code:
/* GNU Guix --- Functional package management for GNU
   Copyright (C) 2012, 2013, 2014, 2015, 2016, 2017, 2018 Ludovic Courtès <ludo@gnu.org>
   Copyright (C) 2006, 2010, 2012, 2014 Eelco Dolstra <e.dolstra@tudelft.nl>

   This file is part of GNU Guix.

   GNU Guix is free software; you can redistribute it and/or modify it
   under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or (at
   your option) any later version.

   GNU Guix is distributed in the hope that it will be useful, but
   WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.  */

#include <config.h>

#include <types.hh>
#include "shared.hh"
#include <globals.hh>
#include <util.hh>

#include <gcrypt.h>

#include <stdlib.h>
#include <argp.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <netdb.h>
#include <strings.h>
#include <exception>
#include <iostream>

#include <libintl.h>
#include <locale.h>

/* Variables used by `nix-daemon.cc'.  */
volatile ::sig_atomic_t blockInt;
char **argvSaved;

using namespace nix;

/* Entry point in `nix-daemon.cc'.  */
extern void run (const std::vector<int> &);

/* Command-line options.  */

#define n_(str)  str
#define _(str)   gettext (str)
static const char guix_textdomain[] = "guix";

const char *argp_program_version =
  "guix-daemon (" PACKAGE_NAME ") " PACKAGE_VERSION;
const char *argp_program_bug_address = PACKAGE_BUGREPORT;

static char doc[] =
  n_("guix-daemon -- perform derivation builds and store accesses")
  "\v\n"
  n_("This program is a daemon meant to run in the background.  It serves \
requests sent over a Unix-domain socket.  It accesses the store, and \
builds derivations on behalf of its clients.");

#define GUIX_OPT_SYSTEM 1
#define GUIX_OPT_DISABLE_CHROOT 2
#define GUIX_OPT_BUILD_USERS_GROUP 3
#define GUIX_OPT_CACHE_FAILURES 4
#define GUIX_OPT_LOSE_LOGS 5
#define GUIX_OPT_DISABLE_LOG_COMPRESSION 6
#define GUIX_OPT_DISABLE_DEDUPLICATION 7
#define GUIX_OPT_IMPERSONATE_LINUX_26 8
#define GUIX_OPT_DEBUG 9
#define GUIX_OPT_CHROOT_DIR 10
#define GUIX_OPT_LISTEN 11
#define GUIX_OPT_NO_SUBSTITUTES 12
#define GUIX_OPT_SUBSTITUTE_URLS 13
#define GUIX_OPT_NO_BUILD_HOOK 14
#define GUIX_OPT_GC_KEEP_OUTPUTS 15
#define GUIX_OPT_GC_KEEP_DERIVATIONS 16
#define GUIX_OPT_BUILD_ROUNDS 17
#define GUIX_OPT_TIMEOUT 18
#define GUIX_OPT_MAX_SILENT_TIME 19
#define GUIX_OPT_LOG_COMPRESSION 20

static const struct argp_option options[] =
  {
    { "system", GUIX_OPT_SYSTEM, n_("SYSTEM"), 0,
      n_("assume SYSTEM as the current system type") },
    { "cores", 'c', n_("N"), 0,
      n_("use N CPU cores to build each derivation; 0 means as many as available")
    },
    { "max-jobs", 'M', n_("N"), 0,
      n_("allow at most N build jobs") },
    { "timeout", GUIX_OPT_TIMEOUT, n_("SECONDS"), 0,
      n_("mark builds as failed after SECONDS of activity") },
    { "max-silent-time", GUIX_OPT_MAX_SILENT_TIME, n_("SECONDS"), 0,
      n_("mark builds as failed after SECONDS of silence") },
    { "disable-chroot", GUIX_OPT_DISABLE_CHROOT, 0, 0,
      n_("disable chroot builds") },
    { "chroot-directory", GUIX_OPT_CHROOT_DIR, n_("DIR"), 0,
      n_("add DIR to the build chroot") },
    { "build-users-group", GUIX_OPT_BUILD_USERS_GROUP, n_("GROUP"), 0,
      n_("perform builds as a user of GROUP") },
    { "no-substitutes", GUIX_OPT_NO_SUBSTITUTES, 0, 0,
      n_("do not use substitutes") },
    { "substitute-urls", GUIX_OPT_SUBSTITUTE_URLS, n_("URLS"), 0,
      n_("use URLS as the default list of substitute providers") },
    { "no-build-hook", GUIX_OPT_NO_BUILD_HOOK, 0, 0,
      n_("do not use the 'build hook'") },
    { "cache-failures", GUIX_OPT_CACHE_FAILURES, 0, 0,
      n_("cache build failures") },
    { "rounds", GUIX_OPT_BUILD_ROUNDS, "N", 0,
      n_("build each derivation N times in a row") },
    { "lose-logs", GUIX_OPT_LOSE_LOGS, 0, 0,
      n_("do not keep build logs") },
    { "disable-log-compression", GUIX_OPT_DISABLE_LOG_COMPRESSION, 0,
      OPTION_HIDDEN,				  // deprecated
      n_("disable compression of the build logs") },
    { "log-compression", GUIX_OPT_LOG_COMPRESSION, "TYPE", 0,
      n_("use the specified compression type for build logs") },

    /* '--disable-deduplication' was known as '--disable-store-optimization'
       up to Guix 0.7 included, so keep the alias around.  */
    { "disable-deduplication", GUIX_OPT_DISABLE_DEDUPLICATION, 0, 0,
      n_("disable automatic file \"deduplication\" in the store") },
    { "disable-store-optimization", GUIX_OPT_DISABLE_DEDUPLICATION, 0,
      OPTION_ALIAS | OPTION_HIDDEN, NULL },

    { "impersonate-linux-2.6", GUIX_OPT_IMPERSONATE_LINUX_26, 0,
#ifdef HAVE_SYS_PERSONALITY_H
      0,
#else
      OPTION_HIDDEN,
#endif
      n_("impersonate Linux 2.6")
    },
    { "gc-keep-outputs", GUIX_OPT_GC_KEEP_OUTPUTS,
      "yes/no", OPTION_ARG_OPTIONAL,
      n_("tell whether the GC must keep outputs of live derivations") },
    { "gc-keep-derivations", GUIX_OPT_GC_KEEP_DERIVATIONS,
      "yes/no", OPTION_ARG_OPTIONAL,
      n_("tell whether the GC must keep derivations corresponding \
to live outputs") },

    { "listen", GUIX_OPT_LISTEN, n_("SOCKET"), 0,
      n_("listen for connections on SOCKET") },
    { "debug", GUIX_OPT_DEBUG, 0, 0,
      n_("produce debugging output") },
    { 0, 0, 0, 0, 0 }
  };

/* Default port for '--listen' on TCP/IP.  */
#define DEFAULT_GUIX_PORT "44146"

/* List of '--listen' options.  */
static std::list<std::string> listen_options;

/* Convert ARG to a Boolean value, or throw an error if it does not denote a
   Boolean.  */
static bool
string_to_bool (const char *arg, bool dflt = true)
{
  if (arg == NULL)
    return dflt;
  else if (strcasecmp (arg, "yes") == 0)
    return true;
  else if (strcasecmp (arg, "no") == 0)
    return false;
  else
    throw nix::Error (format ("'%1%': invalid Boolean value") % arg);
}

/* Parse a single option. */
static error_t
parse_opt (int key, char *arg, struct argp_state *state)
{
  switch (key)
    {
    case GUIX_OPT_DISABLE_CHROOT:
      settings.useChroot = false;
      break;
    case GUIX_OPT_CHROOT_DIR:
      {
	std::string chroot_dirs;

	chroot_dirs = settings.get ("build-extra-chroot-dirs",
				    (std::string) "");
	if (chroot_dirs == "")
	  chroot_dirs = arg;
	else
	  chroot_dirs = chroot_dirs + " " + arg;
	settings.set("build-extra-chroot-dirs", chroot_dirs);
	break;
      }
    case GUIX_OPT_LOG_COMPRESSION:
      if (strcmp (arg, "none") == 0)
	settings.logCompression = COMPRESSION_NONE;
      else if (strcmp (arg, "gzip") == 0)
	settings.logCompression = COMPRESSION_GZIP;
#if HAVE_BZLIB_H
      else if (strcmp (arg, "bzip2") == 0)
	settings.logCompression = COMPRESSION_BZIP2;
#endif
      else
	{
	  fprintf (stderr, _("error: %s: unknown compression type\n"), arg);
	  exit (EXIT_FAILURE);
	}
      break;
    case GUIX_OPT_DISABLE_LOG_COMPRESSION:
      settings.logCompression = COMPRESSION_NONE;
      break;
    case GUIX_OPT_BUILD_USERS_GROUP:
      settings.buildUsersGroup = arg;
      break;
    case GUIX_OPT_DISABLE_DEDUPLICATION:
      settings.autoOptimiseStore = false;
      break;
    case GUIX_OPT_CACHE_FAILURES:
      settings.cacheFailure = true;
      break;
    case GUIX_OPT_BUILD_ROUNDS:
      {
	char *end;
	unsigned long n = strtoul (arg, &end, 10);
	if (end != arg + strlen (arg))
	  {
	    fprintf (stderr, _("error: %s: invalid number of rounds\n"), arg);
	    exit (EXIT_FAILURE);
	  }
	settings.set ("build-repeat", std::to_string (std::max (0UL, n - 1)));
	break;
      }
    case GUIX_OPT_IMPERSONATE_LINUX_26:
      settings.impersonateLinux26 = true;
      break;
    case GUIX_OPT_LOSE_LOGS:
      settings.keepLog = false;
      break;
    case GUIX_OPT_LISTEN:
      listen_options.push_back (arg);
      break;
    case GUIX_OPT_SUBSTITUTE_URLS:
      settings.set ("substitute-urls", arg);
      break;
    case GUIX_OPT_NO_SUBSTITUTES:
      settings.set ("build-use-substitutes", "false");
      break;
    case GUIX_OPT_NO_BUILD_HOOK:
      settings.useBuildHook = false;
      break;
    case GUIX_OPT_DEBUG:
      verbosity = lvlDebug;
      break;
    case GUIX_OPT_GC_KEEP_OUTPUTS:
      settings.gcKeepOutputs = string_to_bool (arg);
      break;
    case GUIX_OPT_GC_KEEP_DERIVATIONS:
      settings.gcKeepDerivations = string_to_bool (arg);
      break;
    case 'c':
      settings.set ("build-cores", arg);
      break;
    case 'M':
      settings.set ("build-max-jobs", arg);
      break;
    case GUIX_OPT_TIMEOUT:
      settings.set ("build-timeout", arg);
      break;
    case GUIX_OPT_MAX_SILENT_TIME:
      settings.set ("build-max-silent-time", arg);
      break;
    case GUIX_OPT_SYSTEM:
      settings.thisSystem = arg;
      break;
    default:
      return (error_t) ARGP_ERR_UNKNOWN;
    }

  return (error_t) 0;
}

/* Argument parsing.  */
static const struct argp argp =
  {
    options, parse_opt,
    NULL, doc,
    NULL, NULL,					  // children and help_filter
    guix_textdomain
  };

static int
open_unix_domain_socket (const char *file)
{
  /* Create and bind to a Unix domain socket. */
  AutoCloseFD fdSocket = socket (PF_UNIX, SOCK_STREAM, 0);
  if (fdSocket == -1)
    throw SysError (_("cannot create Unix domain socket"));

  createDirs (dirOf (file));

  /* Urgh, sockaddr_un allows path names of only 108 characters.
     So chdir to the socket directory so that we can pass a
     relative path name. */
  if (chdir (dirOf (file).c_str ()) == -1)
    throw SysError (_("cannot change current directory"));
  Path fileRel = "./" + baseNameOf (file);

  struct sockaddr_un addr;
  addr.sun_family = AF_UNIX;
  if (fileRel.size () >= sizeof (addr.sun_path))
    throw Error (format (_("socket file name '%1%' is too long")) % fileRel);
  strcpy (addr.sun_path, fileRel.c_str ());

  unlink (file);

  /* Make sure that the socket is created with 0666 permission
     (everybody can connect --- provided they have access to the
     directory containing the socket). */
  mode_t oldMode = umask (0111);
  int res = bind (fdSocket, (struct sockaddr *) &addr, sizeof addr);
  umask (oldMode);
  if (res == -1)
    throw SysError (format (_("cannot bind to socket '%1%'")) % file);

  if (chdir ("/") == -1) /* back to the root */
    throw SysError (_("cannot change current directory"));

  if (listen (fdSocket, 5) == -1)
    throw SysError (format (_("cannot listen on socket '%1%'")) % file);

  return fdSocket.borrow ();
}

/* Return a listening socket for ADDRESS, which has the given LENGTH.  */
static int
open_inet_socket (const struct sockaddr *address, socklen_t length)
{
  AutoCloseFD fd = socket (address->sa_family, SOCK_STREAM, 0);
  if (fd == -1)
    throw SysError (_("cannot create TCP socket"));

  int res = bind (fd, address, length);
  if (res == -1)
    throw SysError (_("cannot bind TCP socket"));

  if (listen (fd, 5) == -1)
    throw SysError (format (_("cannot listen on TCP socket")));

  return fd.borrow ();
}

/* Return a list of file descriptors of listening sockets.  */
static std::vector<int>
listening_sockets (const std::list<std::string> &options)
{
  std::vector<int> result;

  if (options.empty ())
    {
      /* Open the default Unix-domain socket.  */
      auto fd = open_unix_domain_socket (settings.nixDaemonSocketFile.c_str ());
      result.push_back (fd);
      return result;
    }

  /* Open the user-specified sockets.  */
  for (const std::string& option: options)
    {
      if (option[0] == '/')
	{
	  /* Assume OPTION is the file name of a Unix-domain socket.  */
	  settings.nixDaemonSocketFile = canonPath (option);
	  int fd =
	    open_unix_domain_socket (settings.nixDaemonSocketFile.c_str ());
	  result.push_back (fd);
	}
      else
	{
	  /* Assume OPTIONS has the form "HOST" or "HOST:PORT".  */
	  auto colon = option.find_last_of (":");
	  auto host = colon == std::string::npos
	    ? option : option.substr (0, colon);
	  auto port = colon == std::string::npos
	    ? DEFAULT_GUIX_PORT
	    : option.substr (colon + 1, option.size () - colon - 1);

	  struct addrinfo *res, hints;

	  memset (&hints, '\0', sizeof hints);
	  hints.ai_socktype = SOCK_STREAM;
	  hints.ai_flags = AI_NUMERICSERV | AI_ADDRCONFIG;

	  int err = getaddrinfo (host.c_str(), port.c_str (),
				 &hints, &res);

	  if (err != 0)
	    throw Error(format ("failed to look up '%1%': %2%")
			% option % gai_strerror (err));

	  printMsg (lvlDebug, format ("listening on '%1%', port '%2%'")
		    % host % port);

	  /* XXX: Pick the first result, RES.  */
	  result.push_back (open_inet_socket (res->ai_addr,
					      res->ai_addrlen));

	  freeaddrinfo (res);
	}
    }

  return result;
}

int
main (int argc, char *argv[])
{
  setlocale (LC_ALL, "");
  bindtextdomain (guix_textdomain, LOCALEDIR);
  textdomain (guix_textdomain);

  /* Initialize libgcrypt.  */
  if (!gcry_check_version (GCRYPT_VERSION))
    {
      fprintf (stderr, _("error: libgcrypt version mismatch\n"));
      exit (EXIT_FAILURE);
    }

  /* Tell Libgcrypt that initialization has completed, as per the Libgcrypt
     1.6.0 manual (although this does not appear to be strictly needed.)  */
  gcry_control (GCRYCTL_INITIALIZATION_FINISHED, 0);

  /* Set the umask so that the daemon does not end up creating group-writable
     files, which would lead to "suspicious ownership or permission" errors.
     See <http://lists.gnu.org/archive/html/bug-guix/2013-07/msg00033.html>.  */
  umask (S_IWGRP | S_IWOTH);

#ifndef HAVE_CHROOT
# error chroot is assumed to be available
#endif

  /* Always use chroots by default.  */
  settings.useChroot = true;

  /* Turn automatic deduplication on by default.  */
  settings.autoOptimiseStore = true;

  /* Default to using as many cores as possible and one job at a time.  */
  settings.buildCores = 0;
  settings.maxBuildJobs = 1;

  argvSaved = argv;

  try
    {
      settings.processEnvironment ();

      /* Hackily help 'local-store.cc' find our 'guix-authenticate' program, which
	 is known as 'OPENSSL_PATH' here.  */
      std::string search_path;
      search_path = settings.nixLibexecDir;
      if (getenv ("PATH") != NULL)
	{
	  search_path += ":";
	  search_path += getenv ("PATH");
	}

      setenv ("PATH", search_path.c_str (), 1);

      /* Use our substituter by default.  */
      settings.substituters.clear ();
      settings.set ("build-use-substitutes", "true");

      /* Use our substitute server by default.  */
      settings.set ("substitute-urls", GUIX_SUBSTITUTE_URLS);

#ifdef HAVE_DAEMON_OFFLOAD_HOOK
      /* Use our build hook for distributed builds by default.  */
      settings.useBuildHook = true;
      if (getenv ("NIX_BUILD_HOOK") == NULL)
	{
	  std::string build_hook;

	  build_hook = settings.nixLibexecDir + "/guix/offload";
	  setenv ("NIX_BUILD_HOOK", build_hook.c_str (), 1);
	}
#else
      /* We are not installing any build hook, so disable it.  */
      settings.useBuildHook = false;
#endif

      argp_parse (&argp, argc, argv, 0, 0, 0);

      auto sockets = listening_sockets (listen_options);

      /* Effect all the changes made via 'settings.set'.  */
      settings.update ();
      printMsg(lvlDebug,
	       format ("build log compression: %1%") % settings.logCompression);

      if (settings.useSubstitutes)
	{
	  string subs = getEnv ("NIX_SUBSTITUTERS", "default");

	  if (subs == "default")
	    {
	      string subst =
		settings.nixLibexecDir + "/guix/substitute";
	      setenv ("NIX_SUBSTITUTERS", subst.c_str (), 1);
	    }
	}
      else
	/* Clear the substituter list to make sure nothing ever gets
	   substituted, regardless of the client's settings.  */
	setenv ("NIX_SUBSTITUTERS", "", 1);

      /* Effect the $NIX_SUBSTITUTERS change.  */
      settings.update ();

      if (geteuid () == 0 && settings.buildUsersGroup.empty ())
	fprintf (stderr, _("warning: daemon is running as root, so \
using `--build-users-group' is highly recommended\n"));

      if (settings.useChroot)
	{
	  std::string chroot_dirs;

	  chroot_dirs = settings.get ("build-extra-chroot-dirs",
				      (std::string) "");
	  printMsg (lvlDebug,
		    format ("extra chroot directories: '%1%'") % chroot_dirs);
	}

      printMsg (lvlDebug,
		format ("automatic deduplication set to %1%")
		% settings.autoOptimiseStore);

      printMsg (lvlDebug,
		format ("listening on `%1%'") % settings.nixDaemonSocketFile);

      run (sockets);
    }
  catch (std::exception &e)
    {
      fprintf (stderr, _("error: %s\n"), e.what ());
      return EXIT_FAILURE;
    }

  return EXIT_SUCCESS;				  /* never reached */
}


code:
#include "shared.hh"
#include "local-store.hh"
#include "util.hh"
#include "serialise.hh"
#include "worker-protocol.hh"
#include "archive.hh"
#include "affinity.hh"
#include "globals.hh"
#include "builtins.hh"

#include <algorithm>

#include <cstring>
#include <unistd.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <netinet/tcp.h>

#include <fcntl.h>
#include <errno.h>
#include <pwd.h>
#include <grp.h>

using namespace nix;

/* On platforms that have O_ASYNC, we can detect when a client
   disconnects and immediately kill any ongoing builds.  On platforms
   that lack it, we only notice the disconnection the next time we try
   to write to the client.  So if you have a builder that never
   generates output on stdout/stderr, the daemon will never notice
   that the client has disconnected until the builder terminates.

   GNU/Hurd does have O_ASYNC, but its Unix-domain socket translator
   (pflocal) does not implement F_SETOWN.  See
   <http://lists.gnu.org/archive/html/bug-guix/2013-07/msg00021.html> for
   details.*/
#if defined O_ASYNC && !defined __GNU__
#define HAVE_HUP_NOTIFICATION
#ifndef SIGPOLL
#define SIGPOLL SIGIO
#endif
#endif

static FdSource from(STDIN_FILENO);
static FdSink to(STDOUT_FILENO);

bool canSendStderr;

/* This variable is used to keep track of whether a connection
   comes from a host other than the host running guix-daemon. */
static bool isRemoteConnection;

/* This function is called anytime we want to write something to
   stderr.  If we're in a state where the protocol allows it (i.e.,
   when canSendStderr), send the message to the client over the
   socket. */
static void tunnelStderr(const unsigned char * buf, size_t count)
{
    if (canSendStderr) {
        try {
            writeInt(STDERR_NEXT, to);
            writeString(buf, count, to);
            to.flush();
        } catch (...) {
            /* Write failed; that means that the other side is
               gone. */
            canSendStderr = false;
            throw;
        }
    } else
        writeFull(STDERR_FILENO, buf, count);
}

/* Return true if the remote side has closed its end of the
   connection, false otherwise.  Should not be called on any socket on
   which we expect input! */
static bool isFarSideClosed(int socket)
{
    struct timeval timeout;
    timeout.tv_sec = timeout.tv_usec = 0;

    fd_set fds;
    FD_ZERO(&fds);
    FD_SET(socket, &fds);

    while (select(socket + 1, &fds, 0, 0, &timeout) == -1)
        if (errno != EINTR) throw SysError("select()");

    if (!FD_ISSET(socket, &fds)) return false;

    /* Destructive read to determine whether the select() marked the
       socket as readable because there is actual input or because
       we've reached EOF (i.e., a read of size 0 is available). */
    char c;
    int rd;
    if ((rd = read(socket, &c, 1)) > 0)
        throw Error("EOF expected (protocol error?)");
    else if (rd == -1 && errno != ECONNRESET)
        throw SysError("expected connection reset or EOF");

    return true;
}

/* A SIGPOLL signal is received when data is available on the client
   communication socket, or when the client has closed its side of the
   socket.  This handler is enabled at precisely those moments in the
   protocol when we're doing work and the client is supposed to be
   quiet.  Thus, if we get a SIGPOLL signal, it means that the client
   has quit.  So we should quit as well.

   Too bad most operating systems don't support the POLL_HUP value for
   si_code in siginfo_t.  That would make most of the SIGPOLL
   complexity unnecessary, i.e., we could just enable SIGPOLL all the
   time and wouldn't have to worry about races. */
static void sigPollHandler(int sigNo)
{
    using namespace std;
    try {
        /* Check that the far side actually closed.  We're still
           getting spurious signals every once in a while.  I.e.,
           there is no input available, but we get a signal with
           POLL_IN set.  Maybe it's delayed or something. */
        if (isFarSideClosed(from.fd)) {
            if (!blockInt) {
                _isInterrupted = 1;
                blockInt = 1;
                canSendStderr = false;
                const char * s = "SIGPOLL\n";
                write(STDERR_FILENO, s, strlen(s));
            }
        } else {
            const char * s = "spurious SIGPOLL\n";
            write(STDERR_FILENO, s, strlen(s));
        }
    }
    catch (Error & e) {
        /* Shouldn't happen. */
        string s = "impossible: " + e.msg() + '\n';
        write(STDERR_FILENO, s.data(), s.size());
        throw;
    }
}

static void setSigPollAction(bool enable)
{
#ifdef HAVE_HUP_NOTIFICATION
    struct sigaction act, oact;
    act.sa_handler = enable ? sigPollHandler : SIG_IGN;
    sigfillset(&act.sa_mask);
    act.sa_flags = 0;
    if (sigaction(SIGPOLL, &act, &oact))
        throw SysError("setting handler for SIGPOLL");
#endif
}

/* startWork() means that we're starting an operation for which we
   want to send out stderr to the client. */
static void startWork()
{
    canSendStderr = true;

    /* Handle client death asynchronously. */
    setSigPollAction(true);

    /* Of course, there is a race condition here: the socket could
       have closed between when we last read from / wrote to it, and
       between the time we set the handler for SIGPOLL.  In that case
       we won't get the signal.  So do a non-blocking select() to find
       out if any input is available on the socket.  If there is, it
       has to be the 0-byte read that indicates that the socket has
       closed. */
    if (isFarSideClosed(from.fd)) {
        _isInterrupted = 1;
        checkInterrupt();
    }
}

/* stopWork() means that we're done; stop sending stderr to the
   client. */
static void stopWork(bool success = true, const string & msg = "", unsigned int status = 0)
{
    /* Stop handling async client death; we're going to a state where
       we're either sending or receiving from the client, so we'll be
       notified of client death anyway. */
    setSigPollAction(false);

    canSendStderr = false;

    if (success)
        writeInt(STDERR_LAST, to);
    else {
        writeInt(STDERR_ERROR, to);
        writeString(msg, to);
        if (status != 0) writeInt(status, to);
    }
}

struct TunnelSink : BufferedSink
{
    Sink & to;
    TunnelSink(Sink & to) : BufferedSink(64 * 1024), to(to) { }
    virtual void write(const unsigned char * data, size_t len)
    {
        writeInt(STDERR_WRITE, to);
        writeString(data, len, to);
    }
};

struct TunnelSource : BufferedSource
{
    Source & from;
    TunnelSource(Source & from) : from(from) { }
    size_t readUnbuffered(unsigned char * data, size_t len)
    {
        /* Careful: we're going to receive data from the client now,
           so we have to disable the SIGPOLL handler. */
        setSigPollAction(false);
        canSendStderr = false;

        writeInt(STDERR_READ, to);
        writeInt(len, to);
        to.flush();
        size_t n = readString(data, len, from);

        startWork();
        if (n == 0) throw EndOfFile("unexpected end-of-file");
        return n;
    }
};

/* If the NAR archive contains a single file at top-level, then save
   the contents of the file to `s'.  Otherwise barf. */
struct RetrieveRegularNARSink : ParseSink
{
    bool regular;
    string s;

    RetrieveRegularNARSink() : regular(true) { }

    void createDirectory(const Path & path)
    {
        regular = false;
    }

    void receiveContents(unsigned char * data, unsigned int len)
    {
        s.append((const char *) data, len);
    }

    void createSymlink(const Path & path, const string & target)
    {
        regular = false;
    }
};

/* Adapter class of a Source that saves all data read to `s'. */
struct SavingSourceAdapter : Source
{
    Source & orig;
    string s;
    SavingSourceAdapter(Source & orig) : orig(orig) { }
    size_t read(unsigned char * data, size_t len)
    {
        size_t n = orig.read(data, len);
        s.append((const char *) data, n);
        return n;
    }
};

static void performOp(bool trusted, unsigned int clientVersion,
    Source & from, Sink & to, unsigned int op)
{
    switch (op) {

    case wopIsValidPath: {
        /* 'readStorePath' could raise an error leading to the connection
           being closed.  To be able to recover from an invalid path error,
           call 'startWork' early, and do 'assertStorePath' afterwards so
           that the 'Error' exception handler doesn't close the
           connection.  */
        Path path = readString(from);
        startWork();
        assertStorePath(path);
        bool result = store->isValidPath(path);
        stopWork();
        writeInt(result, to);
        break;
    }

    case wopQueryValidPaths: {
        PathSet paths = readStorePaths<PathSet>(from);
        startWork();
        PathSet res = store->queryValidPaths(paths);
        stopWork();
        writeStrings(res, to);
        break;
    }

    case wopHasSubstitutes: {
        Path path = readStorePath(from);
        startWork();
        PathSet res = store->querySubstitutablePaths(singleton<PathSet>(path));
        stopWork();
        writeInt(res.find(path) != res.end(), to);
        break;
    }

    case wopQuerySubstitutablePaths: {
        PathSet paths = readStorePaths<PathSet>(from);
        startWork();
        PathSet res = store->querySubstitutablePaths(paths);
        stopWork();
        writeStrings(res, to);
        break;
    }

    case wopQueryPathHash: {
        Path path = readStorePath(from);
        startWork();
        Hash hash = store->queryPathHash(path);
        stopWork();
        writeString(printHash(hash), to);
        break;
    }

    case wopQueryReferences:
    case wopQueryReferrers:
    case wopQueryValidDerivers:
    case wopQueryDerivationOutputs: {
        Path path = readStorePath(from);
        startWork();
        PathSet paths;
        if (op == wopQueryReferences)
            store->queryReferences(path, paths);
        else if (op == wopQueryReferrers)
            store->queryReferrers(path, paths);
        else if (op == wopQueryValidDerivers)
            paths = store->queryValidDerivers(path);
        else paths = store->queryDerivationOutputs(path);
        stopWork();
        writeStrings(paths, to);
        break;
    }

    case wopQueryDerivationOutputNames: {
        Path path = readStorePath(from);
        startWork();
        StringSet names;
        names = store->queryDerivationOutputNames(path);
        stopWork();
        writeStrings(names, to);
        break;
    }

    case wopQueryDeriver: {
        Path path = readStorePath(from);
        startWork();
        Path deriver = store->queryDeriver(path);
        stopWork();
        writeString(deriver, to);
        break;
    }

    case wopQueryPathFromHashPart: {
        string hashPart = readString(from);
        startWork();
        Path path = store->queryPathFromHashPart(hashPart);
        stopWork();
        writeString(path, to);
        break;
    }

    case wopAddToStore: {
        string baseName = readString(from);
        bool fixed = readInt(from) == 1; /* obsolete */
        bool recursive = readInt(from) == 1;
        string s = readString(from);
        /* Compatibility hack. */
        if (!fixed) {
            s = "sha256";
            recursive = true;
        }
        HashType hashAlgo = parseHashType(s);

        SavingSourceAdapter savedNAR(from);
        RetrieveRegularNARSink savedRegular;

        if (recursive) {
            /* Get the entire NAR dump from the client and save it to
               a string so that we can pass it to
               addToStoreFromDump(). */
            ParseSink sink; /* null sink; just parse the NAR */
            parseDump(sink, savedNAR);
        } else
            parseDump(savedRegular, from);

        startWork();
        if (!savedRegular.regular) throw Error("regular file expected");
        Path path = dynamic_cast<LocalStore *>(store.get())
            ->addToStoreFromDump(recursive ? savedNAR.s : savedRegular.s, baseName, recursive, hashAlgo);
        stopWork();

        writeString(path, to);
        break;
    }

    case wopAddTextToStore: {
        string suffix = readString(from);
        string s = readString(from);
        PathSet refs = readStorePaths<PathSet>(from);
        startWork();
        Path path = store->addTextToStore(suffix, s, refs);
        stopWork();
        writeString(path, to);
        break;
    }

    case wopExportPath: {
        Path path = readStorePath(from);
        bool sign = readInt(from) == 1;
        startWork();
        TunnelSink sink(to);
	try {
	    store->exportPath(path, sign, sink);
	}
	catch (Error &e) {
	    /* Flush SINK beforehand or its destructor will rightfully trigger
	       an assertion failure.  */
	    sink.flush();
	    throw e;
	}
        sink.flush();
        stopWork();
        writeInt(1, to);
        break;
    }

    case wopImportPaths: {
        startWork();
        TunnelSource source(from);

        /* Unlike Nix, always require a signature, even for "trusted"
           users.  */
        Paths paths = store->importPaths(true, source);
        stopWork();
        writeStrings(paths, to);
        break;
    }

    case wopBuildPaths: {
        PathSet drvs = readStorePaths<PathSet>(from);
        BuildMode mode = bmNormal;
        if (GET_PROTOCOL_MINOR(clientVersion) >= 15) {
            mode = (BuildMode)readInt(from);

	    /* Repairing is not atomic, so disallowed for "untrusted"
	       clients.  */
            if (mode == bmRepair && !trusted)
                throw Error("repairing is not supported when building through the Nix daemon");
        }
        startWork();
        store->buildPaths(drvs, mode);
        stopWork();
        writeInt(1, to);
        break;
    }

    case wopEnsurePath: {
        Path path = readStorePath(from);
        startWork();
        store->ensurePath(path);
        stopWork();
        writeInt(1, to);
        break;
    }

    case wopAddTempRoot: {
        Path path = readStorePath(from);
        startWork();
        store->addTempRoot(path);
        stopWork();
        writeInt(1, to);
        break;
    }

    case wopAddIndirectRoot: {
        Path path = absPath(readString(from));
        startWork();
        store->addIndirectRoot(path);
        stopWork();
        writeInt(1, to);
        break;
    }

    case wopSyncWithGC: {
        startWork();
        store->syncWithGC();
        stopWork();
        writeInt(1, to);
        break;
    }

    case wopFindRoots: {
        startWork();
        Roots roots = store->findRoots();
        stopWork();
        writeInt(roots.size(), to);
        for (Roots::iterator i = roots.begin(); i != roots.end(); ++i) {
            writeString(i->first, to);
            writeString(i->second, to);
        }
        break;
    }

    case wopCollectGarbage: {
        if (isRemoteConnection) {
            throw Error("Garbage collection is disabled for remote hosts.");
            break;
        }

        GCOptions options;
        options.action = (GCOptions::GCAction) readInt(from);
        options.pathsToDelete = readStorePaths<PathSet>(from);
        options.ignoreLiveness = readInt(from);
        options.maxFreed = readLongLong(from);
        readInt(from); // obsolete field
        if (GET_PROTOCOL_MINOR(clientVersion) >= 5) {
            /* removed options */
            readInt(from);
            readInt(from);
        }

        GCResults results;

        startWork();
        if (options.ignoreLiveness)
            throw Error("you are not allowed to ignore liveness");
        store->collectGarbage(options, results);
        stopWork();

        writeStrings(results.paths, to);
        writeLongLong(results.bytesFreed, to);
        writeLongLong(0, to); // obsolete

        break;
    }

    case wopSetOptions: {
        settings.keepFailed = readInt(from) != 0;
        settings.keepGoing = readInt(from) != 0;
        settings.set("build-fallback", readInt(from) ? "true" : "false");
        verbosity = (Verbosity) readInt(from);

        if (GET_PROTOCOL_MINOR(clientVersion) < 0x61) {
            settings.set("build-max-jobs", std::to_string(readInt(from)));
            settings.set("build-max-silent-time", std::to_string(readInt(from)));
        }

        if (GET_PROTOCOL_MINOR(clientVersion) >= 2)
            settings.useBuildHook = readInt(from) != 0;
        if (GET_PROTOCOL_MINOR(clientVersion) >= 4) {
            settings.buildVerbosity = (Verbosity) readInt(from);
            logType = (LogType) readInt(from);
            settings.printBuildTrace = readInt(from) != 0;
        }
        if (GET_PROTOCOL_MINOR(clientVersion) >= 6
            && GET_PROTOCOL_MINOR(clientVersion) < 0x61)
            settings.set("build-cores", std::to_string(readInt(from)));
        if (GET_PROTOCOL_MINOR(clientVersion) >= 10)
            settings.set("build-use-substitutes", readInt(from) ? "true" : "false");
        if (GET_PROTOCOL_MINOR(clientVersion) >= 12) {
            unsigned int n = readInt(from);
            for (unsigned int i = 0; i < n; i++) {
                string name = readString(from);
                string value = readString(from);
                if (name == "build-timeout" || name == "build-max-silent-time"
                    || name == "build-max-jobs" || name == "build-cores"
                    || name == "build-repeat"
                    || name == "use-ssh-substituter")
                    settings.set(name, value);
                else
                    settings.set(trusted ? name : "untrusted-" + name, value);
            }
        }
        settings.update();
        startWork();
        stopWork();
        break;
    }

    case wopQuerySubstitutablePathInfo: {
        Path path = absPath(readString(from));
        startWork();
        SubstitutablePathInfos infos;
        store->querySubstitutablePathInfos(singleton<PathSet>(path), infos);
        stopWork();
        SubstitutablePathInfos::iterator i = infos.find(path);
        if (i == infos.end())
            writeInt(0, to);
        else {
            writeInt(1, to);
            writeString(i->second.deriver, to);
            writeStrings(i->second.references, to);
            writeLongLong(i->second.downloadSize, to);
            if (GET_PROTOCOL_MINOR(clientVersion) >= 7)
                writeLongLong(i->second.narSize, to);
        }
        break;
    }

    case wopQuerySubstitutablePathInfos: {
        PathSet paths = readStorePaths<PathSet>(from);
        startWork();
        SubstitutablePathInfos infos;
        store->querySubstitutablePathInfos(paths, infos);
        stopWork();
        writeInt(infos.size(), to);
        foreach (SubstitutablePathInfos::iterator, i, infos) {
            writeString(i->first, to);
            writeString(i->second.deriver, to);
            writeStrings(i->second.references, to);
            writeLongLong(i->second.downloadSize, to);
            writeLongLong(i->second.narSize, to);
        }
        break;
    }

    case wopQueryAllValidPaths: {
        startWork();
        PathSet paths = store->queryAllValidPaths();
        stopWork();
        writeStrings(paths, to);
        break;
    }

    case wopQueryFailedPaths: {
        startWork();
        PathSet paths = store->queryFailedPaths();
        stopWork();
        writeStrings(paths, to);
        break;
    }

    case wopClearFailedPaths: {
        PathSet paths = readStrings<PathSet>(from);
        startWork();
        store->clearFailedPaths(paths);
        stopWork();
        writeInt(1, to);
        break;
    }

    case wopQueryPathInfo: {
        Path path = readStorePath(from);
        startWork();
        ValidPathInfo info = store->queryPathInfo(path);
        stopWork();
        writeString(info.deriver, to);
        writeString(printHash(info.hash), to);
        writeStrings(info.references, to);
        writeInt(info.registrationTime, to);
        writeLongLong(info.narSize, to);
        break;
    }

    case wopOptimiseStore:
        startWork();
        store->optimiseStore();
        stopWork();
        writeInt(1, to);
        break;

    case wopVerifyStore: {
        bool checkContents = readInt(from) != 0;
        bool repair = readInt(from) != 0;
        startWork();
        if (repair && !trusted)
            throw Error("you are not privileged to repair paths");
        bool errors = store->verifyStore(checkContents, repair);
        stopWork();
        writeInt(errors, to);
        break;
    }

    case wopBuiltinBuilders: {
	startWork();
	auto names = builtinBuilderNames();
	stopWork();
	writeStrings(names, to);
	break;
    }

    default:
        throw Error(format("invalid operation %1%") % op);
    }
}

static void processConnection(bool trusted)
{
    canSendStderr = false;
    _writeToStderr = tunnelStderr;

#ifdef HAVE_HUP_NOTIFICATION
    /* Allow us to receive SIGPOLL for events on the client socket. */
    setSigPollAction(false);
    if (fcntl(from.fd, F_SETOWN, getpid()) == -1)
        throw SysError("F_SETOWN");
    if (fcntl(from.fd, F_SETFL, fcntl(from.fd, F_GETFL, 0) | O_ASYNC) == -1)
        throw SysError("F_SETFL");
#endif

    /* Exchange the greeting. */
    unsigned int magic = readInt(from);
    if (magic != WORKER_MAGIC_1) throw Error("protocol mismatch");
    writeInt(WORKER_MAGIC_2, to);
    writeInt(PROTOCOL_VERSION, to);
    to.flush();
    unsigned int clientVersion = readInt(from);

    if (GET_PROTOCOL_MINOR(clientVersion) >= 14 && readInt(from))
        setAffinityTo(readInt(from));

    bool reserveSpace = true;
    if (GET_PROTOCOL_MINOR(clientVersion) >= 11)
        reserveSpace = readInt(from) != 0;

    /* Send startup error messages to the client. */
    startWork();

    try {

        /* If we can't accept clientVersion, then throw an error
           *here* (not above). */

#if 0
        /* Prevent users from doing something very dangerous. */
        if (geteuid() == 0 &&
            querySetting("build-users-group", "") == "")
            throw Error("if you run `nix-daemon' as root, then you MUST set `build-users-group'!");
#endif

        /* Open the store. */
        store = std::shared_ptr<StoreAPI>(new LocalStore(reserveSpace));

        stopWork();
        to.flush();

    } catch (Error & e) {
        stopWork(false, e.msg(), GET_PROTOCOL_MINOR(clientVersion) >= 8 ? 1 : 0);
        to.flush();
        return;
    }

    /* Process client requests. */
    unsigned int opCount = 0;

    while (true) {
        WorkerOp op;
        try {
            op = (WorkerOp) readInt(from);
        } catch (EndOfFile & e) {
            break;
        }

        opCount++;

        try {
            performOp(trusted, clientVersion, from, to, op);
        } catch (Error & e) {
            /* If we're not in a state where we can send replies, then
               something went wrong processing the input of the
               client.  This can happen especially if I/O errors occur
               during addTextToStore() / importPath().  If that
               happens, just send the error message and exit. */
            bool errorAllowed = canSendStderr;
            stopWork(false, e.msg(), GET_PROTOCOL_MINOR(clientVersion) >= 8 ? e.status : 0);
            if (!errorAllowed) throw;
        } catch (std::bad_alloc & e) {
            stopWork(false, "Nix daemon out of memory", GET_PROTOCOL_MINOR(clientVersion) >= 8 ? 1 : 0);
            throw;
        }

        to.flush();

        assert(!canSendStderr);
    };

    canSendStderr = false;
    _isInterrupted = false;
    printMsg(lvlDebug, format("%1% operations") % opCount);
}

static void sigChldHandler(int sigNo)
{
    /* Reap all dead children. */
    while (waitpid(-1, 0, WNOHANG) > 0) ;
}

static void setSigChldAction(bool autoReap)
{
    struct sigaction act, oact;
    act.sa_handler = autoReap ? sigChldHandler : SIG_DFL;
    sigfillset(&act.sa_mask);
    act.sa_flags = 0;
    if (sigaction(SIGCHLD, &act, &oact))
        throw SysError("setting SIGCHLD handler");
}

/* Accept a connection on FDSOCKET and fork a server process to process the
   new connection.  */
static void acceptConnection(int fdSocket)
{
    uid_t clientUid = (uid_t) -1;
    gid_t clientGid = (gid_t) -1;

    try {
	/* Important: the server process *cannot* open the SQLite
	   database, because it doesn't like forks very much. */
	assert(!store);

	/* Accept a connection. */
	struct sockaddr_storage remoteAddr;
	socklen_t remoteAddrLen = sizeof(remoteAddr);

    try_again:
	AutoCloseFD remote = accept(fdSocket,
				    (struct sockaddr *) &remoteAddr, &remoteAddrLen);
	checkInterrupt();
	if (remote == -1) {
	    if (errno == EINTR)
		goto try_again;
	    else
		throw SysError("accepting connection");
	}

	closeOnExec(remote);

	{
	  int enabled = 1;

	  /* If we're on a TCP connection, disable Nagle's algorithm so that
	     data is sent as soon as possible.  */
	  (void) setsockopt(remote, SOL_TCP, TCP_NODELAY,
			    &enabled, sizeof enabled);

#if defined(TCP_QUICKACK)
	  /* Enable TCP quick-ack if applicable; this might help a little.  */
	  (void) setsockopt(remote, SOL_TCP, TCP_QUICKACK,
			    &enabled, sizeof enabled);
#endif
	}

	pid_t clientPid = -1;
	bool trusted = false;

	/* Get the identity of the caller, if possible. */
	if (remoteAddr.ss_family == AF_UNIX) {
#if defined(SO_PEERCRED)
	    ucred cred;
	    socklen_t credLen = sizeof(cred);
	    if (getsockopt(remote, SOL_SOCKET, SO_PEERCRED,
			   &cred, &credLen) == -1)
		throw SysError("getting peer credentials");

	    clientPid = cred.pid;
	    clientUid = cred.uid;
	    clientGid = cred.gid;
	    trusted = clientUid == 0;

            struct passwd * pw = getpwuid(cred.uid);
            string user = pw ? pw->pw_name : std::to_string(cred.uid);

	    printMsg(lvlInfo,
		     format((string) "accepted connection from pid %1%, user %2%")
		     % clientPid % user);
#endif
	} else {
	    char address_str[128];
	    const char *result;

	    if (remoteAddr.ss_family == AF_INET) {
		struct sockaddr_in *addr = (struct sockaddr_in *) &remoteAddr;
		result = inet_ntop(AF_INET, &addr->sin_addr,
				   address_str, sizeof address_str);
	    } else if (remoteAddr.ss_family == AF_INET6) {
		struct sockaddr_in6 *addr = (struct sockaddr_in6 *) &remoteAddr;
		result = inet_ntop(AF_INET6, &addr->sin6_addr,
				   address_str, sizeof address_str);
	    } else {
		result = NULL;
	    }

	    if (result != NULL) {
		printMsg(lvlInfo,
			 format("accepted connection from %1%")
			 % address_str);
	    }
	}

	/* Fork a child to handle the connection. */
	startProcess([&]() {
                close(fdSocket);

                /* Background the daemon. */
                if (setsid() == -1)
                    throw SysError(format("creating a new session"));

                /* Restore normal handling of SIGCHLD. */
                setSigChldAction(false);

                /* For debugging, stuff the pid into argv[1]. */
                if (clientPid != -1 && argvSaved[1]) {
                    string processName = std::to_string(clientPid);
                    strncpy(argvSaved[1], processName.c_str(), strlen(argvSaved[1]));
                }

                /* Store the client's user and group for this connection. This
                   has to be done in the forked process since it is per
                   connection.  Setting these to -1 means: do not change.  */
                settings.clientUid = clientUid;
		settings.clientGid = clientGid;
                isRemoteConnection = (remoteAddr.ss_family != AF_UNIX);

                /* Handle the connection. */
                from.fd = remote;
                to.fd = remote;
                processConnection(trusted);

                exit(0);
            }, false, "unexpected Nix daemon error: ", true);

    } catch (Interrupted & e) {
	throw;
    } catch (Error & e) {
	printMsg(lvlError, format("error processing connection: %1%") % e.msg());
    }
}

static void daemonLoop(const std::vector<int>& sockets)
{
    if (chdir("/") == -1)
        throw SysError("cannot change current directory");

    /* Get rid of children automatically; don't let them become
       zombies. */
    setSigChldAction(true);

    /* Mark sockets as close-on-exec.  */
    for(int fd: sockets) {
	closeOnExec(fd);
    }

    /* Prepare the FD set corresponding to SOCKETS.  */
    auto initializeFDSet = [&](fd_set *set) {
	FD_ZERO(set);
	for (int fd: sockets) {
	    FD_SET(fd, set);
	}
    };

    /* Loop accepting connections. */
    while (1) {
	fd_set readfds;

	initializeFDSet(&readfds);
	int count =
	    select(*std::max_element(sockets.begin(), sockets.end()) + 1,
		   &readfds, NULL, NULL,
		   NULL);
	if (count < 0) {
	    int err = errno;
	    if (err == EINTR)
		continue;
	    throw SysError(format("select error: %1%") % strerror(err));
	}

	for (unsigned int i = 0; i < sockets.size(); i++) {
	    if (FD_ISSET(sockets[i], &readfds)) {
		acceptConnection(sockets[i]);
	    }
	}
    }
}

void run(const std::vector<int>& sockets)
{
    daemonLoop(sockets);
}

void printHelp()
{
    showManPage("nix-daemon");
}

string programId = "nix-daemon";

license: mit


code:
/* GNU Guix --- Functional package management for GNU
   Copyright (C) 2012  Ludovic Courtès <ludo@gnu.org>

   This file is part of GNU Guix.

   GNU Guix is free software; you can redistribute it and/or modify it
   under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or (at
   your option) any later version.

   GNU Guix is distributed in the hope that it will be useful, but
   WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.  */

/* Replacement for Nix's libmain/shared.hh.  */

#pragma once

#include <string>

#include <stdlib.h>
#include <signal.h>

static inline void
showManPage (const char *name)
{
  /* This idea is evil.  Abort.  */
  abort ();
}

extern volatile ::sig_atomic_t blockInt;

extern char **argvSaved;


code:
#!@SHELL@
# A shorthand for "guix perform-download", for use by the daemon.

if test "x$GUIX_UNINSTALLED" = "x"
then
    prefix="@prefix@"
    exec_prefix="@exec_prefix@"
    exec "@bindir@/guix" perform-download "$@"
else
    exec guix perform-download "$@"
fi


code:
#!@SHELL@
# A shorthand for "guix authenticate", for use by the daemon.

if test "x$GUIX_UNINSTALLED" = "x"
then
    prefix="@prefix@"
    exec_prefix="@exec_prefix@"
    exec "@bindir@/guix" authenticate "$@"
else
    exec guix authenticate "$@"
fi


code:
#!@GUILE@ -ds
!#
;;; GNU Guix --- Functional package management for GNU
;;; Copyright © 2012, 2013, 2014, 2017 Ludovic Courtès <ludo@gnu.org>
;;;
;;; This file is part of GNU Guix.
;;;
;;; GNU Guix is free software; you can redistribute it and/or modify it
;;; under the terms of the GNU General Public License as published by
;;; the Free Software Foundation; either version 3 of the License, or (at
;;; your option) any later version.
;;;
;;; GNU Guix is distributed in the hope that it will be useful, but
;;; WITHOUT ANY WARRANTY; without even the implied warranty of
;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;;; GNU General Public License for more details.
;;;
;;; You should have received a copy of the GNU General Public License
;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.

;;;
;;; List files being used at run time; these files are garbage collector
;;; roots.  This is equivalent to `find-runtime-roots.pl' in Nix.
;;;

(use-modules (ice-9 ftw)
             (ice-9 regex)
             (ice-9 rdelim)
             (ice-9 match)
             (srfi srfi-1)
             (srfi srfi-26)
             (rnrs io ports))

(define %proc-directory
  ;; Mount point of Linuxish /proc file system.
  "/proc")

(define %store-directory
  (or (getenv "NIX_STORE_DIR")
      "@storedir@"))

(define (proc-file-roots dir file)
  "Return a one-element list containing the file pointed to by DIR/FILE,
or the empty list."
  (or (and=> (false-if-exception (readlink (string-append dir "/" file)))
             list)
      '()))

(define proc-exe-roots (cut proc-file-roots <> "exe"))
(define proc-cwd-roots (cut proc-file-roots <> "cwd"))

(define (proc-fd-roots dir)
  "Return the list of store files referenced by DIR, which is a
/proc/XYZ directory."
  (let ((dir (string-append dir "/fd")))
    (filter-map (lambda (file)
                  (let ((target (false-if-exception
                                 (readlink (string-append dir "/" file)))))
                    (and target
                         (string-prefix? "/" target)
                         target)))
                (or (scandir dir string->number) '()))))

(define (proc-maps-roots dir)
  "Return the list of store files referenced by DIR, which is a
/proc/XYZ directory."
  (define %file-mapping-line
    (make-regexp "^.*[[:blank:]]+/([^ ]+)$"))

  (call-with-input-file (string-append dir "/maps")
    (lambda (maps)
      (let loop ((line  (read-line maps))
                 (roots '()))
        (cond ((eof-object? line)
               roots)
              ((regexp-exec %file-mapping-line line)
               =>
               (lambda (match)
                 (let ((file (string-append "/"
                                            (match:substring match 1))))
                   (loop (read-line maps)
                         (cons file roots)))))
              (else
               (loop (read-line maps) roots)))))))

(define (proc-environ-roots dir)
  "Return the list of store files referenced by DIR/environ, where DIR is a
/proc/XYZ directory."
  (define split-on-nul
    (cute string-tokenize <>
          (char-set-complement (char-set #\nul))))

  (define (rhs-file-names str)
    (let ((equal (string-index str #\=)))
      (if equal
          (let* ((str (substring str (+ 1 equal)))
                 (rx  (string-append (regexp-quote %store-directory)
                                     "/[0-9a-z]{32}-[a-zA-Z0-9\\._+-]+")))
            (map match:substring (list-matches rx str)))
          '())))

  (define environ
    (string-append dir "/environ"))

  (append-map rhs-file-names
              (split-on-nul
               (call-with-input-file environ
                 get-string-all))))

(define (referenced-files)
  "Return the list of referenced store items."
  (append-map (lambda (pid)
                (let ((proc (string-append %proc-directory "/" pid)))
                  (catch 'system-error
                    (lambda ()
                      (append (proc-exe-roots proc)
                              (proc-cwd-roots proc)
                              (proc-fd-roots proc)
                              (proc-maps-roots proc)
                              (proc-environ-roots proc)))
                    (lambda args
                      (let ((err (system-error-errno args)))
                        (if (or (= ENOENT err)    ;TOCTTOU race
                                (= ESRCH err)     ;ditto
                                (= EACCES err))   ;not running as root
                            '()
                            (apply throw args)))))))
              (scandir %proc-directory string->number
                       (lambda (a b)
                         (< (string->number a) (string->number b))))))

(define canonicalize-store-item
  (let* ((store  (string-append %store-directory "/"))
         (prefix (string-length store)))
    (lambda (file)
      "Return #f if FILE is not a store item; otherwise, return the store file
name without any sub-directory components."
      (and (string-prefix? store file)
           (string-append store
                          (let ((base (string-drop file prefix)))
                            (match (string-index base #\/)
                              (#f    base)
                              (slash (string-take base slash)))))))))

(for-each (cut simple-format #t "~a~%" <>)
          (delete-duplicates
           (filter-map canonicalize-store-item (referenced-files))))


code:
#!@SHELL@
# A shorthand for "guix offload", for use by the daemon.

if test "x$GUIX_UNINSTALLED" = "x"
then
    prefix="@prefix@"
    exec_prefix="@exec_prefix@"
    exec "@bindir@/guix" offload "$@"
else
    exec guix offload "$@"
fi


code:
#!@SHELL@
# A shorthand for "guix substitute", for use by the daemon.

if test "x$GUIX_UNINSTALLED" = "x"
then
    prefix="@prefix@"
    exec_prefix="@exec_prefix@"
    exec "@bindir@/guix" substitute "$@"
else
    exec guix substitute "$@"
fi