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Revision 1.11, Sat Nov 1 04:08:43 2014 UTC (6 years, 3 months ago) by schwarze
Branch: MAIN
Changes since 1.10: +12 -11 lines

Refactor, no functional change: Remove the parse point from struct buf.
Some functions need multiple parse points, some none at all,
and it varies whether any of them need to be passed around.
So better pass them as a separate argument, and only when needed.

/*	$Id: preconv.c,v 1.11 2014/11/01 04:08:43 schwarze Exp $ */
/*
 * Copyright (c) 2011 Kristaps Dzonsons <kristaps@bsd.lv>
 * Copyright (c) 2014 Ingo Schwarze <schwarze@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */
#include "config.h"

#include <sys/types.h>

#include <stdio.h>
#include <string.h>
#include "mandoc.h"
#include "libmandoc.h"

int
preconv_encode(struct buf *ib, size_t *ii, struct buf *ob, size_t *oi,
    int *filenc)
{
	size_t		 i;
	const long	 one = 1L;
	int		 state, be;
	unsigned int	 accum;
	unsigned char	 cu;

	if ( ! (*filenc & MPARSE_UTF8))
		goto latin;

	state = 0;
	accum = 0U;
	be = 0;

	/* Quick test for big-endian value. */

	if ( ! (*((const char *)(&one))))
		be = 1;

	for (i = *ii; i < ib->sz; i++) {
		cu = ib->buf[i];
		if (state) {
			if ( ! (cu & 128) || (cu & 64)) {
				/* Bad sequence header. */
				break;
			}

			/* Accept only legitimate bit patterns. */

			if (cu > 191 || cu < 128) {
				/* Bad in-sequence bits. */
				break;
			}

			accum |= (cu & 63) << --state * 6;

			if (state)
				continue;

			/*
			 * Accum is held in little-endian order as
			 * stipulated by the UTF-8 sequence coding.  We
			 * need to convert to a native big-endian if our
			 * architecture requires it.
			 */

			if (be)
				accum = (accum >> 24) | 
					((accum << 8) & 0x00FF0000) |
					((accum >> 8) & 0x0000FF00) |
					(accum << 24);

			if (accum < 0x80)
				ob->buf[(*oi)++] = accum;
			else
				*oi += snprintf(ob->buf + *oi,
				    11, "\\[u%.4X]", accum);
			*ii = i + 1;
			*filenc &= ~MPARSE_LATIN1;
			return(1);
		} else {
			/*
			 * Entering a UTF-8 state:  if we encounter a
			 * UTF-8 bitmask, calculate the expected UTF-8
			 * state from it.
			 */
			for (state = 0; state < 7; state++) 
				if ( ! (cu & (1 << (7 - state))))
					break;

			/* Accept only legitimate bit patterns. */

			switch (state--) {
			case (4):
				if (cu <= 244 && cu >= 240) {
					accum = (cu & 7) << 18;
					continue;
				}
				/* Bad 4-sequence start bits. */
				break;
			case (3):
				if (cu <= 239 && cu >= 224) {
					accum = (cu & 15) << 12;
					continue;
				}
				/* Bad 3-sequence start bits. */
				break;
			case (2):
				if (cu <= 223 && cu >= 194) {
					accum = (cu & 31) << 6;
					continue;
				}
				/* Bad 2-sequence start bits. */
				break;
			default:
				/* Bad sequence bit mask. */
				break;
			}
			break;
		}
	}

	/* FALLTHROUGH: Invalid or incomplete UTF-8 sequence. */

latin:
	if ( ! (*filenc & MPARSE_LATIN1))
		return(0);

	*oi += snprintf(ob->buf + *oi, 11,
	    "\\[u%.4X]", (unsigned char)ib->buf[(*ii)++]);

	*filenc &= ~MPARSE_UTF8;
	return(1);
}

int
preconv_cue(const struct buf *b, size_t offset)
{
	const char	*ln, *eoln, *eoph;
	size_t		 sz, phsz;

	ln = b->buf + offset;
	sz = b->sz - offset;

	/* Look for the end-of-line. */

	if (NULL == (eoln = memchr(ln, '\n', sz)))
		eoln = ln + sz;

	/* Check if we have the correct header/trailer. */

	if ((sz = (size_t)(eoln - ln)) < 10 || 
	    memcmp(ln, ".\\\" -*-", 7) || memcmp(eoln - 3, "-*-", 3))
		return(MPARSE_UTF8 | MPARSE_LATIN1);

	/* Move after the header and adjust for the trailer. */

	ln += 7;
	sz -= 10;

	while (sz > 0) {
		while (sz > 0 && ' ' == *ln) {
			ln++;
			sz--;
		}
		if (0 == sz)
			break;

		/* Find the end-of-phrase marker (or eoln). */

		if (NULL == (eoph = memchr(ln, ';', sz)))
			eoph = eoln - 3;
		else
			eoph++;

		/* Only account for the "coding" phrase. */

		if ((phsz = eoph - ln) < 7 ||
		    strncasecmp(ln, "coding:", 7)) {
			sz -= phsz;
			ln += phsz;
			continue;
		} 

		sz -= 7;
		ln += 7;

		while (sz > 0 && ' ' == *ln) {
			ln++;
			sz--;
		}
		if (0 == sz)
			return(0);

		/* Check us against known encodings. */

		if (phsz > 4 && !strncasecmp(ln, "utf-8", 5))
			return(MPARSE_UTF8);
		if (phsz > 10 && !strncasecmp(ln, "iso-latin-1", 11))
			return(MPARSE_LATIN1);
		return(0);
	}
	return(MPARSE_UTF8 | MPARSE_LATIN1);
}