foo.c

#include <dlfcn.h>
#include <stdio.h>

#include <jni.h>

typedef void* (*malloc_t)(size_t size);

/* The function */
void
foo(void)
{
	malloc_t real_malloc;
	/* Find the malloc function */
	if ((real_malloc = (void *(*)(size_t))dlfunc(RTLD_NEXT, "malloc")) == NULL) {
		fprintf(stderr, "could not locate function malloc: %s\n", dlerror());
	}
	else {
		fprintf(stderr, "malloc function located at %p\n", real_malloc);
	}
}

/* Java JNI call function */
JNIEXPORT void JNICALL
Java_testfoo_foo(JNIEnv *env, jobject thisObj)
{
	foo();
}

Makefile

JAVA_HOME?=/usr/local/openjdk8

CFLAGS+=-fPIC -I${JAVA_HOME}/include -I${JAVA_HOME}/include/$$(uname|tr '[:upper:]' '[:lower:]')

all: testfoo testfoo.class

testfoo.class: testfoo.java
	javac testfoo.java

testfoo: testfoo.o libfoo.so
	${CC} -o $@ testfoo.o ./libfoo.so

libfoo.so: foo.o
	${CC} -shared -o $@ foo.o

.PHONY: clean
clean:
	rm -f testfoo testfoo.class libfoo.so *.o

testfoo.c

void foo(void);

int
main(void)
{
	foo();
	return 0;
}

testfoo.java

public class testfoo {
	static {
		System.loadLibrary("foo");
	}
 
	private native void foo();
 
	public static void main(String[] args) {
		new testfoo().foo();
	}
}