maint: require that commit messages be of a certain form

* bootstrap.conf (bootstrap_epilogue): Merge from coreutils, so that
a local commit hook will now help enforce consistent commit messages.
* Makefile.am (check-git-hook-script-sync): New rule, largely copied
from coreutils.
* scripts/git-hooks/commit-msg: New file, from coreutils, but
with adapted list of program names.
* scripts/git-hooks/applypatch-msg: New file, from git.
* scripts/git-hooks/pre-applypatch: Likewise.
* scripts/git-hooks/pre-commit: Likewise.

1 files changed, 153 insertions, 0 deletions

diff --git a/scripts/git-hooks/commit-msg b/scripts/git-hooks/commit-msg
new file mode 100755
index 0000000..888b83b
--- /dev/null
+++ b/scripts/git-hooks/commit-msg
@@ -0,0 +1,153 @@
+eval '(exit $?0)' && eval 'exec perl -w "$0" ${1+"$@"}'
+  & eval 'exec perl -w "$0" $argv:q'
+    if 0;
+
+use strict;
+use warnings;
+(my $ME = $0) =~ s|.*/||;
+
+# Emulate Git's choice of the editor for the commit message.
+chomp (my $editor = `git var GIT_EDITOR`);
+# And have a sane, minimal fallback in case of weird failures.
+$editor = "vi" if $? != 0 or $editor =~ /^\s*\z/;
+
+# Keywords allowed before the colon on the first line of a commit message:
+# program names and a few general category names.
+my @valid = qw(
+    diff diff3 cmp sdiff
+
+    gnulib tests maint doc build scripts
+    );
+my $v_or = join '|', @valid;
+my $valid_regex = qr/^(?:$v_or)$/;
+
+# Rewrite the $LOG_FILE (old contents in @$LINE_REF) with an additional
+# a commented diagnostic "# $ERR" line at the top.
+sub rewrite($$$)
+{
+  my ($log_file, $err, $line_ref) = @_;
+  local *LOG;
+  open LOG, '>', $log_file
+    or die "$ME: $log_file: failed to open for writing: $!";
+  print LOG "# $err";
+  print LOG @$line_ref;
+  close LOG
+    or die "$ME: $log_file: failed to rewrite: $!\n";
+}
+
+sub re_edit($)
+{
+  my ($log_file) = @_;
+
+  warn "Interrupt (Ctrl-C) to abort...\n";
+
+  system 'sh', '-c', "$editor $log_file";
+  ($? & 127) || ($? >> 8)
+    and die "$ME: $log_file: the editor ($editor) failed, aborting\n";
+}
+
+sub bad_first_line($)
+{
+  my ($line) = @_;
+
+  $line =~ /^[Vv]ersion \d/
+    and return '';
+
+  $line =~ /:/
+    or return 'missing colon on first line of log message';
+
+  $line =~ /\.$/
+    and return 'do not use a period "." at the end of the first line';
+
+  # The token(s) before the colon on the first line must be on our list
+  # Tokens may be space- or comma-separated.
+  (my $pre_colon = $line) =~ s/:.*//;
+  my @word = split (/[ ,]/, $pre_colon);
+  my @bad = grep !/$valid_regex/, @word;
+  @bad
+    and return 'invalid first word(s) of summary line: ' . join (', ', @bad);
+
+  return '';
+}
+
+# Given a $LOG_FILE name and a \@LINE buffer,
+# read the contents of the file into the buffer and analyze it.
+# If the log message passes muster, return the empty string.
+# If not, return a diagnostic.
+sub check_msg($$)
+{
+  my ($log_file, $line_ref) = @_;
+
+  local *LOG;
+  open LOG, '<', $log_file
+    or return "failed to open for reading: $!";
+  @$line_ref = <LOG>;
+  close LOG;
+
+  my @line = @$line_ref;
+  chomp @line;
+
+  # Don't filter out blank or comment lines; git does that already,
+  # and if we were to ignore them here, it could lead to committing
+  # with lines that start with "#" in the log.
+
+  # Filter out leading blank and comment lines.
+  # while (@line && $line[0] =~ /^(?:#.*|[ \t]*)$/) { shift @line; }
+
+  # Filter out blank and comment lines at EOF.
+  # while (@line && $line[$#line] =~ /^(?:#.*|[ \t]*)$/) { pop @line; }
+
+  @line == 0
+    and return 'no log message';
+
+  my $bad = bad_first_line $line[0];
+  $bad
+    and return $bad;
+
+  # Second line should be blank or not present.
+  2 <= @line && length $line[1]
+    and return 'second line must be empty';
+
+  # Limit line length to allow for the ChangeLog's leading TAB.
+  foreach my $line (@line)
+    {
+      72 < length $line && $line =~ /^[^#]/
+        and return 'line longer than 72';
+    }
+
+  my $buf = join ("\n", @line) . "\n";
+  $buf =~ m!https?://bugzilla\.redhat\.com/show_bug\.cgi\?id=(\d+)!s
+    and return "use shorter http://bugzilla.redhat.com/$1";
+
+  $buf =~ m!https?://debbugs\.gnu\.org/(?:cgi/bugreport\.cgi\?bug=)?(\d+)!s
+    and return "use shorter http://bugs.gnu.org/$1";
+
+  $buf =~ /^ *Signed-off-by:/mi
+    and return q(do not use "Signed-off-by:");
+
+  return '';
+}
+
+{
+  @ARGV == 1
+    or die;
+
+  my $log_file = $ARGV[0];
+
+  while (1)
+    {
+      my @line;
+      my $err = check_msg $log_file, \@line;
+      $err eq ''
+        and last;
+      $err = "$ME: $err\n";
+      warn $err;
+      # Insert the diagnostic as a comment on the first line of $log_file.
+      rewrite $log_file, $err, \@line;
+      re_edit $log_file;
+
+      # Stop if our parent is killed.
+      getppid() == 1
+        and last;
+    }
+}