Invocation: Returning a string
Suppose I have a function that:
1. Takes an input string.
2. Uses Java (via Invocation) to calculate a jstring.
3. Converts the jstring to a a UTF string.
4. Returns the UTF string.
Like this (a JNIRef is a structure with references to classes and methods):
char *f( JNIEnv *env, JNIRef *j,char *strInput )
{
jstring jstrInput, jstrOutput;
char*strOutput;
jstrInput = (*env)->NewStringUTF( env, strInput );
CHECK_FOR_NULL(jstrInput);
// Do the calculation
jstrOutput = (jstring) (*env)->CallStaticObjectMethod(env,j->class,j->method,jstrInput);
CHECK_FOR_NULL(jstrOutput);
strOutput = (*env)->GetStringUTFChars( env, strOutput, NULL );
CHECK_FOR_NULL(strOutput);
return strOutput;
}
I'm leaking memory because I'm not releasing the string that GetStringUTF() generated, aren't I?
If I am leaking memory, what's the best way of doing something like this? I was thinking
something along the lines of (untested):
char *f( JNIEnv *env, JNIRef *j,char *strInput )
{
jstring jstrInput, jstrOutput;
char*strOutput;
jstrInput = (*env)->NewStringUTF( env, strInput );
CHECK_FOR_NULL(jstrInput);
// Do the calculation
jstrOutput = (jstring) (*env)->CallStaticObjectMethod(env,j->class,j->method,jstrInput);
CHECK_FOR_NULL(jstrOutput);
strOutput = (*env)->GetStringUTFChars( env, strOutput, NULL );
CHECK_FOR_NULL(strOutput);
char returnStr = strdup( strOutput );
CHECK_FOR_NULL(returnStr);
env->ReleaseStringUTFChars(jstrOutput, strOutput);
return returnStr;
}
As long as the caller free()'s the returnStr, is this safe?
