Include commit hash in version output

Extracting the abbreviated commit hash will break when git will be
replaced by a different version control system.  But until it does,
get the hash from the git repository.

3 files changed, 36 insertions, 3 deletions

diff --git a/Makefile b/Makefile
index ca0ee68..d061794 100644
--- a/Makefile
+++ b/Makefile
@@ -8,10 +8,11 @@ CC=gcc
 CFLAGS=-ansi -pedantic
 
 colorize:	colorize.c
-			$(CC) $(CFLAGS) -o colorize colorize.c -DCFLAGS="$(CFLAGS)"
+			perl ./version.pl > version.h
+			$(CC) $(CFLAGS) -o colorize colorize.c -DCFLAGS="$(CFLAGS)" -DHAVE_VERSION
 
 check:
 			perl ./test.pl
 
 clean:
-			[ -e colorize ] && rm colorize; exit 0
+			rm -f colorize version.h
diff --git a/colorize.c b/colorize.c
index 54f6889..ea18425 100644
--- a/colorize.c
+++ b/colorize.c
@@ -403,6 +403,11 @@ print_help (void)
 static void
 print_version (void)
 {
+#ifdef HAVE_VERSION
+# include "version.h"
+#else
+    const char *version = NULL;
+#endif
     const char *c_flags;
     struct bytes_size bytes_size;
     bool debug;
@@ -416,7 +421,10 @@ print_version (void)
 #else
     debug = false;
 #endif
-    printf ("%s v%s (compiled at %s, %s)\n", "colorize", VERSION, __DATE__, __TIME__);
+    if (version)
+      printf ("colorize %s (compiled at %s, %s)\n", version, __DATE__, __TIME__);
+    else
+      printf ("colorize v%s (compiled at %s, %s)\n", VERSION, __DATE__, __TIME__);
     printf ("Compiler flags: %s\n", c_flags);
     if (get_bytes_size (BUF_SIZE, &bytes_size))
       {
diff --git a/version.pl b/version.pl
new file mode 100755
index 0000000..850902e
--- /dev/null
+++ b/version.pl
@@ -0,0 +1,24 @@
+#!/usr/bin/perl
+
+use strict;
+use warnings;
+
+my $version = '';
+
+# git repository
+if (system('which git >/dev/null 2>&1') == 0
+and system('git ls-files colorize.c --error-unmatch >/dev/null 2>&1') == 0) {
+    $version = `git describe --tags --dirty`;
+    $version =~ s/\n$//g;
+}
+
+if (length $version) {
+    print <<"EOT";
+const char *version = "$version";
+EOT
+}
+else {
+    print <<'EOT';
+const char *version = NULL;
+EOT
+}