1 files changed, 201 insertions, 0 deletions
diff --git a/third_party/nix/src/nix-daemon/nix-daemon.cc b/third_party/nix/src/nix-daemon/nix-daemon.cc
new file mode 100644
index 0000000000..0551625a3e
--- /dev/null
+++ b/third_party/nix/src/nix-daemon/nix-daemon.cc
@@ -0,0 +1,201 @@
+#include <filesystem>
+
+#include <absl/flags/flag.h>
+#include <absl/flags/parse.h>
+#include <absl/flags/usage_config.h>
+#include <absl/strings/str_format.h>
+#include <fcntl.h>
+#include <glog/logging.h>
+#include <grpcpp/security/server_credentials.h>
+#include <grpcpp/server.h>
+#include <grpcpp/server_builder.h>
+#include <grpcpp/server_posix.h>
+#include <sys/socket.h>
+#include <sys/un.h>
+#include <systemd/sd-daemon.h>
+
+#include "libmain/shared.hh"  // TODO(tazjin): can this be removed?
+#include "libstore/globals.hh"
+#include "libstore/store-api.hh"
+#include "libutil/util.hh"
+#include "nix-daemon-proto.hh"
+#include "nix-daemon/nix-daemon-proto.hh"
+#include "nix/legacy.hh"
+
+ABSL_FLAG(bool, pipe, false, "Use pipes for daemon communication");
+
+namespace nix::daemon {
+
+using grpc::Server;
+using grpc::ServerBuilder;
+
+namespace {
+
+// TODO(grfn): There has to be a better way to do this - this was ported
+// verbatim from the old daemon implementation without much critical evaluation.
+static int ForwardToSocket(nix::Path socket_path) {
+  // Forward on this connection to the real daemon
+  int sockfd = socket(PF_UNIX, SOCK_STREAM, 0);
+  if (sockfd == -1) {
+    throw SysError("creating Unix domain socket");
+  }
+
+  auto socketDir = dirOf(socket_path);
+  if (chdir(socketDir.c_str()) == -1) {
+    throw SysError(format("changing to socket directory '%1%'") % socketDir);
+  }
+
+  auto socketName = baseNameOf(socket_path);
+  auto addr = sockaddr_un{};
+  addr.sun_family = AF_UNIX;
+  if (socketName.size() + 1 >= sizeof(addr.sun_path)) {
+    throw Error(format("socket name %1% is too long") % socketName);
+  }
+  strncpy(addr.sun_path, socketName.c_str(), sizeof(addr.sun_family));
+
+  if (connect(sockfd, reinterpret_cast<struct sockaddr*>(&addr),
+              sizeof(addr)) == -1) {
+    throw SysError(format("cannot connect to daemon at %1%") % socket_path);
+  }
+
+  auto nfds = (sockfd > STDIN_FILENO ? sockfd : STDIN_FILENO) + 1;
+  while (true) {
+    fd_set fds;
+    FD_ZERO(&fds);
+    FD_SET(sockfd, &fds);
+    FD_SET(STDIN_FILENO, &fds);
+    if (select(nfds, &fds, nullptr, nullptr, nullptr) == -1) {
+      throw SysError("waiting for data from client or server");
+    }
+    if (FD_ISSET(sockfd, &fds)) {
+      auto res = splice(sockfd, nullptr, STDOUT_FILENO, nullptr, SSIZE_MAX,
+                        SPLICE_F_MOVE);
+      if (res == -1) {
+        throw SysError("splicing data from daemon socket to stdout");
+      }
+      if (res == 0) {
+        throw EndOfFile("unexpected EOF from daemon socket");
+      }
+    }
+    if (FD_ISSET(STDIN_FILENO, &fds)) {
+      auto res = splice(STDIN_FILENO, nullptr, sockfd, nullptr, SSIZE_MAX,
+                        SPLICE_F_MOVE);
+      if (res == -1) {
+        throw SysError("splicing data from stdin to daemon socket");
+      }
+      if (res == 0) {
+        return 0;
+      }
+    }
+  }
+}
+
+void SetNonBlocking(int fd) {
+  int flags = fcntl(fd, F_GETFL);  // NOLINT
+  PCHECK(flags != 0) << "Error getting socket flags";
+  PCHECK(fcntl(  // NOLINT
+             fd, F_SETFL, flags | O_NONBLOCK) == 0)
+      << "Could not set socket flags";
+}
+
+}  // namespace
+
+int RunServer() {
+  Store::Params params;
+  params["path-info-cache-size"] = "0";
+  auto store = openStore(settings.storeUri, params);
+  auto worker = NewWorkerService(*store);
+  ServerBuilder builder;
+  builder.RegisterService(worker);
+
+  auto n_fds = sd_listen_fds(0);
+
+  if (n_fds > 1) {
+    LOG(FATAL) << "Too many file descriptors (" << n_fds
+               << ") received from systemd socket activation";
+  }
+
+  std::filesystem::path socket_path;
+
+  if (n_fds == 0) {
+    socket_path = settings.nixDaemonSocketFile;
+    std::filesystem::create_directories(socket_path.parent_path());
+    auto socket_addr = absl::StrFormat("unix://%s", socket_path);
+    builder.AddListeningPort(socket_addr, grpc::InsecureServerCredentials());
+  }
+
+  std::unique_ptr<Server> server(builder.BuildAndStart());
+
+  if (!server) {
+    LOG(FATAL) << "Error building server";
+    return 1;
+  }
+
+  // We have been systemd socket-activated - instead of asking grpc to make the
+  // socket path for us, start our own accept loop and pass file descriptors to
+  // grpc.
+  //
+  // This approach was *somewhat* adapted from
+  // https://gist.github.com/yorickvP/8d523a4df2b10c5812fa7789e82b7c1b - at some
+  // point we'd like gRPC to do it for us, though - see
+  // https://github.com/grpc/grpc/issues/19133
+  if (n_fds == 1) {
+    int socket_fd = SD_LISTEN_FDS_START;
+    // Only used for logging
+    socket_path = readLink(absl::StrFormat("/proc/self/fd/%d", socket_fd));
+
+    PCHECK(sd_notify(0, "READY=1") == 0) << "Error notifying systemd";
+    for (;;) {
+      try {
+        struct sockaddr_un remote_addr {};
+        socklen_t remote_addr_len = sizeof(remote_addr);
+        int remote_fd =
+            accept(socket_fd,
+                   reinterpret_cast<struct sockaddr*>(&remote_addr),  // NOLINT
+                   &remote_addr_len);
+        checkInterrupt();
+        if (!remote_fd) {
+          if (errno == EINTR) {
+            continue;
+          }
+          PCHECK(false) << "error accepting connection";
+        }
+
+        LOG(INFO) << "Accepted remote connection on fd " << remote_fd;
+        SetNonBlocking(remote_fd);
+        grpc::AddInsecureChannelFromFd(server.get(), remote_fd);
+      } catch (Interrupted& e) {
+        return -1;
+      } catch (Error& e) {
+        LOG(ERROR) << "error processing connection: " << e.msg();
+      }
+    }
+  }
+
+  LOG(INFO) << "Nix daemon listening at " << socket_path;
+  server->Wait();
+  return 0;
+}
+
+}  // namespace nix::daemon
+
+int main(int argc, char** argv) {  // NOLINT
+  FLAGS_logtostderr = true;
+  google::InitGoogleLogging(argv[0]);  // NOLINT
+
+  absl::SetFlagsUsageConfig({.version_string = [] { return nix::nixVersion; }});
+  absl::ParseCommandLine(argc, argv);
+
+  if (absl::GetFlag(FLAGS_pipe)) {
+    if (nix::getStoreType() == nix::tDaemon) {
+      return nix::daemon::ForwardToSocket(nix::settings.nixDaemonSocketFile);
+    } else {
+      // TODO(grfn): Need to launch a server on stdin here - upstream calls
+      // processConnection(true, "root", 0);
+      LOG(ERROR) << "not implemented";
+      return 1;
+    }
+  }
+
+  return nix::daemon::RunServer();
+}