sbase/libutil/unescape.c

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/* See LICENSE file for copyright and license details. */
#include <string.h>
#include "../util.h"
size_t
unescape(char *s)
{
size_t len, i, off, m, factor, q;
len = strlen(s);
for (i = 0; i < len; i++) {
if (s[i] != '\\')
continue;
off = 0;
switch (s[i + 1]) {
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case '\\': s[i] = '\\'; off++; break;
case '\'': s[i] = '\'', off++; break;
case '"': s[i] = '"', off++; break;
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case 'a': s[i] = '\a'; off++; break;
case 'b': s[i] = '\b'; off++; break;
case 'e': s[i] = 033; off++; break;
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case 'f': s[i] = '\f'; off++; break;
case 'n': s[i] = '\n'; off++; break;
case 'r': s[i] = '\r'; off++; break;
case 't': s[i] = '\t'; off++; break;
case 'v': s[i] = '\v'; off++; break;
case 'x':
/* "\xH[H]" hexadecimal escape */
for (m = i + 2; m < i + 1 + 3 && m < len; m++)
if ((s[m] < '0' && s[m] > '9') &&
(s[m] < 'A' && s[m] > 'F') &&
(s[m] < 'a' && s[m] > 'f'))
break;
if (m == i + 2)
eprintf("invalid escape sequence '\\%c'\n", s[i + 1]);
off += m - i - 1;
for (--m, q = 0, factor = 1; m > i + 1; m--) {
if (s[m] >= '0' && s[m] <= '9')
q += (s[m] - '0') * factor;
else if (s[m] >= 'A' && s[m] <= 'F')
q += ((s[m] - 'A') + 10) * factor;
else if (s[m] >= 'a' && s[m] <= 'f')
q += ((s[m] - 'a') + 10) * factor;
factor *= 16;
}
s[i] = q;
break;
case '\0':
eprintf("null escape sequence\n");
default:
/* "\O[OOO]" octal escape */
for (m = i + 1; m < i + 1 + 4 && m < len; m++)
if (s[m] < '0' || s[m] > '7')
break;
if (m == i + 1)
eprintf("invalid escape sequence '\\%c'\n", s[i + 1]);
off += m - i - 1;
for (--m, q = 0, factor = 1; m > i; m--) {
q += (s[m] - '0') * factor;
factor *= 8;
}
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s[i] = (q > 255) ? 255 : q;
}
for (m = i + 1; m <= len - off; m++)
s[m] = s[m + off];
len -= off;
}
return len;
}