openvino: Fix OpenvinoVersion dangling pointer

Fixed dangling pointer in OpenVinoVersion by copying the version
string into a malloc'd buffer and adding a corresponding 'defer C.free'
call to inference_engine.go.

Also updated the test to ensure the version string length is sensible.
A warning is printed if '2022.1' is not included in the version string.

openvino/ie/inference_engine.cpp

@@ -1,11 +1,18 @@
 #include "inference_engine.h"
 
 const char* OpenVinoVersion() {
-    std::ostringstream res;
-    res << std::to_string(InferenceEngine::GetInferenceEngineVersion()->apiVersion.major) 
+    std::ostringstream buf;
+    buf << std::to_string(InferenceEngine::GetInferenceEngineVersion()->apiVersion.major) 
         << "." 
         << std::to_string(InferenceEngine::GetInferenceEngineVersion()->apiVersion.minor)
         << "." 
         << InferenceEngine::GetInferenceEngineVersion()->buildNumber;
-    return res.str().c_str();
+    auto version = buf.str();
+
+    size_t resLen = version.size() + 1;
+    auto res = (char*)malloc(resLen);
+
+    memset(res ,0, resLen);
+    memcpy(res, version.c_str(), resLen);
+    return res;
 }

openvino/ie/inference_engine.go

@@ -7,8 +7,11 @@ package ie
 import (
 	"C"
 )
+import "unsafe"
 
 // Version returns the current Inference Engine library version
 func Version() string {
-	return C.GoString(C.OpenVinoVersion())
+	v := C.OpenVinoVersion()
+	defer C.free(unsafe.Pointer(v))
+	return C.GoString(v)
 }

openvino/ie/inference_engine_test.go

@@ -1,12 +1,22 @@
 package ie
 
 import (
+	"strings"
 	"testing"
 )
 
 func TestInferenceEngineVersion(t *testing.T) {
-	if Version() == "" {
+	v := Version()
+	expected := "2022.1"
+	if v == "" || len(v) < len(expected) {
 		t.Error("Invalid IE Version")
 		return
 	}
+
+	// Different platforms can have different strings, only warn if expected
+	// version string does not match.
+	// eg. archlinux: 2.1.custom_makepkg_cdb9bec7210f8c24fde3e416c7ada820faaaa23e
+	if !strings.Contains(v, expected) {
+		t.Log("Unexpected IE Version: ", v)
+	}
 }