build: use git version if available.

Borrowed from Arch Linux pacman:

https://projects.archlinux.org/pacman.git/tree/

Makefile.am

@@ -26,6 +26,11 @@ endif
 
 sgminer_CPPFLAGS += $(ADL_CPPFLAGS)
 
+if USE_GIT_VERSION
+GIT_VERSION      := $(shell sh -c 'git describe --abbrev=4 --dirty')
+sgminer_CPPFLAGS += -DGIT_VERSION=\"$(GIT_VERSION)\"
+endif
+
 sgminer_SOURCES := sgminer.c
 sgminer_SOURCES	+= api.c
 sgminer_SOURCES	+= elist.h miner.h compat.h bench_block.h

configure.ac

@@ -225,6 +225,11 @@ else
 	DLOPEN_FLAGS=""
 fi
 
+AC_ARG_ENABLE([git-version],
+	AS_HELP_STRING([--disable-git-version],
+		[Disable use of git version in version string even if available]),
+		[wantgitver=$enableval], [wantgitver=yes])
+
 curses="auto"
 
 AC_ARG_WITH([curses],
@@ -287,6 +292,20 @@ else
 fi
 AC_SUBST(LIBCURL_LIBS)
 
+# Enable or disable use of git version in version string
+AC_MSG_CHECKING(whether to use git version if available)
+if test "x$wantgitver" = "xyes" ; then
+	AC_CHECK_PROGS([GIT], [git])
+	AC_CHECK_FILE([.git/], hasgitdir=yes)
+	usegitver=$ac_cv_file__git_
+	if test $GIT -a "x$hasgitdir" = "xyes"; then
+		AC_DEFINE([USE_GIT_VERSION], [1], [Use GIT version in version string])
+	fi
+else
+	AC_MSG_RESULT([no, disabled by configure])
+	usegitver=no
+fi
+AM_CONDITIONAL(USE_GIT_VERSION, [test x$usegitver = xyes])
 
 #check execv signature
 AC_COMPILE_IFELSE([AC_LANG_SOURCE([
@@ -374,6 +393,8 @@ echo
 echo "Configuration Options Summary:"
 echo
 
+echo "  Use git version......: $usegitver"
+
 if test "x$libcurl" != xno; then
 	echo "  libcurl(GBT+getwork).: Enabled: $LIBCURL_LIBS"
 else
@@ -382,7 +403,6 @@ fi
 
 echo "  curses.TUI...........: $cursesmsg"
 
-
 if test "x$opencl" != xno; then
 	if test $found_opencl = 1; then
 		echo "  OpenCL...............: FOUND. GPU mining support enabled"

sgminer.c

@@ -62,6 +62,11 @@ char *curly = ":D";
 	#include <sys/wait.h>
 #endif
 
+#ifdef GIT_VERSION
+#undef VERSION
+#define VERSION GIT_VERSION
+#endif
+
 struct strategies strategies[] = {
 	{ "Failover" },
 	{ "Round Robin" },
@@ -2124,7 +2129,7 @@ static void curses_print_status(void)
 	struct pool *pool = current_pool();
 
 	wattron(statuswin, A_BOLD);
-	cg_mvwprintw(statuswin, 0, 0, PACKAGE " version " VERSION " - Started: %s", datestamp);
+	cg_mvwprintw(statuswin, 0, 0, PACKAGE " " VERSION " - Started: %s", datestamp);
 	wattroff(statuswin, A_BOLD);
 	mvwhline(statuswin, 1, 0, '-', 80);
 	cg_mvwprintw(statuswin, 2, 0, "%s", statusline);