build: include git info

If enabled with --with-pkg-gitversion on ./configure, this will append
git version strings and branch information at the following places:
 - overall version number: 0.99.21-g0123456
 - login motd and show version: tag information + git id + branches

Sample output:
  Hello, this is Quagga (version 0.99.21-g14b49ad-dirty).
  Copyright 1996-2005 Kunihiro Ishiguro, et al.

  This is a git build of quagga_0_99_21_release-106-g14b49ad-dirty
  Associated branch(es):
	local:master

[v2]: fix build without gitinfo (add "else" branch)
[v2]: fix for repos without any tags (different git describe output)
Signed-off-by: David Lamparter <equinox@opensourcerouting.org>

5 files changed, 86 insertions, 4 deletions

diff --git a/lib/.gitignore b/lib/.gitignore
index 00af85a6..02aa432c 100644
--- a/lib/.gitignore
+++ b/lib/.gitignore
@@ -5,6 +5,8 @@ Makefile.in
 *.la
 version.c
 version.h
+gitversion.h
+gitversion.h.tmp
 .deps
 .nfs*
 .libs
diff --git a/lib/Makefile.am b/lib/Makefile.am
index e00ad54d..690c18ff 100644
--- a/lib/Makefile.am
+++ b/lib/Makefile.am
@@ -14,7 +14,7 @@ libzebra_la_SOURCES = \
 	zclient.c sockopt.c smux.c agentx.c snmp.c md5.c if_rmap.c keychain.c privs.c \
 	sigevent.c pqueue.c jhash.c memtypes.c workqueue.c
 
-BUILT_SOURCES = memtypes.h route_types.h
+BUILT_SOURCES = memtypes.h route_types.h gitversion.h
 
 libzebra_la_DEPENDENCIES = @LIB_REGEX@
 
@@ -36,3 +36,25 @@ memtypes.h: $(srcdir)/memtypes.c $(srcdir)/memtypes.awk
 
 route_types.h: $(srcdir)/route_types.txt $(srcdir)/route_types.pl
 	@PERL@ $(srcdir)/route_types.pl < $(srcdir)/route_types.txt > $@
+
+if GIT_VERSION
+
+# bit of a trick here to always have up-to-date git stamps without triggering
+# unneccessary rebuilds.  .PHONY causes the .tmp file to be rebuilt always,
+# but if we use that on gitversion.h it'll ripple through the .c file deps.
+# (even if gitversion.h's file timestamp doesn't change, make will think it
+# did, because of .PHONY...)
+
+.PHONY: gitversion.h.tmp
+.SILENT: gitversion.h gitversion.h.tmp
+GITH=gitversion.h
+gitversion.h.tmp: $(srcdir)/../.git
+	@PERL@ $(srcdir)/gitversion.pl $(srcdir) > ${GITH}.tmp
+gitversion.h: gitversion.h.tmp
+	{ test -f ${GITH} && diff -s -q ${GITH}.tmp ${GITH}; } || cp -v ${GITH}.tmp ${GITH}
+
+else
+.PHONY: gitversion.h
+gitversion.h:
+	/bin/true
+endif
diff --git a/lib/command.c b/lib/command.c
index 64563b5d..3b3fadac 100644
--- a/lib/command.c
+++ b/lib/command.c
@@ -84,7 +84,7 @@ static const char *default_motd =
 "\r\n\
 Hello, this is " QUAGGA_PROGNAME " (version " QUAGGA_VERSION ").\r\n\
 " QUAGGA_COPYRIGHT "\r\n\
-\r\n";
+" GIT_INFO "\r\n";
 
 
 static const struct facility_map {
@@ -2409,7 +2409,7 @@ DEFUN (show_version,
 {
   vty_out (vty, "Quagga %s (%s).%s", QUAGGA_VERSION, host.name?host.name:"",
 	   VTY_NEWLINE);
-  vty_out (vty, "%s%s", QUAGGA_COPYRIGHT, VTY_NEWLINE);
+  vty_out (vty, "%s%s%s", QUAGGA_COPYRIGHT, GIT_INFO, VTY_NEWLINE);
 
   return CMD_SUCCESS;
 }
diff --git a/lib/gitversion.pl b/lib/gitversion.pl
new file mode 100644
index 00000000..448f13d6
--- /dev/null
+++ b/lib/gitversion.pl
@@ -0,0 +1,47 @@
+#!/usr/bin/perl -w
+use strict;
+
+my $dir = shift;
+chdir $dir || die "$dir: $!\n";
+
+my $gitdesc = `git describe --always --dirty || echo -- \"0-gUNKNOWN\"`;
+chomp $gitdesc;
+my $gitsuffix = ($gitdesc =~ /([0-9a-fA-F]{7}(-dirty)?)$/) ? $1 : "-gUNKNOWN";
+
+printf STDERR "git suffix: %s\n", $gitsuffix;
+printf "#define GIT_SUFFIX \"%s\"\n", $gitsuffix;
+
+my $gitcommit = `git log -1 --format=\"%H\" || echo DEADBEEF`;
+chomp $gitcommit;
+open(BRANCHES, "git branch -a -v --abbrev=40|") || die "git branch: $!\n";
+my @names = ();
+while (<BRANCHES>) {
+	chomp $_;
+	if (/\s+(.*?)\s+$gitcommit/) {
+		my $branch = $1;
+		if ($branch =~ /^remotes\/(.*?)(\/.*)$/) {
+			my $path = $2;
+			my $url = `git config --get "remote.$1.url"`;
+			chomp $url;
+			$url =~ s/^(git:|https?:|git@)\/\/github\.com/github/i;
+			$url =~ s/^(ssh|git):\/\/git\.sv\.gnu\.org\/srv\/git\//savannah:/i;
+			$url =~ s/^(ssh|git):\/\/git\.savannah\.nongnu\.org\//savannah:/i;
+
+			push @names, $url.$path;
+		} else {
+			push @names, 'local:'.$branch;
+		}
+	}
+}
+
+printf STDERR "git branches: %s\n", join(", ", @names);
+
+my $cr = "\\r\\n\\";
+printf <<EOF, $gitdesc, join($cr."\n\\t", @names);
+#define GIT_INFO "$cr
+This is a git build of %s$cr
+Associated branch(es):$cr
+\\t%s$cr
+"
+EOF
+
diff --git a/lib/version.h.in b/lib/version.h.in
index 429474d1..7e9985f0 100644
--- a/lib/version.h.in
+++ b/lib/version.h.in
@@ -24,9 +24,20 @@
 #ifndef _ZEBRA_VERSION_H
 #define _ZEBRA_VERSION_H
 
+#ifdef GIT_VERSION
+#include "gitversion.h"
+#endif
+
+#ifndef GIT_SUFFIX
+#define GIT_SUFFIX ""
+#endif
+#ifndef GIT_INFO
+#define GIT_INFO ""
+#endif
+
 #define QUAGGA_PROGNAME   "@PACKAGE_NAME@"
 
-#define QUAGGA_VERSION     "@PACKAGE_VERSION@"
+#define QUAGGA_VERSION     "@PACKAGE_VERSION@" GIT_SUFFIX
 
 #define ZEBRA_BUG_ADDRESS "@PACKAGE_BUGREPORT@"