109 lines
2.9 KiB
C
109 lines
2.9 KiB
C
#include <stdio.h>
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#include <string.h>
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#include <stdlib.h>
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#include "hescape.h"
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static const char *ESCAPED_STRING[] = {
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"",
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""",
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"&",
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"'",
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"<",
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">",
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};
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// This is strlen(ESCAPED_STRING[x]) optimized specially.
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// Mapping: 1 => 6, 2 => 5, 3 => 5, 4 => 4, 5 => 4
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#define ESC_LEN(x) ((13 - x) / 2)
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/*
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* Given ASCII-compatible character, return index of ESCAPED_STRING.
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*
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* " (34) => 1 (")
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* & (38) => 2 (&)
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* ' (39) => 3 (')
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* < (60) => 4 (<)
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* > (62) => 5 (>)
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*/
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static const char HTML_ESCAPE_TABLE[] = {
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 1, 0, 0, 0, 2, 3, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 0, 5, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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};
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static char*
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ensure_allocated(char *buf, size_t size, size_t *asize)
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{
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size_t new_size;
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if (size < *asize)
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return buf;
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if (*asize == 0) {
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new_size = size;
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} else {
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new_size = *asize;
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}
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// Increase buffer size by 1.5x if realloced multiple times.
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while (new_size < size)
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new_size = (new_size << 1) - (new_size >> 1);
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// Round allocation up to multiple of 8.
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new_size = (new_size + 7) & ~7;
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*asize = new_size;
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return realloc(buf, new_size);
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}
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size_t
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hesc_escape_html(char **dest, const char *buf, size_t size)
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{
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size_t asize = 0, esc_i, esize = 0, i = 0, rbuf_end = 0;
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const char *esc;
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char *rbuf = NULL;
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while (i < size) {
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// Loop here to skip non-escaped characters fast.
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while (i < size && (esc_i = HTML_ESCAPE_TABLE[(unsigned char)buf[i]]) == 0)
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i++;
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if (i < size && esc_i) {
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esc = ESCAPED_STRING[esc_i];
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rbuf = ensure_allocated(rbuf, sizeof(char) * (size + esize + ESC_LEN(esc_i) + 1), &asize);
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// Copy pending characters and escaped string.
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memmove(rbuf + rbuf_end, buf + (rbuf_end - esize), i - (rbuf_end - esize));
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memmove(rbuf + i + esize, esc, ESC_LEN(esc_i));
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rbuf_end = i + esize + ESC_LEN(esc_i);
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esize += ESC_LEN(esc_i) - 1;
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}
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i++;
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}
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if (rbuf_end == 0) {
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// Return given buf and size if there are no escaped characters.
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*dest = (char *)buf;
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return size;
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} else {
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// Copy pending characters including NULL character.
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memmove(rbuf + rbuf_end, buf + (rbuf_end - esize), (size + 1) - (rbuf_end - esize));
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*dest = rbuf;
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return size + esize;
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}
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}
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