Generate ChangeLog automatically from git log.

.gitignore

@@ -9,6 +9,7 @@
 .gdbinit
 .libs
 ABOUT-NLS
+ChangeLog
 INSTALL
 Makefile
 Makefile.in

Makefile.am

@@ -35,3 +35,21 @@ SUBDIRS = \
  pam_sql\
  $(LDAPHOME_DIR)\
  pamck
+
+EXTRA_DIST=ChangeLog.svn
+#  Name of the previous ChangeLog file.
+prev_change_log = ChangeLog.svn
+#  Start Git ChangeLog from this date. 
+gen_start_date = 2012-05-13
+
+.PHONY: ChangeLog
+ChangeLog:
+	$(AM_V_GEN)if test -d .git; then                                     \
+          git log --pretty='format:%ct  %an  <%ae>%n%n%s%n%n%b%n' |          \
+	    awk -f $(top_srcdir)/git2chg.awk                                 \
+              -vsince="$(gen_start_date)" -vappend="$(prev_change_log)"      \
+              > ChangeLog.tmp;                                               \
+          cmp ChangeLog ChangeLog.tmp > /dev/null 2>&1 ||                    \
+            mv ChangeLog.tmp ChangeLog;                                      \
+          rm -f ChangeLog.tmp;                                               \
+	fi

git2chg.awk

@@ -0,0 +1,76 @@
+# This file is part of grecs
+# Copyright (C) 2007, 2009-2012 Sergey Poznyakoff
+#
+# Grecs 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, or (at your option)
+# any later version.
+#
+# Grecs 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 Grecs.  If not, see <http://www.gnu.org/licenses/>.
+
+BEGIN {
+  if (since)
+    split(since,since_a,"-")
+}
+
+function timeok(t,   a) {
+	if (!since)
+		return 1
+	split(t,a,"-")
+	if (a[1] < since_a[1])
+		return 0
+	if (a[1] >= since_a[1])
+		return 1
+	if (a[2] < since_a[2])
+		return 0
+	if (a[2] >= since_a[2])
+		return 1
+	return a[3] >= since_a[3]
+}
+      
+/^[0-9]+ .* +<[^>]+>/ {
+	s = strftime("%F", $1)
+	if (!timeok(s))
+	  exit
+	sub(/^[0-9]+ +/,"")
+	if (s == datestr && author == $0)
+		next
+	datestr = s
+	author = $0
+	if (runlen) { runlen = 0; print "" }
+	printf("%s  %s\n", datestr, author)
+	next
+}
+/^Signed-off-by:/ { next }
+/^git-svn-id:/ { next }
+/^<unknown>$/ { next }
+NF==0 {
+	runlen++
+	next
+}
+{ if (runlen) { runlen = 0; print "" }
+  print "\t" $0 }
+
+END {
+	if (append) {
+		print ""
+		while ((getline < append) > 0) {
+			if (match($0, /^Local *Variables:/))
+				break
+			print
+		}
+	}
+	print "\f"
+	# Make sure Emacs won't recognize this line:
+	print "Local", "Variables:"
+	print "mode: change-log"
+	print "version-control: never"
+	print "buffer-read-only: t"
+	print "End:"
+}