text: /*	$OpenBSD: diffreg.c,v 1.91 2016/03/01 20:57:35 natano 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.
   *
   *	@(#)diffreg.c   8.1 (Berkeley) 6/6/93
   */
  
  #include <sys/stat.h>
  #include <sys/wait.h>
  
  #include <ctype.h>
  #include <err.h>
  #include <errno.h>
  #include <fcntl.h>
  #include <paths.h>
  #include <stddef.h>
  #include <stdint.h>
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  #include <unistd.h>
  #include <limits.h>
  
  #include "diff.h"
  #include "xmalloc.h"
  
  #define MINIMUM(a, b)	(((a) < (b)) ? (a) : (b))
  #define MAXIMUM(a, b)	(((a) > (b)) ? (a) : (b))
  
  /*
   * diff - compare two files.
   */
  
  /*
   *	Uses an algorithm due to Harold Stone, which finds
   *	a pair of longest identical subsequences in the two
   *	files.
   *
   *	The major goal is to generate the match vector J.
   *	J[i] is the index of the line in file1 corresponding
   *	to line i file0. J[i] = 0 if there is no
   *	such line in file1.
   *
   *	Lines are hashed so as to work in core. All potential
   *	matches are located by sorting the lines of each file
   *	on the hash (called ``value''). In particular, this
   *	collects the equivalence classes in file1 together.
   *	Subroutine equiv replaces the value of each line in
   *	file0 by the index of the first element of its
   *	matching equivalence in (the reordered) file1.
   *	To save space equiv squeezes file1 into a single
   *	array member in which the equivalence classes
   *	are simply concatenated, except that their first
   *	members are flagged by changing sign.
   *
   *	Next the indices that point into member are unsorted into
   *	array class according to the original order of file0.
   *
   *	The cleverness lies in routine stone. This marches
   *	through the lines of file0, developing a vector klist
   *	of "k-candidates". At step i a k-candidate is a matched
   *	pair of lines x,y (x in file0 y in file1) such that
   *	there is a common subsequence of length k
   *	between the first i lines of file0 and the first y
   *	lines of file1, but there is no such subsequence for
   *	any smaller y. x is the earliest possible mate to y
   *	that occurs in such a subsequence.
   *
   *	Whenever any of the members of the equivalence class of
   *	lines in file1 matable to a line in file0 has serial number
   *	less than the y of some k-candidate, that k-candidate
   *	with the smallest such y is replaced. The new
   *	k-candidate is chained (via pred) to the current
   *	k-1 candidate so that the actual subsequence can
   *	be recovered. When a member has serial number greater
   *	that the y of all k-candidates, the klist is extended.
   *	At the end, the longest subsequence is pulled out
   *	and placed in the array J by unravel
   *
   *	With J in hand, the matches there recorded are
   *	check'ed against reality to assure that no spurious
   *	matches have crept in due to hashing. If they have,
   *	they are broken, and "jackpot" is recorded--a harmless
   *	matter except that a true match for a spuriously
   *	mated line may now be unnecessarily reported as a change.
   *
   *	Much of the complexity of the program comes simply
   *	from trying to minimize core utilization and
   *	maximize the range of doable problems by dynamically
   *	allocating what is needed and reusing what is not.
   *	The core requirements for problems larger than somewhat
   *	are (in words) 2*length(file0) + length(file1) +
   *	3*(number of k-candidates installed),  typically about
   *	6n words for files of length n.
   */
  
  struct cand {
  	int	x;
  	int	y;
  	int	pred;
  };
  
  struct line {
  	int	serial;
  	int	value;
  } *file[2];
  
  /*
   * The following struct is used to record change information when
   * doing a "context" or "unified" diff.  (see routine "change" to
   * understand the highly mnemonic field names)
   */
  struct context_vec {
  	int	a;		/* start line in old file */
  	int	b;		/* end line in old file */
  	int	c;		/* start line in new file */
  	int	d;		/* end line in new file */
  };
  
  #define	diff_output	printf
  static FILE	*opentemp(const char *);
  static void	 output(char *, FILE *, char *, FILE *, int);
  static void	 check(FILE *, FILE *, int);
  static void	 range(int, int, char *);
  static void	 uni_range(int, int);
  static void	 dump_context_vec(FILE *, FILE *, int);
  static void	 dump_unified_vec(FILE *, FILE *, int);
  static void	 prepare(int, FILE *, off_t, int);
  static void	 prune(void);
  static void	 equiv(struct line *, int, struct line *, int, int *);
  static void	 unravel(int);
  static void	 unsort(struct line *, int, int *);
  static void	 change(char *, FILE *, char *, FILE *, int, int, int, int, int *);
  static void	 sort(struct line *, int);
  static void	 print_header(const char *, const char *);
  static int	 ignoreline(char *);
  static int	 asciifile(FILE *);
  static int	 fetch(long *, int, int, FILE *, int, int, int);
  static int	 newcand(int, int, int);
  static int	 search(int *, int, int);
  static int	 skipline(FILE *);
  static int	 isqrt(int);
  static int	 stone(int *, int, int *, int *, int);
  static int	 readhash(FILE *, int);
  static int	 files_differ(FILE *, FILE *, int);
  static char	*match_function(const long *, int, FILE *);
  static char	*preadline(int, size_t, off_t);
  
  static int  *J;			/* will be overlaid on class */
  static int  *class;		/* will be overlaid on file[0] */
  static int  *klist;		/* will be overlaid on file[0] after class */
  static int  *member;		/* will be overlaid on file[1] */
  static int   clen;
  static int   inifdef;		/* whether or not we are in a #ifdef block */
  static int   len[2];
  static int   pref, suff;	/* length of prefix and suffix */
  static int   slen[2];
  static int   anychange;
  static long *ixnew;		/* will be overlaid on file[1] */
  static long *ixold;		/* will be overlaid on klist */
  static struct cand *clist;	/* merely a free storage pot for candidates */
  static int   clistlen;		/* the length of clist */
  static struct line *sfile[2];	/* shortened by pruning common prefix/suffix */
  static u_char *chrtran;		/* translation table for case-folding */
  static struct context_vec *context_vec_start;
  static struct context_vec *context_vec_end;
  static struct context_vec *context_vec_ptr;
  
  #define FUNCTION_CONTEXT_SIZE	55
  static char lastbuf[FUNCTION_CONTEXT_SIZE];
  static int lastline;
  static int lastmatchline;
  
  
  /*
   * chrtran points to one of 2 translation tables: cup2low if folding upper to
   * lower case clow2low if not folding case
   */
  u_char clow2low[256] = {
  	0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a,
  	0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15,
  	0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f, 0x20,
  	0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2a, 0x2b,
  	0x2c, 0x2d, 0x2e, 0x2f, 0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36,
  	0x37, 0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f, 0x40, 0x41,
  	0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49, 0x4a, 0x4b, 0x4c,
  	0x4d, 0x4e, 0x4f, 0x50, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57,
  	0x58, 0x59, 0x5a, 0x5b, 0x5c, 0x5d, 0x5e, 0x5f, 0x60, 0x61, 0x62,
  	0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d,
  	0x6e, 0x6f, 0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78,
  	0x79, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f, 0x80, 0x81, 0x82, 0x83,
  	0x84, 0x85, 0x86, 0x87, 0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e,
  	0x8f, 0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98, 0x99,
  	0x9a, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f, 0xa0, 0xa1, 0xa2, 0xa3, 0xa4,
  	0xa5, 0xa6, 0xa7, 0xa8, 0xa9, 0xaa, 0xab, 0xac, 0xad, 0xae, 0xaf,
  	0xb0, 0xb1, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6, 0xb7, 0xb8, 0xb9, 0xba,
  	0xbb, 0xbc, 0xbd, 0xbe, 0xbf, 0xc0, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5,
  	0xc6, 0xc7, 0xc8, 0xc9, 0xca, 0xcb, 0xcc, 0xcd, 0xce, 0xcf, 0xd0,
  	0xd1, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7, 0xd8, 0xd9, 0xda, 0xdb,
  	0xdc, 0xdd, 0xde, 0xdf, 0xe0, 0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6,
  	0xe7, 0xe8, 0xe9, 0xea, 0xeb, 0xec, 0xed, 0xee, 0xef, 0xf0, 0xf1,
  	0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8, 0xf9, 0xfa, 0xfb, 0xfc,
  	0xfd, 0xfe, 0xff
  };
  
  u_char cup2low[256] = {
  	0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a,
  	0x0b, 0x0c, 0x0d, 0x0e, 0x0f, 0x10, 0x11, 0x12, 0x13, 0x14, 0x15,
  	0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f, 0x20,
  	0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2a, 0x2b,
  	0x2c, 0x2d, 0x2e, 0x2f, 0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36,
  	0x37, 0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f, 0x60, 0x61,
  	0x62, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 0x6a, 0x6b, 0x6c,
  	0x6d, 0x6e, 0x6f, 0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77,
  	0x78, 0x79, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f, 0x60, 0x61, 0x62,
  	0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 0x6a, 0x6b, 0x6c, 0x6d,
  	0x6e, 0x6f, 0x70, 0x71, 0x72, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78,
  	0x79, 0x7a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f, 0x80, 0x81, 0x82, 0x83,
  	0x84, 0x85, 0x86, 0x87, 0x88, 0x89, 0x8a, 0x8b, 0x8c, 0x8d, 0x8e,
  	0x8f, 0x90, 0x91, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98, 0x99,
  	0x9a, 0x9b, 0x9c, 0x9d, 0x9e, 0x9f, 0xa0, 0xa1, 0xa2, 0xa3, 0xa4,
  	0xa5, 0xa6, 0xa7, 0xa8, 0xa9, 0xaa, 0xab, 0xac, 0xad, 0xae, 0xaf,
  	0xb0, 0xb1, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6, 0xb7, 0xb8, 0xb9, 0xba,
  	0xbb, 0xbc, 0xbd, 0xbe, 0xbf, 0xc0, 0xc1, 0xc2, 0xc3, 0xc4, 0xc5,
  	0xc6, 0xc7, 0xc8, 0xc9, 0xca, 0xcb, 0xcc, 0xcd, 0xce, 0xcf, 0xd0,
  	0xd1, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7, 0xd8, 0xd9, 0xda, 0xdb,
  	0xdc, 0xdd, 0xde, 0xdf, 0xe0, 0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6,
  	0xe7, 0xe8, 0xe9, 0xea, 0xeb, 0xec, 0xed, 0xee, 0xef, 0xf0, 0xf1,
  	0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8, 0xf9, 0xfa, 0xfb, 0xfc,
  	0xfd, 0xfe, 0xff
  };
  
  int
  diffreg(char *file1, char *file2, int flags)
  {
  	FILE *f1, *f2;
  	int i, rval;
  
  	f1 = f2 = NULL;
  	rval = D_SAME;
  	anychange = 0;
  	lastline = 0;
  	lastmatchline = 0;
  	context_vec_ptr = context_vec_start - 1;
  	if (flags & D_IGNORECASE)
  		chrtran = cup2low;
  	else
  		chrtran = clow2low;
  	if (S_ISDIR(stb1.st_mode) != S_ISDIR(stb2.st_mode))
  		return (S_ISDIR(stb1.st_mode) ? D_MISMATCH1 : D_MISMATCH2);
  	if (strcmp(file1, "-") == 0 && strcmp(file2, "-") == 0)
  		goto closem;
  
  	if (flags & D_EMPTY1)
  		f1 = fopen(_PATH_DEVNULL, "r");
  	else {
  		if (!S_ISREG(stb1.st_mode)) {
  			if ((f1 = opentemp(file1)) == NULL ||
  			    fstat(fileno(f1), &stb1) < 0) {
  				warn("%s", file1);
  				status |= 2;
  				goto closem;
  			}
  		} else if (strcmp(file1, "-") == 0)
  			f1 = stdin;
  		else
  			f1 = fopen(file1, "r");
  	}
  	if (f1 == NULL) {
  		warn("%s", file1);
  		status |= 2;
  		goto closem;
  	}
  
  	if (flags & D_EMPTY2)
  		f2 = fopen(_PATH_DEVNULL, "r");
  	else {
  		if (!S_ISREG(stb2.st_mode)) {
  			if ((f2 = opentemp(file2)) == NULL ||
  			    fstat(fileno(f2), &stb2) < 0) {
  				warn("%s", file2);
  				status |= 2;
  				goto closem;
  			}
  		} else if (strcmp(file2, "-") == 0)
  			f2 = stdin;
  		else
  			f2 = fopen(file2, "r");
  	}
  	if (f2 == NULL) {
  		warn("%s", file2);
  		status |= 2;
  		goto closem;
  	}
  
  	switch (files_differ(f1, f2, flags)) {
  	case 0:
  		goto closem;
  	case 1:
  		break;
  	default:
  		/* error */
  		status |= 2;
  		goto closem;
  	}
  
  	if ((flags & D_FORCEASCII) == 0 &&
  	    (!asciifile(f1) || !asciifile(f2))) {
  		rval = D_BINARY;
  		status |= 1;
  		goto closem;
  	}
  	prepare(0, f1, stb1.st_size, flags);
  	prepare(1, f2, stb2.st_size, flags);
  
  	prune();
  	sort(sfile[0], slen[0]);
  	sort(sfile[1], slen[1]);
  
  	member = (int *)file[1];
  	equiv(sfile[0], slen[0], sfile[1], slen[1], member);
  	member = xreallocarray(member, slen[1] + 2, sizeof(*member));
  
  	class = (int *)file[0];
  	unsort(sfile[0], slen[0], class);
  	class = xreallocarray(class, slen[0] + 2, sizeof(*class));
  
  	klist = xcalloc(slen[0] + 2, sizeof(*klist));
  	clen = 0;
  	clistlen = 100;
  	clist = xcalloc(clistlen, sizeof(*clist));
  	i = stone(class, slen[0], member, klist, flags);
  	free(member);
  	free(class);
  
  	J = xreallocarray(J, len[0] + 2, sizeof(*J));
  	unravel(klist[i]);
  	free(clist);
  	free(klist);
  
  	ixold = xreallocarray(ixold, len[0] + 2, sizeof(*ixold));
  	ixnew = xreallocarray(ixnew, len[1] + 2, sizeof(*ixnew));
  	check(f1, f2, flags);
  	output(file1, f1, file2, f2, flags);
  closem:
  	if (anychange) {
  		status |= 1;
  		if (rval == D_SAME)
  			rval = D_DIFFER;
  	}
  	if (f1 != NULL)
  		fclose(f1);
  	if (f2 != NULL)
  		fclose(f2);
  
  	return (rval);
  }
  
  /*
   * Check to see if the given files differ.
   * Returns 0 if they are the same, 1 if different, and -1 on error.
   * XXX - could use code from cmp(1) [faster]
   */
  static int
  files_differ(FILE *f1, FILE *f2, int flags)
  {
  	char buf1[BUFSIZ], buf2[BUFSIZ];
  	size_t i, j;
  
  	if ((flags & (D_EMPTY1|D_EMPTY2)) || stb1.st_size != stb2.st_size ||
  	    (stb1.st_mode & S_IFMT) != (stb2.st_mode & S_IFMT))
  		return (1);
  	for (;;) {
  		i = fread(buf1, 1, sizeof(buf1), f1);
  		j = fread(buf2, 1, sizeof(buf2), f2);
  		if ((!i && ferror(f1)) || (!j && ferror(f2)))
  			return (-1);
  		if (i != j)
  			return (1);
  		if (i == 0)
  			return (0);
  		if (memcmp(buf1, buf2, i) != 0)
  			return (1);
  	}
  }
  
  static FILE *
  opentemp(const char *file)
  {
  	char buf[BUFSIZ], tempfile[PATH_MAX];
  	ssize_t nread;
  	int ifd, ofd;
  
  	if (strcmp(file, "-") == 0)
  		ifd = STDIN_FILENO;
  	else if ((ifd = open(file, O_RDONLY, 0644)) < 0)
  		return (NULL);
  
  	(void)strlcpy(tempfile, _PATH_TMP "/diff.XXXXXXXX", sizeof(tempfile));
  
  	if ((ofd = mkstemp(tempfile)) < 0) {
  		close(ifd);
  		return (NULL);
  	}
  	unlink(tempfile);
  	while ((nread = read(ifd, buf, BUFSIZ)) > 0) {
  		if (write(ofd, buf, nread) != nread) {
  			close(ifd);
  			close(ofd);
  			return (NULL);
  		}
  	}
  	close(ifd);
  	lseek(ofd, (off_t)0, SEEK_SET);
  	return (fdopen(ofd, "r"));
  }
  
  char *
  splice(char *dir, char *file)
  {
  	char *tail, *buf;
  	size_t dirlen;
  
  	dirlen = strlen(dir);
  	while (dirlen != 0 && dir[dirlen - 1] == '/')
  	    dirlen--;
  	if ((tail = strrchr(file, '/')) == NULL)
  		tail = file;
  	else
  		tail++;
  	xasprintf(&buf, "%.*s/%s", (int)dirlen, dir, tail);
  	return (buf);
  }
  
  static void
  prepare(int i, FILE *fd, off_t filesize, int flags)
  {
  	struct line *p;
  	int j, h;
  	size_t sz;
  
  	rewind(fd);
  
  	sz = (filesize <= SIZE_MAX ? filesize : SIZE_MAX) / 25;
  	if (sz < 100)
  		sz = 100;
  
  	p = xcalloc(sz + 3, sizeof(*p));
  	for (j = 0; (h = readhash(fd, flags));) {
  		if (j == sz) {
  			sz = sz * 3 / 2;
  			p = xreallocarray(p, sz + 3, sizeof(*p));
  		}
  		p[++j].value = h;
  	}
  	len[i] = j;
  	file[i] = p;
  }
  
  static void
  prune(void)
  {
  	int i, j;
  
  	for (pref = 0; pref < len[0] && pref < len[1] &&
  	    file[0][pref + 1].value == file[1][pref + 1].value;
  	    pref++)
  		;
  	for (suff = 0; suff < len[0] - pref && suff < len[1] - pref &&
  	    file[0][len[0] - suff].value == file[1][len[1] - suff].value;
  	    suff++)
  		;
  	for (j = 0; j < 2; j++) {
  		sfile[j] = file[j] + pref;
  		slen[j] = len[j] - pref - suff;
  		for (i = 0; i <= slen[j]; i++)
  			sfile[j][i].serial = i;
  	}
  }
  
  static void
  equiv(struct line *a, int n, struct line *b, int m, int *c)
  {
  	int i, j;
  
  	i = j = 1;
  	while (i <= n && j <= m) {
  		if (a[i].value < b[j].value)
  			a[i++].value = 0;
  		else if (a[i].value == b[j].value)
  			a[i++].value = j;
  		else
  			j++;
  	}
  	while (i <= n)
  		a[i++].value = 0;
  	b[m + 1].value = 0;
  	j = 0;
  	while (++j <= m) {
  		c[j] = -b[j].serial;
  		while (b[j + 1].value == b[j].value) {
  			j++;
  			c[j] = b[j].serial;
  		}
  	}
  	c[j] = -1;
  }
  
  /* Code taken from ping.c */
  static int
  isqrt(int n)
  {
  	int y, x = 1;
  
  	if (n == 0)
  		return (0);
  
  	do { /* newton was a stinker */
  		y = x;
  		x = n / x;
  		x += y;
  		x /= 2;
  	} while ((x - y) > 1 || (x - y) < -1);
  
  	return (x);
  }
  
  static int
  stone(int *a, int n, int *b, int *c, int flags)
  {
  	int i, k, y, j, l;
  	int oldc, tc, oldl, sq;
  	u_int numtries, bound;
  
  	if (flags & D_MINIMAL)
  		bound = UINT_MAX;
  	else {
  		sq = isqrt(n);
  		bound = MAXIMUM(256, sq);
  	}
  
  	k = 0;
  	c[0] = newcand(0, 0, 0);
  	for (i = 1; i <= n; i++) {
  		j = a[i];
  		if (j == 0)
  			continue;
  		y = -b[j];
  		oldl = 0;
  		oldc = c[0];
  		numtries = 0;
  		do {
  			if (y <= clist[oldc].y)
  				continue;
  			l = search(c, k, y);
  			if (l != oldl + 1)
  				oldc = c[l - 1];
  			if (l <= k) {
  				if (clist[c[l]].y <= y)
  					continue;
  				tc = c[l];
  				c[l] = newcand(i, y, oldc);
  				oldc = tc;
  				oldl = l;
  				numtries++;
  			} else {
  				c[l] = newcand(i, y, oldc);
  				k++;
  				break;
  			}
  		} while ((y = b[++j]) > 0 && numtries < bound);
  	}
  	return (k);
  }
  
  static int
  newcand(int x, int y, int pred)
  {
  	struct cand *q;
  
  	if (clen == clistlen) {
  		clistlen = clistlen * 11 / 10;
  		clist = xreallocarray(clist, clistlen, sizeof(*clist));
  	}
  	q = clist + clen;
  	q->x = x;
  	q->y = y;
  	q->pred = pred;
  	return (clen++);
  }
  
  static int
  search(int *c, int k, int y)
  {
  	int i, j, l, t;
  
  	if (clist[c[k]].y < y)	/* quick look for typical case */
  		return (k + 1);
  	i = 0;
  	j = k + 1;
  	for (;;) {
  		l = (i + j) / 2;
  		if (l <= i)
  			break;
  		t = clist[c[l]].y;
  		if (t > y)
  			j = l;
  		else if (t < y)
  			i = l;
  		else
  			return (l);
  	}
  	return (l + 1);
  }
  
  static void
  unravel(int p)
  {
  	struct cand *q;
  	int i;
  
  	for (i = 0; i <= len[0]; i++)
  		J[i] = i <= pref ? i :
  		    i > len[0] - suff ? i + len[1] - len[0] : 0;
  	for (q = clist + p; q->y != 0; q = clist + q->pred)
  		J[q->x + pref] = q->y + pref;
  }
  
  /*
   * Check does double duty:
   *  1.	ferret out any fortuitous correspondences due
   *	to confounding by hashing (which result in "jackpot")
   *  2.  collect random access indexes to the two files
   */
  static void
  check(FILE *f1, FILE *f2, int flags)
  {
  	int i, j, jackpot, c, d;
  	long ctold, ctnew;
  
  	rewind(f1);
  	rewind(f2);
  	j = 1;
  	ixold[0] = ixnew[0] = 0;
  	jackpot = 0;
  	ctold = ctnew = 0;
  	for (i = 1; i <= len[0]; i++) {
  		if (J[i] == 0) {
  			ixold[i] = ctold += skipline(f1);
  			continue;
  		}
  		while (j < J[i]) {
  			ixnew[j] = ctnew += skipline(f2);
  			j++;
  		}
  		if (flags & (D_FOLDBLANKS|D_IGNOREBLANKS|D_IGNORECASE)) {
  			for (;;) {
  				c = getc(f1);
  				d = getc(f2);
  				/*
  				 * GNU diff ignores a missing newline
  				 * in one file for -b or -w.
  				 */
  				if (flags & (D_FOLDBLANKS|D_IGNOREBLANKS)) {
  					if (c == EOF && d == '\n') {
  						ctnew++;
  						break;
  					} else if (c == '\n' && d == EOF) {
  						ctold++;
  						break;
  					}
  				}
  				ctold++;
  				ctnew++;
  				if ((flags & D_FOLDBLANKS) && isspace(c) &&
  				    isspace(d)) {
  					do {
  						if (c == '\n')
  							break;
  						ctold++;
  					} while (isspace(c = getc(f1)));
  					do {
  						if (d == '\n')
  							break;
  						ctnew++;
  					} while (isspace(d = getc(f2)));
  				} else if ((flags & D_IGNOREBLANKS)) {
  					while (isspace(c) && c != '\n') {
  						c = getc(f1);
  						ctold++;
  					}
  					while (isspace(d) && d != '\n') {
  						d = getc(f2);
  						ctnew++;
  					}
  				}
  				if (chrtran[c] != chrtran[d]) {
  					jackpot++;
  					J[i] = 0;
  					if (c != '\n' && c != EOF)
  						ctold += skipline(f1);
  					if (d != '\n' && c != EOF)
  						ctnew += skipline(f2);
  					break;
  				}
  				if (c == '\n' || c == EOF)
  					break;
  			}
  		} else {
  			for (;;) {
  				ctold++;
  				ctnew++;
  				if ((c = getc(f1)) != (d = getc(f2))) {
  					/* jackpot++; */
  					J[i] = 0;
  					if (c != '\n' && c != EOF)
  						ctold += skipline(f1);
  					if (d != '\n' && c != EOF)
  						ctnew += skipline(f2);
  					break;
  				}
  				if (c == '\n' || c == EOF)
  					break;
  			}
  		}
  		ixold[i] = ctold;
  		ixnew[j] = ctnew;
  		j++;
  	}
  	for (; j <= len[1]; j++)
  		ixnew[j] = ctnew += skipline(f2);
  	/*
  	 * if (jackpot)
  	 *	fprintf(stderr, "jackpot\n");
  	 */
  }
  
  /* shellsort CACM #201 */
  static void
  sort(struct line *a, int n)
  {
  	struct line *ai, *aim, w;
  	int j, m = 0, k;
  
  	if (n == 0)
  		return;
  	for (j = 1; j <= n; j *= 2)
  		m = 2 * j - 1;
  	for (m /= 2; m != 0; m /= 2) {
  		k = n - m;
  		for (j = 1; j <= k; j++) {
  			for (ai = &a[j]; ai > a; ai -= m) {
  				aim = &ai[m];
  				if (aim < ai)
  					break;	/* wraparound */
  				if (aim->value > ai[0].value ||
  				    (aim->value == ai[0].value &&
  					aim->serial > ai[0].serial))
  					break;
  				w.value = ai[0].value;
  				ai[0].value = aim->value;
  				aim->value = w.value;
  				w.serial = ai[0].serial;
  				ai[0].serial = aim->serial;
  				aim->serial = w.serial;
  			}
  		}
  	}
  }
  
  static void
  unsort(struct line *f, int l, int *b)
  {
  	int *a, i;
  
  	a = xcalloc(l + 1, sizeof(*a));
  	for (i = 1; i <= l; i++)
  		a[f[i].serial] = f[i].value;
  	for (i = 1; i <= l; i++)
  		b[i] = a[i];
  	free(a);
  }
  
  static int
  skipline(FILE *f)
  {
  	int i, c;
  
  	for (i = 1; (c = getc(f)) != '\n' && c != EOF; i++)
  		continue;
  	return (i);
  }
  
  static void
  output(char *file1, FILE *f1, char *file2, FILE *f2, int flags)
  {
  	int m, i0, i1, j0, j1;
  
  	rewind(f1);
  	rewind(f2);
  	m = len[0];
  	J[0] = 0;
  	J[m + 1] = len[1] + 1;
  	if (diff_format != D_EDIT) {
  		for (i0 = 1; i0 <= m; i0 = i1 + 1) {
  			while (i0 <= m && J[i0] == J[i0 - 1] + 1)
  				i0++;
  			j0 = J[i0 - 1] + 1;
  			i1 = i0 - 1;
  			while (i1 < m && J[i1 + 1] == 0)
  				i1++;
  			j1 = J[i1 + 1] - 1;
  			J[i1] = j1;
  			change(file1, f1, file2, f2, i0, i1, j0, j1, &flags);
  		}
  	} else {
  		for (i0 = m; i0 >= 1; i0 = i1 - 1) {
  			while (i0 >= 1 && J[i0] == J[i0 + 1] - 1 && J[i0] != 0)
  				i0--;
  			j0 = J[i0 + 1] - 1;
  			i1 = i0 + 1;
  			while (i1 > 1 && J[i1 - 1] == 0)
  				i1--;
  			j1 = J[i1 - 1] + 1;
  			J[i1] = j1;
  			change(file1, f1, file2, f2, i1, i0, j1, j0, &flags);
  		}
  	}
  	if (m == 0)
  		change(file1, f1, file2, f2, 1, 0, 1, len[1], &flags);
  	if (diff_format == D_IFDEF) {
  		for (;;) {
  #define	c i0
  			if ((c = getc(f1)) == EOF)
  				return;
  			diff_output("%c", c);
  		}
  #undef c
  	}
  	if (anychange != 0) {
  		if (diff_format == D_CONTEXT)
  			dump_context_vec(f1, f2, flags);
  		else if (diff_format == D_UNIFIED)
  			dump_unified_vec(f1, f2, flags);
  	}
  }
  
  static void
  range(int a, int b, char *separator)
  {
  	diff_output("%d", a > b ? b : a);
  	if (a < b)
  		diff_output("%s%d", separator, b);
  }
  
  static void
  uni_range(int a, int b)
  {
  	if (a < b)
  		diff_output("%d,%d", a, b - a + 1);
  	else if (a == b)
  		diff_output("%d", b);
  	else
  		diff_output("%d,0", b);
  }
  
  static char *
  preadline(int fd, size_t rlen, off_t off)
  {
  	char *line;
  	ssize_t nr;
  
  	line = xmalloc(rlen + 1);
  	if ((nr = pread(fd, line, rlen, off)) < 0)
  		err(2, "preadline");
  	if (nr > 0 && line[nr-1] == '\n')
  		nr--;
  	line[nr] = '\0';
  	return (line);
  }
  
  static int
  ignoreline(char *line)
  {
  	int ret;
  
  	ret = regexec(&ignore_re, line, 0, NULL, 0);
  	free(line);
  	return (ret == 0);	/* if it matched, it should be ignored. */
  }
  
  /*
   * Indicate that there is a difference between lines a and b of the from file
   * to get to lines c to d of the to file.  If a is greater then b then there
   * are no lines in the from file involved and this means that there were
   * lines appended (beginning at b).  If c is greater than d then there are
   * lines missing from the to file.
   */
  static void
  change(char *file1, FILE *f1, char *file2, FILE *f2, int a, int b, int c, int d,
      int *pflags)
  {
  	static size_t max_context = 64;
  	int i;
  
  restart:
  	if (diff_format != D_IFDEF && a > b && c > d)
  		return;
  	if (ignore_pats != NULL) {
  		char *line;
  		/*
  		 * All lines in the change, insert, or delete must
  		 * match an ignore pattern for the change to be
  		 * ignored.
  		 */
  		if (a <= b) {		/* Changes and deletes. */
  			for (i = a; i <= b; i++) {
  				line = preadline(fileno(f1),
  				    ixold[i] - ixold[i - 1], ixold[i - 1]);
  				if (!ignoreline(line))
  					goto proceed;
  			}
  		}
  		if (a > b || c <= d) {	/* Changes and inserts. */
  			for (i = c; i <= d; i++) {
  				line = preadline(fileno(f2),
  				    ixnew[i] - ixnew[i - 1], ixnew[i - 1]);
  				if (!ignoreline(line))
  					goto proceed;
  			}
  		}
  		return;
  	}
  proceed:
  	if (*pflags & D_HEADER) {
  		diff_output("%s %s %s\n", diffargs, file1, file2);
  		*pflags &= ~D_HEADER;
  	}
  	if (diff_format == D_CONTEXT || diff_format == D_UNIFIED) {
  		/*
  		 * Allocate change records as needed.
  		 */
  		if (context_vec_ptr == context_vec_end - 1) {
  			ptrdiff_t offset = context_vec_ptr - context_vec_start;
  			max_context <<= 1;
  			context_vec_start = xreallocarray(context_vec_start,
  			    max_context, sizeof(*context_vec_start));
  			context_vec_end = context_vec_start + max_context;
  			context_vec_ptr = context_vec_start + offset;
  		}
  		if (anychange == 0) {
  			/*
  			 * Print the context/unidiff header first time through.
  			 */
  			print_header(file1, file2);
  			anychange = 1;
  		} else if (a > context_vec_ptr->b + (2 * diff_context) + 1 &&
  		    c > context_vec_ptr->d + (2 * diff_context) + 1) {
  			/*
  			 * If this change is more than 'diff_context' lines from the
  			 * previous change, dump the record and reset it.
  			 */
  			if (diff_format == D_CONTEXT)
  				dump_context_vec(f1, f2, *pflags);
  			else
  				dump_unified_vec(f1, f2, *pflags);
  		}
  		context_vec_ptr++;
  		context_vec_ptr->a = a;
  		context_vec_ptr->b = b;
  		context_vec_ptr->c = c;
  		context_vec_ptr->d = d;
  		return;
  	}
  	if (anychange == 0)
  		anychange = 1;
  	switch (diff_format) {
  	case D_BRIEF:
  		return;
  	case D_NORMAL:
  	case D_EDIT:
  		range(a, b, ",");
  		diff_output("%c", a > b ? 'a' : c > d ? 'd' : 'c');
  		if (diff_format == D_NORMAL)
  			range(c, d, ",");
  		diff_output("\n");
  		break;
  	case D_REVERSE:
  		diff_output("%c", a > b ? 'a' : c > d ? 'd' : 'c');
  		range(a, b, " ");
  		diff_output("\n");
  		break;
  	case D_NREVERSE:
  		if (a > b)
  			diff_output("a%d %d\n", b, d - c + 1);
  		else {
  			diff_output("d%d %d\n", a, b - a + 1);
  			if (!(c > d))
  				/* add changed lines */
  				diff_output("a%d %d\n", b, d - c + 1);
  		}
  		break;
  	}
  	if (diff_format == D_NORMAL || diff_format == D_IFDEF) {
  		fetch(ixold, a, b, f1, '<', 1, *pflags);
  		if (a <= b && c <= d && diff_format == D_NORMAL)
  			diff_output("---\n");
  	}
  	i = fetch(ixnew, c, d, f2, diff_format == D_NORMAL ? '>' : '\0', 0, *pflags);
  	if (i != 0 && diff_format == D_EDIT) {
  		/*
  		 * A non-zero return value for D_EDIT indicates that the
  		 * last line printed was a bare dot (".") that has been
  		 * escaped as ".." to prevent ed(1) from misinterpreting
  		 * it.  We have to add a substitute command to change this
  		 * back and restart where we left off.
  		 */
  		diff_output(".\n");
  		diff_output("%ds/.//\n", a + i - 1);
  		b = a + i - 1;
  		a = b + 1;
  		c += i;
  		goto restart;
  	}
  	if ((diff_format == D_EDIT || diff_format == D_REVERSE) && c <= d)
  		diff_output(".\n");
  	if (inifdef) {
  		diff_output("#endif /* %s */\n", ifdefname);
  		inifdef = 0;
  	}
  }
  
  static int
  fetch(long *f, int a, int b, FILE *lb, int ch, int oldfile, int flags)
  {
  	int i, j, c, lastc, col, nc;
  
  	/*
  	 * When doing #ifdef's, copy down to current line
  	 * if this is the first file, so that stuff makes it to output.
  	 */
  	if (diff_format == D_IFDEF && oldfile) {
  		long curpos = ftell(lb);
  		/* print through if append (a>b), else to (nb: 0 vs 1 orig) */
  		nc = f[a > b ? b : a - 1] - curpos;
  		for (i = 0; i < nc; i++)
  			diff_output("%c", getc(lb));
  	}
  	if (a > b)
  		return (0);
  	if (diff_format == D_IFDEF) {
  		if (inifdef) {
  			diff_output("#else /* %s%s */\n",
  			    oldfile == 1 ? "!" : "", ifdefname);
  		} else {
  			if (oldfile)
  				diff_output("#ifndef %s\n", ifdefname);
  			else
  				diff_output("#ifdef %s\n", ifdefname);
  		}
  		inifdef = 1 + oldfile;
  	}
  	for (i = a; i <= b; i++) {
  		fseek(lb, f[i - 1], SEEK_SET);
  		nc = f[i] - f[i - 1];
  		if (diff_format != D_IFDEF && ch != '\0') {
  			diff_output("%c", ch);
  			if (Tflag && (diff_format == D_NORMAL || diff_format == D_CONTEXT
  			    || diff_format == D_UNIFIED))
  				diff_output("\t");
  			else if (diff_format != D_UNIFIED)
  				diff_output(" ");
  		}
  		col = 0;
  		for (j = 0, lastc = '\0'; j < nc; j++, lastc = c) {
  			if ((c = getc(lb)) == EOF) {
  				if (diff_format == D_EDIT || diff_format == D_REVERSE ||
  				    diff_format == D_NREVERSE)
  					warnx("No newline at end of file");
  				else
  					diff_output("\n\\ No newline at end of "
  					    "file\n");
  				return (0);
  			}
  			if (c == '\t' && (flags & D_EXPANDTABS)) {
  				do {
  					diff_output(" ");
  				} while (++col & 7);
  			} else {
  				if (diff_format == D_EDIT && j == 1 && c == '\n'
  				    && lastc == '.') {
  					/*
  					 * Don't print a bare "." line
  					 * since that will confuse ed(1).
  					 * Print ".." instead and return,
  					 * giving the caller an offset
  					 * from which to restart.
  					 */
  					diff_output(".\n");
  					return (i - a + 1);
  				}
  				diff_output("%c", c);
  				col++;
  			}
  		}
  	}
  	return (0);
  }
  
  /*
   * Hash function taken from Robert Sedgewick, Algorithms in C, 3d ed., p 578.
   */
  static int
  readhash(FILE *f, int flags)
  {
  	int i, t, space;
  	int sum;
  
  	sum = 1;
  	space = 0;
  	if ((flags & (D_FOLDBLANKS|D_IGNOREBLANKS)) == 0) {
  		if (flags & D_IGNORECASE)
  			for (i = 0; (t = getc(f)) != '\n'; i++) {
  				if (t == EOF) {
  					if (i == 0)
  						return (0);
  					break;
  				}
  				sum = sum * 127 + chrtran[t];
  			}
  		else
  			for (i = 0; (t = getc(f)) != '\n'; i++) {
  				if (t == EOF) {
  					if (i == 0)
  						return (0);
  					break;
  				}
  				sum = sum * 127 + t;
  			}
  	} else {
  		for (i = 0;;) {
  			switch (t = getc(f)) {
  			case '\t':
  			case '\r':
  			case '\v':
  			case '\f':
  			case ' ':
  				space++;
  				continue;
  			default:
  				if (space && (flags & D_IGNOREBLANKS) == 0) {
  					i++;
  					space = 0;
  				}
  				sum = sum * 127 + chrtran[t];
  				i++;
  				continue;
  			case EOF:
  				if (i == 0)
  					return (0);
  				/* FALLTHROUGH */
  			case '\n':
  				break;
  			}
  			break;
  		}
  	}
  	/*
  	 * There is a remote possibility that we end up with a zero sum.
  	 * Zero is used as an EOF marker, so return 1 instead.
  	 */
  	return (sum == 0 ? 1 : sum);
  }
  
  static int
  asciifile(FILE *f)
  {
  	unsigned char buf[BUFSIZ];
  	size_t cnt;
  
  	if (f == NULL)
  		return (1);
  
  	rewind(f);
  	cnt = fread(buf, 1, sizeof(buf), f);
  	return (memchr(buf, '\0', cnt) == NULL);
  }
  
  #define begins_with(s, pre) (strncmp(s, pre, sizeof(pre)-1) == 0)
  
  static char *
  match_function(const long *f, int pos, FILE *fp)
  {
  	unsigned char buf[FUNCTION_CONTEXT_SIZE];
  	size_t nc;
  	int last = lastline;
  	char *state = NULL;
  
  	lastline = pos;
  	while (pos > last) {
  		fseek(fp, f[pos - 1], SEEK_SET);
  		nc = f[pos] - f[pos - 1];
  		if (nc >= sizeof(buf))
  			nc = sizeof(buf) - 1;
  		nc = fread(buf, 1, nc, fp);
  		if (nc > 0) {
  			buf[nc] = '\0';
  			buf[strcspn(buf, "\n")] = '\0';
  			if (isalpha(buf[0]) || buf[0] == '_' || buf[0] == '$') {
  				if (begins_with(buf, "private:")) {
  					if (!state)
  						state = " (private)";
  				} else if (begins_with(buf, "protected:")) {
  					if (!state)
  						state = " (protected)";
  				} else if (begins_with(buf, "public:")) {
  					if (!state)
  						state = " (public)";
  				} else {
  					strlcpy(lastbuf, buf, sizeof lastbuf);
  					if (state)
  						strlcat(lastbuf, state,
  						    sizeof lastbuf);
  					lastmatchline = pos;
  					return lastbuf;
  				}
  			}
  		}
  		pos--;
  	}
  	return lastmatchline > 0 ? lastbuf : NULL;
  }
  
  /* dump accumulated "context" diff changes */
  static void
  dump_context_vec(FILE *f1, FILE *f2, int flags)
  {
  	struct context_vec *cvp = context_vec_start;
  	int lowa, upb, lowc, upd, do_output;
  	int a, b, c, d;
  	char ch, *f;
  
  	if (context_vec_start > context_vec_ptr)
  		return;
  
  	b = d = 0;		/* gcc */
  	lowa = MAXIMUM(1, cvp->a - diff_context);
  	upb = MINIMUM(len[0], context_vec_ptr->b + diff_context);
  	lowc = MAXIMUM(1, cvp->c - diff_context);
  	upd = MINIMUM(len[1], context_vec_ptr->d + diff_context);
  
  	diff_output("***************");
  	if ((flags & D_PROTOTYPE)) {
  		f = match_function(ixold, lowa-1, f1);
  		if (f != NULL)
  			diff_output(" %s", f);
  	}
  	diff_output("\n*** ");
  	range(lowa, upb, ",");
  	diff_output(" ****\n");
  
  	/*
  	 * Output changes to the "old" file.  The first loop suppresses
  	 * output if there were no changes to the "old" file (we'll see
  	 * the "old" lines as context in the "new" list).
  	 */
  	do_output = 0;
  	for (; cvp <= context_vec_ptr; cvp++)
  		if (cvp->a <= cvp->b) {
  			cvp = context_vec_start;
  			do_output++;
  			break;
  		}
  	if (do_output) {
  		while (cvp <= context_vec_ptr) {
  			a = cvp->a;
  			b = cvp->b;
  			c = cvp->c;
  			d = cvp->d;
  
  			if (a <= b && c <= d)
  				ch = 'c';
  			else
  				ch = (a <= b) ? 'd' : 'a';
  
  			if (ch == 'a')
  				fetch(ixold, lowa, b, f1, ' ', 0, flags);
  			else {
  				fetch(ixold, lowa, a - 1, f1, ' ', 0, flags);
  				fetch(ixold, a, b, f1,
  				    ch == 'c' ? '!' : '-', 0, flags);
  			}
  			lowa = b + 1;
  			cvp++;
  		}
  		fetch(ixold, b + 1, upb, f1, ' ', 0, flags);
  	}
  	/* output changes to the "new" file */
  	diff_output("--- ");
  	range(lowc, upd, ",");
  	diff_output(" ----\n");
  
  	do_output = 0;
  	for (cvp = context_vec_start; cvp <= context_vec_ptr; cvp++)
  		if (cvp->c <= cvp->d) {
  			cvp = context_vec_start;
  			do_output++;
  			break;
  		}
  	if (do_output) {
  		while (cvp <= context_vec_ptr) {
  			a = cvp->a;
  			b = cvp->b;
  			c = cvp->c;
  			d = cvp->d;
  
  			if (a <= b && c <= d)
  				ch = 'c';
  			else
  				ch = (a <= b) ? 'd' : 'a';
  
  			if (ch == 'd')
  				fetch(ixnew, lowc, d, f2, ' ', 0, flags);
  			else {
  				fetch(ixnew, lowc, c - 1, f2, ' ', 0, flags);
  				fetch(ixnew, c, d, f2,
  				    ch == 'c' ? '!' : '+', 0, flags);
  			}
  			lowc = d + 1;
  			cvp++;
  		}
  		fetch(ixnew, d + 1, upd, f2, ' ', 0, flags);
  	}
  	context_vec_ptr = context_vec_start - 1;
  }
  
  /* dump accumulated "unified" diff changes */
  static void
  dump_unified_vec(FILE *f1, FILE *f2, int flags)
  {
  	struct context_vec *cvp = context_vec_start;
  	int lowa, upb, lowc, upd;
  	int a, b, c, d;
  	char ch, *f;
  
  	if (context_vec_start > context_vec_ptr)
  		return;
  
  	b = d = 0;		/* gcc */
  	lowa = MAXIMUM(1, cvp->a - diff_context);
  	upb = MINIMUM(len[0], context_vec_ptr->b + diff_context);
  	lowc = MAXIMUM(1, cvp->c - diff_context);
  	upd = MINIMUM(len[1], context_vec_ptr->d + diff_context);
  
  	diff_output("@@ -");
  	uni_range(lowa, upb);
  	diff_output(" +");
  	uni_range(lowc, upd);
  	diff_output(" @@");
  	if ((flags & D_PROTOTYPE)) {
  		f = match_function(ixold, lowa-1, f1);
  		if (f != NULL)
  			diff_output(" %s", f);
  	}
  	diff_output("\n");
  
  	/*
  	 * Output changes in "unified" diff format--the old and new lines
  	 * are printed together.
  	 */
  	for (; cvp <= context_vec_ptr; cvp++) {
  		a = cvp->a;
  		b = cvp->b;
  		c = cvp->c;
  		d = cvp->d;
  
  		/*
  		 * c: both new and old changes
  		 * d: only changes in the old file
  		 * a: only changes in the new file
  		 */
  		if (a <= b && c <= d)
  			ch = 'c';
  		else
  			ch = (a <= b) ? 'd' : 'a';
  
  		switch (ch) {
  		case 'c':
  			fetch(ixold, lowa, a - 1, f1, ' ', 0, flags);
  			fetch(ixold, a, b, f1, '-', 0, flags);
  			fetch(ixnew, c, d, f2, '+', 0, flags);
  			break;
  		case 'd':
  			fetch(ixold, lowa, a - 1, f1, ' ', 0, flags);
  			fetch(ixold, a, b, f1, '-', 0, flags);
  			break;
  		case 'a':
  			fetch(ixnew, lowc, c - 1, f2, ' ', 0, flags);
  			fetch(ixnew, c, d, f2, '+', 0, flags);
  			break;
  		}
  		lowa = b + 1;
  		lowc = d + 1;
  	}
  	fetch(ixnew, d + 1, upd, f2, ' ', 0, flags);
  
  	context_vec_ptr = context_vec_start - 1;
  }
  
  static void
  print_header(const char *file1, const char *file2)
  {
  	if (label[0] != NULL)
  		diff_output("%s %s\n", diff_format == D_CONTEXT ? "***" : "---",
  		    label[0]);
  	else
  		diff_output("%s %s\t%s", diff_format == D_CONTEXT ? "***" : "---",
  		    file1, ctime(&stb1.st_mtime));
  	if (label[1] != NULL)
  		diff_output("%s %s\n", diff_format == D_CONTEXT ? "---" : "+++",
  		    label[1]);
  	else
  		diff_output("%s %s\t%s", diff_format == D_CONTEXT ? "---" : "+++",
  		    file2, ctime(&stb2.st_mtime));
  }
  