build: Generate 'ChangeLog' upon 'make dist'.

* ChangeLog: Rename to ...
* ChangeLog.old: ... this.
* ChangeLog: New file.
* Makefile.am (gen_start_date): New variable.
(gen-ChangeLog, dist-hook): New targets.
(EXTRA_DIST): Add 'ChangeLog.old'.
* build-aux/gitlog-to-changelog: New file, from Gnulib.

4 files changed, 658 insertions, 165 deletions

diff --git a/ChangeLog b/ChangeLog
index 15e01c0..fe5459d 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,165 +1,4 @@
-2014-05-25  Dale Mellor <dale_mellor@users.sourceforge.net>
+Normally a ChangeLog is generated at "make dist" time and available in
+source tarballs.
 
-	* Juggled build infrastructure so that we can make the minimal man
-	page in the proper autotools way.
-
-	* configure.ac: version to 1.0.8.
-
-
-2014-04-28  Dale Mellor <dale_mellor@users.sourceforge.net>
-
-	* We now run against, and require, guile-2.0.
-
-	* configure.ac: version to 1.0.7.
-
-
-2012-02-04  Dale Mellor <dale_mellor@users.sourceforge.net>
-
-	* main.scm: added search for initial files in
-	$XDG_CONFIG_HOME/cron directory, defaulting to ~/.config/cron if
-	the environment variable is not set) as well as in ~/.cron
-	directory (this is in line with the current FreeDesktop.org
-	standards).
-
-
-2010-06-13  Dale Mellor <dale_mellor@users.sourceforge.net>
-
-	* configure.ac: added --enable-no-vixie-clobber argument to
-	configure so that the root user can avoid overwriting a legacy
-	cron installation.
-
-	* mcron.1: added simple, minimal man page using help2man (the
-	texinfo file is still the primary documentation source).
-
-	* makefile.am: replaced use of mkinstalldirs with install; the
-	former is not supplied with the latest automake (1.11).
-
-
-2008-02-21  Dale Mellor <dale_mellor@users.sourceforge.net>
-
-	* ALL FILES: Replaced version 2 GPL notices with version 3 ones.
-
-	* makefile.am: Do not remove COPYING file with make
-	maintainer-clean; if you do it will eventually get replaced with
-	the old version 2 GPL by a subsequent automake.
-
-	* configure.ac: Bumped version to 1.0.4.
-
-
-2008-01-25  Dale Mellor <dale_mellor@users.sourceforge.net>
-
-	* main.scm (command-type): Files which are listed on the command
-	line are assumed to be guile configurations if they do not end in
-	.guile or .vixie (previously they were silently ignored).
-
-	* main.scm: Argument to --schedule is no longer optional (the
-	options system goes really screwy with optional values, usually
-	pulling the first non-option argument as a value if one was not
-	intended!)
-
-	* makefile.am: Moved target-specific CFLAGS and LDFLAGS to global
-	AM_* variables, to remove problem with automake requiring
-	AM_PROGS_CC_C_O in configure.ac (!)
-
-	* Version is currently at 1.0.3.
-
-
-2005-09-02  Dale Mellor <dale_mellor@users.sourceforge.net>
-
-	* makefile.am, mcron.c.template (main): Modified install-exec-hook
-	so that a proper installation of a Vixie-compatible cron only
-	takes place if we are root - otherwise only mcron is installed as
-	a user-owned program.  The guile modules are now installed under
-	mcron's shared data directory, not guile's global directories.
-
-	* mcron-core.scm: Removed job:advance-time, put the code inline
-	where it was called, and changed the instance in the main loop to
-	compute the new time based on the current-time, rather than the
-	previous job time (this makes things behave more reasonably when a
-	laptop awakes from suspend mode).
-
-	* Bumped version to 1.0.2.
-
-
-2004-05-15  Dale Mellor <dale_mellor@users.sourceforge.net>
-
-	* Modified all auxiliary files to reflect that the package is now
-	properly homed at www.gnu.org.
-
-	* Bumped version to 1.0.1.
-
-
-2003-12-11  Dale Mellor <dale_mellor@users.sourceforge.net>
-
-	* Modified all auxiliary files to reflect that we are now a GNU
-	package.
-
-	* Bumped version to 1.0.0.
-
-
-2003-12-07  Dale Mellor <dale_mellor@users.sourceforge.net>
-
-	* configure.ac: Added switches for files and directories used by
-	mcron: --spool-dir, --socket-file, --allow-file, --deny-file,
-	--pid-file and --tmp-dir. All the code has been modified to use
-	these configure options (including the source for the texinfo
-	manual).
-
-
-2003-12-05  Dale Mellor <dale_mellor@users.sourceforge.net>
-
-	* configure.ac: Added test for guile version >= 1.6.4.
-
-	* bumped version to 0.99.4.
-
-
-2003-08-03  Dale Mellor <dale_mellor@users.sourceforge.net>
-
-        * Third cut, fully functional, modular, production quality, still
-	needs testing...
-
-	* Pulled all functionality into modules, so it can be incorporated
-	into other programs.
-
-	* Bumped version to 0.99.3.
-
-
-2003-07-20  Dale Mellor <dale_mellor@users.sourceforge.net>
-
-        * Second cut, now _really_ fully functional (100% Vixie
-	compatible), production quality code, still needs lots of testing
-	doing...
-
-	* Converted from SIGUP-/var/cron/update to select-/var/cron/socket
-	method of communication between crontab and cron.
-
-	* Added implicit job which checks every minute for updates to
-	/etc/crontab.
-
-	* Removed --enable-vixie configuration option - the Vixie programs
-	are built and installed by default now.
-
-	* Bumped version to 0.99.2.
-
-
-2003-06-28  Dale Mellor <dale_mellor@users.sourceforge.net>
-
-	* First cut, fully functional, production quality code, just needs
-	testing...
-
-	* Broken/incomplete Guile prevents vixie compatibility from
-	working - this has been disabled by default in the configuration.
-
-	* Version set at 0.99.1
-
-
-
-
-
-
-________________________________________________________________________________
-Copyright (C) 2003, 2005, 2006, 2014  Dale Mellor
-
-Copying and distribution of this file, with or without modification,
-are permitted in any medium without royalty provided the copyright
-notice and this notice are preserved.
+If not, see the Git commit log at <http://git.sv.gnu.org/cgit/mcron.git/>.
diff --git a/ChangeLog.old b/ChangeLog.old
new file mode 100644
index 0000000..09c4147
--- /dev/null
+++ b/ChangeLog.old
@@ -0,0 +1,147 @@
+2014-05-25  Dale Mellor  <dale_mellor@users.sourceforge.net>
+
+	* Juggled build infrastructure so that we can make the minimal man
+	page in the proper autotools way.
+
+	* configure.ac: version to 1.0.8.
+
+2014-04-28  Dale Mellor  <dale_mellor@users.sourceforge.net>
+
+	* We now run against, and require, guile-2.0.
+
+	* configure.ac: version to 1.0.7.
+
+2012-02-04  Dale Mellor  <dale_mellor@users.sourceforge.net>
+
+	* main.scm: added search for initial files in
+	$XDG_CONFIG_HOME/cron directory, defaulting to ~/.config/cron if
+	the environment variable is not set) as well as in ~/.cron
+	directory (this is in line with the current FreeDesktop.org
+	standards).
+
+2010-06-13  Dale Mellor  <dale_mellor@users.sourceforge.net>
+
+	* configure.ac: added --enable-no-vixie-clobber argument to
+	configure so that the root user can avoid overwriting a legacy
+	cron installation.
+
+	* mcron.1: added simple, minimal man page using help2man (the
+	texinfo file is still the primary documentation source).
+
+	* makefile.am: replaced use of mkinstalldirs with install; the
+	former is not supplied with the latest automake (1.11).
+
+2008-02-21  Dale Mellor  <dale_mellor@users.sourceforge.net>
+
+	* ALL FILES: Replaced version 2 GPL notices with version 3 ones.
+
+	* makefile.am: Do not remove COPYING file with make
+	maintainer-clean; if you do it will eventually get replaced with
+	the old version 2 GPL by a subsequent automake.
+
+	* configure.ac: Bumped version to 1.0.4.
+
+2008-01-25  Dale Mellor  <dale_mellor@users.sourceforge.net>
+
+	* main.scm (command-type): Files which are listed on the command
+	line are assumed to be guile configurations if they do not end in
+	.guile or .vixie (previously they were silently ignored).
+
+	* main.scm: Argument to --schedule is no longer optional (the
+	options system goes really screwy with optional values, usually
+	pulling the first non-option argument as a value if one was not
+	intended!)
+
+	* makefile.am: Moved target-specific CFLAGS and LDFLAGS to global
+	AM_* variables, to remove problem with automake requiring
+	AM_PROGS_CC_C_O in configure.ac (!)
+
+	* Version is currently at 1.0.3.
+
+2005-09-02  Dale Mellor  <dale_mellor@users.sourceforge.net>
+
+	* makefile.am, mcron.c.template (main): Modified install-exec-hook
+	so that a proper installation of a Vixie-compatible cron only
+	takes place if we are root - otherwise only mcron is installed as
+	a user-owned program.  The guile modules are now installed under
+	mcron's shared data directory, not guile's global directories.
+
+	* mcron-core.scm: Removed job:advance-time, put the code inline
+	where it was called, and changed the instance in the main loop to
+	compute the new time based on the current-time, rather than the
+	previous job time (this makes things behave more reasonably when a
+	laptop awakes from suspend mode).
+
+	* Bumped version to 1.0.2.
+
+2004-05-15  Dale Mellor  <dale_mellor@users.sourceforge.net>
+
+	* Modified all auxiliary files to reflect that the package is now
+	properly homed at www.gnu.org.
+
+	* Bumped version to 1.0.1.
+
+2003-12-11  Dale Mellor  <dale_mellor@users.sourceforge.net>
+
+	* Modified all auxiliary files to reflect that we are now a GNU
+	package.
+
+	* Bumped version to 1.0.0.
+
+2003-12-07  Dale Mellor  <dale_mellor@users.sourceforge.net>
+
+	* configure.ac: Added switches for files and directories used by
+	mcron: --spool-dir, --socket-file, --allow-file, --deny-file,
+	--pid-file and --tmp-dir. All the code has been modified to use
+	these configure options (including the source for the texinfo
+	manual).
+
+2003-12-05  Dale Mellor  <dale_mellor@users.sourceforge.net>
+
+	* configure.ac: Added test for guile version >= 1.6.4.
+
+	* bumped version to 0.99.4.
+
+2003-08-03  Dale Mellor  <dale_mellor@users.sourceforge.net>
+
+        * Third cut, fully functional, modular, production quality, still
+	needs testing...
+
+	* Pulled all functionality into modules, so it can be incorporated
+	into other programs.
+
+	* Bumped version to 0.99.3.
+
+2003-07-20  Dale Mellor  <dale_mellor@users.sourceforge.net>
+
+        * Second cut, now _really_ fully functional (100% Vixie
+	compatible), production quality code, still needs lots of testing
+	doing...
+
+	* Converted from SIGUP-/var/cron/update to select-/var/cron/socket
+	method of communication between crontab and cron.
+
+	* Added implicit job which checks every minute for updates to
+	/etc/crontab.
+
+	* Removed --enable-vixie configuration option - the Vixie programs
+	are built and installed by default now.
+
+	* Bumped version to 0.99.2.
+
+2003-06-28  Dale Mellor  <dale_mellor@users.sourceforge.net>
+
+	* First cut, fully functional, production quality code, just needs
+	testing...
+
+	* Broken/incomplete Guile prevents vixie compatibility from
+	working - this has been disabled by default in the configuration.
+
+	* Version set at 0.99.1
+
+________________________________________________________________________________
+Copyright (C) 2003, 2005, 2006, 2014, 2015  Dale Mellor
+
+Copying and distribution of this file, with or without modification,
+are permitted in any medium without royalty provided the copyright
+notice and this notice are preserved.
diff --git a/build-aux/gitlog-to-changelog b/build-aux/gitlog-to-changelog
new file mode 100755
index 0000000..8f38318
--- /dev/null
+++ b/build-aux/gitlog-to-changelog
@@ -0,0 +1,492 @@
+eval '(exit $?0)' && eval 'exec perl -wS "$0" ${1+"$@"}'
+  & eval 'exec perl -wS "$0" $argv:q'
+    if 0;
+# Convert git log output to ChangeLog format.
+
+my $VERSION = '2015-07-21 22:45'; # UTC
+# The definition above must lie within the first 8 lines in order
+# for the Emacs time-stamp write hook (at end) to update it.
+# If you change this file with Emacs, please let the write hook
+# do its job.  Otherwise, update this string manually.
+
+# Copyright (C) 2008-2015 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 3 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, see <http://www.gnu.org/licenses/>.
+
+# Written by Jim Meyering
+
+use strict;
+use warnings;
+use Getopt::Long;
+use POSIX qw(strftime);
+
+(my $ME = $0) =~ s|.*/||;
+
+# use File::Coda; # http://meyering.net/code/Coda/
+END {
+  defined fileno STDOUT or return;
+  close STDOUT and return;
+  warn "$ME: failed to close standard output: $!\n";
+  $? ||= 1;
+}
+
+sub usage ($)
+{
+  my ($exit_code) = @_;
+  my $STREAM = ($exit_code == 0 ? *STDOUT : *STDERR);
+  if ($exit_code != 0)
+    {
+      print $STREAM "Try '$ME --help' for more information.\n";
+    }
+  else
+    {
+      print $STREAM <<EOF;
+Usage: $ME [OPTIONS] [ARGS]
+
+Convert git log output to ChangeLog format.  If present, any ARGS
+are passed to "git log".  To avoid ARGS being parsed as options to
+$ME, they may be preceded by '--'.
+
+OPTIONS:
+
+   --amend=FILE FILE maps from an SHA1 to perl code (i.e., s/old/new/) that
+                  makes a change to SHA1's commit log text or metadata.
+   --append-dot append a dot to the first line of each commit message if
+                  there is no other punctuation or blank at the end.
+   --no-cluster never cluster commit messages under the same date/author
+                  header; the default is to cluster adjacent commit messages
+                  if their headers are the same and neither commit message
+                  contains multiple paragraphs.
+   --srcdir=DIR the root of the source tree, from which the .git/
+                  directory can be derived.
+   --since=DATE convert only the logs since DATE;
+                  the default is to convert all log entries.
+   --until=DATE convert only the logs older than DATE.
+   --ignore-matching=PAT ignore commit messages whose first lines match PAT.
+   --ignore-line=PAT ignore lines of commit messages that match PAT.
+   --format=FMT set format string for commit subject and body;
+                  see 'man git-log' for the list of format metacharacters;
+                  the default is '%s%n%b%n'
+   --strip-tab  remove one additional leading TAB from commit message lines.
+   --strip-cherry-pick  remove data inserted by "git cherry-pick";
+                  this includes the "cherry picked from commit ..." line,
+                  and the possible final "Conflicts:" paragraph.
+   --help       display this help and exit
+   --version    output version information and exit
+
+EXAMPLE:
+
+  $ME --since=2008-01-01 > ChangeLog
+  $ME -- -n 5 foo > last-5-commits-to-branch-foo
+
+SPECIAL SYNTAX:
+
+The following types of strings are interpreted specially when they appear
+at the beginning of a log message line.  They are not copied to the output.
+
+  Copyright-paperwork-exempt: Yes
+    Append the "(tiny change)" notation to the usual "date name email"
+    ChangeLog header to mark a change that does not require a copyright
+    assignment.
+  Co-authored-by: Joe User <user\@example.com>
+    List the specified name and email address on a second
+    ChangeLog header, denoting a co-author.
+  Signed-off-by: Joe User <user\@example.com>
+    These lines are simply elided.
+
+In a FILE specified via --amend, comment lines (starting with "#") are ignored.
+FILE must consist of <SHA,CODE+> pairs where SHA is a 40-byte SHA1 (alone on
+a line) referring to a commit in the current project, and CODE refers to one
+or more consecutive lines of Perl code.  Pairs must be separated by one or
+more blank line.
+
+Here is sample input for use with --amend=FILE, from coreutils:
+
+3a169f4c5d9159283548178668d2fae6fced3030
+# fix typo in title:
+s/all tile types/all file types/
+
+1379ed974f1fa39b12e2ffab18b3f7a607082202
+# Due to a bug in vc-dwim, I mis-attributed a patch by Paul to myself.
+# Change the author to be Paul.  Note the escaped "@":
+s,Jim .*>,Paul Eggert <eggert\\\@cs.ucla.edu>,
+
+EOF
+    }
+  exit $exit_code;
+}
+
+# If the string $S is a well-behaved file name, simply return it.
+# If it contains white space, quotes, etc., quote it, and return the new string.
+sub shell_quote($)
+{
+  my ($s) = @_;
+  if ($s =~ m![^\w+/.,-]!)
+    {
+      # Convert each single quote to '\''
+      $s =~ s/\'/\'\\\'\'/g;
+      # Then single quote the string.
+      $s = "'$s'";
+    }
+  return $s;
+}
+
+sub quoted_cmd(@)
+{
+  return join (' ', map {shell_quote $_} @_);
+}
+
+# Parse file F.
+# Comment lines (starting with "#") are ignored.
+# F must consist of <SHA,CODE+> pairs where SHA is a 40-byte SHA1
+# (alone on a line) referring to a commit in the current project, and
+# CODE refers to one or more consecutive lines of Perl code.
+# Pairs must be separated by one or more blank line.
+sub parse_amend_file($)
+{
+  my ($f) = @_;
+
+  open F, '<', $f
+    or die "$ME: $f: failed to open for reading: $!\n";
+
+  my $fail;
+  my $h = {};
+  my $in_code = 0;
+  my $sha;
+  while (defined (my $line = <F>))
+    {
+      $line =~ /^\#/
+        and next;
+      chomp $line;
+      $line eq ''
+        and $in_code = 0, next;
+
+      if (!$in_code)
+        {
+          $line =~ /^([0-9a-fA-F]{40})$/
+            or (warn "$ME: $f:$.: invalid line; expected an SHA1\n"),
+              $fail = 1, next;
+          $sha = lc $1;
+          $in_code = 1;
+          exists $h->{$sha}
+            and (warn "$ME: $f:$.: duplicate SHA1\n"),
+              $fail = 1, next;
+        }
+      else
+        {
+          $h->{$sha} ||= '';
+          $h->{$sha} .= "$line\n";
+        }
+    }
+  close F;
+
+  $fail
+    and exit 1;
+
+  return $h;
+}
+
+# git_dir_option $SRCDIR
+#
+# From $SRCDIR, the --git-dir option to pass to git (none if $SRCDIR
+# is undef).  Return as a list (0 or 1 element).
+sub git_dir_option($)
+{
+  my ($srcdir) = @_;
+  my @res = ();
+  if (defined $srcdir)
+    {
+      my $qdir = shell_quote $srcdir;
+      my $cmd = "cd $qdir && git rev-parse --show-toplevel";
+      my $qcmd = shell_quote $cmd;
+      my $git_dir = qx($cmd);
+      defined $git_dir
+        or die "$ME: cannot run $qcmd: $!\n";
+      $? == 0
+        or die "$ME: $qcmd had unexpected exit code or signal ($?)\n";
+      chomp $git_dir;
+      push @res, "--git-dir=$git_dir/.git";
+    }
+  @res;
+}
+
+{
+  my $since_date;
+  my $until_date;
+  my $format_string = '%s%n%b%n';
+  my $amend_file;
+  my $append_dot = 0;
+  my $cluster = 1;
+  my $ignore_matching;
+  my $ignore_line;
+  my $strip_tab = 0;
+  my $strip_cherry_pick = 0;
+  my $srcdir;
+  GetOptions
+    (
+     help => sub { usage 0 },
+     version => sub { print "$ME version $VERSION\n"; exit },
+     'since=s' => \$since_date,
+     'until=s' => \$until_date,
+     'format=s' => \$format_string,
+     'amend=s' => \$amend_file,
+     'append-dot' => \$append_dot,
+     'cluster!' => \$cluster,
+     'ignore-matching=s' => \$ignore_matching,
+     'ignore-line=s' => \$ignore_line,
+     'strip-tab' => \$strip_tab,
+     'strip-cherry-pick' => \$strip_cherry_pick,
+     'srcdir=s' => \$srcdir,
+    ) or usage 1;
+
+  defined $since_date
+    and unshift @ARGV, "--since=$since_date";
+  defined $until_date
+    and unshift @ARGV, "--until=$until_date";
+
+  # This is a hash that maps an SHA1 to perl code (i.e., s/old/new/)
+  # that makes a correction in the log or attribution of that commit.
+  my $amend_code = defined $amend_file ? parse_amend_file $amend_file : {};
+
+  my @cmd = ('git',
+             git_dir_option $srcdir,
+             qw(log --log-size),
+             '--pretty=format:%H:%ct  %an  <%ae>%n%n'.$format_string, @ARGV);
+  open PIPE, '-|', @cmd
+    or die ("$ME: failed to run '". quoted_cmd (@cmd) ."': $!\n"
+            . "(Is your Git too old?  Version 1.5.1 or later is required.)\n");
+
+  my $prev_multi_paragraph;
+  my $prev_date_line = '';
+  my @prev_coauthors = ();
+  my @skipshas = ();
+  while (1)
+    {
+      defined (my $in = <PIPE>)
+        or last;
+      $in =~ /^log size (\d+)$/
+        or die "$ME:$.: Invalid line (expected log size):\n$in";
+      my $log_nbytes = $1;
+
+      my $log;
+      my $n_read = read PIPE, $log, $log_nbytes;
+      $n_read == $log_nbytes
+        or die "$ME:$.: unexpected EOF\n";
+
+      # Extract leading hash.
+      my ($sha, $rest) = split ':', $log, 2;
+      defined $sha
+        or die "$ME:$.: malformed log entry\n";
+      $sha =~ /^[0-9a-fA-F]{40}$/
+        or die "$ME:$.: invalid SHA1: $sha\n";
+
+      my $skipflag = 0;
+      if (@skipshas)
+        {
+          foreach(@skipshas)
+            {
+              if ($sha =~ /^$_/)
+                {
+                  $skipflag = 1;
+                  ## Perhaps only warn if a pattern matches more than once?
+                  warn "$ME: warning: skipping $sha due to $_\n";
+                  last;
+                }
+            }
+        }
+
+      # If this commit's log requires any transformation, do it now.
+      my $code = $amend_code->{$sha};
+      if (defined $code)
+        {
+          eval 'use Safe';
+          my $s = new Safe;
+          # Put the unpreprocessed entry into "$_".
+          $_ = $rest;
+
+          # Let $code operate on it, safely.
+          my $r = $s->reval("$code")
+            or die "$ME:$.:$sha: failed to eval \"$code\":\n$@\n";
+
+          # Note that we've used this entry.
+          delete $amend_code->{$sha};
+
+          # Update $rest upon success.
+          $rest = $_;
+        }
+
+      # Remove lines inserted by "git cherry-pick".
+      if ($strip_cherry_pick)
+        {
+          $rest =~ s/^\s*Conflicts:\n.*//sm;
+          $rest =~ s/^\s*\(cherry picked from commit [\da-f]+\)\n//m;
+        }
+
+      my @line = split /\s*\n/, $rest;
+      my $author_line = shift @line;
+      defined $author_line
+        or die "$ME:$.: unexpected EOF\n";
+      $author_line =~ /^(\d+)  (.*>)$/
+        or die "$ME:$.: Invalid line "
+          . "(expected date/author/email):\n$author_line\n";
+
+      # Format 'Copyright-paperwork-exempt: Yes' as a standard ChangeLog
+      # `(tiny change)' annotation.
+      my $tiny = (grep (/^(?:Copyright-paperwork-exempt|Tiny-change):\s+[Yy]es$/, @line)
+                  ? '  (tiny change)' : '');
+
+      my $date_line = sprintf "%s  %s$tiny\n",
+        strftime ("%Y-%m-%d", localtime ($1)), $2;
+
+      my @coauthors = grep /^Co-authored-by:.*$/, @line;
+      # Omit meta-data lines we've already interpreted.
+      @line = grep !/^(?:Signed-off-by:[ ].*>$
+                       |Co-authored-by:[ ]
+                       |Copyright-paperwork-exempt:[ ]
+                       |Tiny-change:[ ]
+                       )/x, @line;
+
+      # Remove leading and trailing blank lines.
+      if (@line)
+        {
+          while ($line[0] =~ /^\s*$/) { shift @line; }
+          while ($line[$#line] =~ /^\s*$/) { pop @line; }
+        }
+
+      # Handle Emacs gitmerge.el "skipped" commits.
+      # Yes, this should be controlled by an option.  So sue me.
+      if ( grep /^(; )?Merge from /, @line )
+      {
+          my $found = 0;
+          foreach (@line)
+          {
+              if (grep /^The following commit.*skipped:$/, $_)
+              {
+                  $found = 1;
+                  ## Reset at each merge to reduce chance of false matches.
+                  @skipshas = ();
+                  next;
+              }
+              if ($found && $_ =~ /^([0-9a-fA-F]{7,}) [^ ]/)
+              {
+                  push ( @skipshas, $1 );
+              }
+          }
+      }
+
+      # Ignore commits that match the --ignore-matching pattern, if specified.
+      if (! ($skipflag || (defined $ignore_matching
+             && @line && $line[0] =~ /$ignore_matching/)))
+        {
+          if (defined $ignore_line && @line)
+            {
+              @line = grep ! /$ignore_line/, @line;
+              while ($line[$#line] =~ /^\s*$/) { pop @line; }
+            }
+
+          # Record whether there are two or more paragraphs.
+          my $multi_paragraph = grep /^\s*$/, @line;
+
+          # Format 'Co-authored-by: A U Thor <email@example.com>' lines in
+          # standard multi-author ChangeLog format.
+          for (@coauthors)
+            {
+              s/^Co-authored-by:\s*/\t    /;
+              s/\s*</  </;
+
+              /<.*?@.*\..*>/
+                or warn "$ME: warning: missing email address for "
+                  . substr ($_, 5) . "\n";
+            }
+
+          # If clustering of commit messages has been disabled, if this header
+          # would be different from the previous date/name/etc. header,
+          # or if this or the previous entry consists of two or more paragraphs,
+          # then print the header.
+          if ( ! $cluster
+              || $date_line ne $prev_date_line
+              || "@coauthors" ne "@prev_coauthors"
+              || $multi_paragraph
+              || $prev_multi_paragraph)
+            {
+              $prev_date_line eq ''
+                or print "\n";
+              print $date_line;
+              @coauthors
+                and print join ("\n", @coauthors), "\n";
+            }
+          $prev_date_line = $date_line;
+          @prev_coauthors = @coauthors;
+          $prev_multi_paragraph = $multi_paragraph;
+
+          # If there were any lines
+          if (@line == 0)
+            {
+              warn "$ME: warning: empty commit message:\n  $date_line\n";
+            }
+          else
+            {
+              if ($append_dot)
+                {
+                  # If the first line of the message has enough room, then
+                  if (length $line[0] < 72)
+                    {
+                      # append a dot if there is no other punctuation or blank
+                      # at the end.
+                      $line[0] =~ /[[:punct:]\s]$/
+                        or $line[0] .= '.';
+                    }
+                }
+
+              # Remove one additional leading TAB from each line.
+              $strip_tab
+                and map { s/^\t// } @line;
+
+              # Prefix each non-empty line with a TAB.
+              @line = map { length $_ ? "\t$_" : '' } @line;
+
+              print "\n", join ("\n", @line), "\n";
+            }
+        }
+
+      defined ($in = <PIPE>)
+        or last;
+      $in ne "\n"
+        and die "$ME:$.: unexpected line:\n$in";
+    }
+
+  close PIPE
+    or die "$ME: error closing pipe from " . quoted_cmd (@cmd) . "\n";
+  # FIXME-someday: include $PROCESS_STATUS in the diagnostic
+
+  # Complain about any unused entry in the --amend=F specified file.
+  my $fail = 0;
+  foreach my $sha (keys %$amend_code)
+    {
+      warn "$ME:$amend_file: unused entry: $sha\n";
+      $fail = 1;
+    }
+
+  exit $fail;
+}
+
+# Local Variables:
+# mode: perl
+# indent-tabs-mode: nil
+# eval: (add-hook 'write-file-hooks 'time-stamp)
+# time-stamp-start: "my $VERSION = '"
+# time-stamp-format: "%:y-%02m-%02d %02H:%02M"
+# time-stamp-time-zone: "UTC"
+# time-stamp-end: "'; # UTC"
+# End:
diff --git a/makefile.am b/makefile.am
index da26a89..61fbe56 100644
--- a/makefile.am
+++ b/makefile.am
@@ -26,7 +26,7 @@ CP = @CP@
 
 CLEANFILES = mcron.c
 
-EXTRA_DIST = makefile.ed mcron.c.template BUGS
+EXTRA_DIST = makefile.ed mcron.c.template BUGS ChangeLog.old
 
 info_TEXINFOS = doc/mcron.texi
 doc_mcron_TEXINFOS = doc/fdl.texi
@@ -46,6 +46,21 @@ mcron.c : scm/mcron/main.scm scm/mcron/crontab.scm makefile.ed mcron.c.template
 	@$(ED) < makefile.ed > /dev/null 2>&1
 	@rm -f mcron.escaped.scm > /dev/null 2>&1
 
+dist-hook: gen-ChangeLog
+
+gen_start_date = 2015-06-26
+.PHONY: gen-ChangeLog
+gen-ChangeLog:
+	$(AM_V_GEN)if test -d $(srcdir)/.git; then			\
+	  log_fix="$(srcdir)/build-aux/git-log-fix";			\
+	  test -e "$$log_fix"						\
+	    && amend_git_log="--amend=$$log_fix"			\
+	    || amend_git_log=;						\
+	  $(top_srcdir)/build-aux/gitlog-to-changelog			\
+	    $$amend_git_log --since=$(gen_start_date) > $(distdir)/cl-t && \
+	    { rm -f $(distdir)/ChangeLog &&				\
+	      mv $(distdir)/cl-t $(distdir)/ChangeLog; }		\
+	fi
 
 #full program prefix
 fpp = $(DESTDIR)$(bindir)/@real_program_prefix@