path: root/winsup/cygwin/fhandler_socket_unix.cc

/* fhandler_socket_unix.cc.

   See fhandler.h for a description of the fhandler classes.

   This file is part of Cygwin.

   This software is a copyrighted work licensed under the terms of the
   Cygwin license.  Please consult the file "CYGWIN_LICENSE" for
   details. */

#include "winsup.h"

GUID __cygwin_socket_guid = {
  .Data1 = 0xefc1714d,
  .Data2 = 0x7b19,
  .Data3 = 0x4407,
  .Data4 = { 0xba, 0xb3, 0xc5, 0xb1, 0xf9, 0x2c, 0xb8, 0x8c }
};

#ifdef __WITH_AF_UNIX

#include <w32api/winioctl.h>
#include <asm/byteorder.h>
#include <unistd.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <sys/param.h>
#include <sys/statvfs.h>
#include <cygwin/acl.h>
#include <mqueue.h>
#include "cygerrno.h"
#include "path.h"
#include "fhandler.h"
#include "dtable.h"
#include "cygheap.h"
#include "shared_info.h"
#include "ntdll.h"
#include "miscfuncs.h"
#include "tls_pbuf.h"

/*
   Message queue:

     A socket that wants to read creates a POSIX message queue.  The
     name of the mqueue is "/af-unix-[sd]-<uniq_id>".

    - [sd] is s for SOCK_STREAM, d for SOCK_DGRAM
    - <uniq_id> is an 8 byte hex unique number

   Abstract socket:

     An abstract socket is represented by a symlink in the native
     NT namespace, within the Cygwin subdir in BasedNamedObjects.
     So it's globally available but only exists as long as at least on
     descriptor on the socket is open, as desired.

     The name of the symlink is: "af-unix-<sun_path>"

     <sun_path> is the transposed sun_path string, including the leading
     NUL.  The transposition is simplified in that it uses every byte
     in the valid sun_path name as is, no extra multibyte conversion.
     The content of the symlink is the name of the underlying mqueue.

  Named socket:

    A named socket is represented by a reparse point with a Cygwin-specific
    tag and GUID.  The GenericReparseBuffer content is the name of the
    underlying mqueue.

   Note: We use MAX_PATH below for convenience where sufficient.  It's
   big enough to hold sun_paths as well as mqueue names as well as packet
   headers etc., so we don't have to use tmp_pathbuf as often.

   Every packet sent to a peer is a combination of the socket name of the
   local socket, the ancillary data, and the actual user data.  The data
   is always sent in this order.  The header contains length information
   for the entire packet, as well as for all three data blocks.  The
   combined maximum size of a packet is 64K, including the header.

   A connecting, bound STREAM socket sends its local sun_path once after
   a successful connect.  An already connected socket also sends its local
   sun_path after a successful bind (border case, but still...).  These
   packets don't contain any other data (cmsg_len == 0, data_len == 0).

   A bound DGRAM socket sends its sun_path with each sendmsg/sendto.
*/

static inline ptrdiff_t
AF_UNIX_PKT_OFFSETOF_NAME (af_unix_pkt_hdr_t *phdr)
{
  return sizeof (af_unix_pkt_hdr_t);
}

static inline ptrdiff_t
AF_UNIX_PKT_OFFSETOF_CMSG (af_unix_pkt_hdr_t *phdr)
{
  return AF_UNIX_PKT_OFFSETOF_NAME (phdr) + phdr->name_len;
}

static inline ptrdiff_t
AF_UNIX_PKT_OFFSETOF_DATA (af_unix_pkt_hdr_t *phdr)
{
  return AF_UNIX_PKT_OFFSETOF_CMSG (phdr) + phdr->cmsg_len;
}

static inline struct sockaddr_un *
AF_UNIX_PKT_NAME (af_unix_pkt_hdr_t *phdr)
{
  return (struct sockaddr_un *)
	 ((PBYTE)(phdr) + AF_UNIX_PKT_OFFSETOF_NAME (phdr));
}

static inline struct cmsghdr *
AF_UNIX_PKT_CMSG (af_unix_pkt_hdr_t *phdr)
{
   return (struct cmsghdr *)
	  ((PBYTE)(phdr) + AF_UNIX_PKT_OFFSETOF_CMSG (phdr));
}

static inline void *
AF_UNIX_PKT_DATA (af_unix_pkt_hdr_t *phdr)
{
   return (void *) ((PBYTE)(phdr) + AF_UNIX_PKT_OFFSETOF_DATA (phdr));
}

static inline void *
AF_UNIX_PKT_DATA_END (af_unix_pkt_hdr_t *phdr)
{
   return (void *) ((PBYTE)(phdr) + AF_UNIX_PKT_OFFSETOF_DATA (phdr)
				  + (phdr)->data_len);
}

inline bool
AF_UNIX_PKT_DATA_APPEND (af_unix_pkt_hdr_t *phdr, void *data, uint16_t dlen)
{
  if ((uint32_t) phdr->pckt_len + (uint32_t) dlen > MAX_AF_UN_PKT_LEN)
    return false;
  memcpy (AF_UNIX_PKT_DATA_END (phdr), data, dlen);
  phdr->pckt_len += dlen;
  phdr->data_len += dlen;
  return true;
}

/* Some error conditions on pipes have multiple status codes, unfortunately. */
#define STATUS_PIPE_NO_INSTANCE_AVAILABLE(status)	\
		({ NTSTATUS _s = (status); \
		   _s == STATUS_INSTANCE_NOT_AVAILABLE \
		   || _s == STATUS_PIPE_NOT_AVAILABLE \
		   || _s == STATUS_PIPE_BUSY; })

#define STATUS_PIPE_IS_CLOSED(status)	\
		({ NTSTATUS _s = (status); \
		   _s == STATUS_PIPE_CLOSING \
		   || _s == STATUS_PIPE_BROKEN \
		   || _s == STATUS_PIPE_EMPTY; })

#define STATUS_PIPE_INVALID(status) \
		({ NTSTATUS _s = (status); \
		   _s == STATUS_INVALID_INFO_CLASS \
		   || _s == STATUS_INVALID_PIPE_STATE \
		   || _s == STATUS_INVALID_READ_MODE; })

#define STATUS_PIPE_MORE_DATA(status) \
		({ NTSTATUS _s = (status); \
		   _s == STATUS_BUFFER_OVERFLOW \
		   || _s == STATUS_MORE_PROCESSING_REQUIRED; })

/* Default timeout value of connect: 20 secs, as on Linux. */
#define AF_UNIX_CONNECT_TIMEOUT 20

/* Message queue priorities */
enum
{
  af_un_prio_normal,
  af_un_prio_admin,
  af_un_prio_rewrite,		/* For rewritten packet after partial read. */
};

void
sun_name_t::set (const struct sockaddr_un *name, socklen_t namelen)
{
  if (namelen < 0)
    namelen = 0;
  un_len = namelen < (__socklen_t) sizeof un ? namelen : sizeof un;
  un.sun_family = AF_UNIX;
  if (name && un_len)
    memcpy (&un, name, un_len);
  _nul[un_len] = '\0';
}

static HANDLE
create_event ()
{
  NTSTATUS status;
  OBJECT_ATTRIBUTES attr;
  HANDLE evt = NULL;

  InitializeObjectAttributes (&attr, NULL, 0, NULL, NULL);
  status = NtCreateEvent (&evt, EVENT_ALL_ACCESS, &attr,
			  NotificationEvent, FALSE);
  if (!NT_SUCCESS (status))
    __seterrno_from_nt_status (status);
  return evt;
}

/* Called from socket, socketpair, accept4 */
int
fhandler_socket_unix::create_shmem ()
{
  HANDLE sect;
  OBJECT_ATTRIBUTES attr;
  NTSTATUS status;
  LARGE_INTEGER size = { .QuadPart = sizeof (af_unix_shmem_t) };
  SIZE_T viewsize = sizeof (af_unix_shmem_t);
  PVOID addr = NULL;

  InitializeObjectAttributes (&attr, NULL, OBJ_INHERIT, NULL, NULL);
  status = NtCreateSection (&sect, STANDARD_RIGHTS_REQUIRED | SECTION_QUERY
				   | SECTION_MAP_READ | SECTION_MAP_WRITE,
			    &attr, &size, PAGE_READWRITE, SEC_COMMIT, NULL);
  if (!NT_SUCCESS (status))
    {
      __seterrno_from_nt_status (status);
      return -1;
    }
  status = NtMapViewOfSection (sect, NtCurrentProcess (), &addr, 0, viewsize,
			       NULL, &viewsize, ViewShare, 0, PAGE_READWRITE);
  if (!NT_SUCCESS (status))
    {
      NtClose (sect);
      __seterrno_from_nt_status (status);
      return -1;
    }
  shmem_handle = sect;
  shmem = (af_unix_shmem_t *) addr;
  return 0;
}

/* Called from dup, fixup_after_fork.  Expects shmem_handle to be
   valid. */
int
fhandler_socket_unix::reopen_shmem ()
{
  NTSTATUS status;
  SIZE_T viewsize = sizeof (af_unix_shmem_t);
  PVOID addr = NULL;

  status = NtMapViewOfSection (shmem_handle, NtCurrentProcess (), &addr, 0,
			       viewsize, NULL, &viewsize, ViewShare, 0,
			       PAGE_READWRITE);
  if (!NT_SUCCESS (status))
    {
      __seterrno_from_nt_status (status);
      return -1;
    }
  shmem = (af_unix_shmem_t *) addr;
  return 0;
}

/* Character length of mqueue name, excluding trailing NUL. */
#define CYGWIN_MQUEUE_SOCKET_NAME_LEN     27

/* Character position encoding the socket type in an mqueue name. */
#define CYGWIN_MQUEUE_SOCKET_TYPE_POS	9

void
fhandler_socket_unix::gen_mqueue_name ()
{
  char mqueue_name_buf[CYGWIN_MQUEUE_SOCKET_NAME_LEN + 1];

  __small_sprintf (mqueue_name_buf, "/af-unix-%c-%016x",
		    get_type_char (),
		    get_unique_id ());
  set_mqueue_name (mqueue_name_buf);
}

HANDLE
fhandler_socket_unix::create_abstract_link (const sun_name_t *sun,
					    const char *mqueue_name)
{
  WCHAR name[MAX_PATH], wmqueue_name[MAX_PATH];
  OBJECT_ATTRIBUTES attr;
  NTSTATUS status;
  UNICODE_STRING uname, umqueue_name;
  HANDLE fh = NULL;

  PWCHAR p = wcpcpy (name, L"af-unix-");
  /* NUL bytes have no special meaning in an abstract socket name, so
     we assume iso-8859-1 for simplicity and transpose the string.
     transform_chars_af_unix is doing just that. */
  p = transform_chars_af_unix (p, sun->un.sun_path, sun->un_len);
  *p = L'\0';
  RtlInitUnicodeString (&uname, name);
  InitializeObjectAttributes (&attr, &uname, OBJ_CASE_INSENSITIVE,
			      get_shared_parent_dir (), NULL);
  /* Fill symlink with name of mqueue */
  sys_mbstowcs (wmqueue_name, MAX_PATH, mqueue_name);
  RtlInitUnicodeString (&umqueue_name, wmqueue_name);
  status = NtCreateSymbolicLinkObject (&fh, SYMBOLIC_LINK_ALL_ACCESS,
				       &attr, &umqueue_name);
  if (!NT_SUCCESS (status))
    {
      if (status == STATUS_OBJECT_NAME_EXISTS
	  || status == STATUS_OBJECT_NAME_COLLISION)
	set_errno (EADDRINUSE);
      else
	__seterrno_from_nt_status (status);
    }
  return fh;
}

HANDLE
fhandler_socket_unix::create_reparse_point (const sun_name_t *sun,
					    const char *mqueue_name)
{
  ULONG access;
  HANDLE old_trans = NULL, trans = NULL;
  OBJECT_ATTRIBUTES attr;
  IO_STATUS_BLOCK io;
  NTSTATUS status;
  HANDLE fh = NULL;
  PREPARSE_GUID_DATA_BUFFER rp;

  const DWORD data_len = CYGWIN_MQUEUE_SOCKET_NAME_LEN + 1;

  path_conv pc (sun->un.sun_path, PC_SYM_FOLLOW);
  if (pc.error)
    {
      set_errno (pc.error);
      return NULL;
    }
  if (pc.exists ())
    {
      set_errno (EADDRINUSE);
      return NULL;
    }
 /* We will overwrite the DACL after the call to NtCreateFile.  This
    requires READ_CONTROL and WRITE_DAC access, otherwise get_file_sd
    and set_file_sd both have to open the file again.
    FIXME: On remote NTFS shares open sometimes fails because even the
    creator of the file doesn't have the right to change the DACL.
    I don't know what setting that is or how to recognize such a share,
    so for now we don't request WRITE_DAC on remote drives. */
  access = DELETE | FILE_GENERIC_WRITE;
  if (!pc.isremote ())
    access |= READ_CONTROL | WRITE_DAC | WRITE_OWNER;
  if ((pc.fs_flags () & FILE_SUPPORTS_TRANSACTIONS))
    start_transaction (old_trans, trans);

retry_after_transaction_error:
  status = NtCreateFile (&fh, DELETE | FILE_GENERIC_WRITE,
			 pc.get_object_attr (attr, sec_none_nih), &io,
			 NULL, FILE_ATTRIBUTE_NORMAL, 0, FILE_CREATE,
			 FILE_SYNCHRONOUS_IO_NONALERT
			 | FILE_NON_DIRECTORY_FILE
			 | FILE_OPEN_FOR_BACKUP_INTENT
			 | FILE_OPEN_REPARSE_POINT,
			 NULL, 0);
  if (NT_TRANSACTIONAL_ERROR (status) && trans)
    {
      stop_transaction (status, old_trans, trans);
      goto retry_after_transaction_error;
    }

  if (!NT_SUCCESS (status))
    {
      if (io.Information == FILE_EXISTS)
	set_errno (EADDRINUSE);
      else
	__seterrno_from_nt_status (status);
      goto out;
    }
  rp = (PREPARSE_GUID_DATA_BUFFER)
       alloca (REPARSE_GUID_DATA_BUFFER_HEADER_SIZE + data_len);
  rp->ReparseTag = IO_REPARSE_TAG_CYGUNIX;
  rp->ReparseDataLength = data_len;
  rp->Reserved = 0;
  memcpy (&rp->ReparseGuid, CYGWIN_SOCKET_GUID, sizeof (GUID));
  strcpy ((char *) rp->GenericReparseBuffer.DataBuffer, mqueue_name);
  status = NtFsControlFile (fh, NULL, NULL, NULL, &io,
			    FSCTL_SET_REPARSE_POINT, rp,
			    REPARSE_GUID_DATA_BUFFER_HEADER_SIZE
			    + rp->ReparseDataLength, NULL, 0);
  if (NT_SUCCESS (status))
    {
      mode_t perms = (S_IRWXU | S_IRWXG | S_IRWXO) & ~cygheap->umask;
      set_created_file_access (fh, pc, perms);
      NtClose (fh);
      /* We don't have to keep the file open, but the caller needs to
         get a value != NULL to know the file creation went fine. */
      fh = INVALID_HANDLE_VALUE;
    }
  else if (!trans)
    {
      FILE_DISPOSITION_INFORMATION fdi = { TRUE };

      __seterrno_from_nt_status (status);
      status = NtSetInformationFile (fh, &io, &fdi, sizeof fdi,
				     FileDispositionInformation);
      if (!NT_SUCCESS (status))
	debug_printf ("Setting delete dispostion failed, status = %y",
		      status);
      NtClose (fh);
      fh = NULL;
    }

out:
  if (trans)
    stop_transaction (status, old_trans, trans);
  return fh;
}

HANDLE
fhandler_socket_unix::create_socket (const sun_name_t *sun)
{
  if (sun->un_len <= (socklen_t) sizeof (sa_family_t)
      || (sun->un_len == 3 && sun->un.sun_path[0] == '\0'))
    {
      set_errno (EINVAL);
      return NULL;
    }
  if (sun->un.sun_path[0] == '\0')
    return create_abstract_link (sun, get_mqueue_name ());
  return create_reparse_point (sun, get_mqueue_name ());
}

HANDLE
fhandler_socket_unix::open_abstract_link (sun_name_t *sun,
					  char *mqueue_name)
{
  WCHAR name[MAX_PATH], wmqueue_name[MAX_PATH];
  OBJECT_ATTRIBUTES attr;
  NTSTATUS status;
  UNICODE_STRING uname, umqueue_name;
  HANDLE fh;

  PWCHAR p = wcpcpy (name, L"af-unix-");
  p = transform_chars_af_unix (p, sun->un.sun_path, sun->un_len);
  *p = L'\0';
  RtlInitUnicodeString (&uname, name);
  InitializeObjectAttributes (&attr, &uname, OBJ_CASE_INSENSITIVE,
			      get_shared_parent_dir (), NULL);
  status = NtOpenSymbolicLinkObject (&fh, SYMBOLIC_LINK_QUERY, &attr);
  if (!NT_SUCCESS (status))
    {
      __seterrno_from_nt_status (status);
      return NULL;
    }
  if (mqueue_name)
    {
      RtlInitEmptyUnicodeString (&umqueue_name, wmqueue_name,
				 MAX_PATH * sizeof (WCHAR));
      status = NtQuerySymbolicLinkObject (fh, &umqueue_name, NULL);
    }
  if (mqueue_name)
    {
      if (!NT_SUCCESS (status))
	{
	  NtClose (fh);
	  __seterrno_from_nt_status (status);
	  return NULL;
	}
      sys_wcstombs (mqueue_name, MAX_PATH, wmqueue_name);
    }
  return fh;
}

HANDLE
fhandler_socket_unix::open_reparse_point (sun_name_t *sun,
					  char *mqueue_name)
{
  NTSTATUS status;
  HANDLE fh;
  OBJECT_ATTRIBUTES attr;
  IO_STATUS_BLOCK io;
  PREPARSE_GUID_DATA_BUFFER rp;
  tmp_pathbuf tp;

  path_conv pc (sun->un.sun_path, PC_SYM_FOLLOW);
  if (pc.error)
    {
      set_errno (pc.error);
      return NULL;
    }
  if (!pc.exists ())
    {
      set_errno (ENOENT);
      return NULL;
    }
  pc.get_object_attr (attr, sec_none_nih);
  do
    {
      status = NtOpenFile (&fh, FILE_GENERIC_READ, &attr, &io,
			   FILE_SHARE_VALID_FLAGS,
			   FILE_SYNCHRONOUS_IO_NONALERT
			   | FILE_NON_DIRECTORY_FILE
			   | FILE_OPEN_FOR_BACKUP_INTENT
			   | FILE_OPEN_REPARSE_POINT);
      if (status == STATUS_SHARING_VIOLATION)
        {
          /* While we hope that the sharing violation is only temporary, we
             also could easily get stuck here, waiting for a file in use by
             some greedy Win32 application.  Therefore we should never wait
             endlessly without checking for signals and thread cancel event. */
          pthread_testcancel ();
          if (cygwait (NULL, cw_nowait, cw_sig_eintr) == WAIT_SIGNALED
              && !_my_tls.call_signal_handler ())
            {
              set_errno (EINTR);
              return NULL;
            }
          yield ();
        }
      else if (!NT_SUCCESS (status))
        {
          __seterrno_from_nt_status (status);
          return NULL;
        }
    }
  while (status == STATUS_SHARING_VIOLATION);
  rp = (PREPARSE_GUID_DATA_BUFFER) tp.c_get ();
  status = NtFsControlFile (fh, NULL, NULL, NULL, &io, FSCTL_GET_REPARSE_POINT,
			    NULL, 0, rp, MAXIMUM_REPARSE_DATA_BUFFER_SIZE);
  if (rp->ReparseTag == IO_REPARSE_TAG_CYGUNIX
      && memcmp (CYGWIN_SOCKET_GUID, &rp->ReparseGuid, sizeof (GUID)) == 0)
    {
      if (mqueue_name)
	strcpy (mqueue_name, (char *) rp->GenericReparseBuffer.DataBuffer);
      return fh;
    }
  NtClose (fh);
  return NULL;
}

HANDLE
fhandler_socket_unix::open_socket (sun_name_t *sun, int &type,
				   char *mqueue_name)
{
  HANDLE fh = NULL;

  if (sun->un_len <= (socklen_t) sizeof (sa_family_t)
      || (sun->un_len == 3 && sun->un.sun_path[0] == '\0'))
    set_errno (EINVAL);
  else if (sun->un.sun_family != AF_UNIX)
    set_errno (EAFNOSUPPORT);
  else if (sun->un.sun_path[0] == '\0')
    fh = open_abstract_link (sun, mqueue_name);
  else
    fh = open_reparse_point (sun, mqueue_name);
  if (fh)
    switch (mqueue_name[CYGWIN_MQUEUE_SOCKET_TYPE_POS])
      {
      case 'd':
	type = SOCK_DGRAM;
	break;
      case 's':
	type = SOCK_STREAM;
	break;
      default:
	set_errno (EINVAL);
	NtClose (fh);
	fh = NULL;
	break;
      }
  return fh;
}

HANDLE
fhandler_socket_unix::autobind (sun_name_t* sun)
{
  uint32_t id;
  HANDLE fh;

  do
    {
      /* Use only 5 hex digits (up to 2^20 sockets) for Linux compat */
      set_unique_id ();
      id = get_unique_id () & 0xfffff;
      sun->un.sun_path[0] = '\0';
      sun->un_len = sizeof (sa_family_t)
		    + 1 /* leading NUL */
		    + __small_sprintf (sun->un.sun_path + 1, "%5X", id);
    }
  while ((fh = create_abstract_link (sun, get_mqueue_name ())) == NULL);
  return fh;
}

char
fhandler_socket_unix::get_type_char ()
{
  switch (get_socket_type ())
    {
    case SOCK_STREAM:
      return 's';
    case SOCK_DGRAM:
      return 'd';
    default:
      return '?';
    }
}

/* Returns error code, but callers don't check it. */
static int
set_mqueue_non_blocking (mqd_t mqd, bool nonblocking)
{
  struct mq_attr attr;

  if (mq_getattr (mqd, &attr) < 0)
    return get_errno ();
  if (nonblocking)
    attr.mq_flags |= O_NONBLOCK;
  else
    attr.mq_flags &= ~O_NONBLOCK;
  if (mq_setattr (mqd, &attr, NULL) < 0)
    return get_errno ();
  return 0;
}

/* This also sets the pipe to message mode unconditionally. */
void
fhandler_socket_unix::set_pipe_non_blocking (bool nonblocking)
{
  if (get_handle ())
    {
      NTSTATUS status;
      IO_STATUS_BLOCK io;
      FILE_PIPE_INFORMATION fpi;

      fpi.ReadMode = FILE_PIPE_MESSAGE_MODE;
      fpi.CompletionMode = nonblocking ? FILE_PIPE_COMPLETE_OPERATION
				       : FILE_PIPE_QUEUE_OPERATION;
      status = NtSetInformationFile (get_handle (), &io, &fpi, sizeof fpi,
				     FilePipeInformation);
      if (!NT_SUCCESS (status))
	debug_printf ("NtSetInformationFile(FilePipeInformation): %y", status);
    }
}

/* Apart from being called from bind(), from_bind indicates that the caller
   already locked state_lock, so send_sock_info doesn't lock, only unlocks
   state_lock. */
int
fhandler_socket_unix::send_sock_info (bool from_bind)
{
  sun_name_t *sun;
  size_t plen;
  size_t clen = 0;
  af_unix_pkt_hdr_t *packet;
  int ret;

  if (!from_bind)
    {
      state_lock ();
      /* When called from connect, initialize credentials.  accept4 already
	 did it (copied from listening socket). */
      if (sock_cred ()->pid == 0)
	set_cred ();
    }
  sun = sun_path ();
  plen = sizeof *packet + sun->un_len;
  /* When called from connect/accept4, send SCM_CREDENTIALS, too. */
  if (!from_bind)
    {
      clen = CMSG_SPACE (sizeof (struct ucred));
      plen += clen;
    }
  packet = (af_unix_pkt_hdr_t *) alloca (plen);
  packet->init (true, _SHUT_NONE, sun->un_len, clen, 0);
  if (sun)
    memcpy (AF_UNIX_PKT_NAME (packet), &sun->un, sun->un_len);
  if (!from_bind)
    {
      struct cmsghdr *cmsg = AF_UNIX_PKT_CMSG (packet);
      cmsg->cmsg_level = SOL_SOCKET;
      cmsg->cmsg_type = SCM_CREDENTIALS;
      cmsg->cmsg_len = CMSG_LEN (sizeof (struct ucred));
      memcpy (CMSG_DATA(cmsg), sock_cred (), sizeof (struct ucred));
    }

  state_unlock ();

  /* The theory: Fire and forget. */
  io_lock ();
  set_mqueue_non_blocking (get_mqd_out (), true);
  ret = mq_send (get_mqd_out (), (const char *) packet, packet->pckt_len,
		 af_un_prio_admin);
  set_mqueue_non_blocking (get_mqd_out (), is_nonblocking ());
  io_unlock ();
  if (ret < 0)
    debug_printf ("Couldn't send my name: mq_send, %E");
  return ret;
}

/* Called from connect_mqueue and wait_mqueue after successfully
   getting peer's mqueue name. */
void
fhandler_socket_unix::xchg_sock_info ()
{
  send_sock_info (false);
  recv_peer_info ();
}

/* Reads an administrative packet from the pipe and handles it.  If
   PEEK is true, checks first to see if the next packet in the pipe is
   an administrative packet; otherwise the caller must set io_lock and
   check this.  Returns an error code, but callers ignore it. */
int
fhandler_socket_unix::grab_admin_pkt (bool peek)
{
  /* MAX_PATH is more than sufficient for admin packets. */
  af_unix_pkt_hdr_t *packet = (af_unix_pkt_hdr_t *) alloca (MAX_PATH);
  ssize_t nr;

  if (peek)
    {
      io_lock ();
      nr = peek_mqueue ((char *) packet, MAX_PATH);
      if (nr < 0)
	{
	  io_unlock ();
	  if (get_errno () == EAGAIN)
	    return 0;
	  return get_errno ();
	}
      if (!packet->admin_pkt)
	{
	  io_unlock ();
	  return 0;
	}
    }
  nr = _mq_recv (get_mqd_in (), (char *) packet, MAX_PATH, 0);
  io_unlock ();
  if (nr < 0)
    return get_errno ();
  state_lock ();
  if (packet->shut_info)
    {
      /* Peer's shutdown sends the SHUT flags as used by the peer.
	 They have to be reversed for our side. */
      int shut_info = saw_shutdown ();
      if (packet->shut_info & _SHUT_RECV)
	shut_info |= _SHUT_SEND;
      if (packet->shut_info & _SHUT_SEND)
	shut_info |= _SHUT_RECV;
      saw_shutdown (shut_info);
      /* FIXME: anything else here? */
    }
  if (packet->name_len > 0)
    peer_sun_path (AF_UNIX_PKT_NAME (packet), packet->name_len);
  if (packet->cmsg_len > 0)
    {
      struct cmsghdr *cmsg = (struct cmsghdr *)
	alloca (packet->cmsg_len);
      memcpy (cmsg, AF_UNIX_PKT_CMSG (packet), packet->cmsg_len);
      if (cmsg->cmsg_level == SOL_SOCKET
	  && cmsg->cmsg_type == SCM_CREDENTIALS)
	peer_cred ((struct ucred *) CMSG_DATA(cmsg));
    }
  state_unlock ();
  return 0;
}

/* Returns an error code.  Locking is not required when called from accept4,
   user space doesn't know about this socket yet. */
int
fhandler_socket_unix::recv_peer_info ()
{
  af_unix_pkt_hdr_t *packet;
  struct sockaddr_un *un;
  size_t len;
  int ret = 0;
  struct timespec timeout;

  len = sizeof *packet + sizeof *un + CMSG_SPACE (sizeof (struct ucred));
  packet = (af_unix_pkt_hdr_t *) alloca (len);
  set_mqueue_non_blocking (get_mqd_in (), false);
  clock_gettime (CLOCK_REALTIME, &timeout);
  timeout.tv_sec += AF_UNIX_CONNECT_TIMEOUT;
  if (_mq_timedrecv (get_mqd_in (), (char *) packet, len, &timeout, 0) < 0)
    ret = get_errno ();
  if (ret == ETIMEDOUT)
    ret = ECONNABORTED;
  set_mqueue_non_blocking (get_mqd_in (), is_nonblocking ());
  if (ret == 0)
    {
      if (packet->name_len > 0)
	peer_sun_path (AF_UNIX_PKT_NAME (packet), packet->name_len);
      if (packet->cmsg_len > 0)
	{
	  struct cmsghdr *cmsg = (struct cmsghdr *) alloca (packet->cmsg_len);
	  memcpy (cmsg, AF_UNIX_PKT_CMSG (packet), packet->cmsg_len);
	  if (cmsg->cmsg_level == SOL_SOCKET
	      && cmsg->cmsg_type == SCM_CREDENTIALS)
	    peer_cred ((struct ucred *) CMSG_DATA(cmsg));
	}
    }
  return ret;
}

NTSTATUS
fhandler_socket_unix::npfs_handle (HANDLE &nph)
{
  static NO_COPY SRWLOCK npfs_lock;
  static NO_COPY HANDLE npfs_dirh;

  NTSTATUS status = STATUS_SUCCESS;
  OBJECT_ATTRIBUTES attr;
  IO_STATUS_BLOCK io;

  /* Lockless after first call. */
  if (npfs_dirh)
    {
      nph = npfs_dirh;
      return STATUS_SUCCESS;
    }
  AcquireSRWLockExclusive (&npfs_lock);
  if (!npfs_dirh)
    {
      InitializeObjectAttributes (&attr, &ro_u_npfs, 0, NULL, NULL);
      status = NtOpenFile (&npfs_dirh, FILE_READ_ATTRIBUTES | SYNCHRONIZE,
			   &attr, &io, FILE_SHARE_READ | FILE_SHARE_WRITE,
			   0);
    }
  ReleaseSRWLockExclusive (&npfs_lock);
  if (NT_SUCCESS (status))
    nph = npfs_dirh;
  return status;
}

/* FIXME: What about close_on_exec? */
int
fhandler_socket_unix::create_mqueue (bool listener)
{
  mqd_t mqd;
  struct mq_attr attr;
  int flags = O_RDWR | O_CREAT | O_EXCL;
  mode_t mode = S_IRUSR | S_IWUSR | S_IWGRP | S_IWOTH;

  if (mq_unlink (get_mqueue_name ()) < 0 && get_errno () != ENOENT)
    {
      debug_printf ("Can't unlink old mqueue, %E");
      return -1;
    }
  if (listener)
    {
      /* A listener can only handle one connection request at a time,
	 and it is small. */
      attr.mq_maxmsg = 1;
      attr.mq_msgsize = MAX_PATH;
    }
  else
    {
      attr.mq_maxmsg = 10;		/* Probably too small. */
      attr.mq_msgsize = MAX_AF_UN_PKT_LEN;
    }
  if (is_nonblocking ())
    flags |= O_NONBLOCK;
  mqd = mq_open (get_mqueue_name (), flags, mode, &attr);
  if (mqd == (mqd_t) -1)
    return -1;
  set_mqd_in (mqd);
  return 0;
}

mqd_t
fhandler_socket_unix::open_mqueue (const char *mqueue_name, bool nonblocking)
{
  int flags = O_WRONLY;
  if (nonblocking)
    flags |= O_NONBLOCK;
  return mq_open (mqueue_name, flags);
}

struct conn_wait_info_t
{
  fhandler_socket_unix *fh;
  mqd_t mqd;			/* Descriptor for listener's mqueue. */
};

/* Just hop to the wait_mqueue_thread method. */
DWORD WINAPI
connect_wait_func (LPVOID param)
{
  conn_wait_info_t *wait_info = (conn_wait_info_t *) param;
  return wait_info->fh->wait_mqueue_thread (wait_info->mqd);
}

/* Start a waiter thread to wait for the listener's mqueue to have space.
   In blocking mode, wait for the thread to finish.  In nonblocking mode
   just return with errno set to EINPROGRESS. */
int
fhandler_socket_unix::wait_mqueue (mqd_t mqd)
{
  conn_wait_info_t *wait_info;
  DWORD waitret, err;
  int ret = -1;
  HANDLE thr;
  PVOID param;

  if (!(cwt_termination_evt = create_event ()))
    return -1;
  wait_info = (conn_wait_info_t *) cmalloc (HEAP_3_FHANDLER, sizeof *wait_info);
  if (!wait_info)
    return -1;
  wait_info->fh = this;
  wait_info->mqd = mqd;
  cwt_param = (PVOID) wait_info;
  connect_wait_thr = CreateThread (NULL, PREFERRED_IO_BLKSIZE,
				   connect_wait_func, cwt_param, 0, NULL);
  if (!connect_wait_thr)
    {
      cfree (wait_info);
      __seterrno ();
      goto out;
    }
  if (is_nonblocking ())
    {
      set_errno (EINPROGRESS);
      goto out;
    }

  waitret = cygwait (connect_wait_thr, cw_infinite, cw_cancel | cw_sig_eintr);
  if (waitret == WAIT_OBJECT_0)
    GetExitCodeThread (connect_wait_thr, &err);
  else
    {
      SetEvent (cwt_termination_evt);
      NtWaitForSingleObject (connect_wait_thr, FALSE, NULL);
      GetExitCodeThread (connect_wait_thr, &err);
      waitret = WAIT_SIGNALED;
    }
  thr = InterlockedExchangePointer (&connect_wait_thr, NULL);
  if (thr)
    NtClose (thr);
  param = InterlockedExchangePointer (&cwt_param, NULL);
  if (param)
    cfree (param);
  switch (waitret)
    {
    case WAIT_CANCELED:
      pthread::static_cancel_self ();
      /*NOTREACHED*/
    case WAIT_SIGNALED:
      set_errno (EINTR);
      break;
    default:
      so_error (err);
      if (err)
	set_errno (err);
      else
	ret = 0;
      break;
    }
out:
  return ret;
}

int
fhandler_socket_unix::recv_peer_mqueue_name (bool set, bool timeout, mqd_t *mqd)
{
  af_unix_pkt_hdr_t *packet;
  size_t plen;
  mqd_t peer_mqd;
  int flags;
  ssize_t nr;
  timespec tm;

  plen = sizeof *packet + CYGWIN_MQUEUE_SOCKET_NAME_LEN + 1;
  packet = (af_unix_pkt_hdr_t *) alloca (plen);
  if (timeout)
    {
      set_mqueue_non_blocking (get_mqd_in (), false);
      clock_gettime (CLOCK_REALTIME, &tm);
      tm.tv_sec += AF_UNIX_CONNECT_TIMEOUT;
      nr = _mq_timedrecv (get_mqd_in (), (char *) packet, plen, &tm, 0);
      set_mqueue_non_blocking (get_mqd_in (), is_nonblocking ());
    }
  else
    nr = _mq_recv (get_mqd_in (), (char *) packet, plen, 0);
  if (nr < 0)
    {
      if (get_errno () == ETIMEDOUT)
	set_errno (ECONNABORTED);
      return -1;
    }
  flags = O_WRONLY;
  if (is_nonblocking ())
    flags |= O_NONBLOCK;
  peer_mqd = mq_open ((const char *) AF_UNIX_PKT_DATA (packet), flags);
  if (peer_mqd == (mqd_t) -1)
    return -1;
  if (set)
    set_mqd_out (peer_mqd);
  if (mqd)
    *mqd = peer_mqd;
  return 0;
}

/* A socket makes a connection request by sending its own mqueue name
   to the listener's mqueue, first creating its mqueue if necessary. */
int
fhandler_socket_unix::send_mqueue_name (mqd_t mqd, bool wait)
{
  size_t plen;
  size_t dlen = 0;
  af_unix_pkt_hdr_t *packet;
  const char *mqn = get_mqueue_name ();

  if (!mqn || !*mqn)
    {
      gen_mqueue_name ();
      mqn = get_mqueue_name ();
      if (get_mqd_in () == (mqd_t) -1 && create_mqueue () < 0)
	return -1;
    }
  dlen = CYGWIN_MQUEUE_SOCKET_NAME_LEN + 1;
  plen = sizeof *packet + dlen;
  packet = (af_unix_pkt_hdr_t *) alloca (plen);
  packet->init (true, _SHUT_NONE, 0, 0, dlen);
  memcpy (AF_UNIX_PKT_DATA (packet), mqn, dlen);
  if (!wait)
    return mq_send (mqd, (const char *) packet, packet->pckt_len,
		    af_un_prio_admin);
  timespec timeout;
  set_mqueue_non_blocking (mqd, false);
  clock_gettime (CLOCK_REALTIME, &timeout);
  timeout.tv_sec += AF_UNIX_CONNECT_TIMEOUT;
  return mq_timedsend (mqd, (const char *) packet, packet->pckt_len,
		       af_un_prio_admin, &timeout);
}

int
fhandler_socket_unix::connect_mqueue (const char *mqueue_name)
{
  int ret = -1;
  int error = 0;
  mqd_t mqd;

  mqd = mq_open (mqueue_name, O_WRONLY | O_NONBLOCK);

  if (mqd == (mqd_t) -1)
    return -1;
  /* Try sending my mqueue name.  If it doesn't work, wait for the
     listener's mqueue to become available. */
  ret = send_mqueue_name (mqd, false);
  if (ret < 0 && get_errno () == EAGAIN)
    return wait_mqueue (mqd);
  if (ret < 0)
    {
      error = get_errno ();
      goto out;
    }
  /* Wait for response, which should be peer's mqueue name. */
  ret = recv_peer_mqueue_name ();
  if (ret < 0)
    {
      error =get_errno ();
      goto out;
    }
  xchg_sock_info ();
out:
  so_error (error);
  mq_close (mqd);
  return ret;
}

ssize_t
fhandler_socket_unix::peek_mqueue (char *buf, size_t buflen, bool nonblocking)
{
  if (get_mqd_in () == (mqd_t) -1)
    {
      /* FIXME: Set appropriate errno. */
      return -1;
    }
  return _mq_peek (get_mqd_in (), buf, buflen, nonblocking);
}

int
fhandler_socket_unix::disconnect_pipe (HANDLE ph)
{
  NTSTATUS status;
  IO_STATUS_BLOCK io;

  status = NtFsControlFile (ph, NULL, NULL, NULL, &io, FSCTL_PIPE_DISCONNECT,
			    NULL, 0, NULL, 0);
  /* Short-lived.  Don't use cygwait.  We don't want to be interrupted. */
  if (status == STATUS_PENDING
      && NtWaitForSingleObject (ph, FALSE, NULL) == WAIT_OBJECT_0)
    status = io.Status;
  if (!NT_SUCCESS (status))
    {
      __seterrno_from_nt_status (status);
      return -1;
    }
  return 0;
}

void
fhandler_socket_unix::init_cred ()
{
  struct ucred *scred = shmem->sock_cred ();
  struct ucred *pcred = shmem->peer_cred ();
  scred->pid = pcred->pid = (pid_t) 0;
  scred->uid = pcred->uid = (uid_t) -1;
  scred->gid = pcred->gid = (gid_t) -1;
}

void
fhandler_socket_unix::set_cred ()
{
  struct ucred *scred = shmem->sock_cred ();
  scred->pid = myself->pid;
  scred->uid = myself->uid;
  scred->gid = myself->gid;
}

void
fhandler_socket_unix::fixup_helper ()
{
  if (shmem_handle)
    reopen_shmem ();
  connect_wait_thr = NULL;
  cwt_termination_evt = NULL;
  cwt_param = NULL;
  inc_ndesc ();
}

/* ========================== public methods ========================= */

void
fhandler_socket_unix::fixup_after_fork (HANDLE parent)
{
  fhandler_socket::fixup_after_fork (parent);
  if (backing_file_handle && backing_file_handle != INVALID_HANDLE_VALUE)
    fork_fixup (parent, backing_file_handle, "backing_file_handle");
  if (shmem_handle)
    fork_fixup (parent, shmem_handle, "shmem_handle");
  fixup_helper ();
}

void
fhandler_socket_unix::fixup_after_exec ()
{
  if (!close_on_exec ())
    fixup_helper ();
}

void
fhandler_socket_unix::set_close_on_exec (bool val)
{
  fhandler_base::set_close_on_exec (val);
  if (backing_file_handle && backing_file_handle != INVALID_HANDLE_VALUE)
    set_no_inheritance (backing_file_handle, val);
  if (shmem_handle)
    set_no_inheritance (shmem_handle, val);
}

fhandler_socket_unix::fhandler_socket_unix () :
  fhandler_socket (),
  mqd_in ((mqd_t) -1), mqd_out ((mqd_t) -1),
  shmem_handle (NULL), shmem (NULL), backing_file_handle (NULL),
  connect_wait_thr (NULL), cwt_termination_evt (NULL), cwt_param (NULL)
{
  need_fork_fixup (true);
}

fhandler_socket_unix::~fhandler_socket_unix ()
{
}

int
fhandler_socket_unix::dup (fhandler_base *child, int flags)
{
  if (get_flags () & O_PATH)
    /* We're viewing the socket as a disk file, but fhandler_base::dup
       suffices here. */
    return fhandler_base::dup (child, flags);

  if (fhandler_socket::dup (child, flags))
    {
      __seterrno ();
      return -1;
    }
  fhandler_socket_unix *fhs = (fhandler_socket_unix *) child;
  if (backing_file_handle && backing_file_handle != INVALID_HANDLE_VALUE
      && !DuplicateHandle (GetCurrentProcess (), backing_file_handle,
			    GetCurrentProcess (), &fhs->backing_file_handle,
			    0, TRUE, DUPLICATE_SAME_ACCESS))
    {
      __seterrno ();
      fhs->close ();
      return -1;
    }
  if (!DuplicateHandle (GetCurrentProcess (), shmem_handle,
			GetCurrentProcess (), &fhs->shmem_handle,
			0, TRUE, DUPLICATE_SAME_ACCESS))
    {
      __seterrno ();
      fhs->close ();
      return -1;
    }
  if (fhs->reopen_shmem () < 0)
    {
      __seterrno ();
      fhs->close ();
      return -1;
    }
  fhs->sun_path (sun_path ());
  fhs->peer_sun_path (peer_sun_path ());
  fhs->connect_wait_thr = NULL;
  fhs->cwt_termination_evt = NULL;
  fhs->cwt_param = NULL;
  inc_ndesc ();
  return 0;
}

/* Waiter thread method.  Here we wait for the listener's mqueue to
   become available and send our mqueue name to it, if so.  This
   function is running asynchronously if called on a non-blocking
   socket.  The important things to do:

   - Set the output mqueue descriptor if successful
   - Send own sun_path to peer if successful
   - Set connect_state
   - Set so_error for later call to select
*/
DWORD
fhandler_socket_unix::wait_mqueue_thread (mqd_t mqd)
{
  LONG error = 0;

  /* Try for up to AF_UNIX_CONNECT_TIMEOUT seconds to send my mqueue
     name to listening socket. */
  if (send_mqueue_name (mqd, true) < 0)
    {
      error = get_errno ();
      goto out;
    }
  /* Read response from peer, which should be its mqueue name. */
  if (recv_peer_mqueue_name () < 0)
    {
      error = get_errno ();
      goto out;
    }
  xchg_sock_info ();
  /* FIXME: Translate mq errors to socket errors. */
out:
  mq_close (mqd);
  PVOID param = InterlockedExchangePointer (&cwt_param, NULL);
  if (param)
    cfree (param);
  conn_lock ();
  state_lock ();
  so_error (error);
  connect_state (error ? connect_failed : connected);
  state_unlock ();
  conn_unlock ();
  return error;
}

int
fhandler_socket_unix::socket (int af, int type, int protocol, int flags)
{
  if (type != SOCK_STREAM && type != SOCK_DGRAM)
    {
      set_errno (EINVAL);
      return -1;
    }
  if (protocol != 0)
    {
      set_errno (EPROTONOSUPPORT);
      return -1;
    }
  if (create_shmem () < 0)
    return -1;
  /* rmem and wmem have no effect in mqueue implementation. */
  /* rmem (262144); */
  /* wmem (262144); */
  set_addr_family (AF_UNIX);
  set_socket_type (type);
  set_flags (O_RDWR | O_BINARY);
  if (flags & SOCK_NONBLOCK)
    set_nonblocking (true);
  if (flags & SOCK_CLOEXEC)
    set_close_on_exec (true);
  init_cred ();
  set_handle (NULL);
  set_unique_id ();
  set_ino (get_unique_id ());
  inc_ndesc ();
  return 0;
}

int
fhandler_socket_unix::socketpair (int af, int type, int protocol, int flags,
				  fhandler_socket *fh_out)
{
  mqd_t mqd;
  sun_name_t sun;
  fhandler_socket_unix *fh = (fhandler_socket_unix *) fh_out;

  if (type != SOCK_STREAM && type != SOCK_DGRAM)
    {
      set_errno (EINVAL);
      return -1;
    }
  if (protocol != 0)
    {
      set_errno (EPROTONOSUPPORT);
      return -1;
    }

  if (create_shmem () < 0)
    return -1;
  if (fh->create_shmem () < 0)
    goto fh_shmem_failed;
  /* socket() on both sockets */
  /* rmem (262144); */
  /* fh->rmem (262144); */
  /* wmem (262144); */
  /* fh->wmem (262144); */
  set_addr_family (AF_UNIX);
  fh->set_addr_family (AF_UNIX);
  set_socket_type (type);
  fh->set_socket_type (type);
  set_flags (O_RDWR | O_BINARY);
  fh->set_flags (O_RDWR | O_BINARY);
  if (flags & SOCK_NONBLOCK)
    {
      set_nonblocking (true);
      fh->set_nonblocking (true);
    }
  if (flags & SOCK_CLOEXEC)
    {
      set_close_on_exec (true);
      fh->set_close_on_exec (true);
    }
  set_cred ();
  fh->set_cred ();
  set_unique_id ();
  fh->set_unique_id ();
  set_ino (get_unique_id ());
  fh->set_ino (fh->get_unique_id ());
  /* Create and open mqueues. */
  gen_mqueue_name ();
  if (create_mqueue () < 0)
    goto create_mqueue_failed;
  mqd = fh->open_mqueue (get_mqueue_name (), is_nonblocking ());
  if (mqd == (mqd_t) -1)
    goto fh_open_mqueue_failed;
  fh->set_mqd_out (mqd);
  fh->gen_mqueue_name ();
  if (fh->create_mqueue () < 0)
    goto fh_create_mqueue_failed;
  mqd = open_mqueue (get_mqueue_name (), is_nonblocking ());
  if (mqd == (mqd_t) -1)
    goto open_mqueue_failed;
  set_mqd_out (mqd);
  /* bind 1st socket */
  sun_path (&sun);
  fh->peer_sun_path (&sun);
  connect_state (connected);
  /* connect 2nd socket, even for DGRAM.  There's no difference as far
     as socketpairs are concerned. */
  fh->connect_state (connected);
  return 0;
open_mqueue_failed:
  mq_close (fh->get_mqd_in ());
  mq_unlink (fh->get_mqueue_name ());
fh_create_mqueue_failed:
  mq_close (fh->get_mqd_out ());
fh_open_mqueue_failed:
  mq_close (get_mqd_in ());
  mq_unlink (get_mqueue_name ());
create_mqueue_failed:
  NtUnmapViewOfSection (NtCurrentProcess (), fh->shmem);
  NtClose (fh->shmem_handle);
fh_shmem_failed:
  NtUnmapViewOfSection (NtCurrentProcess (), shmem);
  NtClose (shmem_handle);
  return -1;
}

/* Bind creates the backing file, generates the mqueue name and sets
   bind_state.  On DGRAM sockets it also creates the mqueue.  On STREAM
   sockets either listen or connect will do that. */
int
fhandler_socket_unix::bind (const struct sockaddr *name, int namelen)
{
  sun_name_t sun (name, namelen);
  bool unnamed = (sun.un_len == sizeof sun.un.sun_family);

  if (sun.un.sun_family != AF_UNIX)
    {
      set_errno (EINVAL);
      return -1;
    }
  bind_lock ();
  if (binding_state () == bind_pending)
    {
      set_errno (EALREADY);
      bind_unlock ();
      return -1;
    }
  if (binding_state () == bound)
    {
      set_errno (EINVAL);
      bind_unlock ();
      return -1;
    }
  binding_state (bind_pending);
  bind_unlock ();
  gen_mqueue_name ();
  if (get_socket_type () == SOCK_DGRAM && create_mqueue () < 0)
    {
      binding_state (unbound);
      return -1;
    }
  backing_file_handle = unnamed ? autobind (&sun) : create_socket (&sun);
  if (!backing_file_handle)
    {
      if (get_mqd_in () != (mqd_t) -1)
	{
	  mq_close (get_mqd_in ());
	  mq_unlink (get_mqueue_name ());
	}
      binding_state (unbound);
      return -1;
    }
  state_lock ();
  sun_path (&sun);
  /* If we're already connected, send socket info to peer.  In this case
     send_sock_info calls state_unlock */
  if (connect_state () == connected)
    send_sock_info (true);
  else
    state_unlock ();
  binding_state (bound);
  return 0;
}

/* Create mqueue on non-DGRAM sockets and set conn_state to listener. */
int
fhandler_socket_unix::listen (int backlog)
{
  if (get_socket_type () == SOCK_DGRAM)
    {
      set_errno (EOPNOTSUPP);
      return -1;
    }
  bind_lock ();
  while (binding_state () == bind_pending)
    yield ();
  if (binding_state () == unbound)
    {
      set_errno (EDESTADDRREQ);
      bind_unlock ();
      return -1;
    }
  bind_unlock ();
  conn_lock ();
  if (connect_state () != unconnected && connect_state () != connect_failed)
    {
      set_errno (connect_state () == listener ? EADDRINUSE : EINVAL);
      conn_unlock ();
      return -1;
    }
  if (create_mqueue (true) < 0)
    {
      connect_state (unconnected);
      return -1;
    }
  state_lock ();
  set_cred ();
  state_unlock ();
  connect_state (listener);
  conn_unlock ();
  return 0;
}

int
fhandler_socket_unix::accept4 (struct sockaddr *peer, int *len, int flags)
{
  mqd_t peer_mqd;
  fhandler_socket_unix *sock;

  if (get_socket_type () != SOCK_STREAM)
    {
      set_errno (EOPNOTSUPP);
      return -1;
    }
  if (connect_state () != listener
      || (peer && (!len || *len < (int) sizeof (sa_family_t))))
    {
      set_errno (EINVAL);
      return -1;
    }

  if (recv_peer_mqueue_name (false, false, &peer_mqd) < 0)
    return -1;
  if (flags & SOCK_NONBLOCK)
    set_mqueue_non_blocking (peer_mqd, true);
  /* We now have an mqueue descriptor that the accepted socket can use
     for output.  Prepare new file descriptor. */
  int error = ENOBUFS;
  cygheap_fdnew fd;
  if (fd < 0)
    goto err;
  sock = (fhandler_socket_unix *) build_fh_dev (dev ());
  if (!sock)
    goto err;
  if (sock->create_shmem () < 0)
    goto create_shmem_failed;
  sock->set_addr_family (AF_UNIX);
  sock->set_socket_type (get_socket_type ());
  if (flags & SOCK_NONBLOCK)
    sock->set_nonblocking (true);
  if (flags & SOCK_CLOEXEC)
    sock->set_close_on_exec (true);
  sock->set_unique_id ();
  sock->set_ino (sock->get_unique_id ());
  sock->set_mqd_out (peer_mqd);
  if (sock->send_mqueue_name (peer_mqd, false) < 0)
    {
      error = get_errno ();
      goto send_mqueue_name_failed;
    }
  sock->connect_state (connected);
  sock->binding_state (binding_state ());
  sock->sun_path (sun_path ());
  sock->sock_cred (sock_cred ());
  /* Send this socket info to connecting socket. */
  sock->send_sock_info (false);
  /* Fetch the packet sent by send_sock_info called by connecting
     peer. */
  error = sock->recv_peer_info ();
  if (error == 0)
    {
      __try
	{
	  if (peer)
	    {
	      sun_name_t *sun = sock->peer_sun_path ();
	      if (sun)
		{
		  memcpy (peer, &sun->un, MIN (*len, sun->un_len));
		  *len = sun->un_len;
		}
	      else if (len)
		*len = 0;
	    }
	  fd = sock;
	  if (fd <= 2)
	    set_std_handle (fd);
	  return fd;
	}
      __except (NO_ERROR)
	{
	  error = EFAULT;
	}
      __endtry
    }
send_mqueue_name_failed:
  if (sock->get_mqd_in () != (mqd_t) -1)
    {
      mq_close (sock->get_mqd_in ());
      mq_unlink (sock->get_mqueue_name ());
    }
  NtUnmapViewOfSection (NtCurrentProcess (), sock->shmem);
  NtClose (sock->shmem_handle);
create_shmem_failed:
  delete sock;
err:
  set_errno (error);
  mq_close (peer_mqd);
  return -1;
}

int
fhandler_socket_unix::connect (const struct sockaddr *name, int namelen)
{
  sun_name_t sun (name, namelen);
  int peer_type;
  char mqueue_name[CYGWIN_MQUEUE_SOCKET_NAME_LEN + 1];
  HANDLE fh = NULL;

  /* Test and set connection state. */
  conn_lock ();
  if (connect_state () == connect_pending)
    {
      set_errno (EALREADY);
      conn_unlock ();
      return -1;
    }
  if (connect_state () == listener)
    {
      set_errno (EADDRINUSE);
      conn_unlock ();
      return -1;
    }
  if (connect_state () == connected && get_socket_type () != SOCK_DGRAM)
    {
      set_errno (EISCONN);
      conn_unlock ();
      return -1;
    }
  if (name->sa_family == AF_UNSPEC && get_socket_type () == SOCK_DGRAM)
    {
      connect_state (unconnected);
      peer_sun_path (NULL);
      conn_unlock ();
      return 0;
    }
  connect_state (connect_pending);
  conn_unlock ();
  /* Check if peer address exists. */
  fh = open_socket (&sun, peer_type, mqueue_name);
  if (!fh)
    {
      connect_state (unconnected);
      return -1;
    }
  if (peer_type != get_socket_type ())
    {
      set_errno (EINVAL);
      NtClose (fh);
      connect_state (unconnected);
      return -1;
    }
  peer_sun_path (&sun);
  if (get_socket_type () != SOCK_DGRAM && connect_mqueue (mqueue_name) < 0)
    {
      NtClose (fh);
      if (get_errno () != EINPROGRESS)
	{
	  peer_sun_path (NULL);
	  connect_state (connect_failed);
	}
      return -1;
    }
  NtClose (fh);
  connect_state (connected);
  return 0;
}

int
fhandler_socket_unix::getsockname (struct sockaddr *name, int *namelen)
{
  sun_name_t *sun = sun_path ();

  memcpy (name, sun, MIN (*namelen, sun->un_len));
  *namelen = sun->un_len;
  return 0;
}

int
fhandler_socket_unix::getpeername (struct sockaddr *name, int *namelen)
{
  if (connect_state () != connected)
    {
      set_errno (ENOTCONN);
      return -1;
    }

  sun_name_t *sun = peer_sun_path ();
  memcpy (name, sun, MIN (*namelen, sun->un_len));
  *namelen = sun->un_len;
  return 0;
}

int
fhandler_socket_unix::shutdown (int how)
{
  int ret;

  if (how < SHUT_RD || how > SHUT_RDWR)
    {
      set_errno (EINVAL);
      return -1;
    }
  if (connect_state () != connected)
    {
      set_errno (ENOTCONN);
      return -1;
    }
  /* Convert SHUT_RD/SHUT_WR/SHUT_RDWR to _SHUT_RECV/_SHUT_SEND bits. */
  ++how;
  state_lock ();
  int old_shutdown_mask = saw_shutdown ();
  int new_shutdown_mask = old_shutdown_mask | how;
  if (new_shutdown_mask != old_shutdown_mask)
    saw_shutdown (new_shutdown_mask);
  state_unlock ();
  if (new_shutdown_mask != old_shutdown_mask
      && get_socket_type () == SOCK_STREAM)
    {
      /* Send shutdown info to peer.  Note that it's not necessarily fatal
	 if the info isn't sent here.  The info will be reproduced by any
	 followup package sent to the peer. */
      af_unix_pkt_hdr_t packet (true, (shut_state) new_shutdown_mask, 0, 0, 0);
      io_lock ();
      set_mqueue_non_blocking (get_mqd_out (), true);
      ret = mq_send (get_mqd_out (), (const char *) &packet, packet.pckt_len,
		     af_un_prio_admin);
      set_mqueue_non_blocking (get_mqd_out (), is_nonblocking ());
      io_unlock ();
    }
  if (ret < 0)
    {
      debug_printf ("Couldn't send shutdown info, %E");
      if (get_errno () != EAGAIN)
	return -1;
    }
  return 0;
}

int
fhandler_socket_unix::open (int flags, mode_t mode)
{
  /* We don't support opening sockets unless O_PATH is specified. */
  if (flags & O_PATH)
    return open_fs (flags, mode);

  set_errno (EOPNOTSUPP);
  return 0;
}

int
fhandler_socket_unix::close ()
{
  int ret = 0;

  if (get_flags () & O_PATH)
    return fhandler_base::close ();

  HANDLE evt = InterlockedExchangePointer (&cwt_termination_evt, NULL);
  HANDLE thr = InterlockedExchangePointer (&connect_wait_thr, NULL);
  if (thr)
    {
      if (evt)
	SetEvent (evt);
      NtWaitForSingleObject (thr, FALSE, NULL);
      NtClose (thr);
    }
  if (evt)
    NtClose (evt);
  PVOID param = InterlockedExchangePointer (&cwt_param, NULL);
  if (param)
    cfree (param);
  HANDLE hdl = InterlockedExchangePointer (&get_handle (), NULL);
  if (hdl)
    NtClose (hdl);
  if (backing_file_handle && backing_file_handle != INVALID_HANDLE_VALUE)
    NtClose (backing_file_handle);
  HANDLE shm = InterlockedExchangePointer (&shmem_handle, NULL);
  if (shm)
    NtClose (shm);
  param = InterlockedExchangePointer ((PVOID *) &shmem, NULL);
  if (param)
    NtUnmapViewOfSection (NtCurrentProcess (), param);
  if (get_mqd_in () != (mqd_t) -1)
    ret = mq_close (get_mqd_in ());
  if (get_mqd_out () != (mqd_t) -1)
    ret |= mq_close (get_mqd_out ());
  if (dec_ndesc () <= 0)
    {
      shutdown (SHUT_RDWR);
      mq_unlink (get_mqueue_name ());
    }
  return ret;
}

int
fhandler_socket_unix::getpeereid (pid_t *pid, uid_t *euid, gid_t *egid)
{
  int ret = -1;

  if (get_socket_type () != SOCK_STREAM)
    {
      set_errno (EINVAL);
      return -1;
    }
  if (connect_state () != connected)
    set_errno (ENOTCONN);
  else
    {
      __try
	{
	  state_lock ();
	  struct ucred *pcred = peer_cred ();
	  if (pid)
	    *pid = pcred->pid;
	  if (euid)
	    *euid = pcred->uid;
	  if (egid)
	    *egid = pcred->gid;
	  state_unlock ();
	  ret = 0;
	}
      __except (EFAULT) {}
      __endtry
    }
  return ret;
}

ssize_t
fhandler_socket_unix::recvmsg (struct msghdr *msg, int flags)
{
  set_errno (EAFNOSUPPORT);
  return -1;
}

ssize_t
fhandler_socket_unix::recvfrom (void *ptr, size_t len, int flags,
				struct sockaddr *from, int *fromlen)
{
  struct iovec iov;
  struct msghdr msg;
  ssize_t ret;

  iov.iov_base = ptr;
  iov.iov_len = len;
  msg.msg_name = from;
  msg.msg_namelen = from && fromlen ? *fromlen : 0;
  msg.msg_iov = &iov;
  msg.msg_iovlen = 1;
  msg.msg_control = NULL;
  msg.msg_controllen = 0;
  msg.msg_flags = 0;
  ret = recvmsg (&msg, flags);
  if (ret >= 0 && from && fromlen)
    *fromlen = msg.msg_namelen;
  return ret;
}

void __reg3
fhandler_socket_unix::read (void *ptr, size_t& len)
{
  set_errno (EAFNOSUPPORT);
  len = 0;
  struct iovec iov;
  struct msghdr msg;

  iov.iov_base = ptr;
  iov.iov_len = len;
  msg.msg_name = NULL;
  msg.msg_namelen = 0;
  msg.msg_iov = &iov;
  msg.msg_iovlen = 1;
  msg.msg_control = NULL;
  msg.msg_controllen = 0;
  msg.msg_flags = 0;
  len = recvmsg (&msg, 0);
}

ssize_t __stdcall
fhandler_socket_unix::readv (const struct iovec *const iov, int iovcnt,
			     ssize_t tot)
{
  struct msghdr msg;

  msg.msg_name = NULL;
  msg.msg_namelen = 0;
  msg.msg_iov = (struct iovec *) iov;
  msg.msg_iovlen = iovcnt;
  msg.msg_control = NULL;
  msg.msg_controllen = 0;
  msg.msg_flags = 0;
  return recvmsg (&msg, 0);
}

bool
fhandler_socket_unix::create_cmsg_data (af_unix_pkt_hdr_t *packet,
					const struct msghdr *msg)
{
  return true;
}


ssize_t
fhandler_socket_unix::sendmsg (const struct msghdr *msg, int flags)
{
  tmp_pathbuf tp;
  char mqueue_name[CYGWIN_MQUEUE_SOCKET_NAME_LEN + 1];
  ssize_t ret = -1;
  int send_ret = -1;
  HANDLE fh = NULL;
  mqd_t mqd_dgram = (mqd_t) -1;
  mqd_t mqd_out;
  af_unix_pkt_hdr_t *packet;
  int err;

  __try
    {
      /* Valid flags: MSG_DONTWAIT, MSG_NOSIGNAL */
      if (flags & ~(MSG_DONTWAIT | MSG_NOSIGNAL))
	{
	  set_errno (EOPNOTSUPP);
	  __leave;
	}
      /* FIXME: Check this.  It's from Stevens, UNIX Network
	 Programming, discussion of select.  He doesn't say whether we
	 also clear so_error.*/
      err = so_error ();
      if (err)
	{
	  set_errno (err);
	  __leave;
	}
      if (get_socket_type () == SOCK_STREAM)
	{
	  if (msg->msg_namelen)
	    {
	      set_errno (connect_state () == connected ? EISCONN : EOPNOTSUPP);
	      __leave;
	    }
	  if (connect_state () != connected)
	    {
	      set_errno (ENOTCONN);
	      __leave;
	    }
	}
      else
	{
	  sun_name_t sun;
	  int peer_type;

	  if (msg->msg_namelen)
	    sun.set ((const struct sockaddr_un *) msg->msg_name,
		     msg->msg_namelen);
	  else
	    sun = *peer_sun_path ();
	  fh = open_socket (&sun, peer_type, mqueue_name);
	  if (!fh)
	    __leave;
	  NtClose (fh);
	  if (peer_type != SOCK_DGRAM)
	    {
	      set_errno (EPROTOTYPE);
	      __leave;
	    }
	  mqd_dgram = open_mqueue (mqueue_name,
			     is_nonblocking () || flags & MSG_DONTWAIT);
	  if (mqd_dgram == (mqd_t) -1)
	    __leave;
	}
      packet = (af_unix_pkt_hdr_t *) tp.w_get ();
      /* For STREAM sockets, always send shutdown info in case a
	 shutdown call failed. */
      shut_state shut_info =
	get_socket_type () == SOCK_STREAM
	? (shut_state) saw_shutdown ()
	: _SHUT_NONE;
      if (get_socket_type () == SOCK_DGRAM && binding_state () == bound)
	{
	  packet->init (false, shut_info, sun_path ()->un_len, 0, 0);
	  memcpy (AF_UNIX_PKT_NAME (packet), &sun_path ()->un,
		  sun_path ()->un_len);
	}
      else
	packet->init (false, shut_info, 0, 0, 0);
      if (!create_cmsg_data (packet, msg))
	__leave;
      for (int i = 0; i < msg->msg_iovlen; ++i)
	if (!AF_UNIX_PKT_DATA_APPEND (packet, msg->msg_iov[i].iov_base,
				      msg->msg_iov[i].iov_len))
	  {
	    if (packet->data_len == 0)
	      {
		set_errno (EMSGSIZE);
		__leave;
	      }
	    else
	      break;
	  }
      /* A packet can have 0 length only on a datagram socket. */
      if (packet->data_len == 0 && get_socket_type () == SOCK_STREAM)
	{
	  ret = 0;
	  __leave;
	}
      io_lock ();
      /* Handle MSG_DONTWAIT in blocking mode.  Already done in DGRAM case. */
      if (get_socket_type () == SOCK_STREAM && !is_nonblocking ()
	  && (flags & MSG_DONTWAIT))
	set_mqueue_non_blocking (get_mqd_out (), true);

      mqd_out = mqd_dgram != (mqd_t) -1 ? mqd_dgram : get_mqd_out ();
      bool nonblocking = is_nonblocking () || (flags & MSG_DONTWAIT);
      grab_admin_pkt ();
      bool shutdown = saw_shutdown_write ();
      if (!shutdown && nonblocking)
	send_ret = mq_send (mqd_out, (const char *) packet,
			    packet->pckt_len, 0);
      else
	{
	  /* FIXME: Is this reasonable? */
#define AF_UNIX_SEND_TIMEOUT 10 * NSPERSEC/MSPERSEC      /* 10 ms */
	  struct timespec timeout;
	  clock_gettime (CLOCK_REALTIME, &timeout);
	  while (!shutdown)
	    {
	      /* We don't want to block forever if the peer has shut
		 down.  FIXME: This might only be appropriate for
		 STREAM sockets. */
	      timeout.tv_nsec += AF_UNIX_SEND_TIMEOUT;
	      if (timeout.tv_nsec >= NSPERSEC)
		{
		  timeout.tv_nsec -= NSPERSEC;
		  ++timeout.tv_sec;
		}
	      send_ret = mq_timedsend (mqd_out, (const char *) packet,
				       packet->pckt_len, 0, &timeout);
	      if (send_ret >= 0 || get_errno () != ETIMEDOUT)
		break;
	      grab_admin_pkt ();
	      shutdown = saw_shutdown_write ();
	    }
	}
      if (get_socket_type () == SOCK_STREAM && !is_nonblocking ()
	  && (flags & MSG_DONTWAIT))
	set_mqueue_non_blocking (get_mqd_out (), false);
      io_unlock ();
      if (send_ret == 0)
	ret = packet->data_len;
      else if (shutdown && get_socket_type () == SOCK_STREAM)
	{
	  set_errno (EPIPE);
	  if (!(flags & MSG_NOSIGNAL))
	    raise (SIGPIPE);
	}
    }
  __except (EFAULT)
  __endtry
  if (mqd_dgram != (mqd_t) -1)
    mq_close (mqd_dgram);
  return ret;
}

ssize_t
fhandler_socket_unix::sendto (const void *in_ptr, size_t len, int flags,
			       const struct sockaddr *to, int tolen)
{
  struct iovec iov;
  struct msghdr msg;

  iov.iov_base = (void *) in_ptr;
  iov.iov_len = len;
  msg.msg_name = (void *) to;
  msg.msg_namelen = to ? tolen : 0;
  msg.msg_iov = &iov;
  msg.msg_iovlen = 1;
  msg.msg_control = NULL;
  msg.msg_controllen = 0;
  msg.msg_flags = 0;
  return sendmsg (&msg, flags);
}

ssize_t __stdcall
fhandler_socket_unix::write (const void *ptr, size_t len)
{
  struct iovec iov;
  struct msghdr msg;

  iov.iov_base = (void *) ptr;
  iov.iov_len = len;
  msg.msg_name = NULL;
  msg.msg_namelen = 0;
  msg.msg_iov = &iov;
  msg.msg_iovlen = 1;
  msg.msg_control = NULL;
  msg.msg_controllen = 0;
  msg.msg_flags = 0;
  return sendmsg (&msg, 0);
}

ssize_t __stdcall
fhandler_socket_unix::writev (const struct iovec *const iov, int iovcnt,
			      ssize_t tot)
{
  struct msghdr msg;

  msg.msg_name = NULL;
  msg.msg_namelen = 0;
  msg.msg_iov = (struct iovec *) iov;
  msg.msg_iovlen = iovcnt;
  msg.msg_control = NULL;
  msg.msg_controllen = 0;
  msg.msg_flags = 0;
  return sendmsg (&msg, 0);
}

int
fhandler_socket_unix::setsockopt (int level, int optname, const void *optval,
				   socklen_t optlen)
{
  /* Preprocessing setsockopt. */
  switch (level)
    {
    case SOL_SOCKET:
      switch (optname)
	{
	case SO_PASSCRED:
	  if (optlen < (socklen_t) sizeof (int))
	    {
	      set_errno (EINVAL);
	      return -1;
	    }

	  bool val;
	  val = !!*(int *) optval;
	  /* Using bind_lock here to make sure the autobind below is
	     covered.  This is the only place to set so_passcred anyway. */
	  bind_lock ();
	  if (val && binding_state () == unbound)
	    {
	      sun_name_t sun;

	      binding_state (bind_pending);
	      backing_file_handle = autobind (&sun);
	      if (!backing_file_handle)
		{
		  binding_state (unbound);
		  bind_unlock ();
		  return -1;
		}
	      sun_path (&sun);
	      binding_state (bound);
	    }
	  so_passcred (val);
	  bind_unlock ();
	  break;

	case SO_REUSEADDR:
	  if (optlen < (socklen_t) sizeof (int))
	    {
	      set_errno (EINVAL);
	      return -1;
	    }
	  reuseaddr (!!*(int *) optval);
	  break;

	case SO_RCVBUF:
	  if (optlen < (socklen_t) sizeof (int))
	    {
	      set_errno (EINVAL);
	      return -1;
	    }
	  rmem (*(int *) optval);
	  break;

	case SO_SNDBUF:
	  if (optlen < (socklen_t) sizeof (int))
	    {
	      set_errno (EINVAL);
	      return -1;
	    }
	  wmem (*(int *) optval);
	  break;

	case SO_RCVTIMEO:
	case SO_SNDTIMEO:
	  if (optlen < (socklen_t) sizeof (struct timeval))
	    {
	      set_errno (EINVAL);
	      return -1;
	    }
	  if (!timeval_to_ms ((struct timeval *) optval,
			      (optname == SO_RCVTIMEO) ? rcvtimeo ()
						       : sndtimeo ()))
	  {
	    set_errno (EDOM);
	    return -1;
	  }
	  break;

	default:
	  /* AF_UNIX sockets simply ignore all other SOL_SOCKET options. */
	  break;
	}
      break;

    default:
      set_errno (ENOPROTOOPT);
      return -1;
    }

  return 0;
}

int
fhandler_socket_unix::getsockopt (int level, int optname, const void *optval,
				   socklen_t *optlen)
{
  /* Preprocessing getsockopt.*/
  switch (level)
    {
    case SOL_SOCKET:
      switch (optname)
	{
	case SO_ERROR:
	  {
	    if (*optlen < (socklen_t) sizeof (int))
	      {
		set_errno (EINVAL);
		return -1;
	      }

	    int *e = (int *) optval;
	    LONG err;

	    err = so_error (0);
	    *e = err;
	    break;
	  }

	case SO_PASSCRED:
	  {
	    if (*optlen < (socklen_t) sizeof (int))
	      {
		set_errno (EINVAL);
		return -1;
	      }

	    int *e = (int *) optval;
	    *e = so_passcred ();
	    break;
	  }

	case SO_PEERCRED:
	  {
	    struct ucred *cred = (struct ucred *) optval;

	    if (*optlen < (socklen_t) sizeof *cred)
	      {
		set_errno (EINVAL);
		return -1;
	      }
	    int ret = getpeereid (&cred->pid, &cred->uid, &cred->gid);
	    if (!ret)
	      *optlen = (socklen_t) sizeof *cred;
	    return ret;
	  }

	case SO_REUSEADDR:
	  {
	    unsigned int *reuse = (unsigned int *) optval;

	    if (*optlen < (socklen_t) sizeof *reuse)
	      {
		set_errno (EINVAL);
		return -1;
	      }
	    *reuse = reuseaddr ();
	    *optlen = (socklen_t) sizeof *reuse;
	    break;
	  }

	case SO_RCVBUF:
	case SO_SNDBUF:
	  if (*optlen < (socklen_t) sizeof (int))
	    {
	      set_errno (EINVAL);
	      return -1;
	    }
	  *(int *) optval = (optname == SO_RCVBUF) ? rmem () : wmem ();
	  break;

	case SO_RCVTIMEO:
	case SO_SNDTIMEO:
	  {
	    struct timeval *time_out = (struct timeval *) optval;

	    if (*optlen < (socklen_t) sizeof *time_out)
	      {
		set_errno (EINVAL);
		return -1;
	      }
	    DWORD ms = (optname == SO_RCVTIMEO) ? rcvtimeo () : sndtimeo ();
	    if (ms == 0 || ms == INFINITE)
	      {
		time_out->tv_sec = 0;
		time_out->tv_usec = 0;
	      }
	    else
	      {
		time_out->tv_sec = ms / MSPERSEC;
		time_out->tv_usec = ((ms % MSPERSEC) * USPERSEC) / MSPERSEC;
	      }
	    *optlen = (socklen_t) sizeof *time_out;
	    break;
	  }

	case SO_TYPE:
	  {
	    if (*optlen < (socklen_t) sizeof (int))
	      {
		set_errno (EINVAL);
		return -1;
	      }
	    unsigned int *type = (unsigned int *) optval;
	    *type = get_socket_type ();
	    *optlen = (socklen_t) sizeof *type;
	    break;
	  }

	/* AF_UNIX sockets simply ignore all other SOL_SOCKET options. */

	case SO_LINGER:
	  {
	    if (*optlen < (socklen_t) sizeof (struct linger))
	      {
		set_errno (EINVAL);
		return -1;
	      }
	    struct linger *linger = (struct linger *) optval;
	    memset (linger, 0, sizeof *linger);
	    *optlen = (socklen_t) sizeof *linger;
	    break;
	  }

	default:
	  {
	    if (*optlen < (socklen_t) sizeof (int))
	      {
		set_errno (EINVAL);
		return -1;
	      }
	    unsigned int *val = (unsigned int *) optval;
	    *val = 0;
	    *optlen = (socklen_t) sizeof *val;
	    break;
	  }
	}
      break;

    default:
      set_errno (ENOPROTOOPT);
      return -1;
    }

  return 0;
}

int
fhandler_socket_unix::ioctl (unsigned int cmd, void *p)
{
  int ret = -1;

  switch (cmd)
    {
    case FIOASYNC:
#ifdef __x86_64__
    case _IOW('f', 125, int):
#endif
      break;
    case FIONREAD:
#ifdef __x86_64__
    case _IOR('f', 127, int):
#endif
    case FIONBIO:
      {
	const bool was_nonblocking = is_nonblocking ();
	set_nonblocking (*(int *) p);
	const bool now_nonblocking = is_nonblocking ();
	if (was_nonblocking != now_nonblocking)
	  set_pipe_non_blocking (now_nonblocking);
	ret = 0;
	break;
      }
    case SIOCATMARK:
      break;
    default:
      ret = fhandler_socket::ioctl (cmd, p);
      break;
    }
  return ret;
}

int
fhandler_socket_unix::fcntl (int cmd, intptr_t arg)
{
  if (get_flags () & O_PATH)
    /* We're viewing the socket as a disk file, but
       fhandler_base::fcntl suffices here. */
    return fhandler_base::fcntl (cmd, arg);

  int ret = -1;

  switch (cmd)
    {
    case F_SETOWN:
      break;
    case F_GETOWN:
      break;
    case F_SETFL:
      {
	const bool was_nonblocking = is_nonblocking ();
	const int allowed_flags = O_APPEND | O_NONBLOCK_MASK;
	int new_flags = arg & allowed_flags;
	if ((new_flags & OLD_O_NDELAY) && (new_flags & O_NONBLOCK))
	  new_flags &= ~OLD_O_NDELAY;
	set_flags ((get_flags () & ~allowed_flags) | new_flags);
	const bool now_nonblocking = is_nonblocking ();
	if (was_nonblocking != now_nonblocking)
	  set_pipe_non_blocking (now_nonblocking);
	ret = 0;
	break;
      }
    default:
      ret = fhandler_socket::fcntl (cmd, arg);
      break;
    }
  return ret;
}

int __reg2
fhandler_socket_unix::fstat (struct stat *buf)
{
  if (!dev ().isfs ())
    /* fstat called on a socket. */
    return fhandler_socket::fstat (buf);

  /* stat/lstat on a socket file or fstat on a socket opened w/ O_PATH. */
  int ret = fhandler_base::fstat_fs (buf);
  if (!ret)
    {
      buf->st_mode = (buf->st_mode & ~S_IFMT) | S_IFSOCK;
      buf->st_size = 0;
    }
  return ret;
}

int __reg2
fhandler_socket_unix::fstatvfs (struct statvfs *sfs)
{
  if (!dev ().isfs ())
    /* fstatvfs called on a socket. */
    return fhandler_socket::fstatvfs (sfs);

  /* statvfs on a socket file or fstatvfs on a socket opened w/ O_PATH. */
  if (get_flags () & O_PATH)
    /* We already have a handle. */
    {
      HANDLE h = get_handle ();
      if (h)
	return fstatvfs_by_handle (h, sfs);
    }
  fhandler_disk_file fh (pc);
  fh.get_device () = FH_FS;
  return fh.fstatvfs (sfs);
}

int
fhandler_socket_unix::fchmod (mode_t newmode)
{
  if (!dev ().isfs ())
    /* fchmod called on a socket. */
    return fhandler_socket::fchmod (newmode);

  /* chmod on a socket file.  [We won't get here if fchmod is called
     on a socket opened w/ O_PATH.] */
  fhandler_disk_file fh (pc);
  fh.get_device () = FH_FS;
  /* Kludge: Don't allow to remove read bit on socket files for
     user/group/other, if the accompanying write bit is set.  It would
     be nice to have exact permissions on a socket file, but it's
     necessary that somebody able to access the socket can always read
     the contents of the socket file to avoid spurious "permission
     denied" messages. */
  newmode |= (newmode & (S_IWUSR | S_IWGRP | S_IWOTH)) << 1;
  return fh.fchmod (S_IFSOCK | newmode);
}

int
fhandler_socket_unix::fchown (uid_t uid, gid_t gid)
{
  if (!dev ().isfs ())
    /* fchown called on a socket. */
    return fhandler_socket::fchown (uid, gid);

  /* chown/lchown on a socket file.  [We won't get here if fchown is
     called on a socket opened w/ O_PATH.] */
  fhandler_disk_file fh (pc);
  return fh.fchown (uid, gid);
}

int
fhandler_socket_unix::facl (int cmd, int nentries, aclent_t *aclbufp)
{
  if (!dev ().isfs ())
    /* facl called on a socket. */
    return fhandler_socket::facl (cmd, nentries, aclbufp);

  /* facl on a socket file.  [We won't get here if facl is called on a
     socket opened w/ O_PATH.] */
  fhandler_disk_file fh (pc);
  return fh.facl (cmd, nentries, aclbufp);
}

int
fhandler_socket_unix::link (const char *newpath)
{
  if (!dev ().isfs ())
    /* linkat w/ AT_EMPTY_PATH called on a socket not opened w/ O_PATH. */
    return fhandler_socket::link (newpath);
  /* link on a socket file or linkat w/ AT_EMPTY_PATH called on a
     socket opened w/ O_PATH. */
  fhandler_disk_file fh (pc);
  if (get_flags () & O_PATH)
    fh.set_handle (get_handle ());
  return fh.link (newpath);
}

#endif /* __WITH_AF_UNIX */