[PATCH bpf-next 1/6] bpftool: make key and value optional in update command

[Stanislav Fomichev <sdf@google.com>]

Bpftool expects both key and value for 'update' operations. For some
map types, key should not be specified. Support updating those map types.

Before:
bpftool map create /sys/fs/bpf/q type queue value 4 entries 10 name q
bpftool map update pinned /sys/fs/bpf/q value 0 1 2 3
Error: did not find key

After:
bpftool map create /sys/fs/bpf/q type queue value 4 entries 10 name q
bpftool map update pinned /sys/fs/bpf/q value 0 1 2 3

Signed-off-by: Stanislav Fomichev <sdf@google.com>
---
 .../bpf/bpftool/Documentation/bpftool-map.rst |  4 +--
 tools/bpf/bpftool/map.c                       | 36 +++++++++++++++----
 2 files changed, 31 insertions(+), 9 deletions(-)

diff --git a/tools/bpf/bpftool/Documentation/bpftool-map.rst b/tools/bpf/bpftool/Documentation/bpftool-map.rst
index 64b001b4f777..1f1dfe06e66d 100644
--- a/tools/bpf/bpftool/Documentation/bpftool-map.rst
+++ b/tools/bpf/bpftool/Documentation/bpftool-map.rst
@@ -25,7 +25,7 @@ MAP COMMANDS
 |	**bpftool** **map create**     *FILE* **type** *TYPE* **key** *KEY_SIZE* **value** *VALUE_SIZE* \
 |		**entries** *MAX_ENTRIES* **name** *NAME* [**flags** *FLAGS*] [**dev** *NAME*]
 |	**bpftool** **map dump**       *MAP*
-|	**bpftool** **map update**     *MAP*  **key** *DATA*   **value** *VALUE* [*UPDATE_FLAGS*]
+|	**bpftool** **map update**     *MAP* [**key** *DATA*] [**value** *VALUE*] [*UPDATE_FLAGS*]
 |	**bpftool** **map lookup**     *MAP*  **key** *DATA*
 |	**bpftool** **map getnext**    *MAP* [**key** *DATA*]
 |	**bpftool** **map delete**     *MAP*  **key** *DATA*
@@ -62,7 +62,7 @@ DESCRIPTION
 	**bpftool map dump**    *MAP*
 		  Dump all entries in a given *MAP*.
 
-	**bpftool map update**  *MAP*  **key** *DATA*   **value** *VALUE* [*UPDATE_FLAGS*]
+	**bpftool map update**  *MAP* [**key** *DATA*] [**value** *VALUE*] [*UPDATE_FLAGS*]
 		  Update map entry for a given *KEY*.
 
 		  *UPDATE_FLAGS* can be one of: **any** update existing entry
diff --git a/tools/bpf/bpftool/map.c b/tools/bpf/bpftool/map.c
index 2037e3dc864b..61453a1ba6e1 100644
--- a/tools/bpf/bpftool/map.c
+++ b/tools/bpf/bpftool/map.c
@@ -779,6 +779,32 @@ static int do_dump(int argc, char **argv)
 	return err;
 }
 
+static int alloc_key_value(struct bpf_map_info *info, void **key, void **value)
+{
+	*key = NULL;
+	*value = NULL;
+
+	if (info->key_size) {
+		*key = malloc(info->key_size);
+		if (!*key) {
+			p_err("key mem alloc failed");
+			return -1;
+		}
+	}
+
+	if (info->value_size) {
+		*value = alloc_value(info);
+		if (!*value) {
+			p_err("value mem alloc failed");
+			free(*key);
+			*key = NULL;
+			return -1;
+		}
+	}
+
+	return 0;
+}
+
 static int do_update(int argc, char **argv)
 {
 	struct bpf_map_info info = {};
@@ -795,13 +821,9 @@ static int do_update(int argc, char **argv)
 	if (fd < 0)
 		return -1;
 
-	key = malloc(info.key_size);
-	value = alloc_value(&info);
-	if (!key || !value) {
-		p_err("mem alloc failed");
-		err = -1;
+	err = alloc_key_value(&info, &key, &value);
+	if (err)
 		goto exit_free;
-	}
 
 	err = parse_elem(argv, &info, key, value, info.key_size,
 			 info.value_size, &flags, &value_fd);
@@ -1135,7 +1157,7 @@ static int do_help(int argc, char **argv)
 		"                              entries MAX_ENTRIES name NAME [flags FLAGS] \\\n"
 		"                              [dev NAME]\n"
 		"       %s %s dump       MAP\n"
-		"       %s %s update     MAP  key DATA value VALUE [UPDATE_FLAGS]\n"
+		"       %s %s update     MAP [key DATA] [value VALUE] [UPDATE_FLAGS]\n"
 		"       %s %s lookup     MAP  key DATA\n"
 		"       %s %s getnext    MAP [key DATA]\n"
 		"       %s %s delete     MAP  key DATA\n"
-- 
2.20.1.97.g81188d93c3-goog