Cannot Find Implementation for Sun. Nio. Ch. Filechannelimpl. Read

I am using sun.nio.ch.FileChannelImpl.read to read a file in linux environment in my java project, I am getting a permission denied on one of my environments, the file has read/write/execute permissions for everyone, but in my environment we have strict policy to allow some commands so I need to find out what commands is this method using to enable this command on my machine.

To find the command I followed up the code until i hit some native methods inside

sun.nio.ch.FileDispatcherImpl

the method is

 static native int read0(FileDescriptor fd, long address, int len)
     throws IOException;

I followed up and found the implementation which is obviously written with C, you can find it in this link

The native implementation is

JNIEXPORT jint JNICALL
Java_sun_nio_ch_FileDispatcherImpl_read0(JNIEnv *env, jclass clazz,
                             jobject fdo, jlong address, jint len)
{
    jint fd = fdval(env, fdo);
    void *buf = (void *)jlong_to_ptr(address);

    return convertReturnVal(env, read(fd, buf, len), JNI_TRUE);
}

Now I need to open read function to figure out what it exactly does, but I am unable to find the implementation or even the header file where this function is declared, following the header files included

#include "jni.h"
#include "jni_util.h"
#include "jvm.h"
#include "jlong.h"
#include "sun_nio_ch_FileDispatcherImpl.h"
#include "java_lang_Long.h"
#include <sys/types.h>
#include <sys/socket.h>
#include <fcntl.h>
#include <sys/uio.h>
#include <unistd.h>
#if defined(__linux__)
#include <linux/fs.h>
#include <sys/ioctl.h>
#endif
#include "nio.h"
#include "nio_util.h"

any help is appreciated.