thodg/got

diff --git a/lib/buf.c b/lib/buf.c
new file mode 100644
index 0000000..1a9450d
--- /dev/null
+++ b/lib/buf.c
@@ -0,0 +1,333 @@
+/*	$OpenBSD: buf.c,v 1.27 2016/10/16 13:35:51 okan Exp $	*/
+/*
+ * Copyright (c) 2003 Jean-Francois Brousseau <jfb@openbsd.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
+ * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
+ * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
+ * THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL  DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
+ * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+ * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
+ * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <sys/queue.h>
+#include <sys/stat.h>
+
+#include <err.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include "buf.h"
+#include "xmalloc.h"
+#include "worklist.h"
+
+#define BUF_INCR	128
+
+struct buf {
+	/* buffer handle, buffer size, and data length */
+	u_char	*cb_buf;
+	size_t	 cb_size;
+	size_t	 cb_len;
+};
+
+#define SIZE_LEFT(b)	(b->cb_size - b->cb_len)
+
+static void	buf_grow(BUF *, size_t);
+
+/*
+ * Create a new buffer structure and return a pointer to it.  This structure
+ * uses dynamically-allocated memory and must be freed with buf_free(), once
+ * the buffer is no longer needed.
+ */
+BUF *
+buf_alloc(size_t len)
+{
+	BUF *b;
+
+	b = xmalloc(sizeof(*b));
+	/* Postpone creation of zero-sized buffers */
+	if (len > 0)
+		b->cb_buf = xcalloc(1, len);
+	else
+		b->cb_buf = NULL;
+
+	b->cb_size = len;
+	b->cb_len = 0;
+
+	return (b);
+}
+
+/*
+ * Open the file specified by <path> and load all of its contents into a
+ * buffer.
+ * Returns the loaded buffer on success or NULL on failure.
+ * Sets errno on error.
+ */
+BUF *
+buf_load(const char *path)
+{
+	int fd;
+	ssize_t ret;
+	size_t len;
+	u_char *bp;
+	struct stat st;
+	BUF *buf;
+
+	buf = NULL;
+
+	if ((fd = open(path, O_RDONLY, 0600)) == -1)
+		goto out;
+
+	if (fstat(fd, &st) == -1)
+		goto out;
+
+	if ((uintmax_t)st.st_size > SIZE_MAX) {
+		errno = EFBIG;
+		goto out;
+	}
+	buf = buf_alloc(st.st_size);
+	for (bp = buf->cb_buf; ; bp += (size_t)ret) {
+		len = SIZE_LEFT(buf);
+		ret = read(fd, bp, len);
+		if (ret == -1) {
+			int saved_errno;
+
+			saved_errno = errno;
+			buf_free(buf);
+			buf = NULL;
+			errno = saved_errno;
+			goto out;
+		} else if (ret == 0)
+			break;
+
+		buf->cb_len += (size_t)ret;
+	}
+
+out:
+	if (fd != -1) {
+		int saved_errno;
+
+		/* We may want to preserve errno here. */
+		saved_errno = errno;
+		(void)close(fd);
+		errno = saved_errno;
+	}
+
+	return (buf);
+}
+
+void
+buf_free(BUF *b)
+{
+	if (b == NULL)
+		return;
+	free(b->cb_buf);
+	free(b);
+}
+
+/*
+ * Free the buffer <b>'s structural information but do not free the contents
+ * of the buffer.  Instead, they are returned and should be freed later using
+ * free().
+ */
+void *
+buf_release(BUF *b)
+{
+	void *tmp;
+
+	tmp = b->cb_buf;
+	free(b);
+	return (tmp);
+}
+
+u_char *
+buf_get(BUF *b)
+{
+	return (b->cb_buf);
+}
+
+/*
+ * Empty the contents of the buffer <b> and reset pointers.
+ */
+void
+buf_empty(BUF *b)
+{
+	memset(b->cb_buf, 0, b->cb_size);
+	b->cb_len = 0;
+}
+
+/*
+ * Append a single character <c> to the end of the buffer <b>.
+ */
+void
+buf_putc(BUF *b, int c)
+{
+	u_char *bp;
+
+	if (SIZE_LEFT(b) == 0)
+		buf_grow(b, BUF_INCR);
+	bp = b->cb_buf + b->cb_len;
+	*bp = (u_char)c;
+	b->cb_len++;
+}
+
+/*
+ * Append a string <s> to the end of buffer <b>.
+ */
+void
+buf_puts(BUF *b, const char *str)
+{
+	buf_append(b, str, strlen(str));
+}
+
+/*
+ * Return u_char at buffer position <pos>.
+ */
+u_char
+buf_getc(BUF *b, size_t pos)
+{
+	return (b->cb_buf[pos]);
+}
+
+/*
+ * Append <len> bytes of data pointed to by <data> to the buffer <b>.  If the
+ * buffer is too small to accept all data, it will get resized to an
+ * appropriate size to accept all data.
+ * Returns the number of bytes successfully appended to the buffer.
+ */
+size_t
+buf_append(BUF *b, const void *data, size_t len)
+{
+	size_t left, rlen;
+	u_char *bp;
+
+	left = SIZE_LEFT(b);
+	rlen = len;
+
+	if (left < len)
+		buf_grow(b, len - left);
+	bp = b->cb_buf + b->cb_len;
+	memcpy(bp, data, rlen);
+	b->cb_len += rlen;
+
+	return (rlen);
+}
+
+/*
+ * Returns the size of the buffer that is being used.
+ */
+size_t
+buf_len(BUF *b)
+{
+	return (b->cb_len);
+}
+
+/*
+ * Write the contents of the buffer <b> to the specified <fd>
+ */
+int
+buf_write_fd(BUF *b, int fd)
+{
+	u_char *bp;
+	size_t len;
+	ssize_t ret;
+
+	len = b->cb_len;
+	bp = b->cb_buf;
+
+	do {
+		ret = write(fd, bp, len);
+		if (ret == -1) {
+			if (errno == EINTR || errno == EAGAIN)
+				continue;
+			return (-1);
+		}
+
+		len -= (size_t)ret;
+		bp += (size_t)ret;
+	} while (len > 0);
+
+	return (0);
+}
+
+/*
+ * Write the contents of the buffer <b> to the file whose path is given in
+ * <path>.  If the file does not exist, it is created with mode <mode>.
+ */
+int
+buf_write(BUF *b, const char *path, mode_t mode)
+{
+	int fd;
+ open:
+	if ((fd = open(path, O_WRONLY|O_CREAT|O_TRUNC, mode)) == -1) {
+		if (errno == EACCES && unlink(path) != -1)
+			goto open;
+		else
+			err(1, "%s", path);
+	}
+
+	if (buf_write_fd(b, fd) == -1) {
+		(void)unlink(path);
+		errx(1, "buf_write: buf_write_fd: `%s'", path);
+	}
+
+	if (fchmod(fd, mode) < 0)
+		warn("permissions not set on file %s", path);
+
+	(void)close(fd);
+
+	return (0);
+}
+
+/*
+ * Write the contents of the buffer <b> to a temporary file whose path is
+ * specified using <template> (see mkstemp.3).
+ * NB. This function will modify <template>, as per mkstemp
+ */
+void
+buf_write_stmp(BUF *b, char *template)
+{
+	int fd;
+
+	if ((fd = mkstemp(template)) == -1)
+		err(1, "%s", template);
+
+	worklist_add(template, &temp_files);
+
+	if (buf_write_fd(b, fd) == -1) {
+		(void)unlink(template);
+		errx(1, "buf_write_stmp: buf_write_fd: `%s'", template);
+	}
+
+	(void)close(fd);
+}
+
+/*
+ * Grow the buffer <b> by <len> bytes.  The contents are unchanged by this
+ * operation regardless of the result.
+ */
+static void
+buf_grow(BUF *b, size_t len)
+{
+	b->cb_buf = xreallocarray(b->cb_buf, 1, b->cb_size + len);
+	b->cb_size += len;
+}
diff --git a/lib/buf.h b/lib/buf.h
new file mode 100644
index 0000000..f05e7e8
--- /dev/null
+++ b/lib/buf.h
@@ -0,0 +1,60 @@
+/*	$OpenBSD: buf.h,v 1.13 2011/07/06 15:36:52 nicm Exp $	*/
+/*
+ * Copyright (c) 2003 Jean-Francois Brousseau <jfb@openbsd.org>
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES,
+ * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY
+ * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL
+ * THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ * EXEMPLARY, OR CONSEQUENTIAL  DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
+ * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
+ * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
+ * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
+ * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * Buffer management
+ * -----------------
+ *
+ * This code provides an API to generic memory buffer management.  All
+ * operations are performed on a buf structure, which is kept opaque to the
+ * API user in order to avoid corruption of the fields and make sure that only
+ * the internals can modify the fields.
+ *
+ * The first step is to allocate a new buffer using the buf_alloc()
+ * function, which returns a pointer to a new buffer.
+ */
+
+#ifndef BUF_H
+#define BUF_H
+
+#include <sys/types.h>
+
+typedef struct buf BUF;
+
+BUF		*buf_alloc(size_t);
+BUF		*buf_load(const char *);
+void		 buf_free(BUF *);
+void		*buf_release(BUF *);
+u_char		 buf_getc(BUF *, size_t);
+void		 buf_empty(BUF *);
+size_t		 buf_append(BUF *, const void *, size_t);
+void		 buf_putc(BUF *, int);
+void		 buf_puts(BUF *b, const char *str);
+size_t		 buf_len(BUF *);
+int		 buf_write_fd(BUF *, int);
+int		 buf_write(BUF *, const char *, mode_t);
+void		 buf_write_stmp(BUF *, char *);
+u_char		*buf_get(BUF *b);
+
+#endif	/* BUF_H */
diff --git a/lib/diff3.c b/lib/diff3.c
new file mode 100644
index 0000000..16cc1b2
--- /dev/null
+++ b/lib/diff3.c
@@ -0,0 +1,930 @@
+/*	$OpenBSD: diff3.c,v 1.41 2016/10/18 21:06:52 millert Exp $	*/
+
+/*
+ * Copyright (C) Caldera International Inc.  2001-2002.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code and documentation must retain the above
+ *    copyright notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *	This product includes software developed or owned by Caldera
+ *	International, Inc.
+ * 4. Neither the name of Caldera International, Inc. nor the names of other
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * USE OF THE SOFTWARE PROVIDED FOR UNDER THIS LICENSE BY CALDERA
+ * INTERNATIONAL, INC. AND CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL CALDERA INTERNATIONAL, INC. BE LIABLE FOR ANY DIRECT,
+ * INDIRECT INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
+ * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
+ * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+/*-
+ * Copyright (c) 1991, 1993
+ *	The Regents of the University of California.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ *	@(#)diff3.c	8.1 (Berkeley) 6/6/93
+ */
+
+#include <ctype.h>
+#include <err.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+#include <unistd.h>
+
+#include "diff.h"
+#include "rcsprog.h"
+
+/* diff3 - 3-way differential file comparison */
+
+/* diff3 [-ex3EX] d13 d23 f1 f2 f3 [m1 m3]
+ *
+ * d13 = diff report on f1 vs f3
+ * d23 = diff report on f2 vs f3
+ * f1, f2, f3 the 3 files
+ * if changes in f1 overlap with changes in f3, m1 and m3 are used
+ * to mark the overlaps; otherwise, the file names f1 and f3 are used
+ * (only for options E and X).
+ */
+
+/*
+ * "from" is first in range of changed lines; "to" is last+1
+ * from=to=line after point of insertion for added lines.
+ */
+struct range {
+	int from;
+	int to;
+};
+
+struct diff {
+	struct range old;
+	struct range new;
+};
+
+static size_t szchanges;
+
+static struct diff *d13;
+static struct diff *d23;
+
+/*
+ * "de" is used to gather editing scripts.  These are later spewed out in
+ * reverse order.  Its first element must be all zero, the "new" component
+ * of "de" contains line positions or byte positions depending on when you
+ * look (!?).  Array overlap indicates which sections in "de" correspond to
+ * lines that are different in all three files.
+ */
+static struct diff *de;
+static char *overlap;
+static int overlapcnt = 0;
+static FILE *fp[3];
+static int cline[3];		/* # of the last-read line in each file (0-2) */
+
+/*
+ * the latest known correspondence between line numbers of the 3 files
+ * is stored in last[1-3];
+ */
+static int last[4];
+static int eflag = 3;	/* default -E for compatibility with former RCS */
+static int oflag = 1;	/* default -E for compatibility with former RCS */
+static int debug  = 0;
+static char f1mark[PATH_MAX], f3mark[PATH_MAX];	/* markers for -E and -X */
+
+static int duplicate(struct range *, struct range *);
+static int edit(struct diff *, int, int);
+static char *getchange(FILE *);
+static char *get_line(FILE *, size_t *);
+static int number(char **);
+static ssize_t readin(char *, struct diff **);
+static int skip(int, int, char *);
+static int edscript(int);
+static int merge(size_t, size_t);
+static void change(int, struct range *, int);
+static void keep(int, struct range *);
+static void prange(struct range *);
+static void repos(int);
+static void separate(const char *);
+static void increase(void);
+static int diff3_internal(int, char **, const char *, const char *);
+
+int diff3_conflicts = 0;
+
+/*
+ * For merge(1).
+ */
+BUF *
+merge_diff3(char **av, int flags)
+{
+	int argc;
+	char *argv[5], *dp13, *dp23, *path1, *path2, *path3;
+	BUF *b1, *b2, *b3, *d1, *d2, *diffb;
+	u_char *data, *patch;
+	size_t dlen, plen;
+
+	b1 = b2 = b3 = d1 = d2 = diffb = NULL;
+	dp13 = dp23 = path1 = path2 = path3 = NULL;
+	data = patch = NULL;
+
+	if ((flags & MERGE_EFLAG) && !(flags & MERGE_OFLAG))
+		oflag = 0;
+
+	if ((b1 = buf_load(av[0])) == NULL)
+		goto out;
+	if ((b2 = buf_load(av[1])) == NULL)
+		goto out;
+	if ((b3 = buf_load(av[2])) == NULL)
+		goto out;
+
+	d1 = buf_alloc(128);
+	d2 = buf_alloc(128);
+	diffb = buf_alloc(128);
+
+	(void)xasprintf(&path1, "%s/diff1.XXXXXXXXXX", rcs_tmpdir);
+	(void)xasprintf(&path2, "%s/diff2.XXXXXXXXXX", rcs_tmpdir);
+	(void)xasprintf(&path3, "%s/diff3.XXXXXXXXXX", rcs_tmpdir);
+
+	buf_write_stmp(b1, path1);
+	buf_write_stmp(b2, path2);
+	buf_write_stmp(b3, path3);
+
+	buf_free(b2);
+	b2 = NULL;
+
+	if ((diffreg(path1, path3, d1, D_FORCEASCII) == D_ERROR) ||
+	    (diffreg(path2, path3, d2, D_FORCEASCII) == D_ERROR)) {
+		buf_free(diffb);
+		diffb = NULL;
+		goto out;
+	}
+
+	(void)xasprintf(&dp13, "%s/d13.XXXXXXXXXX", rcs_tmpdir);
+	buf_write_stmp(d1, dp13);
+
+	buf_free(d1);
+	d1 = NULL;
+
+	(void)xasprintf(&dp23, "%s/d23.XXXXXXXXXX", rcs_tmpdir);
+	buf_write_stmp(d2, dp23);
+
+	buf_free(d2);
+	d2 = NULL;
+
+	argc = 0;
+	diffbuf = diffb;
+	argv[argc++] = dp13;
+	argv[argc++] = dp23;
+	argv[argc++] = path1;
+	argv[argc++] = path2;
+	argv[argc++] = path3;
+
+	diff3_conflicts = diff3_internal(argc, argv, av[0], av[2]);
+	if (diff3_conflicts < 0) {
+		buf_free(diffb);
+		diffb = NULL;
+		goto out;
+	}
+
+	plen = buf_len(diffb);
+	patch = buf_release(diffb);
+	dlen = buf_len(b1);
+	data = buf_release(b1);
+
+	if ((diffb = rcs_patchfile(data, dlen, patch, plen, ed_patch_lines)) == NULL)
+		goto out;
+
+	if (!(flags & QUIET) && diff3_conflicts != 0)
+		warnx("warning: overlaps or other problems during merge");
+
+out:
+	buf_free(b2);
+	buf_free(b3);
+	buf_free(d1);
+	buf_free(d2);
+
+	(void)unlink(path1);
+	(void)unlink(path2);
+	(void)unlink(path3);
+	(void)unlink(dp13);
+	(void)unlink(dp23);
+
+	free(path1);
+	free(path2);
+	free(path3);
+	free(dp13);
+	free(dp23);
+	free(data);
+	free(patch);
+
+	return (diffb);
+}
+
+BUF *
+rcs_diff3(RCSFILE *rf, char *workfile, RCSNUM *rev1, RCSNUM *rev2, int flags)
+{
+	int argc;
+	char *argv[5], r1[RCS_REV_BUFSZ], r2[RCS_REV_BUFSZ];
+	char *dp13, *dp23, *path1, *path2, *path3;
+	BUF *b1, *b2, *b3, *d1, *d2, *diffb;
+	size_t dlen, plen;
+	u_char *data, *patch;
+
+	b1 = b2 = b3 = d1 = d2 = diffb = NULL;
+	dp13 = dp23 = path1 = path2 = path3 = NULL;
+	data = patch = NULL;
+
+	if ((flags & MERGE_EFLAG) && !(flags & MERGE_OFLAG))
+		oflag = 0;
+
+	rcsnum_tostr(rev1, r1, sizeof(r1));
+	rcsnum_tostr(rev2, r2, sizeof(r2));
+
+	if ((b1 = buf_load(workfile)) == NULL)
+		goto out;
+
+	if (!(flags & QUIET))
+		(void)fprintf(stderr, "retrieving revision %s\n", r1);
+	if ((b2 = rcs_getrev(rf, rev1)) == NULL)
+		goto out;
+
+	if (!(flags & QUIET))
+		(void)fprintf(stderr, "retrieving revision %s\n", r2);
+	if ((b3 = rcs_getrev(rf, rev2)) == NULL)
+		goto out;
+
+	d1 = buf_alloc(128);
+	d2 = buf_alloc(128);
+	diffb = buf_alloc(128);
+
+	(void)xasprintf(&path1, "%s/diff1.XXXXXXXXXX", rcs_tmpdir);
+	(void)xasprintf(&path2, "%s/diff2.XXXXXXXXXX", rcs_tmpdir);
+	(void)xasprintf(&path3, "%s/diff3.XXXXXXXXXX", rcs_tmpdir);
+
+	buf_write_stmp(b1, path1);
+	buf_write_stmp(b2, path2);
+	buf_write_stmp(b3, path3);
+
+	buf_free(b2);
+	b2 = NULL;
+
+	if ((diffreg(path1, path3, d1, D_FORCEASCII) == D_ERROR) ||
+	    (diffreg(path2, path3, d2, D_FORCEASCII) == D_ERROR)) {
+		buf_free(diffb);
+		diffb = NULL;
+		goto out;
+	}
+
+	(void)xasprintf(&dp13, "%s/d13.XXXXXXXXXX", rcs_tmpdir);
+	buf_write_stmp(d1, dp13);
+
+	buf_free(d1);
+	d1 = NULL;
+
+	(void)xasprintf(&dp23, "%s/d23.XXXXXXXXXX", rcs_tmpdir);
+	buf_write_stmp(d2, dp23);
+
+	buf_free(d2);
+	d2 = NULL;
+
+	argc = 0;
+	diffbuf = diffb;
+	argv[argc++] = dp13;
+	argv[argc++] = dp23;
+	argv[argc++] = path1;
+	argv[argc++] = path2;
+	argv[argc++] = path3;
+
+	diff3_conflicts = diff3_internal(argc, argv, workfile, r2);
+	if (diff3_conflicts < 0) {
+		buf_free(diffb);
+		diffb = NULL;
+		goto out;
+	}
+
+	plen = buf_len(diffb);
+	patch = buf_release(diffb);
+	dlen = buf_len(b1);
+	data = buf_release(b1);
+
+	if ((diffb = rcs_patchfile(data, dlen, patch, plen, ed_patch_lines)) == NULL)
+		goto out;
+
+	if (!(flags & QUIET) && diff3_conflicts != 0)
+		warnx("warning: overlaps or other problems during merge");
+
+out:
+	buf_free(b2);
+	buf_free(b3);
+	buf_free(d1);
+	buf_free(d2);
+
+	(void)unlink(path1);
+	(void)unlink(path2);
+	(void)unlink(path3);
+	(void)unlink(dp13);
+	(void)unlink(dp23);
+
+	free(path1);
+	free(path2);
+	free(path3);
+	free(dp13);
+	free(dp23);
+	free(data);
+	free(patch);
+
+	return (diffb);
+}
+
+static int
+diff3_internal(int argc, char **argv, const char *fmark, const char *rmark)
+{
+	ssize_t m, n;
+	int i;
+
+	if (argc < 5)
+		return (-1);
+
+	if (oflag) {
+		i = snprintf(f1mark, sizeof(f1mark), "<<<<<<< %s", fmark);
+		if (i < 0 || i >= (int)sizeof(f1mark))
+			errx(1, "diff3_internal: string truncated");
+
+		i = snprintf(f3mark, sizeof(f3mark), ">>>>>>> %s", rmark);
+		if (i < 0 || i >= (int)sizeof(f3mark))
+			errx(1, "diff3_internal: string truncated");
+	}
+
+	increase();
+	if ((m = readin(argv[0], &d13)) < 0) {
+		warn("%s", argv[0]);
+		return (-1);
+	}
+	if ((n = readin(argv[1], &d23)) < 0) {
+		warn("%s", argv[1]);
+		return (-1);
+	}
+
+	for (i = 0; i <= 2; i++)
+		if ((fp[i] = fopen(argv[i + 2], "r")) == NULL) {
+			warn("%s", argv[i + 2]);
+			return (-1);
+		}
+
+	return (merge(m, n));
+}
+
+int
+ed_patch_lines(struct rcs_lines *dlines, struct rcs_lines *plines)
+{
+	char op, *ep;
+	struct rcs_line *sort, *lp, *dlp, *ndlp, *insert_after;
+	int start, end, i, lineno;
+	u_char tmp;
+
+	dlp = TAILQ_FIRST(&(dlines->l_lines));
+	lp = TAILQ_FIRST(&(plines->l_lines));
+
+	end = 0;
+	for (lp = TAILQ_NEXT(lp, l_list); lp != NULL;
+	    lp = TAILQ_NEXT(lp, l_list)) {
+		/* Skip blank lines */
+		if (lp->l_len < 2)
+			continue;
+
+		/* NUL-terminate line buffer for strtol() safety. */
+		tmp = lp->l_line[lp->l_len - 1];
+		lp->l_line[lp->l_len - 1] = '\0';
+
+		/* len - 1 is NUL terminator so we use len - 2 for 'op' */
+		op = lp->l_line[lp->l_len - 2];
+		start = (int)strtol(lp->l_line, &ep, 10);
+
+		/* Restore the last byte of the buffer */
+		lp->l_line[lp->l_len - 1] = tmp;
+
+		if (op == 'a') {
+			if (start > dlines->l_nblines ||
+			    start < 0 || *ep != 'a')
+				errx(1, "ed_patch_lines");
+		} else if (op == 'c') {
+			if (start > dlines->l_nblines ||
+			    start < 0 || (*ep != ',' && *ep != 'c'))
+				errx(1, "ed_patch_lines");
+
+			if (*ep == ',') {
+				ep++;
+				end = (int)strtol(ep, &ep, 10);
+				if (end < 0 || *ep != 'c')
+					errx(1, "ed_patch_lines");
+			} else {
+				end = start;
+			}
+		}
+
+
+		for (;;) {
+			if (dlp == NULL)
+				break;
+			if (dlp->l_lineno == start)
+				break;
+			if (dlp->l_lineno > start) {
+				dlp = TAILQ_PREV(dlp, tqh, l_list);
+			} else if (dlp->l_lineno < start) {
+				ndlp = TAILQ_NEXT(dlp, l_list);
+				if (ndlp->l_lineno > start)
+					break;
+				dlp = ndlp;
+			}
+		}
+
+		if (dlp == NULL)
+			errx(1, "ed_patch_lines");
+
+
+		if (op == 'c') {
+			insert_after = TAILQ_PREV(dlp, tqh, l_list);
+			for (i = 0; i <= (end - start); i++) {
+				ndlp = TAILQ_NEXT(dlp, l_list);
+				TAILQ_REMOVE(&(dlines->l_lines), dlp, l_list);
+				dlp = ndlp;
+			}
+			dlp = insert_after;
+		}
+
+		if (op == 'a' || op == 'c') {
+			for (;;) {
+				ndlp = lp;
+				lp = TAILQ_NEXT(lp, l_list);
+				if (lp == NULL)
+					errx(1, "ed_patch_lines");
+
+				if (!memcmp(lp->l_line, ".", 1))
+					break;
+
+				TAILQ_REMOVE(&(plines->l_lines), lp, l_list);
+				TAILQ_INSERT_AFTER(&(dlines->l_lines), dlp,
+				    lp, l_list);
+				dlp = lp;
+
+				lp->l_lineno = start;
+				lp = ndlp;
+			}
+		}
+
+		/*
+		 * always resort lines as the markers might be put at the
+		 * same line as we first started editing.
+		 */
+		lineno = 0;
+		TAILQ_FOREACH(sort, &(dlines->l_lines), l_list)
+			sort->l_lineno = lineno++;
+		dlines->l_nblines = lineno - 1;
+	}
+
+	return (0);
+}
+
+/*
+ * Pick up the line numbers of all changes from one change file.
+ * (This puts the numbers in a vector, which is not strictly necessary,
+ * since the vector is processed in one sequential pass.
+ * The vector could be optimized out of existence)
+ */
+static ssize_t
+readin(char *name, struct diff **dd)
+{
+	int a, b, c, d;
+	char kind, *p;
+	size_t i;
+
+	fp[0] = fopen(name, "r");
+	if (fp[0] == NULL)
+		return (-1);
+	for (i = 0; (p = getchange(fp[0])); i++) {
+		if (i >= szchanges - 1)
+			increase();
+		a = b = number(&p);
+		if (*p == ',') {
+			p++;
+			b = number(&p);
+		}
+		kind = *p++;
+		c = d = number(&p);
+		if (*p==',') {
+			p++;
+			d = number(&p);
+		}
+		if (kind == 'a')
+			a++;
+		if (kind == 'd')
+			c++;
+		b++;
+		d++;
+		(*dd)[i].old.from = a;
+		(*dd)[i].old.to = b;
+		(*dd)[i].new.from = c;
+		(*dd)[i].new.to = d;
+	}
+
+	if (i) {
+		(*dd)[i].old.from = (*dd)[i-1].old.to;
+		(*dd)[i].new.from = (*dd)[i-1].new.to;
+	}
+
+	(void)fclose(fp[0]);
+
+	return (i);
+}
+
+static int
+number(char **lc)
+{
+	int nn;
+
+	nn = 0;
+	while (isdigit((unsigned char)(**lc)))
+		nn = nn*10 + *(*lc)++ - '0';
+
+	return (nn);
+}
+
+static char *
+getchange(FILE *b)
+{
+	char *line;
+
+	while ((line = get_line(b, NULL))) {
+		if (isdigit((unsigned char)line[0]))
+			return (line);
+	}
+
+	return (NULL);
+}
+
+static char *
+get_line(FILE *b, size_t *n)
+{
+	char *cp;
+	size_t len;
+	static char *buf;
+	static size_t bufsize;
+
+	if ((cp = fgetln(b, &len)) == NULL)
+		return (NULL);
+
+	if (cp[len - 1] != '\n')
+		len++;
+	if (len + 1 > bufsize) {
+		do {
+			bufsize += 1024;
+		} while (len + 1 > bufsize);
+		buf = xreallocarray(buf, 1, bufsize);
+	}
+	memcpy(buf, cp, len - 1);
+	buf[len - 1] = '\n';
+	buf[len] = '\0';
+	if (n != NULL)
+		*n = len;
+
+	return (buf);
+}
+
+static int
+merge(size_t m1, size_t m2)
+{
+	struct diff *d1, *d2, *d3;
+	int dpl, j, t1, t2;
+
+	d1 = d13;
+	d2 = d23;
+	j = 0;
+	for (;;) {
+		t1 = (d1 < d13 + m1);
+		t2 = (d2 < d23 + m2);
+		if (!t1 && !t2)
+			break;
+
+		if (debug) {
+			printf("%d,%d=%d,%d %d,%d=%d,%d\n",
+			d1->old.from, d1->old.to,
+			d1->new.from, d1->new.to,
+			d2->old.from, d2->old.to,
+			d2->new.from, d2->new.to);
+		}
+
+		/* first file is different from others */
+		if (!t2 || (t1 && d1->new.to < d2->new.from)) {
+			/* stuff peculiar to 1st file */
+			if (eflag==0) {
+				separate("1");
+				change(1, &d1->old, 0);
+				keep(2, &d1->new);
+				change(3, &d1->new, 0);
+			}
+			d1++;
+			continue;
+		}
+
+		/* second file is different from others */
+		if (!t1 || (t2 && d2->new.to < d1->new.from)) {
+			if (eflag==0) {
+				separate("2");
+				keep(1, &d2->new);
+				change(2, &d2->old, 0);
+				change(3, &d2->new, 0);
+			}
+			d2++;
+			continue;
+		}
+
+		/*
+		 * Merge overlapping changes in first file
+		 * this happens after extension (see below).
+		 */
+		if (d1 + 1 < d13 + m1 && d1->new.to >= d1[1].new.from) {
+			d1[1].old.from = d1->old.from;
+			d1[1].new.from = d1->new.from;
+			d1++;
+			continue;
+		}
+
+		/* merge overlapping changes in second */
+		if (d2 + 1 < d23 + m2 && d2->new.to >= d2[1].new.from) {
+			d2[1].old.from = d2->old.from;
+			d2[1].new.from = d2->new.from;
+			d2++;
+			continue;
+		}
+		/* stuff peculiar to third file or different in all */
+		if (d1->new.from == d2->new.from && d1->new.to == d2->new.to) {
+			dpl = duplicate(&d1->old,&d2->old);
+			if (dpl == -1)
+				return (-1);
+
+			/*
+			 * dpl = 0 means all files differ
+			 * dpl = 1 means files 1 and 2 identical
+			 */
+			if (eflag==0) {
+				separate(dpl ? "3" : "");
+				change(1, &d1->old, dpl);
+				change(2, &d2->old, 0);
+				d3 = d1->old.to > d1->old.from ? d1 : d2;
+				change(3, &d3->new, 0);
+			} else
+				j = edit(d1, dpl, j);
+			d1++;
+			d2++;
+			continue;
+		}
+
+		/*
+		 * Overlapping changes from file 1 and 2; extend changes
+		 * appropriately to make them coincide.
+		 */
+		if (d1->new.from < d2->new.from) {
+			d2->old.from -= d2->new.from-d1->new.from;
+			d2->new.from = d1->new.from;
+		} else if (d2->new.from < d1->new.from) {
+			d1->old.from -= d1->new.from-d2->new.from;
+			d1->new.from = d2->new.from;
+		}
+		if (d1->new.to > d2->new.to) {
+			d2->old.to += d1->new.to - d2->new.to;
+			d2->new.to = d1->new.to;
+		} else if (d2->new.to > d1->new.to) {
+			d1->old.to += d2->new.to - d1->new.to;
+			d1->new.to = d2->new.to;
+		}
+	}
+
+	return (edscript(j));
+}
+
+static void
+separate(const char *s)
+{
+	diff_output("====%s\n", s);
+}
+
+/*
+ * The range of lines rold.from thru rold.to in file i is to be changed.
+ * It is to be printed only if it does not duplicate something to be
+ * printed later.
+ */
+static void
+change(int i, struct range *rold, int fdup)
+{
+	diff_output("%d:", i);
+	last[i] = rold->to;
+	prange(rold);
+	if (fdup || debug)
+		return;
+	i--;
+	(void)skip(i, rold->from, NULL);
+	(void)skip(i, rold->to, "  ");
+}
+
+/*
+ * print the range of line numbers, rold.from thru rold.to, as n1,n2 or n1
+ */
+static void
+prange(struct range *rold)
+{
+	if (rold->to <= rold->from)
+		diff_output("%da\n", rold->from - 1);
+	else {
+		diff_output("%d", rold->from);
+		if (rold->to > rold->from+1)
+			diff_output(",%d", rold->to - 1);
+		diff_output("c\n");
+	}
+}
+
+/*
+ * No difference was reported by diff between file 1 (or 2) and file 3,
+ * and an artificial dummy difference (trange) must be ginned up to
+ * correspond to the change reported in the other file.
+ */
+static void
+keep(int i, struct range *rnew)
+{
+	int delta;
+	struct range trange;
+
+	delta = last[3] - last[i];
+	trange.from = rnew->from - delta;
+	trange.to = rnew->to - delta;
+	change(i, &trange, 1);
+}
+
+/*
+ * skip to just before line number from in file "i".  If "pr" is non-NULL,
+ * print all skipped stuff with string pr as a prefix.
+ */
+static int
+skip(int i, int from, char *pr)
+{
+	size_t j, n;
+	char *line;
+
+	for (n = 0; cline[i] < from - 1; n += j) {
+		if ((line = get_line(fp[i], &j)) == NULL)
+			return (-1);
+		if (pr != NULL)
+			diff_output("%s%s", pr, line);
+		cline[i]++;
+	}
+	return ((int) n);
+}
+
+/*
+ * Return 1 or 0 according as the old range (in file 1) contains exactly
+ * the same data as the new range (in file 2).
+ */
+static int
+duplicate(struct range *r1, struct range *r2)
+{
+	int c,d;
+	int nchar;
+	int nline;
+
+	if (r1->to-r1->from != r2->to-r2->from)
+		return (0);
+	(void)skip(0, r1->from, NULL);
+	(void)skip(1, r2->from, NULL);
+	nchar = 0;
+	for (nline=0; nline < r1->to - r1->from; nline++) {
+		do {
+			c = getc(fp[0]);
+			d = getc(fp[1]);
+			if (c == -1 || d== -1)
+				return (-1);
+			nchar++;
+			if (c != d) {
+				repos(nchar);
+				return (0);
+			}
+		} while (c != '\n');
+	}
+	repos(nchar);
+	return (1);
+}
+
+static void
+repos(int nchar)
+{
+	int i;
+
+	for (i = 0; i < 2; i++)
+		(void)fseek(fp[i], (long)-nchar, SEEK_CUR);
+}
+
+/*
+ * collect an editing script for later regurgitation
+ */
+static int
+edit(struct diff *diff, int fdup, int j)
+{
+	if (((fdup + 1) & eflag) == 0)
+		return (j);
+	j++;
+	overlap[j] = !fdup;
+	if (!fdup)
+		overlapcnt++;
+	de[j].old.from = diff->old.from;
+	de[j].old.to = diff->old.to;
+	de[j].new.from = de[j-1].new.to + skip(2, diff->new.from, NULL);
+	de[j].new.to = de[j].new.from + skip(2, diff->new.to, NULL);
+	return (j);
+}
+
+/* regurgitate */
+static int
+edscript(int n)
+{
+	int j, k;
+	char block[BUFSIZ+1];
+
+	for (; n > 0; n--) {
+		if (!oflag || !overlap[n])
+			prange(&de[n].old);
+		else
+			diff_output("%da\n=======\n", de[n].old.to -1);
+		(void)fseek(fp[2], (long)de[n].new.from, SEEK_SET);
+		for (k = de[n].new.to-de[n].new.from; k > 0; k-= j) {
+			j = k > BUFSIZ ? BUFSIZ : k;
+			if (fread(block, 1, j, fp[2]) != (size_t)j)
+				return (-1);
+			block[j] = '\0';
+			diff_output("%s", block);
+		}
+
+		if (!oflag || !overlap[n])
+			diff_output(".\n");
+		else {
+			diff_output("%s\n.\n", f3mark);
+			diff_output("%da\n%s\n.\n", de[n].old.from - 1, f1mark);
+		}
+	}
+
+	return (overlapcnt);
+}
+
+static void
+increase(void)
+{
+	size_t newsz, incr;
+
+	/* are the memset(3) calls needed? */
+	newsz = szchanges == 0 ? 64 : 2 * szchanges;
+	incr = newsz - szchanges;
+
+	d13 = xreallocarray(d13, newsz, sizeof(*d13));
+	memset(d13 + szchanges, 0, incr * sizeof(*d13));
+	d23 = xreallocarray(d23, newsz, sizeof(*d23));
+	memset(d23 + szchanges, 0, incr * sizeof(*d23));
+	de = xreallocarray(de, newsz, sizeof(*de));
+	memset(de + szchanges, 0, incr * sizeof(*de));
+	overlap = xreallocarray(overlap, newsz, sizeof(*overlap));
+	memset(overlap + szchanges, 0, incr * sizeof(*overlap));
+	szchanges = newsz;
+}