kvm tools: Add 'kvm version' command

Add a 'kvm version' command which prints the version of the kernel
used to build kvm tools.

Part of the code is based on and was loaned from perf.

Suggested-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>

Documentation/kvm-version.txt

@@ -0,0 +1,21 @@
+kvm-version(1)
+================
+
+NAME
+----
+kvm-version - Print the version of the kernel tree kvm tools
+was built on.
+
+SYNOPSIS
+--------
+[verse]
+'kvm version'
+
+DESCRIPTION
+-----------
+The command prints the version of the kernel that was used to build
+kvm tools.
+
+Note that the version is not the version of the kernel which is currently
+running on the host, but is the version of the kernel tree from which kvm
+tools was built.

Makefile

@@ -61,6 +61,7 @@ OBJS	+= kvm-pause.o
 OBJS	+= kvm-balloon.o
 OBJS	+= kvm-list.o
 OBJS	+= kvm-run.o
+OBJS	+= kvm-version.o
 OBJS	+= mptable.o
 OBJS	+= rbtree.o
 OBJS	+= threadpool.o
@@ -124,6 +125,7 @@ endif
 
 DEFINES	+= -D_FILE_OFFSET_BITS=64
 DEFINES	+= -D_GNU_SOURCE
+DEFINES	+= -DKVMTOOLS_VERSION='"$(KVMTOOLS_VERSION)"'
 
 KVM_INCLUDE := include
 CFLAGS	+= $(CPPFLAGS) $(DEFINES) -I$(KVM_INCLUDE) -I../../include -I../../arch/$(ARCH)/include/ -Os -g
@@ -152,6 +154,10 @@ CFLAGS	+= $(WARNINGS)
 
 all: $(PROGRAM)
 
+KVMTOOLS-VERSION-FILE:
+	@$(SHELL_PATH) util/KVMTOOLS-VERSION-GEN $(OUTPUT)
+-include $(OUTPUT)KVMTOOLS-VERSION-FILE
+
 $(PROGRAM): $(DEPS) $(OBJS)
 	$(E) "  LINK    " $@
 	$(Q) $(CC) $(OBJS) $(LIBS) -o $@
@@ -168,6 +174,7 @@ $(OBJS):
 
 rbtree.o: ../../lib/rbtree.c
 	$(Q) $(CC) -c $(CFLAGS) $< -o $@
+
 %.o: %.c
 	$(E) "  CC      " $@
 	$(Q) $(CC) -c $(CFLAGS) $< -o $@

command-list.txt

@@ -4,3 +4,4 @@
 #
 kvm-run				mainporcelain common
 kvm-pause			common
+kvm-version			common

include/kvm/kvm-version.h

@@ -0,0 +1,6 @@
+#ifndef KVM__VERSION_H
+#define KVM__VERSION_H
+
+int kvm_cmd_version(int argc, const char **argv, const char *prefix);
+
+#endif

kvm-cmd.c

@@ -9,6 +9,7 @@
 #include "kvm/kvm-pause.h"
 #include "kvm/kvm-balloon.h"
 #include "kvm/kvm-list.h"
+#include "kvm/kvm-version.h"
 #include "kvm/kvm-help.h"
 #include "kvm/kvm-cmd.h"
 #include "kvm/kvm-run.h"
@@ -18,6 +19,7 @@ struct cmd_struct kvm_commands[] = {
 	{ "debug",	kvm_cmd_debug,		NULL,         0 },
 	{ "balloon",	kvm_cmd_balloon,	NULL,         0 },
 	{ "list",	kvm_cmd_list,		NULL,         0 },
+	{ "version",	kvm_cmd_version,	NULL,         0 },
 	{ "help",	kvm_cmd_help,		NULL,         0 },
 	{ "run",	kvm_cmd_run,		kvm_run_help, 0 },
 	{ NULL,		NULL,			NULL,         0 },

kvm-version.c

@@ -0,0 +1,15 @@
+#include <kvm/util.h>
+#include <kvm/kvm-cmd.h>
+#include <kvm/kvm-version.h>
+#include <kvm/kvm.h>
+
+#include <stdio.h>
+#include <string.h>
+#include <signal.h>
+
+int kvm_cmd_version(int argc, const char **argv, const char *prefix)
+{
+	printf("%s\n", KVMTOOLS_VERSION);
+
+	return 0;
+}

util/KVMTOOLS-VERSION-GEN

@@ -0,0 +1,40 @@
+#!/bin/sh
+
+if [ $# -eq 1 ]  ; then
+	OUTPUT=$1
+fi
+
+GVF=${OUTPUT}KVMTOOLS-VERSION-FILE
+
+LF='
+'
+
+# First check if there is a .git to get the version from git describe
+# otherwise try to get the version from the kernel makefile
+if test -d ../../.git -o -f ../../.git &&
+	VN=$(git describe --abbrev=4 HEAD 2>/dev/null) &&
+	case "$VN" in
+	*$LF*) (exit 1) ;;
+	v[0-9]*)
+		git update-index -q --refresh
+		test -z "$(git diff-index --name-only HEAD --)" ||
+		VN="$VN-dirty" ;;
+	esac
+then
+	VN=$(echo "$VN" | sed -e 's/-/./g');
+else
+	VN=$(MAKEFLAGS= make -sC ../.. kernelversion)
+fi
+
+VN=$(expr "$VN" : v*'\(.*\)')
+
+if test -r $GVF
+then
+	VC=$(sed -e 's/^KVMTOOLS_VERSION = //' <$GVF)
+else
+	VC=unset
+fi
+test "$VN" = "$VC" || {
+	echo >&2 "KVMTOOLS_VERSION = $VN"
+	echo "KVMTOOLS_VERSION = $VN" >$GVF
+}