diff --git a/libappfuse/Android.bp b/libappfuse/Android.bp
new file mode 100644
index 0000000..8d24af1
--- /dev/null
+++ b/libappfuse/Android.bp
@@ -0,0 +1,26 @@
+// Copyright 2016 The Android Open Source Project
+
+cc_defaults {
+    name: "libappfuse_defaults",
+    local_include_dirs: ["include"],
+    shared_libs: ["libbase"],
+    cflags: [
+        "-Wall",
+        "-Werror",
+    ],
+    clang: true
+}
+
+cc_library_shared {
+    name: "libappfuse",
+    defaults: ["libappfuse_defaults"],
+    export_include_dirs: ["include"],
+    srcs: ["AppFuse.cc"]
+}
+
+cc_test {
+    name: "libappfuse_test",
+    defaults: ["libappfuse_defaults"],
+    shared_libs: ["libappfuse"],
+    srcs: ["tests/AppFuseTest.cc"]
+}
diff --git a/libappfuse/AppFuse.cc b/libappfuse/AppFuse.cc
new file mode 100644
index 0000000..8701c48
--- /dev/null
+++ b/libappfuse/AppFuse.cc
@@ -0,0 +1,136 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specic language governing permissions and
+ * limitations under the License.
+ */
+
+#include "libappfuse/AppFuse.h"
+
+#include <inttypes.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <algorithm>
+
+#include <android-base/logging.h>
+#include <android-base/macros.h>
+
+namespace android {
+
+template <typename T, typename Header>
+bool FuseMessage<T, Header>::CheckHeaderLength() const {
+  if (sizeof(Header) <= header.len && header.len <= sizeof(T)) {
+    return true;
+  } else {
+    LOG(ERROR) << "Packet size is invalid=" << header.len;
+    return false;
+  }
+}
+
+template <typename T, typename Header>
+bool FuseMessage<T, Header>::CheckResult(
+    int result, const char* operation_name) const {
+  if (result >= 0 && static_cast<uint32_t>(result) == header.len) {
+    return true;
+  } else {
+    PLOG(ERROR) << "Failed to " << operation_name
+        << " a packet from FD. result=" << result << " header.len="
+        << header.len;
+    return false;
+  }
+}
+
+template <typename T, typename Header>
+bool FuseMessage<T, Header>::Read(int fd) {
+  const ssize_t result = TEMP_FAILURE_RETRY(::read(fd, this, sizeof(T)));
+  return CheckHeaderLength() && CheckResult(result, "read");
+}
+
+template <typename T, typename Header>
+bool FuseMessage<T, Header>::Write(int fd) const {
+  if (!CheckHeaderLength()) {
+    return false;
+  }
+  const ssize_t result = TEMP_FAILURE_RETRY(::write(fd, this, header.len));
+  return CheckResult(result, "write");
+}
+
+template struct FuseMessage<FuseRequest, fuse_in_header>;
+template struct FuseMessage<FuseResponse, fuse_out_header>;
+
+void FuseResponse::ResetHeader(
+    uint32_t data_length, int32_t error, uint64_t unique) {
+  CHECK_LE(error, 0) << "error should be zero or negative.";
+  header.len = sizeof(fuse_out_header) + data_length;
+  header.error = error;
+  header.unique = unique;
+}
+
+void FuseResponse::Reset(uint32_t data_length, int32_t error, uint64_t unique) {
+  memset(this, 0, sizeof(fuse_out_header) + data_length);
+  ResetHeader(data_length, error, unique);
+}
+
+void FuseBuffer::HandleInit() {
+  const fuse_init_in* const in = &request.init_in;
+
+  // Before writing |out|, we need to copy data from |in|.
+  const uint64_t unique = request.header.unique;
+  const uint32_t minor = in->minor;
+  const uint32_t max_readahead = in->max_readahead;
+
+  // Kernel 2.6.16 is the first stable kernel with struct fuse_init_out
+  // defined (fuse version 7.6). The structure is the same from 7.6 through
+  // 7.22. Beginning with 7.23, the structure increased in size and added
+  // new parameters.
+  if (in->major != FUSE_KERNEL_VERSION || in->minor < 6) {
+    LOG(ERROR) << "Fuse kernel version mismatch: Kernel version " << in->major
+        << "." << in->minor << " Expected at least " << FUSE_KERNEL_VERSION
+        << ".6";
+    response.Reset(0, -EPERM, unique);
+    return;
+  }
+
+  // We limit ourselves to 15 because we don't handle BATCH_FORGET yet
+  size_t response_size = sizeof(fuse_init_out);
+#if defined(FUSE_COMPAT_22_INIT_OUT_SIZE)
+  // FUSE_KERNEL_VERSION >= 23.
+
+  // If the kernel only works on minor revs older than or equal to 22,
+  // then use the older structure size since this code only uses the 7.22
+  // version of the structure.
+  if (minor <= 22) {
+    response_size = FUSE_COMPAT_22_INIT_OUT_SIZE;
+  }
+#endif
+
+  response.Reset(response_size, kFuseSuccess, unique);
+  fuse_init_out* const out = &response.init_out;
+  out->major = FUSE_KERNEL_VERSION;
+  // We limit ourselves to 15 because we don't handle BATCH_FORGET yet.
+  out->minor = std::min(minor, 15u);
+  out->max_readahead = max_readahead;
+  out->flags = FUSE_ATOMIC_O_TRUNC | FUSE_BIG_WRITES;
+  out->max_background = 32;
+  out->congestion_threshold = 32;
+  out->max_write = kFuseMaxWrite;
+}
+
+void FuseBuffer::HandleNotImpl() {
+  LOG(VERBOSE) << "NOTIMPL op=" << request.header.opcode << " uniq="
+      << request.header.unique << " nid=" << request.header.nodeid;
+  const uint64_t unique = request.header.unique;
+  response.Reset(0, -ENOSYS, unique);
+}
+
+}  // namespace android
diff --git a/libappfuse/include/libappfuse/AppFuse.h b/libappfuse/include/libappfuse/AppFuse.h
new file mode 100644
index 0000000..b6af48d
--- /dev/null
+++ b/libappfuse/include/libappfuse/AppFuse.h
@@ -0,0 +1,76 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specic language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ANDROID_LIBAPPFUSE_APPFUSE_H_
+#define ANDROID_LIBAPPFUSE_APPFUSE_H_
+
+#include <linux/fuse.h>
+
+namespace android {
+
+// The numbers came from sdcard.c.
+// Maximum number of bytes to write/read in one request/one reply.
+constexpr size_t kFuseMaxWrite = 256 * 1024;
+constexpr size_t kFuseMaxRead = 128 * 1024;
+constexpr int32_t kFuseSuccess = 0;
+
+template<typename T, typename Header>
+struct FuseMessage {
+  Header header;
+  bool Read(int fd);
+  bool Write(int fd) const;
+ private:
+  bool CheckHeaderLength() const;
+  bool CheckResult(int result, const char* operation_name) const;
+};
+
+struct FuseRequest : public FuseMessage<FuseRequest, fuse_in_header> {
+  union {
+    struct {
+      fuse_write_in write_in;
+      char write_data[kFuseMaxWrite];
+    };
+    fuse_open_in open_in;
+    fuse_init_in init_in;
+    fuse_read_in read_in;
+    char lookup_name[];
+  };
+};
+
+struct FuseResponse : public FuseMessage<FuseResponse, fuse_out_header> {
+  union {
+    fuse_init_out init_out;
+    fuse_entry_out entry_out;
+    fuse_attr_out attr_out;
+    fuse_open_out open_out;
+    char read_data[kFuseMaxRead];
+    fuse_write_out write_out;
+  };
+  void Reset(uint32_t data_length, int32_t error, uint64_t unique);
+  void ResetHeader(uint32_t data_length, int32_t error, uint64_t unique);
+};
+
+union FuseBuffer {
+  FuseRequest request;
+  FuseResponse response;
+
+  void HandleInit();
+  void HandleNotImpl();
+};
+
+}  // namespace android
+
+#endif  // ANDROID_LIBAPPFUSE_APPFUSE_H_
diff --git a/libappfuse/tests/AppFuseTest.cc b/libappfuse/tests/AppFuseTest.cc
new file mode 100644
index 0000000..8c2cc47
--- /dev/null
+++ b/libappfuse/tests/AppFuseTest.cc
@@ -0,0 +1,187 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specic language governing permissions and
+ * limitations under the License.
+ */
+
+#include "libappfuse/AppFuse.h"
+
+#include <fcntl.h>
+#include <string.h>
+#include <sys/socket.h>
+
+#include <android-base/unique_fd.h>
+#include <gtest/gtest.h>
+
+namespace android {
+
+constexpr char kTempFile[] = "/data/local/tmp/appfuse_test_dump";
+
+void OpenTempFile(android::base::unique_fd* fd) {
+  fd->reset(open(kTempFile, O_CREAT | O_RDWR));
+  ASSERT_NE(-1, *fd) << strerror(errno);
+  unlink(kTempFile);
+  ASSERT_NE(-1, *fd) << strerror(errno);
+}
+
+void TestReadInvalidLength(size_t headerSize, size_t write_size) {
+  android::base::unique_fd fd;
+  OpenTempFile(&fd);
+
+  char buffer[std::max(headerSize, sizeof(FuseRequest))];
+  FuseRequest* const packet = reinterpret_cast<FuseRequest*>(buffer);
+  packet->header.len = headerSize;
+  ASSERT_NE(-1, write(fd, packet, write_size)) << strerror(errno);
+
+  lseek(fd, 0, SEEK_SET);
+  EXPECT_FALSE(packet->Read(fd));
+}
+
+void TestWriteInvalidLength(size_t size) {
+  android::base::unique_fd fd;
+  OpenTempFile(&fd);
+
+  char buffer[std::max(size, sizeof(FuseRequest))];
+  FuseRequest* const packet = reinterpret_cast<FuseRequest*>(buffer);
+  packet->header.len = size;
+  EXPECT_FALSE(packet->Write(fd));
+}
+
+// Use FuseRequest as a template instance of FuseMessage.
+
+TEST(FuseMessageTest, ReadAndWrite) {
+  android::base::unique_fd fd;
+  OpenTempFile(&fd);
+
+  FuseRequest request;
+  request.header.len = sizeof(FuseRequest);
+  request.header.opcode = 1;
+  request.header.unique = 2;
+  request.header.nodeid = 3;
+  request.header.uid = 4;
+  request.header.gid = 5;
+  request.header.pid = 6;
+  strcpy(request.lookup_name, "test");
+
+  ASSERT_TRUE(request.Write(fd));
+
+  memset(&request, 0, sizeof(FuseRequest));
+  lseek(fd, 0, SEEK_SET);
+
+  ASSERT_TRUE(request.Read(fd));
+  EXPECT_EQ(sizeof(FuseRequest), request.header.len);
+  EXPECT_EQ(1u, request.header.opcode);
+  EXPECT_EQ(2u, request.header.unique);
+  EXPECT_EQ(3u, request.header.nodeid);
+  EXPECT_EQ(4u, request.header.uid);
+  EXPECT_EQ(5u, request.header.gid);
+  EXPECT_EQ(6u, request.header.pid);
+  EXPECT_STREQ("test", request.lookup_name);
+}
+
+TEST(FuseMessageTest, Read_InconsistentLength) {
+  TestReadInvalidLength(sizeof(fuse_in_header), sizeof(fuse_in_header) + 1);
+}
+
+TEST(FuseMessageTest, Read_TooLong) {
+  TestReadInvalidLength(sizeof(FuseRequest) + 1, sizeof(FuseRequest) + 1);
+}
+
+TEST(FuseMessageTest, Read_TooShort) {
+  TestReadInvalidLength(sizeof(fuse_in_header) - 1, sizeof(fuse_in_header) - 1);
+}
+
+TEST(FuseMessageTest, Write_TooLong) {
+  TestWriteInvalidLength(sizeof(FuseRequest) + 1);
+}
+
+TEST(FuseMessageTest, Write_TooShort) {
+  TestWriteInvalidLength(sizeof(fuse_in_header) - 1);
+}
+
+TEST(FuseResponseTest, Reset) {
+  FuseResponse response;
+  // Write 1 to the first ten bytes.
+  memset(response.read_data, 'a', 10);
+
+  response.Reset(0, -1, 2);
+  EXPECT_EQ(sizeof(fuse_out_header), response.header.len);
+  EXPECT_EQ(-1, response.header.error);
+  EXPECT_EQ(2u, response.header.unique);
+  EXPECT_EQ('a', response.read_data[0]);
+  EXPECT_EQ('a', response.read_data[9]);
+
+  response.Reset(5, -4, 3);
+  EXPECT_EQ(sizeof(fuse_out_header) + 5, response.header.len);
+  EXPECT_EQ(-4, response.header.error);
+  EXPECT_EQ(3u, response.header.unique);
+  EXPECT_EQ(0, response.read_data[0]);
+  EXPECT_EQ(0, response.read_data[1]);
+  EXPECT_EQ(0, response.read_data[2]);
+  EXPECT_EQ(0, response.read_data[3]);
+  EXPECT_EQ(0, response.read_data[4]);
+  EXPECT_EQ('a', response.read_data[5]);
+}
+
+TEST(FuseResponseTest, ResetHeader) {
+  FuseResponse response;
+  // Write 1 to the first ten bytes.
+  memset(response.read_data, 'a', 10);
+
+  response.ResetHeader(0, -1, 2);
+  EXPECT_EQ(sizeof(fuse_out_header), response.header.len);
+  EXPECT_EQ(-1, response.header.error);
+  EXPECT_EQ(2u, response.header.unique);
+  EXPECT_EQ('a', response.read_data[0]);
+  EXPECT_EQ('a', response.read_data[9]);
+
+  response.ResetHeader(5, -4, 3);
+  EXPECT_EQ(sizeof(fuse_out_header) + 5, response.header.len);
+  EXPECT_EQ(-4, response.header.error);
+  EXPECT_EQ(3u, response.header.unique);
+  EXPECT_EQ('a', response.read_data[0]);
+  EXPECT_EQ('a', response.read_data[9]);
+}
+
+TEST(FuseBufferTest, HandleInit) {
+  FuseBuffer buffer;
+  memset(&buffer, 0, sizeof(FuseBuffer));
+
+  buffer.request.header.opcode = FUSE_INIT;
+  buffer.request.init_in.major = FUSE_KERNEL_VERSION;
+  buffer.request.init_in.minor = FUSE_KERNEL_MINOR_VERSION;
+
+  buffer.HandleInit();
+
+  ASSERT_EQ(sizeof(fuse_out_header) + sizeof(fuse_init_out),
+            buffer.response.header.len);
+  EXPECT_EQ(kFuseSuccess, buffer.response.header.error);
+  EXPECT_EQ(static_cast<unsigned int>(FUSE_KERNEL_VERSION),
+            buffer.response.init_out.major);
+  EXPECT_EQ(15u, buffer.response.init_out.minor);
+  EXPECT_EQ(static_cast<unsigned int>(FUSE_ATOMIC_O_TRUNC | FUSE_BIG_WRITES),
+      buffer.response.init_out.flags);
+  EXPECT_EQ(kFuseMaxWrite, buffer.response.init_out.max_write);
+}
+
+TEST(FuseBufferTest, HandleNotImpl) {
+  FuseBuffer buffer;
+  memset(&buffer, 0, sizeof(FuseBuffer));
+
+  buffer.HandleNotImpl();
+
+  ASSERT_EQ(sizeof(fuse_out_header), buffer.response.header.len);
+  EXPECT_EQ(-ENOSYS, buffer.response.header.error);
+}
+}
+  // namespace android