Makefile: Derive "PKGVERSION" from "git describe" by default

Currently, if not specified in "./configure", QEMU_PKGVERSION will be
empty. Write a rule in Makefile to generate a value from "git describe"
combined with a possible git tree cleanness suffix, and write into a new
header.

    $ cat qemu-version.h
    #define QEMU_PKGVERSION "-v2.6.0-557-gd6550e9-dirty"

Include the header in .c files where the macro is referenced. It's not
necessary to include it in all files, otherwise each time the content of
the file changes, all sources have to be recompiled.

Signed-off-by: Fam Zheng <famz@redhat.com>
Message-Id: <1464774261-648-3-git-send-email-famz@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

Makefile

@@ -50,7 +50,7 @@ endif
 
 include $(SRC_PATH)/rules.mak
 
-GENERATED_HEADERS = config-host.h qemu-options.def
+GENERATED_HEADERS = qemu-version.h config-host.h qemu-options.def
 GENERATED_HEADERS += qmp-commands.h qapi-types.h qapi-visit.h qapi-event.h
 GENERATED_SOURCES += qmp-marshal.c qapi-types.c qapi-visit.c qapi-event.c
 GENERATED_HEADERS += qmp-introspect.h
@@ -167,6 +167,26 @@ endif
 
 all: $(DOCS) $(TOOLS) $(HELPERS-y) recurse-all modules
 
+qemu-version.h: FORCE
+	$(call quiet-command, \
+		(cd $(SRC_PATH); \
+		printf '#define QEMU_PKGVERSION '; \
+		if test -n "$(PKGVERSION)"; then \
+			printf '"$(PKGVERSION)"\n'; \
+		else \
+			if test -d .git; then \
+				printf '" ('; \
+				git describe --match 'v*' 2>/dev/null | tr -d '\n'; \
+				if ! git diff-index --quiet HEAD &>/dev/null; then \
+					printf -- '-dirty'; \
+				fi; \
+				printf ')"\n'; \
+			else \
+				printf '""\n'; \
+			fi; \
+		fi) > $@.tmp)
+	$(call quiet-command, cmp --quiet $@ $@.tmp || mv $@.tmp $@)
+
 config-host.h: config-host.h-timestamp
 config-host.h-timestamp: config-host.mak
 qemu-options.def: $(SRC_PATH)/qemu-options.hx $(SRC_PATH)/scripts/hxtool

linux-user/main.c

@@ -17,6 +17,7 @@
  *  along with this program; if not, see <http://www.gnu.org/licenses/>.
  */
 #include "qemu/osdep.h"
+#include "qemu-version.h"
 #include <sys/mman.h>
 #include <sys/syscall.h>
 #include <sys/resource.h>

qemu-img.c

@@ -22,6 +22,7 @@
  * THE SOFTWARE.
  */
 #include "qemu/osdep.h"
+#include "qemu-version.h"
 #include "qapi/error.h"
 #include "qapi-visit.h"
 #include "qapi/qmp-output-visitor.h"

qmp.c

@@ -14,6 +14,7 @@
  */
 
 #include "qemu/osdep.h"
+#include "qemu-version.h"
 #include "qemu/cutils.h"
 #include "monitor/monitor.h"
 #include "sysemu/sysemu.h"

scripts/create_config

@@ -9,10 +9,6 @@ case $line in
     version=${line#*=}
     echo "#define QEMU_VERSION \"$version\""
     ;;
- PKGVERSION=*) # configuration
-    pkgversion=${line#*=}
-    echo "#define QEMU_PKGVERSION \"$pkgversion\""
-    ;;
  qemu_*dir=*) # qemu-specific directory configuration
     name=${line%=*}
     value=${line#*=}

vl.c

@@ -22,6 +22,7 @@
  * THE SOFTWARE.
  */
 #include "qemu/osdep.h"
+#include "qemu-version.h"
 #include "qemu/cutils.h"
 #include "qemu/help_option.h"