158 lines
3.2 KiB
C
158 lines
3.2 KiB
C
/*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* Jordan K. Hubbard
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* 29 August 1998
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*
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* $Id$
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*
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* Routine for doing backslash elimination.
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*/
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#include <stand.h>
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#include <string.h>
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#define DIGIT(x) (isdigit(x) ? (x) - '0' : islower(x) ? (x) + 10 - 'a' : (x) + 10 - 'A')
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/*
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* backslash: Return malloc'd copy of str with all standard "backslash
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* processing" done on it. Original can be free'd if desired.
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*/
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char *
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backslash(char *str)
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{
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/*
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* Remove backslashes from the strings. Turn \040 etc. into a single
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* character (we allow eight bit values). Currently NUL is not
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* allowed.
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*
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* Turn "\n" and "\t" into '\n' and '\t' characters. Etc.
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*
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*/
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char *new_str;
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int seenbs = 0;
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int i = 0;
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if ((new_str = strdup(str)) == NULL)
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return NULL;
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while (*str) {
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if (seenbs) {
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seenbs = 0;
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switch (*str) {
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case '\\':
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new_str[i++] = '\\';
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str++;
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break;
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case 'b':
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new_str[i++] = '\b';
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str++;
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break;
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case 'f':
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new_str[i++] = '\f';
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str++;
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break;
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case 'r':
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new_str[i++] = '\r';
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str++;
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break;
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case 'n':
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new_str[i++] = '\n';
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str++;
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break;
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case 's':
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new_str[i++] = ' ';
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str++;
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break;
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case 't':
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new_str[i++] = '\t';
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str++;
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break;
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case 'v':
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new_str[i++] = '\13';
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str++;
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break;
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case 'z':
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str++;
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break;
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case '0': case '1': case '2': case '3': case '4':
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case '5': case '6': case '7': case '8': case '9': {
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char val;
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/* Three digit octal constant? */
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if (*str >= '0' && *str <= '3' &&
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*(str + 1) >= '0' && *(str + 1) <= '7' &&
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*(str + 2) >= '0' && *(str + 2) <= '7') {
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val = (DIGIT(*str) << 6) + (DIGIT(*(str + 1)) << 3) +
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DIGIT(*(str + 2));
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/* Allow null value if user really wants to shoot
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at feet, but beware! */
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new_str[i++] = val;
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str += 3;
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break;
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}
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/* One or two digit hex constant?
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* If two are there they will both be taken.
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* Use \z to split them up if this is not wanted.
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*/
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if (*str == '0' &&
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(*(str + 1) == 'x' || *(str + 1) == 'X') &&
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isxdigit(*(str + 2))) {
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val = DIGIT(*(str + 2));
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if (isxdigit(*(str + 3))) {
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val = (val << 4) + DIGIT(*(str + 3));
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str += 4;
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}
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else
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str += 3;
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/* Yep, allow null value here too */
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new_str[i++] = val;
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break;
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}
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}
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break;
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default:
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new_str[i++] = *str++;
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break;
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}
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}
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else {
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if (*str == '\\') {
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seenbs = 1;
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str++;
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}
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else
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new_str[i++] = *str++;
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}
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}
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if (seenbs) {
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/*
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* The final character was a '\'. Put it in as a single backslash.
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*/
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new_str[i++] = '\\';
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}
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new_str[i] = '\0';
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return new_str;
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}
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