tools: bpftool: add a command to display bpftool version

This command can be used to print the version of the tool, which is in
fact the version from Linux taken from usr/include/linux/version.h.

Example usage:

    $ bpftool version
    bpftool v4.14.0

Signed-off-by: Quentin Monnet <quentin.monnet@netronome.com>
Signed-off-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 15 insertions, 1 deletions

diff --git a/tools/bpf/bpftool/Documentation/bpftool.rst b/tools/bpf/bpftool/Documentation/bpftool.rst
index f1df1893fb54..45ad8baf1915 100644
--- a/tools/bpf/bpftool/Documentation/bpftool.rst
+++ b/tools/bpf/bpftool/Documentation/bpftool.rst
@@ -14,6 +14,8 @@ SYNOPSIS
 
         **bpftool** batch file *FILE*
 
+        **bpftool** version
+
         *OBJECT* := { **map** | **program** }
 
         *MAP-COMMANDS* :=
diff --git a/tools/bpf/bpftool/main.c b/tools/bpf/bpftool/main.c
index 8662199ee050..814d19e1b53f 100644
--- a/tools/bpf/bpftool/main.c
+++ b/tools/bpf/bpftool/main.c
@@ -37,6 +37,7 @@
 #include <ctype.h>
 #include <errno.h>
 #include <linux/bpf.h>
+#include <linux/version.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ -62,13 +63,23 @@ static int do_help(int argc, char **argv)
         fprintf(stderr,
                 "Usage: %s OBJECT { COMMAND | help }\n"
                 "       %s batch file FILE\n"
+                "       %s version\n"
                 "\n"
                 "       OBJECT := { prog | map }\n",
-                bin_name, bin_name);
+                bin_name, bin_name, bin_name);
 
         return 0;
 }
 
+static int do_version(int argc, char **argv)
+{
+        printf("%s v%d.%d.%d\n", bin_name,
+               LINUX_VERSION_CODE >> 16,
+               LINUX_VERSION_CODE >> 8 & 0xf,
+               LINUX_VERSION_CODE & 0xf);
+        return 0;
+}
+
 int cmd_select(const struct cmd *cmds, int argc, char **argv,
                int (*help)(int argc, char **argv))
 {
@@ -128,6 +139,7 @@ static const struct cmd cmds[] = {
         { "batch",      do_batch },
         { "prog",       do_prog },
         { "map",        do_map },
+        { "version",    do_version },
         { 0 }
 };