0': case '1': case '2': case '3': case '4':
 105             case '5': case '6': case '7': case '8': case '9': {
 106                 char val;
 107
 108                 /* Three digit octal constant? */
 109                 if (*str >= '0' && *str <= '3' &&
 110                     *(str + 1) >= '0' && *(str + 1) <= '7' &&
 111                     *(str + 2) >= '0' && *(str + 2) <= '7') {
 112
 113                     val = (DIGIT(*str) << 6) + (DIGIT(*(str + 1)) << 3) +
 114                         DIGIT(*(str + 2));
 115
 116                     /* Allow null value if user really wants to shoot
 117                        at feet, but beware! */
 118                     new_str[i++] = val;
 119                     str += 3;
 120                     break;
 121                 }
 122
 123                 /* One or two digit hex constant?
 124                  * If two are there they will both be taken.
 125                  * Use \z to split them up if this is not wanted.
 126                  */
 127                 if (*str == '0' &&
 128                     (*(str + 1) == 'x' || *(str + 1) == 'X') &&
 129                     isxdigit(*(str + 2))) {
 130                     val = DIGIT(*(str + 2));
 131                     if (isxdigit(*(str + 3))) {
 132                         val = (val << 4) + DIGIT(*(str + 3));
 133                         str += 4;
 134                     }
 135                     else
 136                         str += 3;
 137                     /* Yep, allow null value here too */
 138                     new_str[i++] = val;
 139                     break;
 140                 }
 141             }
 142             break;
 143
 144             default:
 145                 new_str[i++] = *str++;
 146                 break;
 147             }
 148         }
 149         else {
 150             if (*str == '\\') {
 151                 seenbs = 1;
 152                 str++;
 153             }
 154             else
 155                 new_str[i++] = *str++;
 156         }
 157     }
 158
 159     if (seenbs) {
 160         /*
 161          * The final character was a '\'. Put it in as a single backslash.
 162          */
 163         new_str[i++] = '\\';
 164     }
 165     new_str[i] = '\0';
 166     return new_str;
 167 }