gecko-dev/mozglue/android/SharedMemNatives.cpp

/* -*- Mode: c++; c-basic-offset: 4; tab-width: 20; indent-tabs-mode: nil; -*-
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include <errno.h>
#include <jni.h>
#include <stdio.h>
#include <string.h>
#include <sys/mman.h>

extern "C" {

JNIEXPORT
void JNICALL
Java_org_mozilla_gecko_media_SharedMemBuffer_nativeReadFromDirectBuffer(JNIEnv* jenv, jclass, jobject src, jlong dest, jint offset, jint size)
{
  uint8_t* from = static_cast<uint8_t*>(jenv->GetDirectBufferAddress(src));
  if (from == nullptr) {
    jenv->ThrowNew(jenv->FindClass("java/lang/NullPointerException"), "Null direct buffer");
    return;
  }

  void* to = reinterpret_cast<void*>(dest);
  if (to == nullptr) {
    jenv->ThrowNew(jenv->FindClass("java/lang/NullPointerException"), "Null shared memory buffer");
    return;
  }

  memcpy(to, from + offset, size);
}

JNIEXPORT
void JNICALL
Java_org_mozilla_gecko_media_SharedMemBuffer_nativeWriteToDirectBuffer(JNIEnv* jenv, jclass, jlong src, jobject dest, jint offset, jint size)
{
  uint8_t* from = reinterpret_cast<uint8_t*>(src);
  if (from == nullptr) {
    jenv->ThrowNew(jenv->FindClass("java/lang/NullPointerException"), "Null shared memory buffer");
    return;
  }

  void* to = jenv->GetDirectBufferAddress(dest);
  if (to == nullptr) {
    jenv->ThrowNew(jenv->FindClass("java/lang/NullPointerException"), "Null direct buffer");
    return;
  }

  memcpy(to, from + offset, size);
}

JNIEXPORT
jlong JNICALL
Java_org_mozilla_gecko_mozglue_SharedMemory_map(JNIEnv *env, jobject jobj, jint fd, jint length)
{
  void* address = mmap(NULL, length, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
  if (address == MAP_FAILED) {
    char msg[128];
    snprintf(msg, sizeof(msg), "mmap failed. errno=%d", errno);
    env->ThrowNew(env->FindClass("java/lang/NullPointerException"), msg);
    return 0;
  }
  return jlong(address);
}

JNIEXPORT
void JNICALL
Java_org_mozilla_gecko_mozglue_SharedMemory_unmap(JNIEnv *env, jobject jobj, jlong address, jint size)
{
  munmap((void*)address, (size_t)size);
}

}