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interp_backslash.c revision 1.1.4.3 
      1 /*	$NetBSD: interp_backslash.c,v 1.1.4.3 2006/05/11 23:26:48 elad Exp $	*/
      2 
      3 /*-
      4  * Redistribution and use in source and binary forms, with or without
      5  * modification, are permitted provided that the following conditions
      6  * are met:
      7  * 1. Redistributions of source code must retain the above copyright
      8  *    notice, this list of conditions and the following disclaimer.
      9  * 2. Redistributions in binary form must reproduce the above copyright
     10  *    notice, this list of conditions and the following disclaimer in the
     11  *    documentation and/or other materials provided with the distribution.
     12  *
     13  * Jordan K. Hubbard
     14  * 29 August 1998
     15  *
     16  * Routine for doing backslash elimination.
     17  */
     18 
     19 #include <sys/cdefs.h>
     20 /* __FBSDID("$FreeBSD: src/sys/boot/common/interp_backslash.c,v 1.6 2003/08/25 23:30:41 obrien Exp $"); */
     21 
     22 #include <lib/libsa/stand.h>
     23 #include <lib/libkern/libkern.h>
     24 
     25 #include "bootstrap.h"
     26 
     27 #define DIGIT(x) (isdigit(x) ? (x) - '0' : islower(x) ? (x) + 10 - 'a' : (x) + 10 - 'A')
     28 
     29 /*
     30  * backslash: Return malloc'd copy of str with all standard "backslash
     31  * processing" done on it.  Original can be free'd if desired.
     32  */
     33 char *
     34 backslash(char *str)
     35 {
     36     /*
     37      * Remove backslashes from the strings. Turn \040 etc. into a single
     38      * character (we allow eight bit values). Currently NUL is not
     39      * allowed.
     40      *
     41      * Turn "\n" and "\t" into '\n' and '\t' characters. Etc.
     42      *
     43      */
     44     char *new_str;
     45     int seenbs = 0;
     46     int i = 0;
     47 
     48     if ((new_str = strdup(str)) == NULL)
     49 	return NULL;
     50 
     51     while (*str) {
     52 	if (seenbs) {
     53 	    seenbs = 0;
     54 	    switch (*str) {
     55 	    case '\\':
     56 		new_str[i++] = '\\';
     57 		str++;
     58 		break;
     59 
     60 	    /* preserve backslashed quotes, dollar signs */
     61 	    case '\'':
     62 	    case '"':
     63 	    case '$':
     64 		new_str[i++] = '\\';
     65 		new_str[i++] = *str++;
     66 		break;
     67 
     68 	    case 'b':
     69 		new_str[i++] = '\b';
     70 		str++;
     71 		break;
     72 
     73 	    case 'f':
     74 		new_str[i++] = '\f';
     75 		str++;
     76 		break;
     77 
     78 	    case 'r':
     79 		new_str[i++] = '\r';
     80 		str++;
     81 		break;
     82 
     83 	    case 'n':
     84 		new_str[i++] = '\n';
     85 		str++;
     86 		break;
     87 
     88 	    case 's':
     89 		new_str[i++] = ' ';
     90 		str++;
     91 		break;
     92 
     93 	    case 't':
     94 		new_str[i++] = '\t';
     95 		str++;
     96 		break;
     97 
     98 	    case 'v':
     99 		new_str[i++] = '\13';
    100 		str++;
    101 		break;
    102 
    103 	    case 'z':
    104 		str++;
    105 		break;
    106 
    107 	    case '0': case '1': case '2': case '3': case '4':
    108 	    case '5': case '6': case '7': case '8': case '9': {
    109 		char val;
    110 
    111 		/* Three digit octal constant? */
    112 		if (*str >= '0' && *str <= '3' &&
    113 		    *(str + 1) >= '0' && *(str + 1) <= '7' &&
    114 		    *(str + 2) >= '0' && *(str + 2) <= '7') {
    115 
    116 		    val = (DIGIT(*str) << 6) + (DIGIT(*(str + 1)) << 3) +
    117 			DIGIT(*(str + 2));
    118 
    119 		    /* Allow null value if user really wants to shoot
    120                        at feet, but beware! */
    121 		    new_str[i++] = val;
    122 		    str += 3;
    123 		    break;
    124 		}
    125 
    126 		/* One or two digit hex constant?
    127 		 * If two are there they will both be taken.
    128 		 * Use \z to split them up if this is not wanted.
    129 		 */
    130 		if (*str == '0' &&
    131 		    (*(str + 1) == 'x' || *(str + 1) == 'X') &&
    132 		    isxdigit(*(str + 2))) {
    133 		    val = DIGIT(*(str + 2));
    134 		    if (isxdigit(*(str + 3))) {
    135 			val = (val << 4) + DIGIT(*(str + 3));
    136 			str += 4;
    137 		    }
    138 		    else
    139 			str += 3;
    140 		    /* Yep, allow null value here too */
    141 		    new_str[i++] = val;
    142 		    break;
    143 		}
    144 	    }
    145 	    break;
    146 
    147 	    default:
    148 		new_str[i++] = *str++;
    149 		break;
    150 	    }
    151 	}
    152         else {
    153             if (*str == '\\') {
    154                 seenbs = 1;
    155                 str++;
    156             }
    157 	    else
    158 		new_str[i++] = *str++;
    159         }
    160     }
    161 
    162     if (seenbs) {
    163         /*
    164          * The final character was a '\'. Put it in as a single backslash.
    165          */
    166 	new_str[i++] = '\\';
    167     }
    168     new_str[i] = '\0';
    169     return new_str;
    170 }
    171