From 6e918705c42f0008ba7633db24e7198209a93661 Mon Sep 17 00:00:00 2001
From: Hiroshi Hatake <hatake@clear-code.com>
Date: Mon, 16 Nov 2020 10:43:44 +0900
Subject: [PATCH] command: Show more human readable error message

Signed-off-by: Hiroshi Hatake <hatake@clear-code.com>
---
 lib/fluent/command/cap_ctl.rb | 19 +++++++++++++++++++
 test/command/test_cap_ctl.rb  |  4 ++--
 2 files changed, 21 insertions(+), 2 deletions(-)

diff --git a/lib/fluent/command/cap_ctl.rb b/lib/fluent/command/cap_ctl.rb
index 6d80f9f4f8..cf5c439455 100644
--- a/lib/fluent/command/cap_ctl.rb
+++ b/lib/fluent/command/cap_ctl.rb
@@ -106,6 +106,7 @@ def add_capabilities(opts, target_file)
         @capng.clear(:caps)
         @capng.caps_file(target_file)
         capabilities = add_caps.split(/\s*,\s*/)
+        check_capabilities(capabilities, get_valid_capabilities)
         ret = @capng.update(:add,
                             CapNG::Type::EFFECTIVE | CapNG::Type::INHERITABLE | CapNG::Type::PERMITTED,
                             capabilities)
@@ -120,6 +121,7 @@ def drop_capabilities(opts, target_file)
         @capng.clear(:caps)
         @capng.caps_file(target_file)
         capabilities = drop_caps.split(/\s*,\s*/)
+        check_capabilities(capabilities, get_valid_capabilities)
         ret = @capng.update(:drop,
                             CapNG::Type::EFFECTIVE | CapNG::Type::INHERITABLE | CapNG::Type::PERMITTED,
                             capabilities)
@@ -140,6 +142,23 @@ def get_capabilities(opts, target_file)
       end
     end
 
+    def get_valid_capabilities
+      capabilities = []
+      cap = CapNG::Capability.new
+      cap.each do |_code, capability|
+        capabilities << capability
+      end
+      capabilities
+    end
+
+    def check_capabilities(capabilities, valid_capabilities)
+      capabilities.each do |capability|
+        unless valid_capabilities.include?(capability)
+          raise ArgumentError, "'#{capability}' is not valid capability. Valid Capabilities are:  #{valid_capabilities.join(", ")}"
+        end
+      end
+    end
+
     def parse_options!(argv)
       begin
         rest = @op.parse(argv)
diff --git a/test/command/test_cap_ctl.rb b/test/command/test_cap_ctl.rb
index dc11236b3d..067880b468 100644
--- a/test/command/test_cap_ctl.rb
+++ b/test/command/test_cap_ctl.rb
@@ -86,13 +86,13 @@ class TestFluentCapCtl < Test::Unit::TestCase
 
   sub_test_case "invalid" do
     test "add capability" do
-      assert_raise(RuntimeError) do
+      assert_raise(ArgumentError) do
         Fluent::CapCtl.new(["--add-cap", "nonexitent"]).call
       end
     end
 
     test "drop capability" do
-      assert_raise(RuntimeError) do
+      assert_raise(ArgumentError) do
         Fluent::CapCtl.new(["--drop-cap", "invalid"]).call
       end
     end