Revert "adb: don't close sockets before hitting EOF."

This reverts commit ffc11d3cf3643c24780f902386be61851531f022.

Reason for revert: DeviceIdleFreqCheckTest failing

Bug: http://b/117630047
Change-Id: Ia51a4a30e785bc5b2526695de3f442aac298198f
diff --git a/adb/Android.bp b/adb/Android.bp
index 7f82ca6..bccc71a 100644
--- a/adb/Android.bp
+++ b/adb/Android.bp
@@ -24,7 +24,6 @@
         "-Wno-missing-field-initializers",
         "-Wvla",
     ],
-    cpp_std: "gnu++17",
     rtti: true,
 
     use_version_lib: true,
diff --git a/adb/sockets.cpp b/adb/sockets.cpp
index dfd9a0a..1534792 100644
--- a/adb/sockets.cpp
+++ b/adb/sockets.cpp
@@ -26,14 +26,10 @@
 #include <unistd.h>
 
 #include <algorithm>
-#include <map>
 #include <mutex>
 #include <string>
-#include <thread>
 #include <vector>
 
-#include <android-base/thread_annotations.h>
-
 #if !ADB_HOST
 #include <android-base/properties.h>
 #include <log/log_properties.h>
@@ -41,150 +37,9 @@
 
 #include "adb.h"
 #include "adb_io.h"
-#include "adb_utils.h"
-#include "sysdeps/chrono.h"
 #include "transport.h"
 #include "types.h"
 
-// The standard (RFC 1122 - 4.2.2.13) says that if we call close on a
-// socket while we have pending data, a TCP RST should be sent to the
-// other end to notify it that we didn't read all of its data. However,
-// this can result in data that we've successfully written out to be dropped
-// on the other end. To avoid this, instead of immediately closing a
-// socket, call shutdown on it instead, and then read from the file
-// descriptor until we hit EOF or an error before closing.
-struct LingeringSocketCloser {
-    LingeringSocketCloser() = default;
-    ~LingeringSocketCloser() = delete;
-
-    // Defer thread creation until it's needed, because we need for there to
-    // only be one thread when dropping privileges in adbd.
-    void Start() {
-        CHECK(!thread_.joinable());
-
-        int fds[2];
-        if (adb_socketpair(fds) != 0) {
-            PLOG(FATAL) << "adb_socketpair failed";
-        }
-
-        set_file_block_mode(fds[0], false);
-        set_file_block_mode(fds[1], false);
-
-        notify_fd_read_.reset(fds[0]);
-        notify_fd_write_.reset(fds[1]);
-
-        thread_ = std::thread([this]() { Run(); });
-    }
-
-    void EnqueueSocket(unique_fd socket) {
-        // Shutdown the socket in the outgoing direction only, so that
-        // we don't have the same problem on the opposite end.
-        adb_shutdown(socket.get(), SHUT_WR);
-        set_file_block_mode(socket.get(), false);
-
-        std::lock_guard<std::mutex> lock(mutex_);
-        int fd = socket.get();
-        SocketInfo info = {
-                .fd = std::move(socket),
-                .deadline = std::chrono::steady_clock::now() + 1s,
-        };
-
-        D("LingeringSocketCloser received fd %d", fd);
-
-        fds_.emplace(fd, std::move(info));
-        if (adb_write(notify_fd_write_, "", 1) == -1 && errno != EAGAIN) {
-            PLOG(FATAL) << "failed to write to LingeringSocketCloser notify fd";
-        }
-    }
-
-  private:
-    std::vector<adb_pollfd> GeneratePollFds() {
-        std::lock_guard<std::mutex> lock(mutex_);
-        std::vector<adb_pollfd> result;
-        result.push_back(adb_pollfd{.fd = notify_fd_read_, .events = POLLIN});
-        for (auto& [fd, _] : fds_) {
-            result.push_back(adb_pollfd{.fd = fd, .events = POLLIN});
-        }
-        return result;
-    }
-
-    void Run() {
-        while (true) {
-            std::vector<adb_pollfd> pfds = GeneratePollFds();
-            int rc = adb_poll(pfds.data(), pfds.size(), 1000);
-            if (rc == -1) {
-                PLOG(FATAL) << "poll failed in LingeringSocketCloser";
-            }
-
-            std::lock_guard<std::mutex> lock(mutex_);
-            if (rc == 0) {
-                // Check deadlines.
-                auto now = std::chrono::steady_clock::now();
-                for (auto it = fds_.begin(); it != fds_.end();) {
-                    if (now > it->second.deadline) {
-                        D("LingeringSocketCloser closing fd %d due to deadline", it->first);
-                        it = fds_.erase(it);
-                    } else {
-                        D("deadline still not expired for fd %d", it->first);
-                        ++it;
-                    }
-                }
-                continue;
-            }
-
-            for (auto& pfd : pfds) {
-                if ((pfd.revents & POLLIN) == 0) {
-                    continue;
-                }
-
-                // Empty the fd.
-                ssize_t rc;
-                char buf[32768];
-                while ((rc = adb_read(pfd.fd, buf, sizeof(buf))) > 0) {
-                    continue;
-                }
-
-                if (pfd.fd == notify_fd_read_) {
-                    continue;
-                }
-
-                auto it = fds_.find(pfd.fd);
-                if (it == fds_.end()) {
-                    LOG(FATAL) << "fd is missing";
-                }
-
-                if (rc == -1 && errno == EAGAIN) {
-                    if (std::chrono::steady_clock::now() > it->second.deadline) {
-                        D("LingeringSocketCloser closing fd %d due to deadline", pfd.fd);
-                    } else {
-                        continue;
-                    }
-                } else if (rc == -1) {
-                    D("LingeringSocketCloser closing fd %d due to error %d", pfd.fd, errno);
-                } else {
-                    D("LingeringSocketCloser closing fd %d due to EOF", pfd.fd);
-                }
-
-                fds_.erase(it);
-            }
-        }
-    }
-
-    std::thread thread_;
-    unique_fd notify_fd_read_;
-    unique_fd notify_fd_write_;
-
-    struct SocketInfo {
-        unique_fd fd;
-        std::chrono::steady_clock::time_point deadline;
-    };
-
-    std::mutex mutex_;
-    std::map<int, SocketInfo> fds_ GUARDED_BY(mutex_);
-};
-
-static auto& socket_closer = *new LingeringSocketCloser();
-
 static std::recursive_mutex& local_socket_list_lock = *new std::recursive_mutex();
 static unsigned local_socket_next_id = 1;
 
@@ -388,12 +243,10 @@
 
     D("LS(%d): destroying fde.fd=%d", s->id, s->fd);
 
-    // Defer thread creation until it's needed, because we need for there to
-    // only be one thread when dropping privileges in adbd.
-    static std::once_flag once;
-    std::call_once(once, []() { socket_closer.Start(); });
-
-    socket_closer.EnqueueSocket(fdevent_release(s->fde));
+    /* IMPORTANT: the remove closes the fd
+    ** that belongs to this socket
+    */
+    fdevent_destroy(s->fde);
 
     remove_socket(s);
     delete s;
diff --git a/adb/test_device.py b/adb/test_device.py
index 4c45a73..c3166ff 100755
--- a/adb/test_device.py
+++ b/adb/test_device.py
@@ -35,8 +35,6 @@
 import time
 import unittest
 
-from datetime import datetime
-
 import adb
 
 def requires_root(func):
@@ -1337,63 +1335,6 @@
             self.device.forward_remove("tcp:{}".format(local_port))
 
 
-class SocketTest(DeviceTest):
-    def test_socket_flush(self):
-        """Test that we handle socket closure properly.
-
-        If we're done writing to a socket, closing before the other end has
-        closed will send a TCP_RST if we have incoming data queued up, which
-        may result in data that we've written being discarded.
-
-        Bug: http://b/74616284
-        """
-        s = socket.create_connection(("localhost", 5037))
-
-        def adb_length_prefixed(string):
-            encoded = string.encode("utf8")
-            result = b"%04x%s" % (len(encoded), encoded)
-            return result
-
-        if "ANDROID_SERIAL" in os.environ:
-            transport_string = "host:transport:" + os.environ["ANDROID_SERIAL"]
-        else:
-            transport_string = "host:transport-any"
-
-        s.sendall(adb_length_prefixed(transport_string))
-        response = s.recv(4)
-        self.assertEquals(b"OKAY", response)
-
-        shell_string = "shell:sleep 0.5; dd if=/dev/zero bs=1m count=1 status=none; echo foo"
-        s.sendall(adb_length_prefixed(shell_string))
-
-        response = s.recv(4)
-        self.assertEquals(b"OKAY", response)
-
-        # Spawn a thread that dumps garbage into the socket until failure.
-        def spam():
-            buf = b"\0" * 16384
-            try:
-                while True:
-                    s.sendall(buf)
-            except Exception as ex:
-                print(ex)
-
-        thread = threading.Thread(target=spam)
-        thread.start()
-
-        time.sleep(1)
-
-        received = b""
-        while True:
-            read = s.recv(512)
-            if len(read) == 0:
-                break
-            received += read
-
-        self.assertEquals(1024 * 1024 + len("foo\n"), len(received))
-        thread.join()
-
-
 if sys.platform == "win32":
     # From https://stackoverflow.com/a/38749458
     import os