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#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_impl::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();
}
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