git

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/*
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 *  LibXDiff by Davide Libenzi ( File Differential Library )
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 *  Copyright (C) 2003	Davide Libenzi
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 *
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 *  This library is free software; you can redistribute it and/or
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 *  modify it under the terms of the GNU Lesser General Public
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 *  License as published by the Free Software Foundation; either
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 *  version 2.1 of the License, or (at your option) any later version.
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 *
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 *  This library is distributed in the hope that it will be useful,
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 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
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 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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 *  Lesser General Public License for more details.
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 *
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 *  You should have received a copy of the GNU Lesser General Public
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 *  License along with this library; if not, see
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 *  <http://www.gnu.org/licenses/>.
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 *
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 *  Davide Libenzi <davidel@xmailserver.org>
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 *
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 */
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#include "xinclude.h"
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static long xdl_get_rec(xdfile_t *xdf, long ri, char const **rec) {
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	*rec = xdf->recs[ri]->ptr;
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	return xdf->recs[ri]->size;
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}
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static int xdl_emit_record(xdfile_t *xdf, long ri, char const *pre, xdemitcb_t *ecb) {
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	long size, psize = strlen(pre);
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	char const *rec;
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	size = xdl_get_rec(xdf, ri, &rec);
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	if (xdl_emit_diffrec(rec, size, pre, psize, ecb) < 0) {
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		return -1;
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	}
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	return 0;
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}
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/*
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 * Starting at the passed change atom, find the latest change atom to be included
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 * inside the differential hunk according to the specified configuration.
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 * Also advance xscr if the first changes must be discarded.
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 */
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xdchange_t *xdl_get_hunk(xdchange_t **xscr, xdemitconf_t const *xecfg)
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{
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	xdchange_t *xch, *xchp, *lxch;
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	long max_common = 2 * xecfg->ctxlen + xecfg->interhunkctxlen;
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	long max_ignorable = xecfg->ctxlen;
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	unsigned long ignored = 0; /* number of ignored blank lines */
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	/* remove ignorable changes that are too far before other changes */
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	for (xchp = *xscr; xchp && xchp->ignore; xchp = xchp->next) {
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		xch = xchp->next;
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		if (xch == NULL ||
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		    xch->i1 - (xchp->i1 + xchp->chg1) >= max_ignorable)
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			*xscr = xch;
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	}
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	if (!*xscr)
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		return NULL;
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	lxch = *xscr;
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	for (xchp = *xscr, xch = xchp->next; xch; xchp = xch, xch = xch->next) {
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		long distance = xch->i1 - (xchp->i1 + xchp->chg1);
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		if (distance > max_common)
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			break;
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		if (distance < max_ignorable && (!xch->ignore || lxch == xchp)) {
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			lxch = xch;
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			ignored = 0;
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		} else if (distance < max_ignorable && xch->ignore) {
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			ignored += xch->chg2;
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		} else if (lxch != xchp &&
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			   xch->i1 + ignored - (lxch->i1 + lxch->chg1) > max_common) {
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			break;
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		} else if (!xch->ignore) {
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			lxch = xch;
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			ignored = 0;
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		} else {
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			ignored += xch->chg2;
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		}
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	}
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	return lxch;
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}
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static long def_ff(const char *rec, long len, char *buf, long sz)
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{
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	if (len > 0 &&
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			(isalpha((unsigned char)*rec) || /* identifier? */
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			 *rec == '_' || /* also identifier? */
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			 *rec == '$')) { /* identifiers from VMS and other esoterico */
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		if (len > sz)
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			len = sz;
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		while (0 < len && isspace((unsigned char)rec[len - 1]))
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			len--;
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		memcpy(buf, rec, len);
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		return len;
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	}
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	return -1;
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}
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static long match_func_rec(xdfile_t *xdf, xdemitconf_t const *xecfg, long ri,
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			   char *buf, long sz)
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{
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	const char *rec;
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	long len = xdl_get_rec(xdf, ri, &rec);
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	if (!xecfg->find_func)
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		return def_ff(rec, len, buf, sz);
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	return xecfg->find_func(rec, len, buf, sz, xecfg->find_func_priv);
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}
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static int is_func_rec(xdfile_t *xdf, xdemitconf_t const *xecfg, long ri)
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{
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	char dummy[1];
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	return match_func_rec(xdf, xecfg, ri, dummy, sizeof(dummy)) >= 0;
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}
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struct func_line {
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	long len;
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	char buf[80];
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};
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static long get_func_line(xdfenv_t *xe, xdemitconf_t const *xecfg,
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			  struct func_line *func_line, long start, long limit)
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{
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	long l, size, step = (start > limit) ? -1 : 1;
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	char *buf, dummy[1];
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	buf = func_line ? func_line->buf : dummy;
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	size = func_line ? sizeof(func_line->buf) : sizeof(dummy);
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	for (l = start; l != limit && 0 <= l && l < xe->xdf1.nrec; l += step) {
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		long len = match_func_rec(&xe->xdf1, xecfg, l, buf, size);
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		if (len >= 0) {
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			if (func_line)
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				func_line->len = len;
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			return l;
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		}
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	}
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	return -1;
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}
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static int is_empty_rec(xdfile_t *xdf, long ri)
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{
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	const char *rec;
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	long len = xdl_get_rec(xdf, ri, &rec);
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	while (len > 0 && XDL_ISSPACE(*rec)) {
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		rec++;
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		len--;
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	}
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	return !len;
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}
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int xdl_emit_diff(xdfenv_t *xe, xdchange_t *xscr, xdemitcb_t *ecb,
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		  xdemitconf_t const *xecfg) {
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	long s1, s2, e1, e2, lctx;
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	xdchange_t *xch, *xche;
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	long funclineprev = -1;
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	struct func_line func_line = { 0 };
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	for (xch = xscr; xch; xch = xche->next) {
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		xdchange_t *xchp = xch;
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		xche = xdl_get_hunk(&xch, xecfg);
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		if (!xch)
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			break;
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pre_context_calculation:
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		s1 = XDL_MAX(xch->i1 - xecfg->ctxlen, 0);
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		s2 = XDL_MAX(xch->i2 - xecfg->ctxlen, 0);
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		if (xecfg->flags & XDL_EMIT_FUNCCONTEXT) {
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			long fs1, i1 = xch->i1;
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			/* Appended chunk? */
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			if (i1 >= xe->xdf1.nrec) {
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				long i2 = xch->i2;
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				/*
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				 * We don't need additional context if
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				 * a whole function was added.
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				 */
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				while (i2 < xe->xdf2.nrec) {
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					if (is_func_rec(&xe->xdf2, xecfg, i2))
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						goto post_context_calculation;
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					i2++;
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				}
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				/*
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				 * Otherwise get more context from the
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				 * pre-image.
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				 */
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				i1 = xe->xdf1.nrec - 1;
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			}
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			fs1 = get_func_line(xe, xecfg, NULL, i1, -1);
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			while (fs1 > 0 && !is_empty_rec(&xe->xdf1, fs1 - 1) &&
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			       !is_func_rec(&xe->xdf1, xecfg, fs1 - 1))
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				fs1--;
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			if (fs1 < 0)
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				fs1 = 0;
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			if (fs1 < s1) {
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				s2 = XDL_MAX(s2 - (s1 - fs1), 0);
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				s1 = fs1;
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				/*
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				 * Did we extend context upwards into an
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				 * ignored change?
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				 */
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				while (xchp != xch &&
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				       xchp->i1 + xchp->chg1 <= s1 &&
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				       xchp->i2 + xchp->chg2 <= s2)
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					xchp = xchp->next;
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				/* If so, show it after all. */
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				if (xchp != xch) {
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					xch = xchp;
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					goto pre_context_calculation;
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				}
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			}
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		}
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 post_context_calculation:
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		lctx = xecfg->ctxlen;
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		lctx = XDL_MIN(lctx, xe->xdf1.nrec - (xche->i1 + xche->chg1));
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		lctx = XDL_MIN(lctx, xe->xdf2.nrec - (xche->i2 + xche->chg2));
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		e1 = xche->i1 + xche->chg1 + lctx;
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		e2 = xche->i2 + xche->chg2 + lctx;
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		if (xecfg->flags & XDL_EMIT_FUNCCONTEXT) {
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			long fe1 = get_func_line(xe, xecfg, NULL,
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						 xche->i1 + xche->chg1,
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						 xe->xdf1.nrec);
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			while (fe1 > 0 && is_empty_rec(&xe->xdf1, fe1 - 1))
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				fe1--;
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			if (fe1 < 0)
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				fe1 = xe->xdf1.nrec;
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			if (fe1 > e1) {
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				e2 = XDL_MIN(e2 + (fe1 - e1), xe->xdf2.nrec);
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				e1 = fe1;
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			}
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			/*
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			 * Overlap with next change?  Then include it
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			 * in the current hunk and start over to find
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			 * its new end.
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			 */
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			if (xche->next) {
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				long l = XDL_MIN(xche->next->i1,
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						 xe->xdf1.nrec - 1);
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				if (l - xecfg->ctxlen <= e1 ||
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				    get_func_line(xe, xecfg, NULL, l, e1) < 0) {
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					xche = xche->next;
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					goto post_context_calculation;
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				}
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			}
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		}
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		/*
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		 * Emit current hunk header.
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		 */
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		if (xecfg->flags & XDL_EMIT_FUNCNAMES) {
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			get_func_line(xe, xecfg, &func_line,
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				      s1 - 1, funclineprev);
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			funclineprev = s1 - 1;
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		}
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		if (!(xecfg->flags & XDL_EMIT_NO_HUNK_HDR) &&
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		    xdl_emit_hunk_hdr(s1 + 1, e1 - s1, s2 + 1, e2 - s2,
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				      func_line.buf, func_line.len, ecb) < 0)
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			return -1;
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		/*
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		 * Emit pre-context.
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		 */
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		for (; s2 < xch->i2; s2++)
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			if (xdl_emit_record(&xe->xdf2, s2, " ", ecb) < 0)
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				return -1;
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		for (s1 = xch->i1, s2 = xch->i2;; xch = xch->next) {
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			/*
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			 * Merge previous with current change atom.
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			 */
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			for (; s1 < xch->i1 && s2 < xch->i2; s1++, s2++)
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				if (xdl_emit_record(&xe->xdf2, s2, " ", ecb) < 0)
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					return -1;
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			/*
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			 * Removes lines from the first file.
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			 */
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			for (s1 = xch->i1; s1 < xch->i1 + xch->chg1; s1++)
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				if (xdl_emit_record(&xe->xdf1, s1, "-", ecb) < 0)
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					return -1;
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			/*
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			 * Adds lines from the second file.
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			 */
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			for (s2 = xch->i2; s2 < xch->i2 + xch->chg2; s2++)
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				if (xdl_emit_record(&xe->xdf2, s2, "+", ecb) < 0)
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					return -1;
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315
			if (xch == xche)
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				break;
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			s1 = xch->i1 + xch->chg1;
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			s2 = xch->i2 + xch->chg2;
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		}
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321
		/*
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		 * Emit post-context.
323
		 */
324
		for (s2 = xche->i2 + xche->chg2; s2 < e2; s2++)
325
			if (xdl_emit_record(&xe->xdf2, s2, " ", ecb) < 0)
326
				return -1;
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	}
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	return 0;
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}
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