From ae3ceedd69cad73fa69850e88352f584952bf361 Mon Sep 17 00:00:00 2001
From: Eugene Yakubovich <eugene.yakubovich@coreos.com>
Date: Fri, 18 Sep 2015 10:30:10 -0700
Subject: [PATCH] bug fix: exec of DEL cmd caused JSON decode error

When plugin is executed with a DEL command, it does not
print result to stdout unless there is an error. Therefore
it stdout bytes should not be passed to json.Unmarshal.
---
 invoke/exec.go | 22 ++++++++++++++++++----
 ipam/ipam.go   |  5 ++---
 2 files changed, 20 insertions(+), 7 deletions(-)

diff --git a/invoke/exec.go b/invoke/exec.go
index d7c5b7ab..cf0cff47 100644
--- a/invoke/exec.go
+++ b/invoke/exec.go
@@ -41,7 +41,23 @@ func pluginErr(err error, output []byte) error {
 	return err
 }
 
-func ExecPlugin(pluginPath string, netconf []byte, args CNIArgs) (*types.Result, error) {
+func ExecPluginWithResult(pluginPath string, netconf []byte, args CNIArgs) (*types.Result, error) {
+	stdoutBytes, err := execPlugin(pluginPath, netconf, args)
+	if err != nil {
+		return nil, err
+	}
+
+	res := &types.Result{}
+	err = json.Unmarshal(stdoutBytes, res)
+	return res, err
+}
+
+func ExecPluginWithoutResult(pluginPath string, netconf []byte, args CNIArgs) error {
+	_, err := execPlugin(pluginPath, netconf, args)
+	return err
+}
+
+func execPlugin(pluginPath string, netconf []byte, args CNIArgs) ([]byte, error) {
 	if pluginPath == "" {
 		return nil, fmt.Errorf("could not find %q plugin", filepath.Base(pluginPath))
 	}
@@ -60,7 +76,5 @@ func ExecPlugin(pluginPath string, netconf []byte, args CNIArgs) (*types.Result,
 		return nil, pluginErr(err, stdout.Bytes())
 	}
 
-	res := &types.Result{}
-	err := json.Unmarshal(stdout.Bytes(), res)
-	return res, err
+	return stdout.Bytes(), nil
 }
diff --git a/ipam/ipam.go b/ipam/ipam.go
index a76299d7..6a593a26 100644
--- a/ipam/ipam.go
+++ b/ipam/ipam.go
@@ -29,15 +29,14 @@ func ExecAdd(plugin string, netconf []byte) (*types.Result, error) {
 	if os.Getenv("CNI_COMMAND") != "ADD" {
 		return nil, fmt.Errorf("CNI_COMMAND is not ADD")
 	}
-	return invoke.ExecPlugin(invoke.Find(plugin), netconf, invoke.ArgsFromEnv())
+	return invoke.ExecPluginWithResult(invoke.Find(plugin), netconf, invoke.ArgsFromEnv())
 }
 
 func ExecDel(plugin string, netconf []byte) error {
 	if os.Getenv("CNI_COMMAND") != "DEL" {
 		return fmt.Errorf("CNI_COMMAND is not DEL")
 	}
-	_, err := invoke.ExecPlugin(invoke.Find(plugin), netconf, invoke.ArgsFromEnv())
-	return err
+	return invoke.ExecPluginWithoutResult(invoke.Find(plugin), netconf, invoke.ArgsFromEnv())
 }
 
 // ConfigureIface takes the result of IPAM plugin and