Update diff, diff3, and sdiff's makefiles to use .PATH: instead of

copying the same files to multiple directories.  This should make
things easier when it comes time to update to a newer version of
diffutils.

With this checkin, this brings the netbsd and freebsd diff dists
into sync.

3 files changed, 3099 insertions, 0 deletions

diff --git a/gnu/usr.bin/diff/COPYING b/gnu/usr.bin/diff/COPYING
new file mode 100644
index 0000000..a43ea21
--- /dev/null
+++ b/gnu/usr.bin/diff/COPYING
@@ -0,0 +1,339 @@
+		    GNU GENERAL PUBLIC LICENSE
+		       Version 2, June 1991
+
+ Copyright (C) 1989, 1991 Free Software Foundation, Inc.
+                          675 Mass Ave, Cambridge, MA 02139, USA
+ Everyone is permitted to copy and distribute verbatim copies
+ of this license document, but changing it is not allowed.
+
+			    Preamble
+
+  The licenses for most software are designed to take away your
+freedom to share and change it.  By contrast, the GNU General Public
+License is intended to guarantee your freedom to share and change free
+software--to make sure the software is free for all its users.  This
+General Public License applies to most of the Free Software
+Foundation's software and to any other program whose authors commit to
+using it.  (Some other Free Software Foundation software is covered by
+the GNU Library General Public License instead.)  You can apply it to
+your programs, too.
+
+  When we speak of free software, we are referring to freedom, not
+price.  Our General Public Licenses are designed to make sure that you
+have the freedom to distribute copies of free software (and charge for
+this service if you wish), that you receive source code or can get it
+if you want it, that you can change the software or use pieces of it
+in new free programs; and that you know you can do these things.
+
+  To protect your rights, we need to make restrictions that forbid
+anyone to deny you these rights or to ask you to surrender the rights.
+These restrictions translate to certain responsibilities for you if you
+distribute copies of the software, or if you modify it.
+
+  For example, if you distribute copies of such a program, whether
+gratis or for a fee, you must give the recipients all the rights that
+you have.  You must make sure that they, too, receive or can get the
+source code.  And you must show them these terms so they know their
+rights.
+
+  We protect your rights with two steps: (1) copyright the software, and
+(2) offer you this license which gives you legal permission to copy,
+distribute and/or modify the software.
+
+  Also, for each author's protection and ours, we want to make certain
+that everyone understands that there is no warranty for this free
+software.  If the software is modified by someone else and passed on, we
+want its recipients to know that what they have is not the original, so
+that any problems introduced by others will not reflect on the original
+authors' reputations.
+
+  Finally, any free program is threatened constantly by software
+patents.  We wish to avoid the danger that redistributors of a free
+program will individually obtain patent licenses, in effect making the
+program proprietary.  To prevent this, we have made it clear that any
+patent must be licensed for everyone's free use or not licensed at all.
+
+  The precise terms and conditions for copying, distribution and
+modification follow.
+
+		    GNU GENERAL PUBLIC LICENSE
+   TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
+
+  0. This License applies to any program or other work which contains
+a notice placed by the copyright holder saying it may be distributed
+under the terms of this General Public License.  The "Program", below,
+refers to any such program or work, and a "work based on the Program"
+means either the Program or any derivative work under copyright law:
+that is to say, a work containing the Program or a portion of it,
+either verbatim or with modifications and/or translated into another
+language.  (Hereinafter, translation is included without limitation in
+the term "modification".)  Each licensee is addressed as "you".
+
+Activities other than copying, distribution and modification are not
+covered by this License; they are outside its scope.  The act of
+running the Program is not restricted, and the output from the Program
+is covered only if its contents constitute a work based on the
+Program (independent of having been made by running the Program).
+Whether that is true depends on what the Program does.
+
+  1. You may copy and distribute verbatim copies of the Program's
+source code as you receive it, in any medium, provided that you
+conspicuously and appropriately publish on each copy an appropriate
+copyright notice and disclaimer of warranty; keep intact all the
+notices that refer to this License and to the absence of any warranty;
+and give any other recipients of the Program a copy of this License
+along with the Program.
+
+You may charge a fee for the physical act of transferring a copy, and
+you may at your option offer warranty protection in exchange for a fee.
+
+  2. You may modify your copy or copies of the Program or any portion
+of it, thus forming a work based on the Program, and copy and
+distribute such modifications or work under the terms of Section 1
+above, provided that you also meet all of these conditions:
+
+    a) You must cause the modified files to carry prominent notices
+    stating that you changed the files and the date of any change.
+
+    b) You must cause any work that you distribute or publish, that in
+    whole or in part contains or is derived from the Program or any
+    part thereof, to be licensed as a whole at no charge to all third
+    parties under the terms of this License.
+
+    c) If the modified program normally reads commands interactively
+    when run, you must cause it, when started running for such
+    interactive use in the most ordinary way, to print or display an
+    announcement including an appropriate copyright notice and a
+    notice that there is no warranty (or else, saying that you provide
+    a warranty) and that users may redistribute the program under
+    these conditions, and telling the user how to view a copy of this
+    License.  (Exception: if the Program itself is interactive but
+    does not normally print such an announcement, your work based on
+    the Program is not required to print an announcement.)
+
+These requirements apply to the modified work as a whole.  If
+identifiable sections of that work are not derived from the Program,
+and can be reasonably considered independent and separate works in
+themselves, then this License, and its terms, do not apply to those
+sections when you distribute them as separate works.  But when you
+distribute the same sections as part of a whole which is a work based
+on the Program, the distribution of the whole must be on the terms of
+this License, whose permissions for other licensees extend to the
+entire whole, and thus to each and every part regardless of who wrote it.
+
+Thus, it is not the intent of this section to claim rights or contest
+your rights to work written entirely by you; rather, the intent is to
+exercise the right to control the distribution of derivative or
+collective works based on the Program.
+
+In addition, mere aggregation of another work not based on the Program
+with the Program (or with a work based on the Program) on a volume of
+a storage or distribution medium does not bring the other work under
+the scope of this License.
+
+  3. You may copy and distribute the Program (or a work based on it,
+under Section 2) in object code or executable form under the terms of
+Sections 1 and 2 above provided that you also do one of the following:
+
+    a) Accompany it with the complete corresponding machine-readable
+    source code, which must be distributed under the terms of Sections
+    1 and 2 above on a medium customarily used for software interchange; or,
+
+    b) Accompany it with a written offer, valid for at least three
+    years, to give any third party, for a charge no more than your
+    cost of physically performing source distribution, a complete
+    machine-readable copy of the corresponding source code, to be
+    distributed under the terms of Sections 1 and 2 above on a medium
+    customarily used for software interchange; or,
+
+    c) Accompany it with the information you received as to the offer
+    to distribute corresponding source code.  (This alternative is
+    allowed only for noncommercial distribution and only if you
+    received the program in object code or executable form with such
+    an offer, in accord with Subsection b above.)
+
+The source code for a work means the preferred form of the work for
+making modifications to it.  For an executable work, complete source
+code means all the source code for all modules it contains, plus any
+associated interface definition files, plus the scripts used to
+control compilation and installation of the executable.  However, as a
+special exception, the source code distributed need not include
+anything that is normally distributed (in either source or binary
+form) with the major components (compiler, kernel, and so on) of the
+operating system on which the executable runs, unless that component
+itself accompanies the executable.
+
+If distribution of executable or object code is made by offering
+access to copy from a designated place, then offering equivalent
+access to copy the source code from the same place counts as
+distribution of the source code, even though third parties are not
+compelled to copy the source along with the object code.
+
+  4. You may not copy, modify, sublicense, or distribute the Program
+except as expressly provided under this License.  Any attempt
+otherwise to copy, modify, sublicense or distribute the Program is
+void, and will automatically terminate your rights under this License.
+However, parties who have received copies, or rights, from you under
+this License will not have their licenses terminated so long as such
+parties remain in full compliance.
+
+  5. You are not required to accept this License, since you have not
+signed it.  However, nothing else grants you permission to modify or
+distribute the Program or its derivative works.  These actions are
+prohibited by law if you do not accept this License.  Therefore, by
+modifying or distributing the Program (or any work based on the
+Program), you indicate your acceptance of this License to do so, and
+all its terms and conditions for copying, distributing or modifying
+the Program or works based on it.
+
+  6. Each time you redistribute the Program (or any work based on the
+Program), the recipient automatically receives a license from the
+original licensor to copy, distribute or modify the Program subject to
+these terms and conditions.  You may not impose any further
+restrictions on the recipients' exercise of the rights granted herein.
+You are not responsible for enforcing compliance by third parties to
+this License.
+
+  7. If, as a consequence of a court judgment or allegation of patent
+infringement or for any other reason (not limited to patent issues),
+conditions are imposed on you (whether by court order, agreement or
+otherwise) that contradict the conditions of this License, they do not
+excuse you from the conditions of this License.  If you cannot
+distribute so as to satisfy simultaneously your obligations under this
+License and any other pertinent obligations, then as a consequence you
+may not distribute the Program at all.  For example, if a patent
+license would not permit royalty-free redistribution of the Program by
+all those who receive copies directly or indirectly through you, then
+the only way you could satisfy both it and this License would be to
+refrain entirely from distribution of the Program.
+
+If any portion of this section is held invalid or unenforceable under
+any particular circumstance, the balance of the section is intended to
+apply and the section as a whole is intended to apply in other
+circumstances.
+
+It is not the purpose of this section to induce you to infringe any
+patents or other property right claims or to contest validity of any
+such claims; this section has the sole purpose of protecting the
+integrity of the free software distribution system, which is
+implemented by public license practices.  Many people have made
+generous contributions to the wide range of software distributed
+through that system in reliance on consistent application of that
+system; it is up to the author/donor to decide if he or she is willing
+to distribute software through any other system and a licensee cannot
+impose that choice.
+
+This section is intended to make thoroughly clear what is believed to
+be a consequence of the rest of this License.
+
+  8. If the distribution and/or use of the Program is restricted in
+certain countries either by patents or by copyrighted interfaces, the
+original copyright holder who places the Program under this License
+may add an explicit geographical distribution limitation excluding
+those countries, so that distribution is permitted only in or among
+countries not thus excluded.  In such case, this License incorporates
+the limitation as if written in the body of this License.
+
+  9. The Free Software Foundation may publish revised and/or new versions
+of the General Public License from time to time.  Such new versions will
+be similar in spirit to the present version, but may differ in detail to
+address new problems or concerns.
+
+Each version is given a distinguishing version number.  If the Program
+specifies a version number of this License which applies to it and "any
+later version", you have the option of following the terms and conditions
+either of that version or of any later version published by the Free
+Software Foundation.  If the Program does not specify a version number of
+this License, you may choose any version ever published by the Free Software
+Foundation.
+
+  10. If you wish to incorporate parts of the Program into other free
+programs whose distribution conditions are different, write to the author
+to ask for permission.  For software which is copyrighted by the Free
+Software Foundation, write to the Free Software Foundation; we sometimes
+make exceptions for this.  Our decision will be guided by the two goals
+of preserving the free status of all derivatives of our free software and
+of promoting the sharing and reuse of software generally.
+
+			    NO WARRANTY
+
+  11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
+FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW.  EXCEPT WHEN
+OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
+PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED
+OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
+MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.  THE ENTIRE RISK AS
+TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU.  SHOULD THE
+PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING,
+REPAIR OR CORRECTION.
+
+  12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
+WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
+REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES,
+INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING
+OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED
+TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY
+YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER
+PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE
+POSSIBILITY OF SUCH DAMAGES.
+
+		     END OF TERMS AND CONDITIONS
+
+	Appendix: How to Apply These Terms to Your New Programs
+
+  If you develop a new program, and you want it to be of the greatest
+possible use to the public, the best way to achieve this is to make it
+free software which everyone can redistribute and change under these terms.
+
+  To do so, attach the following notices to the program.  It is safest
+to attach them to the start of each source file to most effectively
+convey the exclusion of warranty; and each file should have at least
+the "copyright" line and a pointer to where the full notice is found.
+
+    <one line to give the program's name and a brief idea of what it does.>
+    Copyright (C) 19yy  <name of author>
+
+    This program is free software; you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program; if not, write to the Free Software
+    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+
+Also add information on how to contact you by electronic and paper mail.
+
+If the program is interactive, make it output a short notice like this
+when it starts in an interactive mode:
+
+    Gnomovision version 69, Copyright (C) 19yy name of author
+    Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
+    This is free software, and you are welcome to redistribute it
+    under certain conditions; type `show c' for details.
+
+The hypothetical commands `show w' and `show c' should show the appropriate
+parts of the General Public License.  Of course, the commands you use may
+be called something other than `show w' and `show c'; they could even be
+mouse-clicks or menu items--whatever suits your program.
+
+You should also get your employer (if you work as a programmer) or your
+school, if any, to sign a "copyright disclaimer" for the program, if
+necessary.  Here is a sample; alter the names:
+
+  Yoyodyne, Inc., hereby disclaims all copyright interest in the program
+  `Gnomovision' (which makes passes at compilers) written by James Hacker.
+
+  <signature of Ty Coon>, 1 April 1989
+  Ty Coon, President of Vice
+
+This General Public License does not permit incorporating your program into
+proprietary programs.  If your program is a subroutine library, you may
+consider it more useful to permit linking proprietary applications with the
+library.  If this is what you want to do, use the GNU Library General
+Public License instead of this License.
diff --git a/gnu/usr.bin/diff/diff3.c b/gnu/usr.bin/diff/diff3.c
new file mode 100644
index 0000000..b9952fc
--- /dev/null
+++ b/gnu/usr.bin/diff/diff3.c
@@ -0,0 +1,1693 @@
+/* Three way file comparison program (diff3) for Project GNU.
+   Copyright (C) 1988, 1989, 1992 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2, or (at your option)
+   any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.  */
+
+/* Written by Randy Smith */
+
+#if __STDC__
+#define VOID void
+#else
+#define VOID char
+#endif
+
+#include <stdio.h>
+#include <ctype.h>
+#include "getopt.h"
+#include "system.h"
+
+/*
+ * Internal data structures and macros for the diff3 program; includes
+ * data structures for both diff3 diffs and normal diffs.
+ */
+
+/* Different files within a three way diff.  */
+#define	FILE0	0
+#define	FILE1	1
+#define	FILE2	2
+
+/*
+ * A three way diff is built from two two-way diffs; the file which
+ * the two two-way diffs share is:
+ */
+#define	FILEC	FILE2
+
+/*
+ * Different files within a two way diff.
+ * FC is the common file, FO the other file.
+ */
+#define FO 0
+#define FC 1
+
+/* The ranges are indexed by */
+#define	START	0
+#define	END	1
+
+enum diff_type {
+  ERROR,			/* Should not be used */
+  ADD,				/* Two way diff add */
+  CHANGE,			/* Two way diff change */
+  DELETE,			/* Two way diff delete */
+  DIFF_ALL,			/* All three are different */
+  DIFF_1ST,			/* Only the first is different */
+  DIFF_2ND,			/* Only the second */
+  DIFF_3RD			/* Only the third */
+};
+
+/* Two way diff */
+struct diff_block {
+  int ranges[2][2];		/* Ranges are inclusive */
+  char **lines[2];		/* The actual lines (may contain nulls) */
+  int *lengths[2];		/* Line lengths (including newlines, if any) */
+  struct diff_block *next;
+};
+
+/* Three way diff */
+
+struct diff3_block {
+  enum diff_type correspond;	/* Type of diff */
+  int ranges[3][2];		/* Ranges are inclusive */
+  char **lines[3];		/* The actual lines (may contain nulls) */
+  int *lengths[3];		/* Line lengths (including newlines, if any) */
+  struct diff3_block *next;
+};
+
+/*
+ * Access the ranges on a diff block.
+ */
+#define	D_LOWLINE(diff, filenum)	\
+  ((diff)->ranges[filenum][START])
+#define	D_HIGHLINE(diff, filenum)	\
+  ((diff)->ranges[filenum][END])
+#define	D_NUMLINES(diff, filenum)	\
+  (D_HIGHLINE (diff, filenum) - D_LOWLINE (diff, filenum) + 1)
+
+/*
+ * Access the line numbers in a file in a diff by relative line
+ * numbers (i.e. line number within the diff itself).  Note that these
+ * are lvalues and can be used for assignment.
+ */
+#define	D_RELNUM(diff, filenum, linenum)	\
+  ((diff)->lines[filenum][linenum])
+#define	D_RELLEN(diff, filenum, linenum)	\
+  ((diff)->lengths[filenum][linenum])
+
+/*
+ * And get at them directly, when that should be necessary.
+ */
+#define	D_LINEARRAY(diff, filenum)	\
+  ((diff)->lines[filenum])
+#define	D_LENARRAY(diff, filenum)	\
+  ((diff)->lengths[filenum])
+
+/*
+ * Next block.
+ */
+#define	D_NEXT(diff)	((diff)->next)
+
+/*
+ * Access the type of a diff3 block.
+ */
+#define	D3_TYPE(diff)	((diff)->correspond)
+
+/*
+ * Line mappings based on diffs.  The first maps off the top of the
+ * diff, the second off of the bottom.
+ */
+#define	D_HIGH_MAPLINE(diff, fromfile, tofile, lineno)	\
+  ((lineno)						\
+   - D_HIGHLINE ((diff), (fromfile))			\
+   + D_HIGHLINE ((diff), (tofile)))
+
+#define	D_LOW_MAPLINE(diff, fromfile, tofile, lineno)	\
+  ((lineno)						\
+   - D_LOWLINE ((diff), (fromfile))			\
+   + D_LOWLINE ((diff), (tofile)))
+
+/*
+ * General memory allocation function.
+ */
+#define	ALLOCATE(number, type)	\
+  (type *) xmalloc ((number) * sizeof (type))
+
+/* Options variables for flags set on command line.  */
+
+/* If nonzero, treat all files as text files, never as binary.  */
+static int always_text;
+
+/* If nonzero, write out an ed script instead of the standard diff3 format.  */
+static int edscript;
+
+/* If nonzero, in the case of overlapping diffs (type DIFF_ALL),
+   preserve the lines which would normally be deleted from
+   file 1 with a special flagging mechanism.  */
+static int flagging;
+
+/* Number of lines to keep in identical prefix and suffix.  */
+static int horizon_lines = 10;
+
+/* If nonzero, do not output information for overlapping diffs.  */
+static int simple_only;
+
+/* If nonzero, do not output information for non-overlapping diffs.  */
+static int overlap_only;
+
+/* If nonzero, show information for DIFF_2ND diffs.  */
+static int show_2nd;
+
+/* If nonzero, include `:wq' at the end of the script
+   to write out the file being edited.   */
+static int finalwrite;
+
+/* If nonzero, output a merged file.  */
+static int merge;
+
+static char *argv0;
+
+/*
+ * Forward function declarations.
+ */
+static int myread ();
+static void fatal ();
+static void perror_with_exit ();
+static struct diff_block *process_diff ();
+static struct diff3_block *make_3way_diff ();
+static void output_diff3 ();
+static int output_diff3_edscript ();
+static int output_diff3_merge ();
+static void usage ();
+
+static struct diff3_block *using_to_diff3_block ();
+static int copy_stringlist ();
+static struct diff3_block *create_diff3_block ();
+static int compare_line_list ();
+
+static char *read_diff ();
+static enum diff_type process_diff_control ();
+static char *scan_diff_line ();
+
+static struct diff3_block *reverse_diff3_blocklist ();
+
+VOID *xmalloc ();
+static VOID *xrealloc ();
+
+static char diff_program[] = DIFF_PROGRAM;
+
+static struct option longopts[] =
+{
+  {"text", 0, NULL, 'a'},
+  {"show-all", 0, NULL, 'A'},
+  {"ed", 0, NULL, 'e'},
+  {"show-overlap", 0, NULL, 'E'},
+  {"label", 1, NULL, 'L'},
+  {"merge", 0, NULL, 'm'},
+  {"overlap-only", 0, NULL, 'x'},
+  {"easy-only", 0, NULL, '3'},
+  {"version", 0, NULL, 'v'},
+  {0, 0, 0, 0}
+};
+
+/*
+ * Main program.  Calls diff twice on two pairs of input files,
+ * combines the two diffs, and outputs them.
+ */
+int
+main (argc, argv)
+     int argc;
+     char **argv;
+{
+  extern char *version_string;
+  int c, i;
+  int mapping[3];
+  int rev_mapping[3];
+  int incompat;
+  int conflicts_found;
+  struct diff_block *thread0, *thread1, *last_block;
+  struct diff3_block *diff3;
+  int tag_count = 0;
+  char *tag_strings[3];
+  extern char *optarg;
+  char *commonname;
+  char **file;
+  struct stat statb;
+
+  incompat = 0;
+
+  argv0 = argv[0];
+
+  while ((c = getopt_long (argc, argv, "aeimvx3AEXL:", longopts, (int *) 0))
+	 != EOF)
+    {
+      switch (c)
+	{
+	case 'a':
+	  always_text = 1;
+	  break;
+	case 'A':
+	  show_2nd = 1;
+	  flagging = 1;
+	  incompat++;
+	  break;
+	case 'x':
+	  overlap_only = 1;
+	  incompat++;
+	  break;
+	case '3':
+	  simple_only = 1;
+	  incompat++;
+	  break;
+	case 'i':
+	  finalwrite = 1;
+	  break;
+	case 'm':
+	  merge = 1;
+	  break;
+	case 'X':
+	  overlap_only = 1;
+	  /* Falls through */
+	case 'E':
+	  flagging = 1;
+	  /* Falls through */
+	case 'e':
+	  incompat++;
+	  break;
+	case 'v':
+	  fprintf (stderr, "GNU diff3 version %s\n", version_string);
+	  break;
+	case 'L':
+	  /* Handle up to three -L options.  */
+	  if (tag_count < 3)
+	    {
+	      tag_strings[tag_count++] = optarg;
+	      break;
+	    }
+	  /* Falls through */
+	default:
+	  usage ();
+	  /* NOTREACHED */
+	}
+    }
+
+  edscript = incompat & ~merge;  /* -AeExX3 without -m implies ed script.  */
+  show_2nd |= ~incompat & merge;  /* -m without -AeExX3 implies -A.  */
+  flagging |= ~incompat & merge;
+
+  if (incompat > 1  /* Ensure at most one of -AeExX3.  */
+      || finalwrite & merge /* -i -m would rewrite input file.  */
+      || (tag_count && ! flagging) /* -L requires one of -AEX.  */
+      || argc - optind != 3)
+    usage ();
+
+  file = &argv[optind];
+
+  for (i = tag_count; i < 3; i++)
+    tag_strings[i] = file[i];
+
+  /* Always compare file1 to file2, even if file2 is "-".
+     This is needed for -mAeExX3.  Using the file0 as
+     the common file would produce wrong results, because if the
+     file0-file1 diffs didn't line up with the file0-file2 diffs
+     (which is entirely possible since we don't use diff's -n option),
+     diff3 might report phantom changes from file1 to file2.  */
+
+  if (strcmp (file[2], "-") == 0)
+    {
+      /* Sigh.  We've got standard input as the last arg.  We can't
+	 call diff twice on stdin.  Use the middle arg as the common
+	 file instead.  */
+      if (strcmp (file[0], "-") == 0 || strcmp (file[1], "-") == 0)
+	fatal ("`-' specified for more than one input file");
+      mapping[0] = 0;
+      mapping[1] = 2;
+      mapping[2] = 1;
+    }
+  else
+    {
+      /* Normal, what you'd expect */
+      mapping[0] = 0;
+      mapping[1] = 1;
+      mapping[2] = 2;
+    }
+
+  for (i = 0; i < 3; i++)
+    rev_mapping[mapping[i]] = i;
+
+  for (i = 0; i < 3; i++)
+    if (strcmp (file[i], "-") != 0)
+      if (stat (file[i], &statb) < 0)
+	perror_with_exit (file[i]);
+      else if (S_ISDIR(statb.st_mode))
+	{
+	  fprintf (stderr, "%s: %s: Is a directory\n", argv0, file[i]);
+	  exit (2);
+	}
+
+
+  commonname = file[rev_mapping[FILEC]];
+  thread1 = process_diff (file[rev_mapping[FILE1]], commonname, &last_block);
+  if (thread1)
+    for (i = 0; i < 2; i++)
+      {
+	horizon_lines = max (horizon_lines, D_NUMLINES (thread1, i));
+	horizon_lines = max (horizon_lines, D_NUMLINES (last_block, i));
+      }
+  thread0 = process_diff (file[rev_mapping[FILE0]], commonname, &last_block);
+  diff3 = make_3way_diff (thread0, thread1);
+  if (edscript)
+    conflicts_found
+      = output_diff3_edscript (stdout, diff3, mapping, rev_mapping,
+			       tag_strings[0], tag_strings[1], tag_strings[2]);
+  else if (merge)
+    {
+      if (! freopen (file[rev_mapping[FILE0]], "r", stdin))
+	perror_with_exit (file[rev_mapping[FILE0]]);
+      conflicts_found
+	= output_diff3_merge (stdin, stdout, diff3, mapping, rev_mapping,
+			      tag_strings[0], tag_strings[1], tag_strings[2]);
+      if (ferror (stdin))
+	fatal ("read error");
+    }
+  else
+    {
+      output_diff3 (stdout, diff3, mapping, rev_mapping);
+      conflicts_found = 0;
+    }
+
+  if (ferror (stdout) || fclose (stdout) != 0)
+    fatal ("write error");
+  exit (conflicts_found);
+  return conflicts_found;
+}
+
+/*
+ * Explain, patiently and kindly, how to use this program.  Then exit.
+ */
+static void
+usage ()
+{
+  fprintf (stderr, "\
+Usage: %s [options] my-file older-file your-file\n\
+Options:\n\
+       [-exAEX3v] [-i|-m] [-L label1 [-L label2 [-L label3]]] [--text] [--ed]\n\
+       [--merge] [--show-all] [--show-overlap] [--overlap-only] [--easy-only]\n\
+       [--label=label1 [--label=label2 [--label=label3]]] [--version]\n\
+       Only one of [exAEX3] is allowed\n", argv0);
+  exit (2);
+}
+
+/*
+ * Routines that combine the two diffs together into one.  The
+ * algorithm used follows:
+ *
+ *   File2 is shared in common between the two diffs.
+ *   Diff02 is the diff between 0 and 2.
+ *   Diff12 is the diff between 1 and 2.
+ *
+ *	1) Find the range for the first block in File2.
+ *	    a) Take the lowest of the two ranges (in File2) in the two
+ *	       current blocks (one from each diff) as being the low
+ *	       water mark.  Assign the upper end of this block as
+ *	       being the high water mark and move the current block up
+ *	       one.  Mark the block just moved over as to be used.
+ *	    b) Check the next block in the diff that the high water
+ *	       mark is *not* from.
+ *
+ *	       *If* the high water mark is above
+ *	       the low end of the range in that block,
+ *
+ *		   mark that block as to be used and move the current
+ *		   block up.  Set the high water mark to the max of
+ *		   the high end of this block and the current.  Repeat b.
+ *
+ *	 2) Find the corresponding ranges in File0 (from the blocks
+ *	    in diff02; line per line outside of diffs) and in File1.
+ *	    Create a diff3_block, reserving space as indicated by the ranges.
+ *
+ *	 3) Copy all of the pointers for file2 in.  At least for now,
+ *	    do bcmp's between corresponding strings in the two diffs.
+ *
+ *	 4) Copy all of the pointers for file0 and 1 in.  Get what you
+ *	    need from file2 (when there isn't a diff block, it's
+ *	    identical to file2 within the range between diff blocks).
+ *
+ *	 5) If the diff blocks you used came from only one of the two
+ *	    strings of diffs, then that file (i.e. the one other than
+ *	    the common file in that diff) is the odd person out.  If you used
+ *	    diff blocks from both sets, check to see if files 0 and 1 match:
+ *
+ *		Same number of lines?  If so, do a set of bcmp's (if a
+ *	    bcmp matches; copy the pointer over; it'll be easier later
+ *	    if you have to do any compares).  If they match, 0 & 1 are
+ *	    the same.  If not, all three different.
+ *
+ *   Then you do it again, until you run out of blocks.
+ *
+ */
+
+/*
+ * This routine makes a three way diff (chain of diff3_block's) from two
+ * two way diffs (chains of diff_block's).  It is assumed that each of
+ * the two diffs passed are onto the same file (i.e. that each of the
+ * diffs were made "to" the same file).  The three way diff pointer
+ * returned will have numbering FILE0--the other file in diff02,
+ * FILE1--the other file in diff12, and FILEC--the common file.
+ */
+static struct diff3_block *
+make_3way_diff (thread0, thread1)
+     struct diff_block *thread0, *thread1;
+{
+/*
+ * This routine works on the two diffs passed to it as threads.
+ * Thread number 0 is diff02, thread number 1 is diff12.  The USING
+ * array is set to the base of the list of blocks to be used to
+ * construct each block of the three way diff; if no blocks from a
+ * particular thread are to be used, that element of the using array
+ * is set to 0.  The elements LAST_USING array are set to the last
+ * elements on each of the using lists.
+ *
+ * The HIGH_WATER_MARK is set to the highest line number in the common file
+ * described in any of the diffs in either of the USING lists.  The
+ * HIGH_WATER_THREAD names the thread.  Similarly the BASE_WATER_MARK
+ * and BASE_WATER_THREAD describe the lowest line number in the common file
+ * described in any of the diffs in either of the USING lists.  The
+ * HIGH_WATER_DIFF is the diff from which the HIGH_WATER_MARK was
+ * taken.
+ *
+ * The HIGH_WATER_DIFF should always be equal to LAST_USING
+ * [HIGH_WATER_THREAD].  The OTHER_DIFF is the next diff to check for
+ * higher water, and should always be equal to
+ * CURRENT[HIGH_WATER_THREAD ^ 0x1].  The OTHER_THREAD is the thread
+ * in which the OTHER_DIFF is, and hence should always be equal to
+ * HIGH_WATER_THREAD ^ 0x1.
+ *
+ * The variable LAST_DIFF is kept set to the last diff block produced
+ * by this routine, for line correspondence purposes between that diff
+ * and the one currently being worked on.  It is initialized to
+ * ZERO_DIFF before any blocks have been created.
+ */
+
+  struct diff_block
+    *using[2],
+    *last_using[2],
+    *current[2];
+
+  int
+    high_water_mark;
+
+  int
+    high_water_thread,
+    base_water_thread,
+    other_thread;
+
+  struct diff_block
+    *high_water_diff,
+    *other_diff;
+
+  struct diff3_block
+    *result,
+    *tmpblock,
+    **result_end,
+    *last_diff3;
+
+  static struct diff3_block zero_diff3 = {
+      ERROR,
+      { {0, 0}, {0, 0}, {0, 0} },
+      { (char **) 0, (char **) 0, (char **) 0 },
+      { (int *) 0, (int *) 0, (int *) 0 },
+      (struct diff3_block *) 0
+      };
+
+  /* Initialization */
+  result = 0;
+  result_end = &result;
+  current[0] = thread0; current[1] = thread1;
+  last_diff3 = &zero_diff3;
+
+  /* Sniff up the threads until we reach the end */
+
+  while (current[0] || current[1])
+    {
+      using[0] = using[1] = last_using[0] = last_using[1] =
+	(struct diff_block *) 0;
+
+      /* Setup low and high water threads, diffs, and marks.  */
+      if (!current[0])
+	base_water_thread = 1;
+      else if (!current[1])
+	base_water_thread = 0;
+      else
+	base_water_thread =
+	  (D_LOWLINE (current[0], FC) > D_LOWLINE (current[1], FC));
+
+      high_water_thread = base_water_thread;
+
+      high_water_diff = current[high_water_thread];
+
+#if 0
+      /* low and high waters start off same diff */
+      base_water_mark = D_LOWLINE (high_water_diff, FC);
+#endif
+
+      high_water_mark = D_HIGHLINE (high_water_diff, FC);
+
+      /* Make the diff you just got info from into the using class */
+      using[high_water_thread]
+	= last_using[high_water_thread]
+	= high_water_diff;
+      current[high_water_thread] = high_water_diff->next;
+      last_using[high_water_thread]->next
+	= (struct diff_block *) 0;
+
+      /* And mark the other diff */
+      other_thread = high_water_thread ^ 0x1;
+      other_diff = current[other_thread];
+
+      /* Shuffle up the ladder, checking the other diff to see if it
+	 needs to be incorporated.  */
+      while (other_diff
+	     && D_LOWLINE (other_diff, FC) <= high_water_mark + 1)
+	{
+
+	  /* Incorporate this diff into the using list.  Note that
+	     this doesn't take it off the current list */
+	  if (using[other_thread])
+	    last_using[other_thread]->next = other_diff;
+	  else
+	    using[other_thread] = other_diff;
+	  last_using[other_thread] = other_diff;
+
+	  /* Take it off the current list.  Note that this following
+	     code assumes that other_diff enters it equal to
+	     current[high_water_thread ^ 0x1] */
+	  current[other_thread]
+	    = current[other_thread]->next;
+	  other_diff->next
+	    = (struct diff_block *) 0;
+
+	  /* Set the high_water stuff
+	     If this comparison is equal, then this is the last pass
+	     through this loop; since diff blocks within a given
+	     thread cannot overlap, the high_water_mark will be
+	     *below* the range_start of either of the next diffs.  */
+
+	  if (high_water_mark < D_HIGHLINE (other_diff, FC))
+	    {
+	      high_water_thread ^= 1;
+	      high_water_diff = other_diff;
+	      high_water_mark = D_HIGHLINE (other_diff, FC);
+	    }
+
+	  /* Set the other diff */
+	  other_thread = high_water_thread ^ 0x1;
+	  other_diff = current[other_thread];
+	}
+
+      /* The using lists contain a list of all of the blocks to be
+	 included in this diff3_block.  Create it.  */
+
+      tmpblock = using_to_diff3_block (using, last_using,
+				       base_water_thread, high_water_thread,
+				       last_diff3);
+
+      if (!tmpblock)
+	fatal ("internal error: screwup in format of diff blocks");
+
+      /* Put it on the list.  */
+      *result_end = tmpblock;
+      result_end = &tmpblock->next;
+
+      /* Set up corresponding lines correctly.  */
+      last_diff3 = tmpblock;
+    }
+  return result;
+}
+
+/*
+ * using_to_diff3_block:
+ *   This routine takes two lists of blocks (from two separate diff
+ * threads) and puts them together into one diff3 block.
+ * It then returns a pointer to this diff3 block or 0 for failure.
+ *
+ * All arguments besides using are for the convenience of the routine;
+ * they could be derived from the using array.
+ * LAST_USING is a pair of pointers to the last blocks in the using
+ * structure.
+ * LOW_THREAD and HIGH_THREAD tell which threads contain the lowest
+ * and highest line numbers for File0.
+ * last_diff3 contains the last diff produced in the calling routine.
+ * This is used for lines mappings which would still be identical to
+ * the state that diff ended in.
+ *
+ * A distinction should be made in this routine between the two diffs
+ * that are part of a normal two diff block, and the three diffs that
+ * are part of a diff3_block.
+ */
+static struct diff3_block *
+using_to_diff3_block (using, last_using, low_thread, high_thread, last_diff3)
+     struct diff_block
+       *using[2],
+       *last_using[2];
+     int low_thread, high_thread;
+     struct diff3_block *last_diff3;
+{
+  int low[2], high[2];
+  struct diff3_block *result;
+  struct diff_block *ptr;
+  int d, i;
+
+  /* Find the range in the common file.  */
+  int lowc = D_LOWLINE (using[low_thread], FC);
+  int highc = D_HIGHLINE (last_using[high_thread], FC);
+
+  /* Find the ranges in the other files.
+     If using[d] is null, that means that the file to which that diff
+     refers is equivalent to the common file over this range.  */
+
+  for (d = 0; d < 2; d++)
+    if (using[d])
+      {
+	low[d] = D_LOW_MAPLINE (using[d], FC, FO, lowc);
+	high[d] = D_HIGH_MAPLINE (last_using[d], FC, FO, highc);
+      }
+    else
+      {
+	low[d] = D_HIGH_MAPLINE (last_diff3, FILEC, FILE0 + d, lowc);
+	high[d] = D_HIGH_MAPLINE (last_diff3, FILEC, FILE0 + d, highc);
+      }
+
+  /* Create a block with the appropriate sizes */
+  result = create_diff3_block (low[0], high[0], low[1], high[1], lowc, highc);
+
+  /* Copy information for the common file.
+     Return with a zero if any of the compares failed.  */
+
+  for (d = 0; d < 2; d++)
+    for (ptr = using[d]; ptr; ptr = D_NEXT (ptr))
+      {
+	int result_offset = D_LOWLINE (ptr, FC) - lowc;
+
+	if (!copy_stringlist (D_LINEARRAY (ptr, FC),
+			      D_LENARRAY (ptr, FC),
+			      D_LINEARRAY (result, FILEC) + result_offset,
+			      D_LENARRAY (result, FILEC) + result_offset,
+			      D_NUMLINES (ptr, FC)))
+	  return 0;
+      }
+
+  /* Copy information for file d.  First deal with anything that might be
+     before the first diff.  */
+
+  for (d = 0; d < 2; d++)
+    {
+      struct diff_block *u = using[d];
+      int lo = low[d], hi = high[d];
+
+      for (i = 0;
+	   i + lo < (u ? D_LOWLINE (u, FO) : hi + 1);
+	   i++)
+	{
+	  D_RELNUM (result, FILE0 + d, i) = D_RELNUM (result, FILEC, i);
+	  D_RELLEN (result, FILE0 + d, i) = D_RELLEN (result, FILEC, i);
+	}
+
+      for (ptr = u; ptr; ptr = D_NEXT (ptr))
+	{
+	  int result_offset = D_LOWLINE (ptr, FO) - lo;
+	  int linec;
+
+	  if (!copy_stringlist (D_LINEARRAY (ptr, FO),
+				D_LENARRAY (ptr, FO),
+				D_LINEARRAY (result, FILE0 + d) + result_offset,
+				D_LENARRAY (result, FILE0 + d) + result_offset,
+				D_NUMLINES (ptr, FO)))
+	    return 0;
+
+	  /* Catch the lines between here and the next diff */
+	  linec = D_HIGHLINE (ptr, FC) + 1 - lowc;
+	  for (i = D_HIGHLINE (ptr, FO) + 1 - lo;
+	       i < (D_NEXT (ptr) ? D_LOWLINE (D_NEXT (ptr), FO) : hi + 1) - lo;
+	       i++)
+	    {
+	      D_RELNUM (result, FILE0 + d, i) = D_RELNUM (result, FILEC, linec);
+	      D_RELLEN (result, FILE0 + d, i) = D_RELLEN (result, FILEC, linec);
+	      linec++;
+	    }
+	}
+    }
+
+  /* Set correspond */
+  if (!using[0])
+    D3_TYPE (result) = DIFF_2ND;
+  else if (!using[1])
+    D3_TYPE (result) = DIFF_1ST;
+  else
+    {
+      int nl0 = D_NUMLINES (result, FILE0);
+      int nl1 = D_NUMLINES (result, FILE1);
+
+      if (nl0 != nl1
+	  || !compare_line_list (D_LINEARRAY (result, FILE0),
+				 D_LENARRAY (result, FILE0),
+				 D_LINEARRAY (result, FILE1),
+				 D_LENARRAY (result, FILE1),
+				 nl0))
+	D3_TYPE (result) = DIFF_ALL;
+      else
+	D3_TYPE (result) = DIFF_3RD;
+    }
+
+  return result;
+}
+
+/*
+ * This routine copies pointers from a list of strings to a different list
+ * of strings.  If a spot in the second list is already filled, it
+ * makes sure that it is filled with the same string; if not it
+ * returns 0, the copy incomplete.
+ * Upon successful completion of the copy, it returns 1.
+ */
+static int
+copy_stringlist (fromptrs, fromlengths, toptrs, tolengths, copynum)
+     char *fromptrs[], *toptrs[];
+     int *fromlengths, *tolengths;
+     int copynum;
+{
+  register char
+    **f = fromptrs,
+    **t = toptrs;
+  register int
+    *fl = fromlengths,
+    *tl = tolengths;
+
+  while (copynum--)
+    {
+      if (*t)
+	{ if (*fl != *tl || bcmp (*f, *t, *fl)) return 0; }
+      else
+	{ *t = *f ; *tl = *fl; }
+
+      t++; f++; tl++; fl++;
+    }
+  return 1;
+}
+
+/*
+ * Create a diff3_block, with ranges as specified in the arguments.
+ * Allocate the arrays for the various pointers (and zero them) based
+ * on the arguments passed.  Return the block as a result.
+ */
+static struct diff3_block *
+create_diff3_block (low0, high0, low1, high1, low2, high2)
+     register int low0, high0, low1, high1, low2, high2;
+{
+  struct diff3_block *result = ALLOCATE (1, struct diff3_block);
+  int numlines;
+
+  D3_TYPE (result) = ERROR;
+  D_NEXT (result) = 0;
+
+  /* Assign ranges */
+  D_LOWLINE (result, FILE0) = low0;
+  D_HIGHLINE (result, FILE0) = high0;
+  D_LOWLINE (result, FILE1) = low1;
+  D_HIGHLINE (result, FILE1) = high1;
+  D_LOWLINE (result, FILE2) = low2;
+  D_HIGHLINE (result, FILE2) = high2;
+
+  /* Allocate and zero space */
+  numlines = D_NUMLINES (result, FILE0);
+  if (numlines)
+    {
+      D_LINEARRAY (result, FILE0) = ALLOCATE (numlines, char *);
+      D_LENARRAY (result, FILE0) = ALLOCATE (numlines, int);
+      bzero (D_LINEARRAY (result, FILE0), (numlines * sizeof (char *)));
+      bzero (D_LENARRAY (result, FILE0), (numlines * sizeof (int)));
+    }
+  else
+    {
+      D_LINEARRAY (result, FILE0) = (char **) 0;
+      D_LENARRAY (result, FILE0) = (int *) 0;
+    }
+
+  numlines = D_NUMLINES (result, FILE1);
+  if (numlines)
+    {
+      D_LINEARRAY (result, FILE1) = ALLOCATE (numlines, char *);
+      D_LENARRAY (result, FILE1) = ALLOCATE (numlines, int);
+      bzero (D_LINEARRAY (result, FILE1), (numlines * sizeof (char *)));
+      bzero (D_LENARRAY (result, FILE1), (numlines * sizeof (int)));
+    }
+  else
+    {
+      D_LINEARRAY (result, FILE1) = (char **) 0;
+      D_LENARRAY (result, FILE1) = (int *) 0;
+    }
+
+  numlines = D_NUMLINES (result, FILE2);
+  if (numlines)
+    {
+      D_LINEARRAY (result, FILE2) = ALLOCATE (numlines, char *);
+      D_LENARRAY (result, FILE2) = ALLOCATE (numlines, int);
+      bzero (D_LINEARRAY (result, FILE2), (numlines * sizeof (char *)));
+      bzero (D_LENARRAY (result, FILE2), (numlines * sizeof (int)));
+    }
+  else
+    {
+      D_LINEARRAY (result, FILE2) = (char **) 0;
+      D_LENARRAY (result, FILE2) = (int *) 0;
+    }
+
+  /* Return */
+  return result;
+}
+
+/*
+ * Compare two lists of lines of text.
+ * Return 1 if they are equivalent, 0 if not.
+ */
+static int
+compare_line_list (list1, lengths1, list2, lengths2, nl)
+     char *list1[], *list2[];
+     int *lengths1, *lengths2;
+     int nl;
+{
+  char
+    **l1 = list1,
+    **l2 = list2;
+  int
+    *lgths1 = lengths1,
+    *lgths2 = lengths2;
+
+  while (nl--)
+    if (!*l1 || !*l2 || *lgths1 != *lgths2++
+	|| bcmp (*l1++, *l2++, *lgths1++))
+      return 0;
+  return 1;
+}
+
+/*
+ * Routines to input and parse two way diffs.
+ */
+
+extern char **environ;
+
+#define	DIFF_CHUNK_SIZE	10000
+
+static struct diff_block *
+process_diff (filea, fileb, last_block)
+     char *filea, *fileb;
+     struct diff_block **last_block;
+{
+  char *diff_contents;
+  char *diff_limit;
+  char *scan_diff;
+  enum diff_type dt;
+  int i;
+  struct diff_block *block_list, **block_list_end, *bptr;
+
+  diff_limit = read_diff (filea, fileb, &diff_contents);
+  scan_diff = diff_contents;
+  block_list_end = &block_list;
+
+  while (scan_diff < diff_limit)
+    {
+      bptr = ALLOCATE (1, struct diff_block);
+      bptr->lines[0] = bptr->lines[1] = (char **) 0;
+      bptr->lengths[0] = bptr->lengths[1] = (int *) 0;
+
+      dt = process_diff_control (&scan_diff, bptr);
+      if (dt == ERROR || *scan_diff != '\n')
+	{
+	  fprintf (stderr, "%s: diff error: ", argv0);
+	  do
+	    {
+	      putc (*scan_diff, stderr);
+	    }
+	  while (*scan_diff++ != '\n');
+	  exit (2);
+	}
+      scan_diff++;
+
+      /* Force appropriate ranges to be null, if necessary */
+      switch (dt)
+	{
+	case ADD:
+	  bptr->ranges[0][0]++;
+	  break;
+	case DELETE:
+	  bptr->ranges[1][0]++;
+	  break;
+	case CHANGE:
+	  break;
+	default:
+	  fatal ("internal error: invalid diff type in process_diff");
+	  break;
+	}
+
+      /* Allocate space for the pointers for the lines from filea, and
+	 parcel them out among these pointers */
+      if (dt != ADD)
+	{
+	  int numlines = D_NUMLINES (bptr, 0);
+	  bptr->lines[0] = ALLOCATE (numlines, char *);
+	  bptr->lengths[0] = ALLOCATE (numlines, int);
+	  for (i = 0; i < numlines; i++)
+	    scan_diff = scan_diff_line (scan_diff,
+					&(bptr->lines[0][i]),
+					&(bptr->lengths[0][i]),
+					diff_limit,
+					'<');
+	}
+
+      /* Get past the separator for changes */
+      if (dt == CHANGE)
+	{
+	  if (strncmp (scan_diff, "---\n", 4))
+	    fatal ("invalid diff format; invalid change separator");
+	  scan_diff += 4;
+	}
+
+      /* Allocate space for the pointers for the lines from fileb, and
+	 parcel them out among these pointers */
+      if (dt != DELETE)
+	{
+	  int numlines = D_NUMLINES (bptr, 1);
+	  bptr->lines[1] = ALLOCATE (numlines, char *);
+	  bptr->lengths[1] = ALLOCATE (numlines, int);
+	  for (i = 0; i < numlines; i++)
+	    scan_diff = scan_diff_line (scan_diff,
+					&(bptr->lines[1][i]),
+					&(bptr->lengths[1][i]),
+					diff_limit,
+					'>');
+	}
+
+      /* Place this block on the blocklist.  */
+      *block_list_end = bptr;
+      block_list_end = &bptr->next;
+    }
+
+  *block_list_end = 0;
+  *last_block = bptr;
+  return block_list;
+}
+
+/*
+ * This routine will parse a normal format diff control string.  It
+ * returns the type of the diff (ERROR if the format is bad).  All of
+ * the other important information is filled into to the structure
+ * pointed to by db, and the string pointer (whose location is passed
+ * to this routine) is updated to point beyond the end of the string
+ * parsed.  Note that only the ranges in the diff_block will be set by
+ * this routine.
+ *
+ * If some specific pair of numbers has been reduced to a single
+ * number, then both corresponding numbers in the diff block are set
+ * to that number.  In general these numbers are interpetted as ranges
+ * inclusive, unless being used by the ADD or DELETE commands.  It is
+ * assumed that these will be special cased in a superior routine.
+ */
+
+static enum diff_type
+process_diff_control (string, db)
+     char **string;
+     struct diff_block *db;
+{
+  char *s = *string;
+  int holdnum;
+  enum diff_type type;
+
+/* These macros are defined here because they can use variables
+   defined in this function.  Don't try this at home kids, we're
+   trained professionals!
+
+   Also note that SKIPWHITE only recognizes tabs and spaces, and
+   that READNUM can only read positive, integral numbers */
+
+#define	SKIPWHITE(s)	{ while (*s == ' ' || *s == '\t') s++; }
+#define	READNUM(s, num)	\
+	{ if (!isdigit (*s)) return ERROR; holdnum = 0;	\
+	  do { holdnum = (*s++ - '0' + holdnum * 10); }	\
+	  while (isdigit (*s)); (num) = holdnum; }
+
+  /* Read first set of digits */
+  SKIPWHITE (s);
+  READNUM (s, db->ranges[0][START]);
+
+  /* Was that the only digit? */
+  SKIPWHITE (s);
+  if (*s == ',')
+    {
+      /* Get the next digit */
+      s++;
+      READNUM (s, db->ranges[0][END]);
+    }
+  else
+    db->ranges[0][END] = db->ranges[0][START];
+
+  /* Get the letter */
+  SKIPWHITE (s);
+  switch (*s)
+    {
+    case 'a':
+      type = ADD;
+      break;
+    case 'c':
+      type = CHANGE;
+      break;
+    case 'd':
+      type = DELETE;
+      break;
+    default:
+      return ERROR;			/* Bad format */
+    }
+  s++;				/* Past letter */
+
+  /* Read second set of digits */
+  SKIPWHITE (s);
+  READNUM (s, db->ranges[1][START]);
+
+  /* Was that the only digit? */
+  SKIPWHITE (s);
+  if (*s == ',')
+    {
+      /* Get the next digit */
+      s++;
+      READNUM (s, db->ranges[1][END]);
+      SKIPWHITE (s);		/* To move to end */
+    }
+  else
+    db->ranges[1][END] = db->ranges[1][START];
+
+  *string = s;
+  return type;
+}
+
+static char *
+read_diff (filea, fileb, output_placement)
+     char *filea, *fileb;
+     char **output_placement;
+{
+  char *argv[7];
+  char horizon_arg[256];
+  char **ap;
+  int fds[2];
+  char *diff_result;
+  int current_chunk_size;
+  int bytes;
+  int total;
+  int pid, w;
+  int wstatus;
+
+  ap = argv;
+  *ap++ = diff_program;
+  if (always_text)
+    *ap++ = "-a";
+  sprintf (horizon_arg, "--horizon-lines=%d", horizon_lines);
+  *ap++ = horizon_arg;
+  *ap++ = "--";
+  *ap++ = filea;
+  *ap++ = fileb;
+  *ap = (char *) 0;
+
+  if (pipe (fds) < 0)
+    perror_with_exit ("pipe failed");
+
+  pid = vfork ();
+  if (pid == 0)
+    {
+      /* Child */
+      close (fds[0]);
+      if (fds[1] != fileno (stdout))
+	{
+	  dup2 (fds[1], fileno (stdout));
+	  close (fds[1]);
+	}
+      execve (diff_program, argv, environ);
+      /* Avoid stdio, because the parent process's buffers are inherited.  */
+      write (fileno (stderr), diff_program, strlen (diff_program));
+      write (fileno (stderr), ": not found\n", 12);
+      _exit (2);
+    }
+
+  if (pid == -1)
+    perror_with_exit ("fork failed");
+
+  close (fds[1]);		/* Prevent erroneous lack of EOF */
+  current_chunk_size = DIFF_CHUNK_SIZE;
+  diff_result = (char *) xmalloc (current_chunk_size);
+  total = 0;
+  do {
+    bytes = myread (fds[0],
+		    diff_result + total,
+		    current_chunk_size - total);
+    total += bytes;
+    if (total == current_chunk_size)
+      diff_result = (char *) xrealloc (diff_result, (current_chunk_size *= 2));
+  } while (bytes);
+
+  if (total != 0 && diff_result[total-1] != '\n')
+    fatal ("invalid diff format; incomplete last line");
+
+  *output_placement = diff_result;
+
+  do
+    if ((w = wait (&wstatus)) == -1)
+      perror_with_exit ("wait failed");
+  while (w != pid);
+
+  if (! (WIFEXITED (wstatus) && WEXITSTATUS (wstatus) < 2))
+    fatal ("subsidiary diff failed");
+
+  return diff_result + total;
+}
+
+
+/*
+ * Scan a regular diff line (consisting of > or <, followed by a
+ * space, followed by text (including nulls) up to a newline.
+ *
+ * This next routine began life as a macro and many parameters in it
+ * are used as call-by-reference values.
+ */
+static char *
+scan_diff_line (scan_ptr, set_start, set_length, limit, firstchar)
+     char *scan_ptr, **set_start;
+     int *set_length;
+     char *limit;
+     char firstchar;
+{
+  char *line_ptr;
+
+  if (!(scan_ptr[0] == (firstchar)
+	&& scan_ptr[1] == ' '))
+    fatal ("invalid diff format; incorrect leading line chars");
+
+  *set_start = line_ptr = scan_ptr + 2;
+  while (*line_ptr++ != '\n')
+    ;
+
+  /* Include newline if the original line ended in a newline,
+     or if an edit script is being generated.
+     Copy any missing newline message to stderr if an edit script is being
+     generated, because edit scripts cannot handle missing newlines.
+     Return the beginning of the next line.  */
+  *set_length = line_ptr - *set_start;
+  if (line_ptr < limit && *line_ptr == '\\')
+    {
+      if (edscript)
+	fprintf (stderr, "%s:", argv0);
+      else
+	--*set_length;
+      line_ptr++;
+      do
+	{
+	  if (edscript)
+	    putc (*line_ptr, stderr);
+	}
+      while (*line_ptr++ != '\n');
+    }
+
+  return line_ptr;
+}
+
+/*
+ * This routine outputs a three way diff passed as a list of
+ * diff3_block's.
+ * The argument MAPPING is indexed by external file number (in the
+ * argument list) and contains the internal file number (from the
+ * diff passed).  This is important because the user expects his
+ * outputs in terms of the argument list number, and the diff passed
+ * may have been done slightly differently (if the last argument
+ * was "-", for example).
+ * REV_MAPPING is the inverse of MAPPING.
+ */
+static void
+output_diff3 (outputfile, diff, mapping, rev_mapping)
+     FILE *outputfile;
+     struct diff3_block *diff;
+     int mapping[3], rev_mapping[3];
+{
+  int i;
+  int oddoneout;
+  char *cp;
+  struct diff3_block *ptr;
+  int line;
+  int length;
+  int dontprint;
+  static int skew_increment[3] = { 2, 3, 1 }; /* 0==>2==>1==>3 */
+
+  for (ptr = diff; ptr; ptr = D_NEXT (ptr))
+    {
+      char x[2];
+
+      switch (ptr->correspond)
+	{
+	case DIFF_ALL:
+	  x[0] = '\0';
+	  dontprint = 3;	/* Print them all */
+	  oddoneout = 3;	/* Nobody's odder than anyone else */
+	  break;
+	case DIFF_1ST:
+	case DIFF_2ND:
+	case DIFF_3RD:
+	  oddoneout = rev_mapping[(int) ptr->correspond - (int) DIFF_1ST];
+
+	  x[0] = oddoneout + '1';
+	  x[1] = '\0';
+	  dontprint = oddoneout==0;
+	  break;
+	default:
+	  fatal ("internal error: invalid diff type passed to output");
+	}
+      fprintf (outputfile, "====%s\n", x);
+
+      /* Go 0, 2, 1 if the first and third outputs are equivalent.  */
+      for (i = 0; i < 3;
+	   i = (oddoneout == 1 ? skew_increment[i] : i + 1))
+	{
+	  int realfile = mapping[i];
+	  int
+	    lowt = D_LOWLINE (ptr, realfile),
+	    hight = D_HIGHLINE (ptr, realfile);
+
+	  fprintf (outputfile, "%d:", i + 1);
+	  switch (lowt - hight)
+	    {
+	    case 1:
+	      fprintf (outputfile, "%da\n", lowt - 1);
+	      break;
+	    case 0:
+	      fprintf (outputfile, "%dc\n", lowt);
+	      break;
+	    default:
+	      fprintf (outputfile, "%d,%dc\n", lowt, hight);
+	      break;
+	    }
+
+	  if (i == dontprint) continue;
+
+	  for (line = 0; line < hight - lowt + 1; line++)
+	    {
+	      fprintf (outputfile, "  ");
+	      cp = D_RELNUM (ptr, realfile, line);
+	      length = D_RELLEN (ptr, realfile, line);
+	      fwrite (cp, sizeof (char), length, outputfile);
+	    }
+	  if (line != 0 && cp[length - 1] != '\n')
+	    fprintf (outputfile, "\n\\ No newline at end of file\n");
+	}
+    }
+}
+
+
+/*
+ * Output to OUTPUTFILE the lines of B taken from FILENUM.
+ * Double any initial '.'s; yield nonzero if any initial '.'s were doubled.
+ */
+static int
+dotlines (outputfile, b, filenum)
+     FILE *outputfile;
+     struct diff3_block *b;
+     int filenum;
+{
+  int i;
+  int leading_dot = 0;
+
+  for (i = 0;
+       i < D_NUMLINES (b, filenum);
+       i++)
+    {
+      char *line = D_RELNUM (b, filenum, i);
+      if (line[0] == '.')
+	{
+	  leading_dot = 1;
+	  fprintf (outputfile, ".");
+	}
+      fwrite (line, sizeof (char),
+	      D_RELLEN (b, filenum, i), outputfile);
+    }
+
+  return leading_dot;
+}
+
+/*
+ * Output to OUTPUTFILE a '.' line.  If LEADING_DOT is nonzero,
+ * also output a command that removes initial '.'s
+ * starting with line START and continuing for NUM lines.
+ */
+static void
+undotlines (outputfile, leading_dot, start, num)
+     FILE *outputfile;
+     int leading_dot, start, num;
+{
+  fprintf (outputfile, ".\n");
+  if (leading_dot)
+    if (num == 1)
+      fprintf (outputfile, "%ds/^\\.//\n", start);
+    else
+      fprintf (outputfile, "%d,%ds/^\\.//\n", start, start + num - 1);
+}
+
+/*
+ * This routine outputs a diff3 set of blocks as an ed script.  This
+ * script applies the changes between file's 2 & 3 to file 1.  It
+ * takes the precise format of the ed script to be output from global
+ * variables set during options processing.  Note that it does
+ * destructive things to the set of diff3 blocks it is passed; it
+ * reverses their order (this gets around the problems involved with
+ * changing line numbers in an ed script).
+ *
+ * Note that this routine has the same problem of mapping as the last
+ * one did; the variable MAPPING maps from file number according to
+ * the argument list to file number according to the diff passed.  All
+ * files listed below are in terms of the argument list.
+ * REV_MAPPING is the inverse of MAPPING.
+ *
+ * The arguments FILE0, FILE1 and FILE2 are the strings to print
+ * as the names of the three files.  These may be the actual names,
+ * or may be the arguments specified with -L.
+ *
+ * Returns 1 if conflicts were found.
+ */
+
+static int
+output_diff3_edscript (outputfile, diff, mapping, rev_mapping,
+		       file0, file1, file2)
+     FILE *outputfile;
+     struct diff3_block *diff;
+     int mapping[3], rev_mapping[3];
+     char *file0, *file1, *file2;
+{
+  int leading_dot;
+  int conflicts_found = 0, conflict;
+  struct diff3_block *b;
+
+  for (b = reverse_diff3_blocklist (diff); b; b = b->next)
+    {
+      /* Must do mapping correctly.  */
+      enum diff_type type
+	= ((b->correspond == DIFF_ALL) ?
+	   DIFF_ALL :
+	   ((enum diff_type)
+	    (((int) DIFF_1ST)
+	     + rev_mapping[(int) b->correspond - (int) DIFF_1ST])));
+
+      /* If we aren't supposed to do this output block, skip it.  */
+      switch (type)
+	{
+	default: continue;
+	case DIFF_2ND: if (!show_2nd) continue; conflict = 1; break;
+	case DIFF_3RD: if (overlap_only) continue; conflict = 0; break;
+	case DIFF_ALL: if (simple_only) continue; conflict = flagging; break;
+	}
+
+      if (conflict)
+	{
+	  conflicts_found = 1;
+
+
+	  /* Mark end of conflict.  */
+
+	  fprintf (outputfile, "%da\n", D_HIGHLINE (b, mapping[FILE0]));
+	  leading_dot = 0;
+	  if (type == DIFF_ALL)
+	    {
+	      if (show_2nd)
+		{
+		  /* Append lines from FILE1.  */
+		  fprintf (outputfile, "||||||| %s\n", file1);
+		  leading_dot = dotlines (outputfile, b, mapping[FILE1]);
+		}
+	      /* Append lines from FILE2.  */
+	      fprintf (outputfile, "=======\n");
+	      leading_dot |= dotlines (outputfile, b, mapping[FILE2]);
+	    }
+	  fprintf (outputfile, ">>>>>>> %s\n", file2);
+	  undotlines (outputfile, leading_dot,
+		      D_HIGHLINE (b, mapping[FILE0]) + 2,
+		      (D_NUMLINES (b, mapping[FILE1])
+		       + D_NUMLINES (b, mapping[FILE2]) + 1));
+
+
+	  /* Mark start of conflict.  */
+
+	  fprintf (outputfile, "%da\n<<<<<<< %s\n",
+		   D_LOWLINE (b, mapping[FILE0]) - 1,
+		   type == DIFF_ALL ? file0 : file1);
+	  leading_dot = 0;
+	  if (type == DIFF_2ND)
+	    {
+	      /* Prepend lines from FILE1.  */
+	      leading_dot = dotlines (outputfile, b, mapping[FILE1]);
+	      fprintf (outputfile, "=======\n");
+	    }
+	  undotlines (outputfile, leading_dot,
+		      D_LOWLINE (b, mapping[FILE0]) + 1,
+		      D_NUMLINES (b, mapping[FILE1]));
+	}
+      else if (D_NUMLINES (b, mapping[FILE2]) == 0)
+	/* Write out a delete */
+	{
+	  if (D_NUMLINES (b, mapping[FILE0]) == 1)
+	    fprintf (outputfile, "%dd\n",
+		     D_LOWLINE (b, mapping[FILE0]));
+	  else
+	    fprintf (outputfile, "%d,%dd\n",
+		     D_LOWLINE (b, mapping[FILE0]),
+		     D_HIGHLINE (b, mapping[FILE0]));
+	}
+      else
+	/* Write out an add or change */
+	{
+	  switch (D_NUMLINES (b, mapping[FILE0]))
+	    {
+	    case 0:
+	      fprintf (outputfile, "%da\n",
+		       D_HIGHLINE (b, mapping[FILE0]));
+	      break;
+	    case 1:
+	      fprintf (outputfile, "%dc\n",
+		       D_HIGHLINE (b, mapping[FILE0]));
+	      break;
+	    default:
+	      fprintf (outputfile, "%d,%dc\n",
+		       D_LOWLINE (b, mapping[FILE0]),
+		       D_HIGHLINE (b, mapping[FILE0]));
+	      break;
+	    }
+
+	  undotlines (outputfile, dotlines (outputfile, b, mapping[FILE2]),
+		      D_LOWLINE (b, mapping[FILE0]),
+		      D_NUMLINES (b, mapping[FILE2]));
+	}
+    }
+  if (finalwrite) fprintf (outputfile, "w\nq\n");
+  return conflicts_found;
+}
+
+/*
+ * Read from INFILE and output to OUTPUTFILE a set of diff3_ blocks DIFF
+ * as a merged file.  This acts like 'ed file0 <[output_diff3_edscript]',
+ * except that it works even for binary data or incomplete lines.
+ *
+ * As before, MAPPING maps from arg list file number to diff file number,
+ * REV_MAPPING is its inverse,
+ * and FILE0, FILE1, and FILE2 are the names of the files.
+ *
+ * Returns 1 if conflicts were found.
+ */
+
+static int
+output_diff3_merge (infile, outputfile, diff, mapping, rev_mapping,
+		    file0, file1, file2)
+     FILE *infile, *outputfile;
+     struct diff3_block *diff;
+     int mapping[3], rev_mapping[3];
+     char *file0, *file1, *file2;
+{
+  int c, i;
+  int conflicts_found = 0, conflict;
+  struct diff3_block *b;
+  int linesread = 0;
+
+  for (b = diff; b; b = b->next)
+    {
+      /* Must do mapping correctly.  */
+      enum diff_type type
+	= ((b->correspond == DIFF_ALL) ?
+	   DIFF_ALL :
+	   ((enum diff_type)
+	    (((int) DIFF_1ST)
+	     + rev_mapping[(int) b->correspond - (int) DIFF_1ST])));
+      char *format_2nd = "<<<<<<< %s\n";
+
+      /* If we aren't supposed to do this output block, skip it.  */
+      switch (type)
+	{
+	default: continue;
+	case DIFF_2ND: if (!show_2nd) continue; conflict = 1; break;
+	case DIFF_3RD: if (overlap_only) continue; conflict = 0; break;
+	case DIFF_ALL: if (simple_only) continue; conflict = flagging;
+	  format_2nd = "||||||| %s\n";
+	  break;
+	}
+
+      /* Copy I lines from file 0.  */
+      i = D_LOWLINE (b, FILE0) - linesread - 1;
+      linesread += i;
+      while (0 <= --i)
+	do
+	  {
+	    c = getc (infile);
+	    if (c == EOF)
+	      if (ferror (infile))
+		perror_with_exit ("input file");
+	      else if (feof (infile))
+		fatal ("input file shrank");
+	    putc (c, outputfile);
+	  }
+	while (c != '\n');
+
+      if (conflict)
+	{
+	  conflicts_found = 1;
+
+	  if (type == DIFF_ALL)
+	    {
+	      /* Put in lines from FILE0 with bracket.  */
+	      fprintf (outputfile, "<<<<<<< %s\n", file0);
+	      for (i = 0;
+		   i < D_NUMLINES (b, mapping[FILE0]);
+		   i++)
+		fwrite (D_RELNUM (b, mapping[FILE0], i), sizeof (char),
+			D_RELLEN (b, mapping[FILE0], i), outputfile);
+	    }
+
+	  if (show_2nd)
+	    {
+	      /* Put in lines from FILE1 with bracket.  */
+	      fprintf (outputfile, format_2nd, file1);
+	      for (i = 0;
+		   i < D_NUMLINES (b, mapping[FILE1]);
+		   i++)
+		fwrite (D_RELNUM (b, mapping[FILE1], i), sizeof (char),
+			D_RELLEN (b, mapping[FILE1], i), outputfile);
+	    }
+
+	  fprintf (outputfile, "=======\n");
+	}
+
+      /* Put in lines from FILE2.  */
+      for (i = 0;
+	   i < D_NUMLINES (b, mapping[FILE2]);
+	   i++)
+	fwrite (D_RELNUM (b, mapping[FILE2], i), sizeof (char),
+		D_RELLEN (b, mapping[FILE2], i), outputfile);
+
+      if (conflict)
+	fprintf (outputfile, ">>>>>>> %s\n", file2);
+
+      /* Skip I lines in file 0.  */
+      i = D_NUMLINES (b, FILE0);
+      linesread += i;
+      while (0 <= --i)
+	while ((c = getc (infile)) != '\n')
+	  if (c == EOF)
+	    if (ferror (infile))
+	      perror_with_exit ("input file");
+	    else if (feof (infile))
+	      {
+		if (i || b->next)
+		  fatal ("input file shrank");
+		return conflicts_found;
+	      }
+    }
+  /* Copy rest of common file.  */
+  while ((c = getc (infile)) != EOF || !(ferror (infile) | feof (infile)))
+    putc (c, outputfile);
+  return conflicts_found;
+}
+
+/*
+ * Reverse the order of the list of diff3 blocks.
+ */
+static struct diff3_block *
+reverse_diff3_blocklist (diff)
+     struct diff3_block *diff;
+{
+  register struct diff3_block *tmp, *next, *prev;
+
+  for (tmp = diff, prev = (struct diff3_block *) 0;
+       tmp; tmp = next)
+    {
+      next = tmp->next;
+      tmp->next = prev;
+      prev = tmp;
+    }
+
+  return prev;
+}
+
+static int
+myread (fd, ptr, size)
+     int fd, size;
+     char *ptr;
+{
+  int result = read (fd, ptr, size);
+  if (result < 0)
+    perror_with_exit ("read failed");
+  return result;
+}
+
+VOID *
+xmalloc (size)
+     unsigned size;
+{
+  VOID *result = (VOID *) malloc (size ? size : 1);
+  if (!result)
+    fatal ("virtual memory exhausted");
+  return result;
+}
+
+static VOID *
+xrealloc (ptr, size)
+     VOID *ptr;
+     unsigned size;
+{
+  VOID *result = (VOID *) realloc (ptr, size ? size : 1);
+  if (!result)
+    fatal ("virtual memory exhausted");
+  return result;
+}
+
+static void
+fatal (string)
+     char *string;
+{
+  fprintf (stderr, "%s: %s\n", argv0, string);
+  exit (2);
+}
+
+static void
+perror_with_exit (string)
+     char *string;
+{
+  int e = errno;
+  fprintf (stderr, "%s: ", argv0);
+  errno = e;
+  perror (string);
+  exit (2);
+}
diff --git a/gnu/usr.bin/diff/sdiff.c b/gnu/usr.bin/diff/sdiff.c
new file mode 100644
index 0000000..7f1019e
--- /dev/null
+++ b/gnu/usr.bin/diff/sdiff.c
@@ -0,0 +1,1067 @@
+/* SDIFF -- interactive merge front end to diff
+   Copyright (C) 1992 Free Software Foundation, Inc.
+
+This file is part of GNU DIFF.
+
+GNU DIFF is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation; either version 2, or (at your option)
+any later version.
+
+GNU DIFF is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with GNU DIFF; see the file COPYING.  If not, write to
+the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.  */
+
+/* GNU SDIFF was written by Thomas Lord. */
+
+#include <stdio.h>
+#include <ctype.h>
+#include "system.h"
+#include <signal.h>
+#include "getopt.h"
+
+#ifndef SEEK_SET
+#define SEEK_SET 0
+#endif
+
+/* Size of chunks read from files which must be parsed into lines. */
+#define SDIFF_BUFSIZE 65536
+
+/* Default name of the diff program */
+#ifndef DIFF_PROGRAM
+#define DIFF_PROGRAM "/usr/bin/diff"
+#endif
+
+/* Users' editor of nonchoice */
+#ifndef DEFAULT_EDITOR
+#define DEFAULT_EDITOR "ed"
+#endif
+
+extern char *version_string;
+static char const *prog;
+static char const *diffbin = DIFF_PROGRAM;
+static char const *edbin = DEFAULT_EDITOR;
+
+static char *tmpname;
+static int volatile tmpmade;
+static pid_t volatile diffpid;
+
+struct line_filter;
+static void diffarg (); /* (char *); */
+static void execdiff (); /* (int, char const *, char const *, char const *); */
+static int edit (); /* (struct line_filter *left, int lenl, struct
+		       line_filter *right, int lenr, FILE *outfile); */
+static int interact (); /* (struct line_filter *diff,
+			  struct line_filter *left,
+			  struct line_filter *right, FILE *outfile); */
+static void trapsigs (); /* (void); */
+/* this lossage until the gnu libc conquers the universe */
+#define TMPNAMSIZE 1024
+#define PVT_tmpdir "/tmp"
+static char *private_tempnam (); /* (const char *, const char *, int, int *); */
+static int diraccess ();
+
+/* Options: */
+
+/* name of output file if -o spec'd */
+static char *out_file;
+
+/* do not print common lines if true, set by -s option */
+static int suppress_common_flag;
+
+static struct option longopts[] =
+{
+  {"ignore-blank-lines", 0, NULL, 'B'},
+  {"speed-large-files", 0, NULL, 'H'},
+  {"ignore-matching-lines", 1, NULL, 'I'},
+  {"ignore-all-space", 0, NULL, 'W'}, /* swap W and w for historical reasons */
+  {"text", 0, NULL, 'a'},
+  {"ignore-space-change", 0, NULL, 'b'},
+  {"minimal", 0, NULL, 'd'},
+  {"ignore-case", 0, NULL, 'i'},
+  {"left-column", 0, NULL, 'l'},
+  {"output", 1, NULL, 'o'},
+  {"suppress-common-lines", 0, NULL, 's'},
+  {"expand-tabs", 0, NULL, 't'},
+  {"width", 1, NULL, 'w'},
+  {"version", 0, NULL, 'v'},
+  {NULL, 0, NULL, 0}
+};
+
+/* prints usage message and quits */
+static void
+usage ()
+{
+  fprintf (stderr, "Usage: %s [options] from-file to-file\n", prog);
+  fprintf (stderr, "Options:\n\
+       [-abBdHilstv] [-I regexp] [-o outfile] [-w columns]\n\
+       [--text] [--minimal] [--speed-large-files] [--expand-tabs]\n\
+       [--ignore-case] [--ignore-matching-lines=regexp]\n\
+       [--ignore-space-change] [--ignore-blank-lines] [--ignore-all-space]\n\
+       [--suppress-common-lines] [--left-column] [--output=outfile]\n\
+       [--version] [--width=columns]\n");
+  exit (2);
+}
+
+static void
+cleanup ()
+{
+  if (0 < diffpid)
+    kill (diffpid, SIGPIPE);
+  if (tmpmade)
+    unlink (tmpname);
+}
+
+static void
+exiterr ()
+{
+  cleanup ();
+  exit (2);
+}
+
+static void
+fatal (msg)
+     char *msg;
+{
+  fprintf (stderr, "%s: %s\n", prog, msg);
+  exiterr ();
+}
+
+static void
+perror_fatal (msg)
+     char *msg;
+{
+  int e = errno;
+  fprintf (stderr, "%s: ", prog);
+  errno = e;
+  perror (msg);
+  exiterr ();
+}
+
+
+/* malloc freely or DIE! */
+char *
+xmalloc (size)
+     size_t size;
+{
+  char *r = malloc (size);
+  if (!r)
+    fatal ("virtual memory exhausted");
+  return r;
+}
+
+static FILE *
+ck_fopen (fname, type)
+     char *fname, *type;
+{
+  FILE *r = fopen (fname, type);
+  if (!r)
+    perror_fatal (fname);
+  return r;
+}
+
+
+static FILE *
+ck_fdopen (fd, type)
+     int fd;
+     char *type;
+{
+  FILE *r = fdopen (fd, type);
+  if (!r)
+    perror_fatal ("fdopen");
+  return r;
+}
+
+static void
+ck_fclose (f)
+     FILE *f;
+{
+  if (fclose (f))
+    perror_fatal ("input/output error");
+}
+
+static size_t
+ck_fread (buf, size, f)
+     char *buf;
+     size_t size;
+     FILE *f;
+{
+  size_t r = fread (buf, sizeof (char), size, f);
+  if (r == 0 && ferror (f))
+    perror_fatal ("input error");
+  return r;
+}
+
+static void
+ck_fwrite (buf, size, f)
+     char *buf;
+     size_t size;
+     FILE *f;
+{
+  if (fwrite (buf, sizeof (char), size, f) != size)
+    perror_fatal ("output error");
+}
+
+static void
+ck_fflush (f)
+     FILE *f;
+{
+  if (fflush (f) != 0)
+    perror_fatal ("output error");
+}
+
+#if !HAVE_MEMCHR
+char *
+memchr (s, c, n)
+     char *s;
+     int c;
+     size_t n;
+{
+  unsigned char *p = (unsigned char *) s, *lim = p + n;
+  for (;  p < lim;  p++)
+    if (*p == c)
+      return (char *) p;
+  return 0;
+}
+#endif
+
+#ifndef HAVE_WAITPID
+/* Emulate waitpid well enough for sdiff, which has at most two children.  */
+static pid_t
+waitpid (pid, stat_loc, options)
+     pid_t pid;
+     int *stat_loc;
+     int options;
+{
+  static int ostatus;
+  static pid_t opid;
+  int npid, status;
+
+  if (pid == opid)
+    {
+      opid = 0;
+      status = ostatus;
+    }
+  else
+    while ((npid = wait (&status)) != pid)
+      {
+	if (npid < 0)
+	  return npid;
+	opid = npid;
+	ostatus = status;
+      }
+  *stat_loc = status;
+  return pid;
+}
+#endif
+
+static char const *
+expand_name (name, isdir, other_name)
+     char *name;
+     int isdir;
+     char const *other_name;
+{
+  if (strcmp (name, "-") == 0)
+    fatal ("cannot interactively merge standard input");
+  if (!isdir)
+    return name;
+  else
+    {
+      /* Yield NAME/BASE, where BASE is OTHER_NAME's basename.  */
+      const char
+	*p = rindex (other_name, '/'),
+	*base = p ? p+1 : other_name;
+      size_t namelen = strlen (name), baselen = strlen (base);
+      char *r = xmalloc (namelen + baselen + 2);
+      bcopy (name, r, namelen);
+      r[namelen] = '/';
+      bcopy (base, r + namelen + 1, baselen + 1);
+      return r;
+    }
+}
+
+
+
+struct line_filter {
+  FILE *infile;
+  char *bufpos;
+  char *buffer;
+  char *buflim;
+};
+
+static void
+lf_init (lf, infile)
+     struct line_filter *lf;
+     FILE *infile;
+{
+  lf->infile = infile;
+  lf->bufpos = lf->buffer = lf->buflim = xmalloc (SDIFF_BUFSIZE + 1);
+  lf->buflim[0] = '\n';
+}
+
+/* Fill an exhausted line_filter buffer from its INFILE */
+static size_t
+lf_refill (lf)
+     struct line_filter *lf;
+{
+  size_t s = ck_fread (lf->buffer, SDIFF_BUFSIZE, lf->infile);
+  lf->bufpos = lf->buffer;
+  lf->buflim = lf->buffer + s;
+  lf->buflim[0] = '\n';
+  return s;
+}
+
+/* Advance LINES on LF's infile, copying lines to OUTFILE */
+static void
+lf_copy (lf, lines, outfile)
+     struct line_filter *lf;
+     int lines;
+     FILE *outfile;
+{
+  char *start = lf->bufpos;
+
+  while (lines)
+    {
+      lf->bufpos = memchr (lf->bufpos, '\n', lf->buflim - lf->bufpos);
+      if (! lf->bufpos)
+	{
+	  ck_fwrite (start, lf->buflim - start, outfile);
+	  if (! lf_refill (lf))
+	    return;
+	  start = lf->bufpos;
+	}
+      else
+	{
+	  --lines;
+	  ++lf->bufpos;
+	}
+    }
+
+  ck_fwrite (start, lf->bufpos - start, outfile);
+}
+
+/* Advance LINES on LF's infile without doing output */
+static void
+lf_skip (lf, lines)
+     struct line_filter *lf;
+     int lines;
+{
+  while (lines)
+    {
+      lf->bufpos = memchr (lf->bufpos, '\n', lf->buflim - lf->bufpos);
+      if (! lf->bufpos)
+	{
+	  if (! lf_refill (lf))
+	    break;
+	}
+      else
+	{
+	  --lines;
+	  ++lf->bufpos;
+	}
+    }
+}
+
+/* Snarf a line into a buffer.  Return EOF if EOF, 0 if error, 1 if OK.  */
+static int
+lf_snarf (lf, buffer, bufsize)
+     struct line_filter *lf;
+     char *buffer;
+     size_t bufsize;
+{
+  char *start = lf->bufpos;
+
+  for (;;)
+    {
+      char *next = memchr (start, '\n', lf->buflim + 1 - start);
+      size_t s = next - start;
+      if (bufsize <= s)
+	return 0;
+      bcopy (start, buffer, s);
+      if (next < lf->buflim)
+	{
+	  buffer[s] = 0;
+	  lf->bufpos = next + 1;
+	  return 1;
+	}
+      if (! lf_refill (lf))
+	return s ? 0 : EOF;
+      buffer += s;
+      bufsize -= s;
+      start = next;
+    }
+}
+
+
+
+int
+main (argc, argv)
+     int argc;
+     char *argv[];
+{
+  int opt;
+  int version_requested = 0;
+  char *editor = getenv ("EDITOR");
+  char *differ = getenv ("DIFF");
+
+  prog = argv[0];
+  if (editor)
+    edbin = editor;
+  if (differ)
+    diffbin = differ;
+
+  diffarg ("diff");
+
+  /* parse command line args */
+  while ((opt=getopt_long (argc, argv, "abBdHiI:lo:stvw:W", longopts, (int *)0)) != EOF)
+    {
+      switch (opt)
+	{
+	case 'a':
+	  diffarg ("-a");
+	  break;
+
+	case 'b':
+	  diffarg ("-b");
+	  break;
+
+	case 'B':
+	  diffarg ("-B");
+	  break;
+
+	case 'd':
+	  diffarg ("-d");
+	  break;
+
+	case 'H':
+	  diffarg ("-H");
+	  break;
+
+	case 'i':
+	  diffarg ("-i");
+	  break;
+
+	case 'I':
+	  diffarg ("-I");
+	  diffarg (optarg);
+	  break;
+
+	case 'l':
+	  diffarg ("--left-column");
+	  break;
+
+	case 'o':
+	  out_file = optarg;
+	  break;
+
+	case 's':
+	  suppress_common_flag = 1;
+	  break;
+
+	case 't':
+	  diffarg ("-t");
+	  break;
+
+	case 'v':
+	  version_requested = 1;
+	  fprintf (stderr, "GNU sdiff version %s\n", version_string);
+	  ck_fflush (stderr);
+	  break;
+
+	case 'w':
+	  diffarg ("-W");
+	  diffarg (optarg);
+	  break;
+
+	case 'W':
+	  diffarg ("-w");
+	  break;
+
+	default:
+	  usage ();
+	}
+    }
+
+  /* check: did user just want version message? if so exit. */
+  if (version_requested && argc - optind == 0)
+    exit (0);
+
+  if (argc - optind != 2)
+    usage ();
+
+  if (! out_file)
+    /* easy case: diff does everything for us */
+    execdiff (suppress_common_flag, "-y", argv[optind], argv[optind + 1]);
+  else
+    {
+      FILE *left, *right, *out, *diffout;
+      int diff_fds[2];
+      int interact_ok;
+      pid_t pid;
+      struct line_filter lfilt;
+      struct line_filter rfilt;
+      struct line_filter diff_filt;
+      int leftdir = diraccess (argv[optind]);
+      int rightdir = diraccess (argv[optind + 1]);
+
+      if (leftdir && rightdir)
+	fatal ("both files to be compared are directories");
+
+      left = ck_fopen (expand_name (argv[optind], leftdir, argv[optind + 1]), "r");
+      ;
+      right = ck_fopen (expand_name (argv[optind + 1], rightdir, argv[optind]), "r");
+      out = ck_fopen (out_file, "w");
+
+      if (pipe (diff_fds))
+	perror_fatal ("pipe");
+
+      trapsigs ();
+
+      diffpid = pid = vfork ();
+
+      if (pid == 0)
+	{
+	  signal (SIGINT, SIG_IGN);  /* in case user interrupts editor */
+	  signal (SIGPIPE, SIG_DFL);
+
+	  close (diff_fds[0]);
+	  if (diff_fds[1] != fileno (stdout))
+	    {
+	      dup2 (diff_fds[1], fileno (stdout));
+	      close (diff_fds[1]);
+	    }
+
+	  execdiff (0, "--sdiff-merge-assist", argv[optind], argv[optind + 1]);
+	}
+
+      if (pid < 0)
+	perror_fatal ("fork failed");
+
+      close (diff_fds[1]);
+      diffout = ck_fdopen (diff_fds[0], "r");
+
+      lf_init (&diff_filt, diffout);
+      lf_init (&lfilt, left);
+      lf_init (&rfilt, right);
+
+      interact_ok = interact (&diff_filt, &lfilt, &rfilt, out);
+
+      ck_fclose (diffout);
+      ck_fclose (left);
+      ck_fclose (right);
+      ck_fclose (out);
+
+      {
+	int wstatus;
+
+	if (waitpid (pid, &wstatus, 0) < 0)
+	  perror_fatal ("wait failed");
+	diffpid = 0;
+
+	if (tmpmade)
+	  {
+	    unlink (tmpname);
+	    tmpmade = 0;
+	  }
+
+	if (! interact_ok)
+	  exit (2);
+
+	if (! (WIFEXITED (wstatus) && WEXITSTATUS (wstatus) < 2))
+	  fatal ("Subsidiary diff failed");
+
+	exit (WEXITSTATUS (wstatus));
+      }
+    }
+  return 0;			/* Fool -Wall . . . */
+}
+
+static char **diffargv;
+
+static void
+diffarg (a)
+     char *a;
+{
+  static unsigned diffargs, diffargsmax;
+
+  if (diffargs == diffargsmax)
+    {
+      if (! diffargsmax)
+	{
+	  diffargv = (char **) xmalloc (sizeof (char));
+	  diffargsmax = 8;
+	}
+      diffargsmax *= 2;
+      diffargv = (char **) realloc (diffargv, diffargsmax * sizeof (char *));
+      if (! diffargv)
+	fatal ("out of memory");
+    }
+  diffargv[diffargs++] = a;
+}
+
+static void
+execdiff (differences_only, option, file1, file2)
+     int differences_only;
+     char *option, *file1, *file2;
+{
+  if (differences_only)
+    diffarg ("--suppress-common-lines");
+  diffarg (option);
+  diffarg ("--");
+  diffarg (file1);
+  diffarg (file2);
+  diffarg (0);
+
+  execvp (diffbin, diffargv);
+  write (fileno (stderr), diffbin, strlen (diffbin));
+  write (fileno (stderr), ": not found\n", 12);
+  _exit (2);
+}
+
+
+
+
+/* Signal handling */
+
+static int volatile ignore_signals;
+
+static void
+catchsig (s)
+     int s;
+{
+  signal (s, catchsig);
+  if (! ignore_signals)
+    {
+      cleanup ();
+      _exit (2);
+    }
+}
+
+static void
+trapsigs ()
+{
+  static int const sigs[] = {
+#   ifdef SIGHUP
+	  SIGHUP,
+#   endif
+#   ifdef SIGQUIT
+	  SIGQUIT,
+#   endif
+#   ifdef SIGTERM
+	  SIGTERM,
+#   endif
+#   ifdef SIGXCPU
+	  SIGXCPU,
+#   endif
+#   ifdef SIGXFSZ
+	  SIGXFSZ,
+#   endif
+	  SIGINT,
+	  SIGPIPE
+  };
+  int const *p;
+
+  for (p = sigs;  p < sigs + sizeof (sigs) / sizeof (*sigs);  p++)
+    if (signal (*p, SIG_IGN) != SIG_IGN  &&  signal (*p, catchsig) != SIG_IGN)
+      fatal ("signal error");
+}
+
+
+
+static void
+give_help ()
+{
+  fprintf (stderr,"l:\tuse the left version\n");
+  fprintf (stderr,"r:\tuse the right version\n");
+  fprintf (stderr,"e l:\tedit then use the left version\n");
+  fprintf (stderr,"e r:\tedit then use the right version\n");
+  fprintf (stderr,"e b:\tedit then use the left and right versions concatenated\n");
+  fprintf (stderr,"e:\tedit a new version\n");
+  fprintf (stderr,"s:\tsilently include common lines\n");
+  fprintf (stderr,"v:\tverbosely include common lines\n");
+  fprintf (stderr,"q:\tquit\n");
+}
+
+static int
+skip_white ()
+{
+  int c;
+  while (isspace (c = getchar ()) && c != '\n')
+    ;
+  if (ferror (stdin))
+    perror_fatal ("input error");
+  return c;
+}
+
+static void
+flush_line ()
+{
+  int c;
+  while ((c = getchar ()) != '\n' && c != EOF)
+    ;
+  if (ferror (stdin))
+    perror_fatal ("input error");
+}
+
+
+/* interpret an edit command */
+static int
+edit (left, lenl, right, lenr, outfile)
+     struct line_filter *left;
+     int lenl;
+     struct line_filter *right;
+     int lenr;
+     FILE *outfile;
+{
+  for (;;)
+    {
+      int cmd0, cmd1;
+      int gotcmd = 0;
+
+      while (!gotcmd)
+	{
+	  if (putchar ('%') != '%')
+	    perror_fatal ("output error");
+	  ck_fflush (stdout);
+
+	  cmd0 = skip_white ();
+	  switch (cmd0)
+	    {
+	    case 'l': case 'r': case 's': case 'v': case 'q':
+	      if (skip_white () != '\n')
+		{
+		  give_help ();
+		  flush_line ();
+		  continue;
+		}
+	      gotcmd = 1;
+	      break;
+
+	    case 'e':
+	      cmd1 = skip_white ();
+	      switch (cmd1)
+		{
+		case 'l': case 'r': case 'b':
+		  if (skip_white () != '\n')
+		    {
+		      give_help ();
+		      flush_line ();
+		      continue;
+		    }
+		  gotcmd = 1;
+		  break;
+		case '\n':
+		  gotcmd = 1;
+		  break;
+		default:
+		  give_help ();
+		  flush_line ();
+		  continue;
+		}
+	      break;
+	    case EOF:
+	      if (feof (stdin))
+		{
+		  gotcmd = 1;
+		  cmd0 = 'q';
+		  break;
+		}
+	      /* falls through */
+	    default:
+	      give_help ();
+	      flush_line ();
+	      continue;
+	    }
+	}
+
+      switch (cmd0)
+	{
+	case 'l':
+	  lf_copy (left, lenl, outfile);
+	  lf_skip (right, lenr);
+	  return 1;
+	case 'r':
+	  lf_copy (right, lenr, outfile);
+	  lf_skip (left, lenl);
+	  return 1;
+	case 's':
+	  suppress_common_flag = 1;
+	  break;
+	case 'v':
+	  suppress_common_flag = 0;
+	  break;
+	case 'q':
+	  return 0;
+	case 'e':
+	  if (! tmpname && ! (tmpname = private_tempnam (0, "sdiff", 1, 0)))
+	    perror_fatal ("temporary file name");
+
+	  tmpmade = 1;
+
+	  {
+	    FILE *tmp = ck_fopen (tmpname, "w+");
+
+	    if (cmd1 == 'l' || cmd1 == 'b')
+	      lf_copy (left, lenl, tmp);
+	    else
+	      lf_skip (left, lenl);
+
+	    if (cmd1 == 'r' || cmd1 == 'b')
+	      lf_copy (right, lenr, tmp);
+	    else
+	      lf_skip (right, lenr);
+
+	    ck_fflush (tmp);
+
+	    {
+	      pid_t pid;
+	      int wstatus;
+
+	      ignore_signals = 1;
+
+	      pid = vfork ();
+	      if (pid == 0)
+		{
+		  char const *argv[3];
+		  int i = 0;
+
+		  argv[i++] = edbin;
+		  argv[i++] = tmpname;
+		  argv[i++] = 0;
+
+		  execvp (edbin, (char **) argv);
+		  write (fileno (stderr), edbin, strlen (edbin));
+		  write (fileno (stderr), ": not found\n", 12);
+		  _exit (1);
+		}
+
+	      if (pid < 0)
+		perror_fatal ("fork failed");
+
+	      while (waitpid (pid, &wstatus, 0) < 0)
+		if (errno != EINTR)
+		  perror_fatal ("wait failed");
+
+	      ignore_signals = 0;
+
+	      if (! (WIFEXITED (wstatus) && WEXITSTATUS (wstatus) < 1))
+		fatal ("Subsidiary editor failed");
+	    }
+
+	    if (fseek (tmp, 0L, SEEK_SET) != 0)
+	      perror_fatal ("fseek");
+	    {
+	      /* SDIFF_BUFSIZE is too big for a local var
+		 in some compilers, so we allocate it dynamically.  */
+	      char *buf = (char *) xmalloc (SDIFF_BUFSIZE);
+	      size_t size;
+
+	      while ((size = ck_fread (buf, SDIFF_BUFSIZE, tmp)) != 0)
+		ck_fwrite (buf, size, outfile);
+	      ck_fclose (tmp);
+
+	      free (buf);
+	    }
+	    return 1;
+	  }
+	default:
+	  give_help ();
+	  break;
+	}
+    }
+}
+
+
+
+/* Alternately reveal bursts of diff output and handle user editing comands.  */
+static int
+interact (diff, left, right, outfile)
+     struct line_filter *diff;
+     struct line_filter *left;
+     struct line_filter *right;
+     FILE *outfile;
+{
+  for (;;)
+    {
+      char diff_help[256];
+      int snarfed = lf_snarf (diff, diff_help, sizeof (diff_help));
+
+      if (snarfed <= 0)
+	return snarfed;
+
+      switch (diff_help[0])
+	{
+	case ' ':
+	  puts (diff_help + 1);
+	  break;
+	case 'i':
+	  {
+	    int lenl = atoi (diff_help + 1), lenr, lenmax;
+	    char *p = index (diff_help, ',');
+
+	    if (!p)
+	      fatal (diff_help);
+	    lenr = atoi (p + 1);
+	    lenmax = max (lenl, lenr);
+
+	    if (suppress_common_flag)
+	      lf_skip (diff, lenmax);
+	    else
+	      lf_copy (diff, lenmax, stdout);
+
+	    lf_copy (left, lenl, outfile);
+	    lf_skip (right, lenr);
+	    break;
+	  }
+	case 'c':
+	  {
+	    int lenl = atoi (diff_help + 1), lenr;
+	    char *p = index (diff_help, ',');
+
+	    if (!p)
+	      fatal (diff_help);
+	    lenr = atoi (p + 1);
+	    lf_copy (diff, max (lenl, lenr), stdout);
+	    if (! edit (left, lenl, right, lenr, outfile))
+	      return 0;
+	    break;
+	  }
+	default:
+	  fatal (diff_help);
+	  break;
+	}
+    }
+}
+
+
+
+/* temporary lossage: this is torn from gnu libc */
+/* Return nonzero if DIR is an existent directory.  */
+static int
+diraccess (dir)
+     const char *dir;
+{
+  struct stat buf;
+  return stat (dir, &buf) == 0 && S_ISDIR (buf.st_mode);
+}
+
+/* Return nonzero if FILE exists.  */
+static int
+exists (file)
+     const char *file;
+{
+  struct stat buf;
+  return stat (file, &buf) == 0;
+}
+
+/* These are the characters used in temporary filenames.  */
+static const char letters[] =
+  "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
+
+/* Generate a temporary filename.
+   If DIR_SEARCH is nonzero, DIR and PFX are used as
+   described for tempnam.  If not, a temporary filename
+   in P_tmpdir with no special prefix is generated.  If LENPTR
+   is not NULL, *LENPTR is set the to length (including the
+   terminating '\0') of the resultant filename, which is returned.
+   This goes through a cyclic pattern of all possible filenames
+   consisting of five decimal digits of the current pid and three
+   of the characters in `letters'.  Data for tempnam and tmpnam
+   is kept separate, but when tempnam is using P_tmpdir and no
+   prefix (i.e, it is identical to tmpnam), the same data is used.
+   Each potential filename is tested for an already-existing file of
+   the same name, and no name of an existing file will be returned.
+   When the cycle reaches its end (12345ZZZ), NULL is returned.  */
+
+
+static char *
+private_tempnam (dir, pfx, dir_search, lenptr)
+     const char *dir;
+     const char *pfx;
+     int dir_search;
+     size_t *lenptr;
+{
+  static const char tmpdir[] = PVT_tmpdir;
+  static struct
+    {
+      char buf[3];
+      char *s;
+      size_t i;
+    } infos[2], *info;
+  static char buf[TMPNAMSIZE];
+  static pid_t oldpid = 0;
+  pid_t pid = getpid ();
+  register size_t len, plen;
+
+  if (dir_search)
+    {
+      register const char *d = getenv ("TMPDIR");
+      if (d != NULL && !diraccess (d))
+	d = NULL;
+      if (d == NULL && dir != NULL && diraccess (dir))
+	d = dir;
+      if (d == NULL && diraccess (tmpdir))
+	d = tmpdir;
+      if (d == NULL && diraccess ("/tmp"))
+	d = "/tmp";
+      if (d == NULL)
+	{
+	  errno = ENOENT;
+	  return NULL;
+	}
+      dir = d;
+    }
+  else
+    dir = tmpdir;
+
+  if (pfx != NULL && *pfx != '\0')
+    {
+      plen = strlen (pfx);
+      if (plen > 5)
+	plen = 5;
+    }
+  else
+    plen = 0;
+
+  if (dir != tmpdir && !strcmp (dir, tmpdir))
+    dir = tmpdir;
+  info = &infos[(plen == 0 && dir == tmpdir) ? 1 : 0];
+
+  if (pid != oldpid)
+    {
+      oldpid = pid;
+      info->buf[0] = info->buf[1] = info->buf[2] = '0';
+      info->s = &info->buf[0];
+      info->i = 0;
+    }
+
+  len = strlen (dir) + 1 + plen + 8;
+  for (;;)
+    {
+      *info->s = letters[info->i];
+      sprintf (buf, "%s/%.*s%.5d%.3s", dir, (int) plen, pfx,
+	      pid % 100000, info->buf);
+      if (!exists (buf))
+	break;
+      ++info->i;
+      if (info->i > sizeof (letters) - 1)
+	{
+	  info->i = 0;
+	  if (info->s == &info->buf[2])
+	    {
+	      errno = EEXIST;
+	      return NULL;
+	    }
+	  ++info->s;
+	}
+    }
+
+  if (lenptr != NULL)
+    *lenptr = len;
+  return buf;
+}