From 5aec6d6f62373af7d8312e07267be366dbdc96e8 Mon Sep 17 00:00:00 2001
From: Lasan Mahaliyana <limahaliyana@gmail.com>
Date: Sat, 20 Jun 2026 10:52:08 +0530
Subject: [PATCH] added IPC server

---
 sharing/linux/daemon/BUILD              |  20 ++
 sharing/linux/daemon/ipc_server.cc      | 160 ++++++++++++++
 sharing/linux/daemon/ipc_server.h       |  44 ++++
 sharing/linux/daemon/ipc_server_test.cc | 279 ++++++++++++++++++++++++
 sharing/linux/daemon/main.cc            |  52 +++++
 sharing/linux/daemon/main.h             |  45 ++++
 6 files changed, 600 insertions(+)
 create mode 100644 sharing/linux/daemon/BUILD
 create mode 100644 sharing/linux/daemon/ipc_server.cc
 create mode 100644 sharing/linux/daemon/ipc_server.h
 create mode 100644 sharing/linux/daemon/ipc_server_test.cc
 create mode 100644 sharing/linux/daemon/main.cc
 create mode 100644 sharing/linux/daemon/main.h

diff --git a/sharing/linux/daemon/BUILD b/sharing/linux/daemon/BUILD
new file mode 100644
index 00000000..7fe8b40c
--- /dev/null
+++ b/sharing/linux/daemon/BUILD
@@ -0,0 +1,20 @@
+load("@rules_cc//cc:cc_library.bzl", "cc_library")
+load("@rules_cc//cc:cc_test.bzl", "cc_test")
+
+cc_test(
+    name = "ipc_server_test",
+    srcs = ["ipc_server_test.cc"],
+    deps = [
+        ":ipc_server",
+        "@com_google_googletest//:gtest_main",
+        "@com_google_absl//absl/synchronization",
+    ],
+)
+
+cc_library(
+  name = "ipc_server",
+  hdrs = ["ipc_server.h"],
+  deps = [
+        "@com_google_absl//absl/synchronization",
+  ],
+)
diff --git a/sharing/linux/daemon/ipc_server.cc b/sharing/linux/daemon/ipc_server.cc
new file mode 100644
index 00000000..260ecd97
--- /dev/null
+++ b/sharing/linux/daemon/ipc_server.cc
@@ -0,0 +1,160 @@
+#include "ipc_server.h"
+#include <thread>
+#include <cerrno>
+#include <cstring>
+#include <iostream>
+
+std::string IPCServer::Read() {
+  std::string cmd;
+  absl::MutexLock lock(lock_);
+
+  size_t pos = read_buf.find('\n');
+
+  if (pos != std::string::npos) {
+    cmd = read_buf.substr(0, pos);
+    read_buf.erase(0, pos + 1);
+  }
+
+  return cmd;
+}
+
+void IPCServer::Stop() {
+  running_.store(false);
+
+  if (client_fd_ >= 0) {
+    shutdown(client_fd_, SHUT_RDWR);
+    close(client_fd_);
+    client_fd_ = -1;
+  }
+
+  if (sock_fd_ >= 0) {
+    shutdown(sock_fd_, SHUT_RDWR);
+    close(sock_fd_);
+    sock_fd_ = -1;
+  }
+
+  unlink(SOCK_PATH.data());
+}
+
+void IPCServer::InitialiseSock() {
+  sock_fd_ = socket(AF_UNIX, SOCK_STREAM, 0);
+  if (sock_fd_ == -1) {
+    return;
+  }
+
+  unlink(SOCK_PATH.data());
+
+  memset(&addr, 0, sizeof(addr));
+  addr.sun_family = AF_UNIX;
+  strncpy(addr.sun_path, SOCK_PATH.data(), sizeof(addr.sun_path) - 1);
+
+  if (bind(sock_fd_, reinterpret_cast<sockaddr*>(&addr), sizeof(addr)) == -1) {
+    close(sock_fd_);
+    sock_fd_ = -1;
+    return;
+  }
+
+  if (listen(sock_fd_, 1) == -1) {
+    close(sock_fd_);
+    sock_fd_ = -1;
+    return;
+  }
+}
+void IPCServer::Recv() {
+  while (running_.load()) {
+    pollfd pfd{};
+    pfd.fd = client_fd_;
+    pfd.events = POLLIN;
+
+    int poll_result = poll(&pfd, 1, 100);
+
+    if (!running_.load()) {
+      return;
+    }
+
+    if (poll_result < 0) {
+      if (errno == EINTR) {
+        continue;
+      }
+      return;
+    }
+
+    if (poll_result == 0) {
+      continue;
+    }
+
+    if (pfd.revents & (POLLNVAL | POLLERR)) {
+      return;
+    }
+
+    if (pfd.revents & (POLLIN | POLLHUP)) {
+      char buf[1024]{};
+
+      ssize_t n = recv(client_fd_, buf, sizeof(buf), 0);
+
+      if (n > 0) {
+        absl::MutexLock lock(lock_);
+        read_buf.append(buf, static_cast<size_t>(n));
+        continue;
+      }
+
+      if (n == 0) {
+        return;
+      }
+
+      if (errno == EINTR) {
+        continue;
+      }
+
+      if (errno == EAGAIN || errno == EWOULDBLOCK) {
+        continue;
+      }
+
+      return;
+    }
+  }
+}
+
+void IPCServer::StartEventLoop() {
+  running_.store(true);
+
+  InitialiseSock();
+
+  if (sock_fd_ < 0) {
+    running_.store(false);
+    return;
+  }
+
+  while (running_.load()) {
+    sockaddr_un client_addr{};
+    socklen_t addr_len = sizeof(client_addr);
+
+    int accepted_fd =
+        accept(sock_fd_, reinterpret_cast<sockaddr*>(&client_addr), &addr_len);
+
+    if (!running_.load()) {
+      if (accepted_fd >= 0) {
+        close(accepted_fd);
+      }
+      break;
+    }
+
+    if (accepted_fd < 0) {
+      if (errno == EINTR) {
+        continue;
+      }
+      break;
+    }
+
+    client_fd_ = accepted_fd;
+
+    Recv();
+
+    if (client_fd_ >= 0) {
+      close(client_fd_);
+      client_fd_ = -1;
+    }
+  }
+
+  Stop();
+}
diff --git a/sharing/linux/daemon/ipc_server.h b/sharing/linux/daemon/ipc_server.h
new file mode 100644
index 00000000..2da6cfd9
--- /dev/null
+++ b/sharing/linux/daemon/ipc_server.h
@@ -0,0 +1,44 @@
+#include <atomic>
+#include <string>
+#include <string_view>
+
+#include <poll.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <unistd.h>
+
+#include "absl/synchronization/mutex.h"
+#include "gtest/gtest_prod.h"
+
+constexpr std::string_view SOCK_PATH = "/tmp/nearby_sharing_sock";
+
+class IPCServer {
+ public:
+  IPCServer() = default;
+
+  ~IPCServer() { Stop(); }
+  void Stop();
+  void InitialiseSock();
+  void Recv();
+  void StartEventLoop();
+  std::string Read();
+
+ private:
+  FRIEND_TEST(IPCServerEventLoopTest, ClientCanConnectSendAndServerCanRead);
+  FRIEND_TEST(IPCServerEventLoopTest, ServerCanReadMultipleCommands);
+  FRIEND_TEST(IPCServerEventLoopTest, PartialCommandIsBufferedUntilDelimiter);
+  FRIEND_TEST(IPCServerEventLoopTest, LargeCommandAcrossMultipleRecvCalls);
+  FRIEND_TEST(IPCServerEventLoopTest, MultipleCommandsSplitAcrossSends);
+  FRIEND_TEST(IPCServerEventLoopTest, ClientDisconnectDoesNotCrashServer);
+  FRIEND_TEST(IPCServerEventLoopTest, ClientCanReconnectAfterDisconnect);
+  FRIEND_TEST(IPCServerEventLoopTest, StopEndsEventLoopThread);
+  FRIEND_TEST(IPCServerEventLoopTest, StopWhileClientConnected);
+  FRIEND_TEST(IPCServerEventLoopTest, StaleSocketPathIsCleanedUp);
+
+  int sock_fd_ = -1;
+  int client_fd_ = -1;
+  sockaddr_un addr{};
+  std::string read_buf;
+  absl::Mutex lock_;
+  std::atomic<bool> running_{false};
+};
diff --git a/sharing/linux/daemon/ipc_server_test.cc b/sharing/linux/daemon/ipc_server_test.cc
new file mode 100644
index 00000000..cc9009e8
--- /dev/null
+++ b/sharing/linux/daemon/ipc_server_test.cc
@@ -0,0 +1,279 @@
+#include <gtest/gtest.h>
+
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <unistd.h>
+
+#include <chrono>
+#include <cstring>
+#include <string>
+#include <fstream>
+#include <thread>
+
+#include "ipc_server.h"
+
+namespace {
+
+
+int ConnectClientWithRetry() {
+  int client_fd = socket(AF_UNIX, SOCK_STREAM, 0);
+  EXPECT_GE(client_fd, 0);
+
+  sockaddr_un addr{};
+  addr.sun_family = AF_UNIX;
+  strncpy(addr.sun_path, SOCK_PATH.data(), sizeof(addr.sun_path) - 1);
+
+  for (int i = 0; i < 100; ++i) {
+    int result = connect(
+        client_fd,
+        reinterpret_cast<sockaddr*>(&addr),
+        sizeof(addr));
+
+    if (result == 0) {
+      return client_fd;
+    }
+
+    std::this_thread::sleep_for(std::chrono::milliseconds(10));
+  }
+
+  ADD_FAILURE() << "connect failed: " << strerror(errno);
+  close(client_fd);
+  return -1;
+}
+
+void SendAll(int fd, std::string_view data) {
+  size_t total_sent = 0;
+
+  while (total_sent < data.size()) {
+    ssize_t sent = send(
+        fd,
+        data.data() + total_sent,
+        data.size() - total_sent,
+        0);
+
+    ASSERT_GT(sent, 0) << "send failed: " << strerror(errno);
+
+    total_sent += static_cast<size_t>(sent);
+  }
+}
+
+std::string WaitRead(IPCServer& server) {
+  for (int i = 0; i < 100; ++i) {
+    std::string cmd = server.Read();
+
+    if (!cmd.empty()) {
+      return cmd;
+    }
+
+    std::this_thread::sleep_for(std::chrono::milliseconds(10));
+  }
+
+  return "";
+}
+
+
+void StopAndJoin(IPCServer& server, std::thread& server_thread) {
+  server.Stop();
+
+  if (server_thread.joinable()) {
+    server_thread.join();
+  }
+
+  unlink(SOCK_PATH.data());
+}
+
+TEST(IPCServerEventLoopTest, ServerCanReadMultipleCommands) {
+  IPCServer server;
+
+  std::thread server_thread([&server]() {
+    server.StartEventLoop();
+  });
+
+  int client_fd = ConnectClientWithRetry();
+  ASSERT_GE(client_fd, 0);
+
+  SendAll(client_fd, "A\nB\nC\n");
+
+  EXPECT_EQ(WaitRead(server), "A");
+  EXPECT_EQ(WaitRead(server), "B");
+  EXPECT_EQ(WaitRead(server), "C");
+
+  close(client_fd);
+  StopAndJoin(server, server_thread);
+}
+
+TEST(IPCServerEventLoopTest, PartialCommandIsBufferedUntilDelimiter) {
+  IPCServer server;
+
+  std::thread server_thread([&server]() {
+    server.StartEventLoop();
+  });
+
+  int client_fd = ConnectClientWithRetry();
+  ASSERT_GE(client_fd, 0);
+
+  SendAll(client_fd, "PIN");
+
+  std::this_thread::sleep_for(std::chrono::milliseconds(50));
+
+  EXPECT_EQ(server.Read(), "");
+
+  SendAll(client_fd, "G\n");
+
+  EXPECT_EQ(WaitRead(server), "PING");
+
+  close(client_fd);
+  StopAndJoin(server, server_thread);
+}
+
+TEST(IPCServerEventLoopTest, LargeCommandAcrossMultipleRecvCalls) {
+  IPCServer server;
+
+  std::thread server_thread([&server]() {
+    server.StartEventLoop();
+  });
+
+  int client_fd = ConnectClientWithRetry();
+  ASSERT_GE(client_fd, 0);
+
+  std::string large(8192, 'A');
+  SendAll(client_fd, large + "\n");
+
+  EXPECT_EQ(WaitRead(server), large);
+
+  close(client_fd);
+  StopAndJoin(server, server_thread);
+}
+
+TEST(IPCServerEventLoopTest, MultipleCommandsSplitAcrossSends) {
+  IPCServer server;
+
+  std::thread server_thread([&server]() {
+    server.StartEventLoop();
+  });
+
+  int client_fd = ConnectClientWithRetry();
+  ASSERT_GE(client_fd, 0);
+
+  SendAll(client_fd, "A\nB");
+  std::this_thread::sleep_for(std::chrono::milliseconds(20));
+  SendAll(client_fd, "\nC\n");
+
+  EXPECT_EQ(WaitRead(server), "A");
+  EXPECT_EQ(WaitRead(server), "B");
+  EXPECT_EQ(WaitRead(server), "C");
+
+  close(client_fd);
+  StopAndJoin(server, server_thread);
+}
+
+TEST(IPCServerEventLoopTest, ClientDisconnectDoesNotCrashServer) {
+  IPCServer server;
+
+  std::thread server_thread([&server]() {
+    server.StartEventLoop();
+  });
+
+  int client_fd = ConnectClientWithRetry();
+  ASSERT_GE(client_fd, 0);
+
+  close(client_fd);
+
+  std::this_thread::sleep_for(std::chrono::milliseconds(100));
+
+  // Main expectation: server did not crash/hang.
+  StopAndJoin(server, server_thread);
+
+  SUCCEED();
+}
+
+TEST(IPCServerEventLoopTest, ClientCanReconnectAfterDisconnect) {
+  IPCServer server;
+
+  std::thread server_thread([&server]() {
+    server.StartEventLoop();
+  });
+
+  int client1_fd = ConnectClientWithRetry();
+  ASSERT_GE(client1_fd, 0);
+
+  SendAll(client1_fd, "FIRST\n");
+  EXPECT_EQ(WaitRead(server), "FIRST");
+
+  close(client1_fd);
+
+  std::this_thread::sleep_for(std::chrono::milliseconds(100));
+
+  int client2_fd = ConnectClientWithRetry();
+  ASSERT_GE(client2_fd, 0);
+
+  SendAll(client2_fd, "SECOND\n");
+  EXPECT_EQ(WaitRead(server), "SECOND");
+
+  close(client2_fd);
+  StopAndJoin(server, server_thread);
+}
+
+TEST(IPCServerEventLoopTest, StopEndsEventLoopThread) {
+  IPCServer server;
+
+  std::thread server_thread([&server]() {
+    server.StartEventLoop();
+  });
+
+  std::this_thread::sleep_for(std::chrono::milliseconds(50));
+
+  StopAndJoin(server, server_thread);
+
+  SUCCEED();
+}
+
+TEST(IPCServerEventLoopTest, StopWhileClientConnected) {
+  IPCServer server;
+
+  std::thread server_thread([&server]() {
+    server.StartEventLoop();
+  });
+
+  int client_fd = ConnectClientWithRetry();
+  ASSERT_GE(client_fd, 0);
+
+  SendAll(client_fd, "PING\n");
+  EXPECT_EQ(WaitRead(server), "PING");
+
+  StopAndJoin(server, server_thread);
+
+  close(client_fd);
+
+  SUCCEED();
+}
+
+TEST(IPCServerEventLoopTest, StaleSocketPathIsCleanedUp) {
+  unlink(SOCK_PATH.data());
+
+  {
+    std::ofstream stale_file{SOCK_PATH.data()};
+    stale_file << "stale";
+  }
+
+  struct stat before{};
+  ASSERT_EQ(stat(SOCK_PATH.data(), &before), 0);
+  ASSERT_TRUE(S_ISREG(before.st_mode));
+
+  IPCServer server;
+
+  std::thread server_thread([&server]() {
+    server.StartEventLoop();
+  });
+
+  int client_fd = ConnectClientWithRetry();
+  ASSERT_GE(client_fd, 0);
+
+  struct stat after{};
+  ASSERT_EQ(stat(SOCK_PATH.data(), &after), 0);
+  EXPECT_TRUE(S_ISSOCK(after.st_mode));
+
+  close(client_fd);
+  StopAndJoin(server, server_thread);
+}
+}  // namespace
diff --git a/sharing/linux/daemon/main.cc b/sharing/linux/daemon/main.cc
new file mode 100644
index 00000000..2a4ee706
--- /dev/null
+++ b/sharing/linux/daemon/main.cc
@@ -0,0 +1,52 @@
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <unistd.h>
+#include <string>
+#include <stdio.h>
+#include <string.h>
+#include <errno.h>
+
+constexpr std::string_view sock_path = "/tmp/nearby_sharing.sock";
+
+
+int main() {
+  // should always be waiting on the socket for new connections
+  int retries = 3;
+  while (retries >= 0) {
+    int server_fd;
+    struct sockaddr_un addr;
+
+    server_fd = socket(AF_UNIX, SOCK_STREAM, 0);
+    if (server_fd == -1) {
+      retries--;
+      continue;
+    }
+
+    // removes old socket
+    unlink(sock_path.data());
+
+    memset(&addr, 0, sizeof(addr));
+    addr.sun_family = AF_UNIX;
+    strncpy(addr.sun_path, sock_path.data(), sizeof(addr.sun_path) - 1);
+
+    if (bind(server_fd, (struct sockaddr*)&addr, sizeof(addr)) == -1) {
+      close(server_fd);
+      retries--;
+      continue;
+    }
+
+    if (listen(server_fd, 10) == -1) {
+      close(server_fd);
+      retries--;
+      continue;
+    }
+    socklen_t addr_len = sizeof(addr);
+
+    // blocks till connection is present
+    if (accept(server_fd, (struct sockaddr*)&addr, &addr_len)) {
+      close(server_fd);
+      retries--;
+      continue;
+    }
+  }
+}
diff --git a/sharing/linux/daemon/main.h b/sharing/linux/daemon/main.h
new file mode 100644
index 00000000..aa7a8ec1
--- /dev/null
+++ b/sharing/linux/daemon/main.h
@@ -0,0 +1,45 @@
+#include <signal.h>
+#include <unistd.h>
+
+#include <atomic>
+#include <chrono>
+#include <condition_variable>
+#include <cstdint>
+#include <cstdlib>
+#include <filesystem>
+#include <functional>
+#include <iostream>
+#include <memory>
+#include <mutex>
+#include <optional>
+#include <string>
+#include <system_error>
+#include <utility>
+#include "absl/time/time.h"
+#include "connections/implementation/flags/nearby_connections_feature_flags.h"
+#include "internal/base/file_path.h"
+#include "internal/flags/nearby_flags.h"
+#include "sharing/advertisement.h"
+#include "sharing/attachment_container.h"
+#include "sharing/common/nearby_share_enums.h"
+#include "sharing/file_attachment.h"
+#include "sharing/linux/platform/linux_sharing_platform.h"
+#include "sharing/linux/nearby_noop_analytics_recorder.h"
+#include "sharing/flags/generated/nearby_sharing_feature_flags.h"
+#include "sharing/nearby_sharing_service.h"
+#include "sharing/nearby_sharing_service_factory.h"
+#include "sharing/nearby_sharing_settings.h"
+#include "sharing/share_target.h"
+#include "sharing/share_target_discovered_callback.h"
+#include "sharing/transfer_metadata.h"
+#include "sharing/transfer_update_callback.h"
+#include "sharing/proto/enums.pb.h"
+
+namespace nearby {
+namespace sharing {
+namespace linux {
+
+}
+}  // namespace sharing
+}  // namespace nearby
+