diff --git a/init/action.cpp b/init/action.cpp
index a12f225..ccc18cf 100644
--- a/init/action.cpp
+++ b/init/action.cpp
@@ -118,16 +118,14 @@
     Timer t;
     int result = command.InvokeFunc();
 
-    double duration_ms = t.duration() * 1000;
-    // Any action longer than 50ms will be warned to user as slow operation
-    if (duration_ms > 50.0 ||
-        android::base::GetMinimumLogSeverity() <= android::base::DEBUG) {
+    // TODO: this should probably be changed to "if (failed || took a long time)"...
+    if (android::base::GetMinimumLogSeverity() <= android::base::DEBUG) {
         std::string trigger_name = BuildTriggersString();
         std::string cmd_str = command.BuildCommandString();
         std::string source = command.BuildSourceString();
 
         LOG(INFO) << "Command '" << cmd_str << "' action=" << trigger_name << source
-                  << " returned " << result << " took " << duration_ms << "ms.";
+                  << " returned " << result << " took " << t.duration() << "s";
     }
 }
 
@@ -249,7 +247,9 @@
         result += event_trigger_;
         result += ' ';
     }
-    result.pop_back();
+    if (!result.empty()) {
+        result.pop_back();
+    }
     return result;
 }
 
diff --git a/libappfuse/Android.bp b/libappfuse/Android.bp
index 8b46154..f729faf 100644
--- a/libappfuse/Android.bp
+++ b/libappfuse/Android.bp
@@ -15,12 +15,20 @@
     name: "libappfuse",
     defaults: ["libappfuse_defaults"],
     export_include_dirs: ["include"],
-    srcs: ["FuseBuffer.cc", "FuseBridgeLoop.cc"]
+    srcs: [
+        "FuseAppLoop.cc",
+        "FuseBuffer.cc",
+        "FuseBridgeLoop.cc",
+    ]
 }
 
 cc_test {
     name: "libappfuse_test",
     defaults: ["libappfuse_defaults"],
     shared_libs: ["libappfuse"],
-    srcs: ["tests/FuseBridgeLoopTest.cc", "tests/FuseBufferTest.cc"]
+    srcs: [
+        "tests/FuseAppLoopTest.cc",
+        "tests/FuseBridgeLoopTest.cc",
+        "tests/FuseBufferTest.cc",
+    ]
 }
diff --git a/libappfuse/FuseAppLoop.cc b/libappfuse/FuseAppLoop.cc
new file mode 100644
index 0000000..a31880e
--- /dev/null
+++ b/libappfuse/FuseAppLoop.cc
@@ -0,0 +1,221 @@
+/*
+ * 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/FuseAppLoop.h"
+
+#include <sys/stat.h>
+
+#include <android-base/logging.h>
+#include <android-base/unique_fd.h>
+
+namespace android {
+namespace fuse {
+
+namespace {
+
+void HandleLookUp(FuseBuffer* buffer, FuseAppLoopCallback* callback) {
+  // AppFuse does not support directory structure now.
+  // It can lookup only files under the mount point.
+  if (buffer->request.header.nodeid != FUSE_ROOT_ID) {
+    LOG(ERROR) << "Nodeid is not FUSE_ROOT_ID.";
+    buffer->response.Reset(0, -ENOENT, buffer->request.header.unique);
+    return;
+  }
+
+  // Ensure that the filename ends with 0.
+  const size_t filename_length =
+      buffer->request.header.len - sizeof(fuse_in_header);
+  if (buffer->request.lookup_name[filename_length - 1] != 0) {
+    LOG(ERROR) << "File name does not end with 0.";
+    buffer->response.Reset(0, -ENOENT, buffer->request.header.unique);
+    return;
+  }
+
+  const uint64_t inode =
+      static_cast<uint64_t>(atol(buffer->request.lookup_name));
+  if (inode == 0 || inode == LONG_MAX) {
+    LOG(ERROR) << "Invalid filename";
+    buffer->response.Reset(0, -ENOENT, buffer->request.header.unique);
+    return;
+  }
+
+  const int64_t size = callback->OnGetSize(inode);
+  if (size < 0) {
+    buffer->response.Reset(0, size, buffer->request.header.unique);
+    return;
+  }
+
+  buffer->response.Reset(sizeof(fuse_entry_out), 0,
+                         buffer->request.header.unique);
+  buffer->response.entry_out.nodeid = inode;
+  buffer->response.entry_out.attr_valid = 10;
+  buffer->response.entry_out.entry_valid = 10;
+  buffer->response.entry_out.attr.ino = inode;
+  buffer->response.entry_out.attr.mode = S_IFREG | 0777;
+  buffer->response.entry_out.attr.size = size;
+}
+
+void HandleGetAttr(FuseBuffer* buffer, FuseAppLoopCallback* callback) {
+  const uint64_t nodeid = buffer->request.header.nodeid;
+  int64_t size;
+  uint32_t mode;
+  if (nodeid == FUSE_ROOT_ID) {
+    size = 0;
+    mode = S_IFDIR | 0777;
+  } else {
+    size = callback->OnGetSize(buffer->request.header.nodeid);
+    if (size < 0) {
+      buffer->response.Reset(0, size, buffer->request.header.unique);
+      return;
+    }
+    mode = S_IFREG | 0777;
+  }
+
+  buffer->response.Reset(sizeof(fuse_attr_out), 0,
+                         buffer->request.header.unique);
+  buffer->response.attr_out.attr_valid = 10;
+  buffer->response.attr_out.attr.ino = nodeid;
+  buffer->response.attr_out.attr.mode = mode;
+  buffer->response.attr_out.attr.size = size;
+}
+
+void HandleOpen(FuseBuffer* buffer, FuseAppLoopCallback* callback) {
+  const int32_t file_handle = callback->OnOpen(buffer->request.header.nodeid);
+  if (file_handle < 0) {
+    buffer->response.Reset(0, file_handle, buffer->request.header.unique);
+    return;
+  }
+  buffer->response.Reset(sizeof(fuse_open_out), kFuseSuccess,
+                         buffer->request.header.unique);
+  buffer->response.open_out.fh = file_handle;
+}
+
+void HandleFsync(FuseBuffer* buffer, FuseAppLoopCallback* callback) {
+  buffer->response.Reset(0, callback->OnFsync(buffer->request.header.nodeid),
+                         buffer->request.header.unique);
+}
+
+void HandleRelease(FuseBuffer* buffer, FuseAppLoopCallback* callback) {
+  buffer->response.Reset(0, callback->OnRelease(buffer->request.header.nodeid),
+                         buffer->request.header.unique);
+}
+
+void HandleRead(FuseBuffer* buffer, FuseAppLoopCallback* callback) {
+  const uint64_t unique = buffer->request.header.unique;
+  const uint64_t nodeid = buffer->request.header.nodeid;
+  const uint64_t offset = buffer->request.read_in.offset;
+  const uint32_t size = buffer->request.read_in.size;
+
+  if (size > kFuseMaxRead) {
+    buffer->response.Reset(0, -EINVAL, buffer->request.header.unique);
+    return;
+  }
+
+  const int32_t read_size = callback->OnRead(nodeid, offset, size,
+                                             buffer->response.read_data);
+  if (read_size < 0) {
+    buffer->response.Reset(0, read_size, buffer->request.header.unique);
+    return;
+  }
+
+  buffer->response.ResetHeader(read_size, kFuseSuccess, unique);
+}
+
+void HandleWrite(FuseBuffer* buffer, FuseAppLoopCallback* callback) {
+  const uint64_t unique = buffer->request.header.unique;
+  const uint64_t nodeid = buffer->request.header.nodeid;
+  const uint64_t offset = buffer->request.write_in.offset;
+  const uint32_t size = buffer->request.write_in.size;
+
+  if (size > kFuseMaxWrite) {
+    buffer->response.Reset(0, -EINVAL, buffer->request.header.unique);
+    return;
+  }
+
+  const int32_t write_size = callback->OnWrite(nodeid, offset, size,
+                                               buffer->request.write_data);
+  if (write_size < 0) {
+    buffer->response.Reset(0, write_size, buffer->request.header.unique);
+    return;
+  }
+
+  buffer->response.Reset(sizeof(fuse_write_out), kFuseSuccess, unique);
+  buffer->response.write_out.size = write_size;
+}
+
+} // namespace
+
+bool StartFuseAppLoop(int raw_fd, FuseAppLoopCallback* callback) {
+  base::unique_fd fd(raw_fd);
+  FuseBuffer buffer;
+
+  LOG(DEBUG) << "Start fuse loop.";
+  while (callback->IsActive()) {
+    if (!buffer.request.Read(fd)) {
+      return false;
+    }
+
+    const uint32_t opcode = buffer.request.header.opcode;
+    LOG(VERBOSE) << "Read a fuse packet, opcode=" << opcode;
+    switch (opcode) {
+      case FUSE_FORGET:
+        // Do not reply to FUSE_FORGET.
+        continue;
+
+      case FUSE_LOOKUP:
+        HandleLookUp(&buffer, callback);
+        break;
+
+      case FUSE_GETATTR:
+        HandleGetAttr(&buffer, callback);
+        break;
+
+      case FUSE_OPEN:
+        HandleOpen(&buffer, callback);
+        break;
+
+      case FUSE_READ:
+        HandleRead(&buffer, callback);
+        break;
+
+      case FUSE_WRITE:
+        HandleWrite(&buffer, callback);
+        break;
+
+      case FUSE_RELEASE:
+        HandleRelease(&buffer, callback);
+        break;
+
+      case FUSE_FSYNC:
+        HandleFsync(&buffer, callback);
+        break;
+
+      default:
+        buffer.HandleNotImpl();
+        break;
+    }
+
+    if (!buffer.response.Write(fd)) {
+      LOG(ERROR) << "Failed to write a response to the device.";
+      return false;
+    }
+  }
+
+  return true;
+}
+
+}  // namespace fuse
+}  // namespace android
diff --git a/libappfuse/FuseBridgeLoop.cc b/libappfuse/FuseBridgeLoop.cc
index 332556d..acb963c 100644
--- a/libappfuse/FuseBridgeLoop.cc
+++ b/libappfuse/FuseBridgeLoop.cc
@@ -25,14 +25,15 @@
     int raw_dev_fd, int raw_proxy_fd, FuseBridgeLoop::Callback* callback) {
   base::unique_fd dev_fd(raw_dev_fd);
   base::unique_fd proxy_fd(raw_proxy_fd);
+  fuse::FuseBuffer buffer;
 
   LOG(DEBUG) << "Start fuse loop.";
   while (true) {
-    if (!buffer_.request.Read(dev_fd)) {
+    if (!buffer.request.Read(dev_fd)) {
       return false;
     }
 
-    const uint32_t opcode = buffer_.request.header.opcode;
+    const uint32_t opcode = buffer.request.header.opcode;
     LOG(VERBOSE) << "Read a fuse packet, opcode=" << opcode;
     switch (opcode) {
       case FUSE_FORGET:
@@ -45,27 +46,27 @@
       case FUSE_READ:
       case FUSE_WRITE:
       case FUSE_RELEASE:
-      case FUSE_FLUSH:
-        if (!buffer_.request.Write(proxy_fd)) {
+      case FUSE_FSYNC:
+        if (!buffer.request.Write(proxy_fd)) {
           LOG(ERROR) << "Failed to write a request to the proxy.";
           return false;
         }
-        if (!buffer_.response.Read(proxy_fd)) {
+        if (!buffer.response.Read(proxy_fd)) {
           LOG(ERROR) << "Failed to read a response from the proxy.";
           return false;
         }
         break;
 
       case FUSE_INIT:
-        buffer_.HandleInit();
+        buffer.HandleInit();
         break;
 
       default:
-        buffer_.HandleNotImpl();
+        buffer.HandleNotImpl();
         break;
     }
 
-    if (!buffer_.response.Write(dev_fd)) {
+    if (!buffer.response.Write(dev_fd)) {
       LOG(ERROR) << "Failed to write a response to the device.";
       return false;
     }
@@ -76,4 +77,12 @@
   }
 }
 
+namespace fuse {
+
+bool StartFuseBridgeLoop(
+    int raw_dev_fd, int raw_proxy_fd, FuseBridgeLoopCallback* callback) {
+  return FuseBridgeLoop().Start(raw_dev_fd, raw_proxy_fd, callback);
+}
+
+}  // namespace fuse
 }  // namespace android
diff --git a/libappfuse/FuseBuffer.cc b/libappfuse/FuseBuffer.cc
index 45280a5..74fe756 100644
--- a/libappfuse/FuseBuffer.cc
+++ b/libappfuse/FuseBuffer.cc
@@ -21,15 +21,22 @@
 #include <unistd.h>
 
 #include <algorithm>
+#include <type_traits>
 
 #include <android-base/logging.h>
 #include <android-base/macros.h>
 
 namespace android {
+namespace fuse {
 
-template <typename T, typename Header>
-bool FuseMessage<T, Header>::CheckHeaderLength() const {
-  if (sizeof(Header) <= header.len && header.len <= sizeof(T)) {
+static_assert(
+    std::is_standard_layout<FuseBuffer>::value,
+    "FuseBuffer must be standard layout union.");
+
+template <typename T>
+bool FuseMessage<T>::CheckHeaderLength() const {
+  const auto& header = static_cast<const T*>(this)->header;
+  if (sizeof(header) <= header.len && header.len <= sizeof(T)) {
     return true;
   } else {
     LOG(ERROR) << "Packet size is invalid=" << header.len;
@@ -37,27 +44,29 @@
   }
 }
 
-template <typename T, typename Header>
-bool FuseMessage<T, Header>::CheckResult(
+template <typename T>
+bool FuseMessage<T>::CheckResult(
     int result, const char* operation_name) const {
+  const auto& header = static_cast<const T*>(this)->header;
   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="
+        << " a packet. result=" << result << " header.len="
         << header.len;
     return false;
   }
 }
 
-template <typename T, typename Header>
-bool FuseMessage<T, Header>::Read(int fd) {
+template <typename T>
+bool FuseMessage<T>::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 {
+template <typename T>
+bool FuseMessage<T>::Write(int fd) const {
+  const auto& header = static_cast<const T*>(this)->header;
   if (!CheckHeaderLength()) {
     return false;
   }
@@ -65,8 +74,16 @@
   return CheckResult(result, "write");
 }
 
-template struct FuseMessage<FuseRequest, fuse_in_header>;
-template struct FuseMessage<FuseResponse, fuse_out_header>;
+template class FuseMessage<FuseRequest>;
+template class FuseMessage<FuseResponse>;
+
+void FuseRequest::Reset(
+    uint32_t data_length, uint32_t opcode, uint64_t unique) {
+  memset(this, 0, sizeof(fuse_in_header) + data_length);
+  header.len = sizeof(fuse_in_header) + data_length;
+  header.opcode = opcode;
+  header.unique = unique;
+}
 
 void FuseResponse::ResetHeader(
     uint32_t data_length, int32_t error, uint64_t unique) {
@@ -133,4 +150,5 @@
   response.Reset(0, -ENOSYS, unique);
 }
 
+}  // namespace fuse
 }  // namespace android
diff --git a/libappfuse/include/libappfuse/FuseAppLoop.h b/libappfuse/include/libappfuse/FuseAppLoop.h
new file mode 100644
index 0000000..c3edfcc
--- /dev/null
+++ b/libappfuse/include/libappfuse/FuseAppLoop.h
@@ -0,0 +1,44 @@
+/*
+ * 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_FUSEAPPLOOP_H_
+#define ANDROID_LIBAPPFUSE_FUSEAPPLOOP_H_
+
+#include "libappfuse/FuseBuffer.h"
+
+namespace android {
+namespace fuse {
+
+class FuseAppLoopCallback {
+ public:
+  virtual bool IsActive() = 0;
+  virtual int64_t OnGetSize(uint64_t inode) = 0;
+  virtual int32_t OnFsync(uint64_t inode) = 0;
+  virtual int32_t OnWrite(
+      uint64_t inode, uint64_t offset, uint32_t size, const void* data) = 0;
+  virtual int32_t OnRead(
+      uint64_t inode, uint64_t offset, uint32_t size, void* data) = 0;
+  virtual int32_t OnOpen(uint64_t inode) = 0;
+  virtual int32_t OnRelease(uint64_t inode) = 0;
+  virtual ~FuseAppLoopCallback() = default;
+};
+
+bool StartFuseAppLoop(int fd, FuseAppLoopCallback* callback);
+
+}  // namespace fuse
+}  // namespace android
+
+#endif  // ANDROID_LIBAPPFUSE_FUSEAPPLOOP_H_
diff --git a/libappfuse/include/libappfuse/FuseBridgeLoop.h b/libappfuse/include/libappfuse/FuseBridgeLoop.h
index 2006532..38043bc 100644
--- a/libappfuse/include/libappfuse/FuseBridgeLoop.h
+++ b/libappfuse/include/libappfuse/FuseBridgeLoop.h
@@ -21,7 +21,9 @@
 
 namespace android {
 
-class FuseBridgeLoop {
+// TODO: Remove the class after switching to StartFuseBridgeLoop in the
+// framework code.
+class FuseBridgeLoop final {
  public:
   class Callback {
    public:
@@ -30,11 +32,15 @@
   };
 
   bool Start(int dev_fd, int proxy_fd, Callback* callback);
-
- private:
-  FuseBuffer buffer_;
 };
 
+namespace fuse {
+
+class FuseBridgeLoopCallback : public FuseBridgeLoop::Callback {};
+bool StartFuseBridgeLoop(
+    int dev_fd, int proxy_fd, FuseBridgeLoopCallback* callback);
+
+}  // namespace fuse
 }  // namespace android
 
 #endif  // ANDROID_LIBAPPFUSE_FUSEBRIDGELOOP_H_
diff --git a/libappfuse/include/libappfuse/FuseBuffer.h b/libappfuse/include/libappfuse/FuseBuffer.h
index 071b777..e7f620c 100644
--- a/libappfuse/include/libappfuse/FuseBuffer.h
+++ b/libappfuse/include/libappfuse/FuseBuffer.h
@@ -20,6 +20,7 @@
 #include <linux/fuse.h>
 
 namespace android {
+namespace fuse {
 
 // The numbers came from sdcard.c.
 // Maximum number of bytes to write/read in one request/one reply.
@@ -27,9 +28,9 @@
 constexpr size_t kFuseMaxRead = 128 * 1024;
 constexpr int32_t kFuseSuccess = 0;
 
-template<typename T, typename Header>
-struct FuseMessage {
-  Header header;
+template<typename T>
+class FuseMessage {
+ public:
   bool Read(int fd);
   bool Write(int fd) const;
  private:
@@ -37,33 +38,53 @@
   bool CheckResult(int result, const char* operation_name) const;
 };
 
-struct FuseRequest : public FuseMessage<FuseRequest, fuse_in_header> {
+// FuseRequest represents file operation requests from /dev/fuse. It starts
+// from fuse_in_header. The body layout depends on the operation code.
+struct FuseRequest : public FuseMessage<FuseRequest> {
+  fuse_in_header header;
   union {
+    // for FUSE_WRITE
     struct {
       fuse_write_in write_in;
       char write_data[kFuseMaxWrite];
     };
+    // for FUSE_OPEN
     fuse_open_in open_in;
+    // for FUSE_INIT
     fuse_init_in init_in;
+    // for FUSE_READ
     fuse_read_in read_in;
+    // for FUSE_LOOKUP
     char lookup_name[0];
   };
+  void Reset(uint32_t data_length, uint32_t opcode, uint64_t unique);
 };
 
-struct FuseResponse : public FuseMessage<FuseResponse, fuse_out_header> {
+// FuseResponse represents file operation responses to /dev/fuse. It starts
+// from fuse_out_header. The body layout depends on the operation code.
+struct FuseResponse : public FuseMessage<FuseResponse> {
+  fuse_out_header header;
   union {
+    // for FUSE_INIT
     fuse_init_out init_out;
+    // for FUSE_LOOKUP
     fuse_entry_out entry_out;
+    // for FUSE_GETATTR
     fuse_attr_out attr_out;
+    // for FUSE_OPEN
     fuse_open_out open_out;
+    // for FUSE_READ
     char read_data[kFuseMaxRead];
+    // for FUSE_WRITE
     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 {
+// To reduce memory usage, FuseBuffer shares the memory region for request and
+// response.
+union FuseBuffer final {
   FuseRequest request;
   FuseResponse response;
 
@@ -71,19 +92,7 @@
   void HandleNotImpl();
 };
 
-class FuseProxyLoop {
-  class IFuseProxyLoopCallback {
-   public:
-    virtual void OnMount() = 0;
-    virtual ~IFuseProxyLoopCallback() = default;
-  };
-
-  bool Start(int dev_fd, int proxy_fd, IFuseProxyLoopCallback* callback);
-
- private:
-  FuseBuffer buffer_;
-};
-
+}  // namespace fuse
 }  // namespace android
 
 #endif  // ANDROID_LIBAPPFUSE_FUSEBUFFER_H_
diff --git a/libappfuse/tests/FuseAppLoopTest.cc b/libappfuse/tests/FuseAppLoopTest.cc
new file mode 100644
index 0000000..25906cf
--- /dev/null
+++ b/libappfuse/tests/FuseAppLoopTest.cc
@@ -0,0 +1,307 @@
+/*
+ * 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/FuseAppLoop.h"
+
+#include <sys/socket.h>
+
+#include <android-base/logging.h>
+#include <android-base/unique_fd.h>
+#include <gtest/gtest.h>
+#include <thread>
+
+namespace android {
+namespace fuse {
+namespace {
+
+constexpr unsigned int kTestFileSize = 1024;
+
+struct CallbackRequest {
+  uint32_t code;
+  uint64_t inode;
+};
+
+class Callback : public FuseAppLoopCallback {
+ public:
+  std::vector<CallbackRequest> requests;
+
+  bool IsActive() override {
+    return true;
+  }
+
+  int64_t OnGetSize(uint64_t inode) override {
+    if (inode == FUSE_ROOT_ID) {
+      return 0;
+    } else {
+      return kTestFileSize;
+    }
+  }
+
+  int32_t OnFsync(uint64_t inode) override {
+    requests.push_back({
+      .code = FUSE_FSYNC,
+      .inode = inode
+    });
+    return 0;
+  }
+
+  int32_t OnWrite(uint64_t inode,
+                  uint64_t offset ATTRIBUTE_UNUSED,
+                  uint32_t size ATTRIBUTE_UNUSED,
+                  const void* data ATTRIBUTE_UNUSED) override {
+    requests.push_back({
+      .code = FUSE_WRITE,
+      .inode = inode
+    });
+    return 0;
+  }
+
+  int32_t OnRead(uint64_t inode,
+                 uint64_t offset ATTRIBUTE_UNUSED,
+                 uint32_t size ATTRIBUTE_UNUSED,
+                 void* data ATTRIBUTE_UNUSED) override {
+    requests.push_back({
+      .code = FUSE_READ,
+      .inode = inode
+    });
+    return 0;
+  }
+
+  int32_t OnOpen(uint64_t inode) override {
+    requests.push_back({
+      .code = FUSE_OPEN,
+      .inode = inode
+    });
+    return 0;
+  }
+
+  int32_t OnRelease(uint64_t inode) override {
+    requests.push_back({
+      .code = FUSE_RELEASE,
+      .inode = inode
+    });
+    return 0;
+  }
+};
+
+class FuseAppLoopTest : public ::testing::Test {
+ private:
+  std::thread thread_;
+
+ protected:
+  base::unique_fd sockets_[2];
+  Callback callback_;
+  FuseRequest request_;
+  FuseResponse response_;
+
+  void SetUp() override {
+    base::SetMinimumLogSeverity(base::VERBOSE);
+    int sockets[2];
+    ASSERT_EQ(0, socketpair(AF_UNIX, SOCK_SEQPACKET, 0, sockets));
+    sockets_[0].reset(sockets[0]);
+    sockets_[1].reset(sockets[1]);
+    thread_ = std::thread([this] {
+      StartFuseAppLoop(sockets_[1].release(), &callback_);
+    });
+  }
+
+  void CheckCallback(
+      size_t data_size, uint32_t code, size_t expected_out_size) {
+    request_.Reset(data_size, code, 1);
+    request_.header.nodeid = 10;
+
+    ASSERT_TRUE(request_.Write(sockets_[0]));
+    ASSERT_TRUE(response_.Read(sockets_[0]));
+
+    Close();
+
+    EXPECT_EQ(kFuseSuccess, response_.header.error);
+    EXPECT_EQ(sizeof(fuse_out_header) + expected_out_size,
+              response_.header.len);
+    EXPECT_EQ(1u, response_.header.unique);
+
+    ASSERT_EQ(1u, callback_.requests.size());
+    EXPECT_EQ(code, callback_.requests[0].code);
+    EXPECT_EQ(10u, callback_.requests[0].inode);
+  }
+
+  void Close() {
+    sockets_[0].reset();
+    sockets_[1].reset();
+    if (thread_.joinable()) {
+      thread_.join();
+    }
+  }
+
+  void TearDown() override {
+    Close();
+  }
+};
+
+}  // namespace
+
+TEST_F(FuseAppLoopTest, LookUp) {
+  request_.Reset(3u, FUSE_LOOKUP, 1);
+  request_.header.nodeid = FUSE_ROOT_ID;
+  strcpy(request_.lookup_name, "10");
+
+  ASSERT_TRUE(request_.Write(sockets_[0].get()));
+  ASSERT_TRUE(response_.Read(sockets_[0].get()));
+
+  EXPECT_EQ(kFuseSuccess, response_.header.error);
+  EXPECT_EQ(sizeof(fuse_out_header) + sizeof(fuse_entry_out),
+            response_.header.len);
+  EXPECT_EQ(1u, response_.header.unique);
+
+  EXPECT_EQ(10u, response_.entry_out.nodeid);
+  EXPECT_EQ(0u, response_.entry_out.generation);
+  EXPECT_EQ(10u, response_.entry_out.entry_valid);
+  EXPECT_EQ(10u, response_.entry_out.attr_valid);
+  EXPECT_EQ(0u, response_.entry_out.entry_valid_nsec);
+  EXPECT_EQ(0u, response_.entry_out.attr_valid_nsec);
+
+  EXPECT_EQ(10u, response_.entry_out.attr.ino);
+  EXPECT_EQ(kTestFileSize, response_.entry_out.attr.size);
+  EXPECT_EQ(0u, response_.entry_out.attr.blocks);
+  EXPECT_EQ(0u, response_.entry_out.attr.atime);
+  EXPECT_EQ(0u, response_.entry_out.attr.mtime);
+  EXPECT_EQ(0u, response_.entry_out.attr.ctime);
+  EXPECT_EQ(0u, response_.entry_out.attr.atimensec);
+  EXPECT_EQ(0u, response_.entry_out.attr.mtimensec);
+  EXPECT_EQ(0u, response_.entry_out.attr.ctimensec);
+  EXPECT_EQ(S_IFREG | 0777u, response_.entry_out.attr.mode);
+  EXPECT_EQ(0u, response_.entry_out.attr.nlink);
+  EXPECT_EQ(0u, response_.entry_out.attr.uid);
+  EXPECT_EQ(0u, response_.entry_out.attr.gid);
+  EXPECT_EQ(0u, response_.entry_out.attr.rdev);
+  EXPECT_EQ(0u, response_.entry_out.attr.blksize);
+  EXPECT_EQ(0u, response_.entry_out.attr.padding);
+}
+
+TEST_F(FuseAppLoopTest, LookUp_InvalidName) {
+  request_.Reset(3u, FUSE_LOOKUP, 1);
+  request_.header.nodeid = FUSE_ROOT_ID;
+  strcpy(request_.lookup_name, "aa");
+
+  ASSERT_TRUE(request_.Write(sockets_[0].get()));
+  ASSERT_TRUE(response_.Read(sockets_[0].get()));
+
+  EXPECT_EQ(sizeof(fuse_out_header), response_.header.len);
+  EXPECT_EQ(-ENOENT, response_.header.error);
+  EXPECT_EQ(1u, response_.header.unique);
+}
+
+TEST_F(FuseAppLoopTest, LookUp_TooLargeName) {
+  request_.Reset(21u, FUSE_LOOKUP, 1);
+  request_.header.nodeid = FUSE_ROOT_ID;
+  strcpy(request_.lookup_name, "18446744073709551616");
+
+  ASSERT_TRUE(request_.Write(sockets_[0].get()));
+  ASSERT_TRUE(response_.Read(sockets_[0].get()));
+
+  EXPECT_EQ(sizeof(fuse_out_header), response_.header.len);
+  EXPECT_EQ(-ENOENT, response_.header.error);
+  EXPECT_EQ(1u, response_.header.unique);
+}
+
+TEST_F(FuseAppLoopTest, GetAttr) {
+  request_.Reset(sizeof(fuse_getattr_in), FUSE_GETATTR, 1);
+  request_.header.nodeid = 10;
+
+  ASSERT_TRUE(request_.Write(sockets_[0].get()));
+  ASSERT_TRUE(response_.Read(sockets_[0].get()));
+
+  EXPECT_EQ(kFuseSuccess, response_.header.error);
+  EXPECT_EQ(sizeof(fuse_out_header) + sizeof(fuse_attr_out),
+            response_.header.len);
+  EXPECT_EQ(1u, response_.header.unique);
+
+  EXPECT_EQ(10u, response_.attr_out.attr_valid);
+  EXPECT_EQ(0u, response_.attr_out.attr_valid_nsec);
+
+  EXPECT_EQ(10u, response_.attr_out.attr.ino);
+  EXPECT_EQ(kTestFileSize, response_.attr_out.attr.size);
+  EXPECT_EQ(0u, response_.attr_out.attr.blocks);
+  EXPECT_EQ(0u, response_.attr_out.attr.atime);
+  EXPECT_EQ(0u, response_.attr_out.attr.mtime);
+  EXPECT_EQ(0u, response_.attr_out.attr.ctime);
+  EXPECT_EQ(0u, response_.attr_out.attr.atimensec);
+  EXPECT_EQ(0u, response_.attr_out.attr.mtimensec);
+  EXPECT_EQ(0u, response_.attr_out.attr.ctimensec);
+  EXPECT_EQ(S_IFREG | 0777u, response_.attr_out.attr.mode);
+  EXPECT_EQ(0u, response_.attr_out.attr.nlink);
+  EXPECT_EQ(0u, response_.attr_out.attr.uid);
+  EXPECT_EQ(0u, response_.attr_out.attr.gid);
+  EXPECT_EQ(0u, response_.attr_out.attr.rdev);
+  EXPECT_EQ(0u, response_.attr_out.attr.blksize);
+  EXPECT_EQ(0u, response_.attr_out.attr.padding);
+}
+
+TEST_F(FuseAppLoopTest, GetAttr_Root) {
+  request_.Reset(sizeof(fuse_getattr_in), FUSE_GETATTR, 1);
+  request_.header.nodeid = FUSE_ROOT_ID;
+
+  ASSERT_TRUE(request_.Write(sockets_[0].get()));
+  ASSERT_TRUE(response_.Read(sockets_[0].get()));
+
+  EXPECT_EQ(kFuseSuccess, response_.header.error);
+  EXPECT_EQ(sizeof(fuse_out_header) + sizeof(fuse_attr_out),
+            response_.header.len);
+  EXPECT_EQ(1u, response_.header.unique);
+
+  EXPECT_EQ(10u, response_.attr_out.attr_valid);
+  EXPECT_EQ(0u, response_.attr_out.attr_valid_nsec);
+
+  EXPECT_EQ(static_cast<unsigned>(FUSE_ROOT_ID), response_.attr_out.attr.ino);
+  EXPECT_EQ(0u, response_.attr_out.attr.size);
+  EXPECT_EQ(0u, response_.attr_out.attr.blocks);
+  EXPECT_EQ(0u, response_.attr_out.attr.atime);
+  EXPECT_EQ(0u, response_.attr_out.attr.mtime);
+  EXPECT_EQ(0u, response_.attr_out.attr.ctime);
+  EXPECT_EQ(0u, response_.attr_out.attr.atimensec);
+  EXPECT_EQ(0u, response_.attr_out.attr.mtimensec);
+  EXPECT_EQ(0u, response_.attr_out.attr.ctimensec);
+  EXPECT_EQ(S_IFDIR | 0777u, response_.attr_out.attr.mode);
+  EXPECT_EQ(0u, response_.attr_out.attr.nlink);
+  EXPECT_EQ(0u, response_.attr_out.attr.uid);
+  EXPECT_EQ(0u, response_.attr_out.attr.gid);
+  EXPECT_EQ(0u, response_.attr_out.attr.rdev);
+  EXPECT_EQ(0u, response_.attr_out.attr.blksize);
+  EXPECT_EQ(0u, response_.attr_out.attr.padding);
+}
+
+TEST_F(FuseAppLoopTest, Open) {
+  CheckCallback(sizeof(fuse_open_in), FUSE_OPEN, sizeof(fuse_open_out));
+}
+
+TEST_F(FuseAppLoopTest, Fsync) {
+  CheckCallback(0u, FUSE_FSYNC, 0u);
+}
+
+TEST_F(FuseAppLoopTest, Release) {
+  CheckCallback(0u, FUSE_RELEASE, 0u);
+}
+
+TEST_F(FuseAppLoopTest, Read) {
+  CheckCallback(sizeof(fuse_read_in), FUSE_READ, 0u);
+}
+
+TEST_F(FuseAppLoopTest, Write) {
+  CheckCallback(sizeof(fuse_write_in), FUSE_WRITE, sizeof(fuse_write_out));
+}
+
+}  // namespace fuse
+}  // namespace android
diff --git a/libappfuse/tests/FuseBridgeLoopTest.cc b/libappfuse/tests/FuseBridgeLoopTest.cc
index 31e3690..bd503eb 100644
--- a/libappfuse/tests/FuseBridgeLoopTest.cc
+++ b/libappfuse/tests/FuseBridgeLoopTest.cc
@@ -21,11 +21,15 @@
 #include <sstream>
 #include <thread>
 
+#include <android-base/logging.h>
+#include <android-base/unique_fd.h>
 #include <gtest/gtest.h>
 
 namespace android {
+namespace fuse {
+namespace {
 
-class Callback : public FuseBridgeLoop::Callback {
+class Callback : public FuseBridgeLoopCallback {
  public:
   bool mounted;
   Callback() : mounted(false) {}
@@ -36,20 +40,28 @@
 
 class FuseBridgeLoopTest : public ::testing::Test {
  protected:
-  int dev_sockets_[2];
-  int proxy_sockets_[2];
+  base::unique_fd dev_sockets_[2];
+  base::unique_fd proxy_sockets_[2];
   Callback callback_;
   std::thread thread_;
 
   FuseRequest request_;
   FuseResponse response_;
 
-  void SetUp() {
-    ASSERT_EQ(0, socketpair(AF_UNIX, SOCK_SEQPACKET, 0, dev_sockets_));
-    ASSERT_EQ(0, socketpair(AF_UNIX, SOCK_SEQPACKET, 0, proxy_sockets_));
+  void SetUp() override {
+    base::SetMinimumLogSeverity(base::VERBOSE);
+    int dev_sockets[2];
+    int proxy_sockets[2];
+    ASSERT_EQ(0, socketpair(AF_UNIX, SOCK_SEQPACKET, 0, dev_sockets));
+    ASSERT_EQ(0, socketpair(AF_UNIX, SOCK_SEQPACKET, 0, proxy_sockets));
+    dev_sockets_[0].reset(dev_sockets[0]);
+    dev_sockets_[1].reset(dev_sockets[1]);
+    proxy_sockets_[0].reset(proxy_sockets[0]);
+    proxy_sockets_[1].reset(proxy_sockets[1]);
+
     thread_ = std::thread([this] {
-      FuseBridgeLoop loop;
-      loop.Start(dev_sockets_[1], proxy_sockets_[0], &callback_);
+      StartFuseBridgeLoop(
+          dev_sockets_[1].release(), proxy_sockets_[0].release(), &callback_);
     });
   }
 
@@ -103,20 +115,22 @@
   }
 
   void Close() {
-    close(dev_sockets_[0]);
-    close(dev_sockets_[1]);
-    close(proxy_sockets_[0]);
-    close(proxy_sockets_[1]);
+    dev_sockets_[0].reset();
+    dev_sockets_[1].reset();
+    proxy_sockets_[0].reset();
+    proxy_sockets_[1].reset();
     if (thread_.joinable()) {
       thread_.join();
     }
   }
 
-  void TearDown() {
+  void TearDown() override {
     Close();
   }
 };
 
+} //  namespace
+
 TEST_F(FuseBridgeLoopTest, FuseInit) {
   SendInitRequest(1u);
 
@@ -156,11 +170,11 @@
   CheckNotImpl(FUSE_RENAME);
   CheckNotImpl(FUSE_LINK);
   CheckNotImpl(FUSE_STATFS);
-  CheckNotImpl(FUSE_FSYNC);
   CheckNotImpl(FUSE_SETXATTR);
   CheckNotImpl(FUSE_GETXATTR);
   CheckNotImpl(FUSE_LISTXATTR);
   CheckNotImpl(FUSE_REMOVEXATTR);
+  CheckNotImpl(FUSE_FLUSH);
   CheckNotImpl(FUSE_OPENDIR);
   CheckNotImpl(FUSE_READDIR);
   CheckNotImpl(FUSE_RELEASEDIR);
@@ -190,7 +204,8 @@
   CheckProxy(FUSE_READ);
   CheckProxy(FUSE_WRITE);
   CheckProxy(FUSE_RELEASE);
-  CheckProxy(FUSE_FLUSH);
+  CheckProxy(FUSE_FSYNC);
 }
 
-}  // android
+}  // namespace fuse
+}  // namespace android
diff --git a/libappfuse/tests/FuseBufferTest.cc b/libappfuse/tests/FuseBufferTest.cc
index 1aacfe3..17f1306 100644
--- a/libappfuse/tests/FuseBufferTest.cc
+++ b/libappfuse/tests/FuseBufferTest.cc
@@ -24,6 +24,7 @@
 #include <gtest/gtest.h>
 
 namespace android {
+namespace fuse {
 
 constexpr char kTempFile[] = "/data/local/tmp/appfuse_test_dump";
 
@@ -183,5 +184,6 @@
   ASSERT_EQ(sizeof(fuse_out_header), buffer.response.header.len);
   EXPECT_EQ(-ENOSYS, buffer.response.header.error);
 }
-}
-  // namespace android
+
+} // namespace fuse
+} // namespace android
diff --git a/libprocinfo/.clang-format b/libprocinfo/.clang-format
new file mode 100644
index 0000000..b8c6428
--- /dev/null
+++ b/libprocinfo/.clang-format
@@ -0,0 +1,14 @@
+BasedOnStyle: Google
+AllowShortBlocksOnASingleLine: false
+AllowShortFunctionsOnASingleLine: false
+
+ColumnLimit: 100
+CommentPragmas: NOLINT:.*
+DerivePointerAlignment: false
+IndentWidth: 2
+PointerAlignment: Left
+TabWidth: 2
+UseTab: Never
+PenaltyExcessCharacter: 32
+
+Cpp11BracedListStyle: false
diff --git a/libprocinfo/Android.bp b/libprocinfo/Android.bp
new file mode 100644
index 0000000..8e17f1b
--- /dev/null
+++ b/libprocinfo/Android.bp
@@ -0,0 +1,73 @@
+//
+// Copyright (C) 2015 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 specific language governing permissions and
+// limitations under the License.
+//
+
+libprocinfo_cppflags = [
+    "-Wall",
+    "-Wextra",
+    "-Werror",
+]
+
+cc_library {
+    name: "libprocinfo",
+    host_supported: true,
+    srcs: [
+        "process.cpp",
+    ],
+    cppflags: libprocinfo_cppflags,
+
+    local_include_dirs: ["include"],
+    export_include_dirs: ["include"],
+    shared_libs: ["libbase"],
+    target: {
+        darwin: {
+            enabled: false,
+        },
+        windows: {
+            enabled: false,
+        },
+    },
+}
+
+// Tests
+// ------------------------------------------------------------------------------
+cc_test {
+    name: "libprocinfo_test",
+    host_supported: true,
+    srcs: [
+        "process_test.cpp",
+    ],
+    target: {
+        darwin: {
+            enabled: false,
+        },
+        windows: {
+            enabled: false,
+        },
+    },
+
+    cppflags: libprocinfo_cppflags,
+    shared_libs: ["libbase", "libprocinfo"],
+
+    compile_multilib: "both",
+    multilib: {
+        lib32: {
+            suffix: "32",
+        },
+        lib64: {
+            suffix: "64",
+        },
+    },
+}
diff --git a/libprocinfo/include/procinfo/process.h b/libprocinfo/include/procinfo/process.h
new file mode 100644
index 0000000..fb140ff
--- /dev/null
+++ b/libprocinfo/include/procinfo/process.h
@@ -0,0 +1,106 @@
+/*
+ * 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 specific language governing permissions and
+ * limitations under the License.
+ */
+
+#pragma once
+
+#include <dirent.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include <memory>
+#include <string>
+#include <type_traits>
+
+#include <android-base/logging.h>
+#include <android-base/parseint.h>
+#include <android-base/unique_fd.h>
+
+namespace android {
+namespace procinfo {
+
+#if defined(__linux__)
+
+struct ProcessInfo {
+  std::string name;
+  pid_t tid;
+  pid_t pid;
+  pid_t ppid;
+  pid_t tracer;
+  uid_t uid;
+  uid_t gid;
+};
+
+// Parse the contents of /proc/<tid>/status into |process_info|.
+bool GetProcessInfo(pid_t tid, ProcessInfo* process_info);
+
+// Parse the contents of <fd>/status into |process_info|.
+// |fd| should be an fd pointing at a /proc/<pid> directory.
+bool GetProcessInfoFromProcPidFd(int fd, ProcessInfo* process_info);
+
+// Fetch the list of threads from a given process's /proc/<pid> directory.
+// |fd| should be an fd pointing at a /proc/<pid> directory.
+template <typename Collection>
+auto GetProcessTidsFromProcPidFd(int fd, Collection* out) ->
+    typename std::enable_if<sizeof(typename Collection::value_type) >= sizeof(pid_t), bool>::type {
+  out->clear();
+
+  int task_fd = openat(fd, "task", O_DIRECTORY | O_RDONLY | O_CLOEXEC);
+  std::unique_ptr<DIR, int (*)(DIR*)> dir(fdopendir(task_fd), closedir);
+  if (!dir) {
+    PLOG(ERROR) << "failed to open task directory";
+    return false;
+  }
+
+  struct dirent* dent;
+  while ((dent = readdir(dir.get()))) {
+    if (strcmp(dent->d_name, ".") != 0 && strcmp(dent->d_name, "..") != 0) {
+      pid_t tid;
+      if (!android::base::ParseInt(dent->d_name, &tid, 1, std::numeric_limits<pid_t>::max())) {
+        LOG(ERROR) << "failed to parse task id: " << dent->d_name;
+        return false;
+      }
+
+      out->insert(out->end(), tid);
+    }
+  }
+
+  return true;
+}
+
+template <typename Collection>
+auto GetProcessTids(pid_t pid, Collection* out) ->
+    typename std::enable_if<sizeof(typename Collection::value_type) >= sizeof(pid_t), bool>::type {
+  char task_path[PATH_MAX];
+  if (snprintf(task_path, PATH_MAX, "/proc/%d", pid) >= PATH_MAX) {
+    LOG(ERROR) << "task path overflow (pid = " << pid << ")";
+    return false;
+  }
+
+  android::base::unique_fd fd(open(task_path, O_DIRECTORY | O_RDONLY | O_CLOEXEC));
+  if (fd == -1) {
+    PLOG(ERROR) << "failed to open " << task_path;
+    return false;
+  }
+
+  return GetProcessTidsFromProcPidFd(fd.get(), out);
+}
+
+#endif
+
+} /* namespace procinfo */
+} /* namespace android */
diff --git a/libprocinfo/process.cpp b/libprocinfo/process.cpp
new file mode 100644
index 0000000..c513e16
--- /dev/null
+++ b/libprocinfo/process.cpp
@@ -0,0 +1,109 @@
+/*
+ * 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 specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <procinfo/process.h>
+
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+#include <string>
+
+#include <android-base/unique_fd.h>
+
+using android::base::unique_fd;
+
+namespace android {
+namespace procinfo {
+
+bool GetProcessInfo(pid_t tid, ProcessInfo* process_info) {
+  char path[PATH_MAX];
+  snprintf(path, sizeof(path), "/proc/%d", tid);
+
+  unique_fd dirfd(open(path, O_DIRECTORY | O_RDONLY));
+  if (dirfd == -1) {
+    PLOG(ERROR) << "failed to open " << path;
+    return false;
+  }
+
+  return GetProcessInfoFromProcPidFd(dirfd.get(), process_info);
+}
+
+bool GetProcessInfoFromProcPidFd(int fd, ProcessInfo* process_info) {
+  int status_fd = openat(fd, "status", O_RDONLY | O_CLOEXEC);
+
+  if (status_fd == -1) {
+    PLOG(ERROR) << "failed to open status fd in GetProcessInfoFromProcPidFd";
+    return false;
+  }
+
+  std::unique_ptr<FILE, decltype(&fclose)> fp(fdopen(status_fd, "r"), fclose);
+  if (!fp) {
+    PLOG(ERROR) << "failed to open status file in GetProcessInfoFromProcPidFd";
+    close(status_fd);
+    return false;
+  }
+
+  int field_bitmap = 0;
+  static constexpr int finished_bitmap = 127;
+  char* line = nullptr;
+  size_t len = 0;
+
+  while (getline(&line, &len, fp.get()) != -1 && field_bitmap != finished_bitmap) {
+    char* tab = strchr(line, '\t');
+    if (tab == nullptr) {
+      continue;
+    }
+
+    size_t header_len = tab - line;
+    std::string header = std::string(line, header_len);
+    if (header == "Name:") {
+      std::string name = line + header_len + 1;
+
+      // line includes the trailing newline.
+      name.pop_back();
+      process_info->name = std::move(name);
+
+      field_bitmap |= 1;
+    } else if (header == "Pid:") {
+      process_info->tid = atoi(tab + 1);
+      field_bitmap |= 2;
+    } else if (header == "Tgid:") {
+      process_info->pid = atoi(tab + 1);
+      field_bitmap |= 4;
+    } else if (header == "PPid:") {
+      process_info->ppid = atoi(tab + 1);
+      field_bitmap |= 8;
+    } else if (header == "TracerPid:") {
+      process_info->tracer = atoi(tab + 1);
+      field_bitmap |= 16;
+    } else if (header == "Uid:") {
+      process_info->uid = atoi(tab + 1);
+      field_bitmap |= 32;
+    } else if (header == "Gid:") {
+      process_info->gid = atoi(tab + 1);
+      field_bitmap |= 64;
+    }
+  }
+
+  free(line);
+  return field_bitmap == finished_bitmap;
+}
+
+} /* namespace procinfo */
+} /* namespace android */
diff --git a/libprocinfo/process_test.cpp b/libprocinfo/process_test.cpp
new file mode 100644
index 0000000..5ffd236
--- /dev/null
+++ b/libprocinfo/process_test.cpp
@@ -0,0 +1,84 @@
+/*
+ * 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 specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <procinfo/process.h>
+
+#include <fcntl.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include <set>
+#include <thread>
+#include <vector>
+
+#include <gtest/gtest.h>
+
+#include <android-base/stringprintf.h>
+
+#if !defined(__BIONIC__)
+#include <syscall.h>
+static pid_t gettid() {
+  return syscall(__NR_gettid);
+}
+#endif
+
+TEST(process_info, process_info_smoke) {
+  android::procinfo::ProcessInfo self;
+  ASSERT_TRUE(android::procinfo::GetProcessInfo(gettid(), &self));
+  ASSERT_EQ(gettid(), self.tid);
+  ASSERT_EQ(getpid(), self.pid);
+  ASSERT_EQ(getppid(), self.ppid);
+  ASSERT_EQ(getuid(), self.uid);
+  ASSERT_EQ(getgid(), self.gid);
+}
+
+TEST(process_info, process_info_proc_pid_fd_smoke) {
+  android::procinfo::ProcessInfo self;
+  int fd = open(android::base::StringPrintf("/proc/%d", gettid()).c_str(), O_DIRECTORY | O_RDONLY);
+  ASSERT_NE(-1, fd);
+  ASSERT_TRUE(android::procinfo::GetProcessInfoFromProcPidFd(fd, &self));
+
+  // Process name is capped at 15 bytes.
+  ASSERT_EQ("libprocinfo_tes", self.name);
+  ASSERT_EQ(gettid(), self.tid);
+  ASSERT_EQ(getpid(), self.pid);
+  ASSERT_EQ(getppid(), self.ppid);
+  ASSERT_EQ(getuid(), self.uid);
+  ASSERT_EQ(getgid(), self.gid);
+  close(fd);
+}
+
+TEST(process_info, process_tids_smoke) {
+  pid_t main_tid = gettid();
+  std::thread([main_tid]() {
+    pid_t thread_tid = gettid();
+
+    {
+      std::vector<pid_t> vec;
+      ASSERT_TRUE(android::procinfo::GetProcessTids(getpid(), &vec));
+      ASSERT_EQ(1, std::count(vec.begin(), vec.end(), main_tid));
+      ASSERT_EQ(1, std::count(vec.begin(), vec.end(), thread_tid));
+    }
+
+    {
+      std::set<pid_t> set;
+      ASSERT_TRUE(android::procinfo::GetProcessTids(getpid(), &set));
+      ASSERT_EQ(1, std::count(set.begin(), set.end(), main_tid));
+      ASSERT_EQ(1, std::count(set.begin(), set.end(), thread_tid));
+    }
+  }).join();
+}