/* fhandler_fifo.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" #include #include "miscfuncs.h" #include "cygerrno.h" #include "security.h" #include "path.h" #include "fhandler.h" #include "dtable.h" #include "cygheap.h" #include "sigproc.h" #include "cygtls.h" #include "shared_info.h" #include "ntdll.h" #include "cygwait.h" /* This is only to be used for writers. When reading, STATUS_PIPE_EMPTY simply means there's no data to be read. */ #define STATUS_PIPE_IS_CLOSED(status) \ ({ NTSTATUS _s = (status); \ _s == STATUS_PIPE_CLOSING \ || _s == STATUS_PIPE_BROKEN \ || _s == STATUS_PIPE_EMPTY; }) #define STATUS_PIPE_NO_INSTANCE_AVAILABLE(status) \ ({ NTSTATUS _s = (status); \ _s == STATUS_INSTANCE_NOT_AVAILABLE \ || _s == STATUS_PIPE_NOT_AVAILABLE \ || _s == STATUS_PIPE_BUSY; }) fhandler_fifo::fhandler_fifo (): fhandler_base (), read_ready (NULL), write_ready (NULL), listen_client_thr (NULL), lct_termination_evt (NULL), nhandlers (0), nconnected (0), reader (false), writer (false), duplexer (false), max_atomic_write (DEFAULT_PIPEBUFSIZE) { pipe_name_buf[0] = L'\0'; need_fork_fixup (true); } PUNICODE_STRING fhandler_fifo::get_pipe_name () { if (!pipe_name_buf[0]) { __small_swprintf (pipe_name_buf, L"%S-fifo.%08x.%016X", &cygheap->installation_key, get_dev (), get_ino ()); RtlInitUnicodeString (&pipe_name, pipe_name_buf); } return &pipe_name; } inline PSECURITY_ATTRIBUTES sec_user_cloexec (bool cloexec, PSECURITY_ATTRIBUTES sa, PSID sid) { return cloexec ? sec_user_nih (sa, sid) : sec_user (sa, sid); } bool inline fhandler_fifo::arm (HANDLE h) { #ifdef DEBUGGING const char *what; if (h == read_ready) what = "reader"; else what = "writer"; debug_only_printf ("arming %s", what); #endif bool res = SetEvent (h); if (!res) #ifdef DEBUGGING debug_printf ("SetEvent for %s failed, %E", what); #else debug_printf ("SetEvent failed, %E"); #endif return res; } 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; } static void set_pipe_non_blocking (HANDLE ph, bool nonblocking) { 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 (ph, &io, &fpi, sizeof fpi, FilePipeInformation); if (!NT_SUCCESS (status)) debug_printf ("NtSetInformationFile(FilePipeInformation): %y", status); } NTSTATUS fhandler_fifo::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; } /* Called when a FIFO is first opened for reading and again each time a new client handler is needed. Each pipe instance is created in blocking mode so that we can easily wait for a connection. After it is connected, it is put in nonblocking mode. */ HANDLE fhandler_fifo::create_pipe_instance (bool first) { NTSTATUS status; HANDLE npfsh; HANDLE ph = NULL; ACCESS_MASK access; OBJECT_ATTRIBUTES attr; IO_STATUS_BLOCK io; ULONG hattr; ULONG sharing; ULONG nonblocking = FILE_PIPE_QUEUE_OPERATION; ULONG max_instances = -1; LARGE_INTEGER timeout; status = npfs_handle (npfsh); if (!NT_SUCCESS (status)) { __seterrno_from_nt_status (status); return NULL; } access = GENERIC_READ | FILE_READ_ATTRIBUTES | FILE_WRITE_ATTRIBUTES | SYNCHRONIZE; sharing = FILE_SHARE_READ | FILE_SHARE_WRITE; hattr = openflags & O_CLOEXEC ? 0 : OBJ_INHERIT; if (first) hattr |= OBJ_CASE_INSENSITIVE; InitializeObjectAttributes (&attr, get_pipe_name (), hattr, npfsh, NULL); timeout.QuadPart = -500000; status = NtCreateNamedPipeFile (&ph, access, &attr, &io, sharing, first ? FILE_CREATE : FILE_OPEN, 0, FILE_PIPE_MESSAGE_TYPE, FILE_PIPE_MESSAGE_MODE, nonblocking, max_instances, DEFAULT_PIPEBUFSIZE, DEFAULT_PIPEBUFSIZE, &timeout); if (!NT_SUCCESS (status)) __seterrno_from_nt_status (status); return ph; } /* Connect to a pipe instance. */ NTSTATUS fhandler_fifo::open_pipe (HANDLE& ph) { NTSTATUS status; HANDLE npfsh; ACCESS_MASK access; OBJECT_ATTRIBUTES attr; IO_STATUS_BLOCK io; ULONG sharing; status = npfs_handle (npfsh); if (!NT_SUCCESS (status)) return status; access = GENERIC_WRITE | SYNCHRONIZE; InitializeObjectAttributes (&attr, get_pipe_name (), openflags & O_CLOEXEC ? 0 : OBJ_INHERIT, npfsh, NULL); sharing = FILE_SHARE_READ | FILE_SHARE_WRITE; status = NtOpenFile (&ph, access, &attr, &io, sharing, 0); return status; } int fhandler_fifo::add_client_handler () { int ret = -1; fifo_client_handler fc; fhandler_base *fh; HANDLE ph = NULL; bool first = (nhandlers == 0); if (nhandlers == MAX_CLIENTS) { set_errno (EMFILE); goto out; } if (!(fc.connect_evt = create_event ())) goto out; if (!(fh = build_fh_dev (dev ()))) { set_errno (EMFILE); goto out; } ph = create_pipe_instance (first); if (!ph) { delete fh; goto out; } else { fh->set_handle (ph); fh->set_flags ((openflags & ~O_ACCMODE) | O_RDONLY); fh->set_nonblocking (false); ret = 0; fc.fh = fh; fc_handler[nhandlers++] = fc; } out: return ret; } void fhandler_fifo::delete_client_handler (int i) { fc_handler[i].close (); if (i < --nhandlers) memmove (fc_handler + i, fc_handler + i + 1, (nhandlers - i) * sizeof (fc_handler[i])); } /* Just hop to the listen_client_thread method. */ DWORD WINAPI listen_client_func (LPVOID param) { fhandler_fifo *fh = (fhandler_fifo *) param; return fh->listen_client_thread (); } /* Start a thread that listens for client connections. */ bool fhandler_fifo::listen_client () { if (!(lct_termination_evt = create_event ())) return false; listen_client_thr = CreateThread (NULL, PREFERRED_IO_BLKSIZE, listen_client_func, (PVOID) this, 0, NULL); if (!listen_client_thr) { __seterrno (); HANDLE evt = InterlockedExchangePointer (&lct_termination_evt, NULL); if (evt) CloseHandle (evt); return false; } return true; } void fhandler_fifo::record_connection (fifo_client_handler& fc) { fifo_client_lock (); fc.state = fc_connected; nconnected++; fc.fh->set_nonblocking (true); set_pipe_non_blocking (fc.fh->get_handle (), true); fifo_client_unlock (); HANDLE evt = InterlockedExchangePointer (&fc.connect_evt, NULL); if (evt) CloseHandle (evt); } DWORD fhandler_fifo::listen_client_thread () { DWORD ret = -1; while (1) { /* At the beginning of the loop, all client handlers are in the fc_connected or fc_invalid state. */ /* Delete any invalid clients. */ fifo_client_lock (); int i = 0; while (i < nhandlers) { if (fc_handler[i].state == fc_invalid) delete_client_handler (i); else i++; } /* Create a new client handler. */ if (add_client_handler () < 0) { fifo_client_unlock (); goto out; } /* Allow a writer to open. */ if (!arm (read_ready)) { fifo_client_unlock (); __seterrno (); goto out; } /* Listen for a writer to connect to the new client handler. */ fifo_client_handler& fc = fc_handler[nhandlers - 1]; NTSTATUS status; IO_STATUS_BLOCK io; status = NtFsControlFile (fc.fh->get_handle (), fc.connect_evt, NULL, NULL, &io, FSCTL_PIPE_LISTEN, NULL, 0, NULL, 0); fifo_client_unlock (); if (status == STATUS_PENDING) { HANDLE w[2] = { fc.connect_evt, lct_termination_evt }; DWORD waitret = WaitForMultipleObjects (2, w, false, INFINITE); switch (waitret) { case WAIT_OBJECT_0: status = io.Status; break; case WAIT_OBJECT_0 + 1: ret = 0; status = STATUS_THREAD_IS_TERMINATING; break; default: __seterrno (); debug_printf ("WaitForMultipleObjects failed, %E"); status = STATUS_THREAD_IS_TERMINATING; break; } } HANDLE ph = NULL; switch (status) { case STATUS_SUCCESS: case STATUS_PIPE_CONNECTED: record_connection (fc); break; case STATUS_THREAD_IS_TERMINATING: /* Try to cancel the pending listen. Otherwise the first writer to connect after the thread is restarted will be invisible. FIXME: Is there a direct way to do this? We do it by opening and closing a write handle to the client side. */ open_pipe (ph); /* We don't care about the return value of open_pipe. Even if the latter failed, a writer might have connected. */ if (WaitForSingleObject (fc.connect_evt, 0) == WAIT_OBJECT_0 && (NT_SUCCESS (io.Status) || io.Status == STATUS_PIPE_CONNECTED)) record_connection (fc); else fc.state = fc_invalid; /* By closing ph we ensure that if fc connected to ph, fc will be declared invalid on the next read attempt. */ if (ph) CloseHandle (ph); goto out; default: __seterrno_from_nt_status (status); fc.state = fc_invalid; goto out; } /* Check for thread termination in case WaitForMultipleObjects didn't get called above. */ if (IsEventSignalled (lct_termination_evt)) { ret = 0; goto out; } } out: if (ret < 0) debug_printf ("exiting lct with error, %E"); ResetEvent (read_ready); return ret; } int fhandler_fifo::open (int flags, mode_t) { enum { success, error_errno_set, error_set_errno } res; /* Determine what we're doing with this fhandler: reading, writing, both */ switch (flags & O_ACCMODE) { case O_RDONLY: reader = true; break; case O_WRONLY: writer = true; break; case O_RDWR: reader = true; duplexer = true; break; default: set_errno (EINVAL); res = error_errno_set; goto out; } debug_only_printf ("reader %d, writer %d, duplexer %d", reader, writer, duplexer); set_flags (flags); if (reader && !duplexer) nohandle (true); /* Create control events for this named pipe */ char char_sa_buf[1024]; LPSECURITY_ATTRIBUTES sa_buf; sa_buf = sec_user_cloexec (flags & O_CLOEXEC, (PSECURITY_ATTRIBUTES) char_sa_buf, cygheap->user.sid()); char npbuf[MAX_PATH]; __small_sprintf (npbuf, "r-event.%08x.%016X", get_dev (), get_ino ()); if (!(read_ready = CreateEvent (sa_buf, false, false, npbuf))) { debug_printf ("CreateEvent for %s failed, %E", npbuf); res = error_set_errno; goto out; } npbuf[0] = 'w'; if (!(write_ready = CreateEvent (sa_buf, false, false, npbuf))) { debug_printf ("CreateEvent for %s failed, %E", npbuf); res = error_set_errno; goto out; } /* If we're a duplexer, create the pipe and the first client handler. */ if (duplexer) { HANDLE ph = NULL; if (add_client_handler () < 0) { res = error_errno_set; goto out; } NTSTATUS status = open_pipe (ph); if (NT_SUCCESS (status)) { record_connection (fc_handler[0]); set_handle (ph); set_pipe_non_blocking (ph, flags & O_NONBLOCK); } else { __seterrno_from_nt_status (status); res = error_errno_set; goto out; } } /* If we're reading, start the listen_client thread (which should signal read_ready), and wait for a writer. */ if (reader) { if (!listen_client ()) { debug_printf ("create of listen_client thread failed"); res = error_errno_set; goto out; } else if (!duplexer && !wait (write_ready)) { res = error_errno_set; goto out; } else { init_fixup_before (); res = success; } } /* If we're writing, wait for read_ready and then connect to the pipe. This should always succeed quickly if the reader's listen_client thread is running. Then signal write_ready. */ if (writer) { while (1) { if (!wait (read_ready)) { res = error_errno_set; goto out; } NTSTATUS status = open_pipe (get_handle ()); if (NT_SUCCESS (status)) { set_pipe_non_blocking (get_handle (), flags & O_NONBLOCK); if (!arm (write_ready)) res = error_set_errno; else res = success; goto out; } else if (STATUS_PIPE_NO_INSTANCE_AVAILABLE (status)) Sleep (1); else { debug_printf ("create of writer failed"); __seterrno_from_nt_status (status); res = error_errno_set; goto out; } } } out: if (res == error_set_errno) __seterrno (); if (res != success) { if (read_ready) { CloseHandle (read_ready); read_ready = NULL; } if (write_ready) { CloseHandle (write_ready); write_ready = NULL; } if (get_handle ()) CloseHandle (get_handle ()); if (listen_client_thr) stop_listen_client (); } debug_printf ("res %d", res); return res == success; } off_t fhandler_fifo::lseek (off_t offset, int whence) { debug_printf ("(%D, %d)", offset, whence); set_errno (ESPIPE); return -1; } bool fhandler_fifo::wait (HANDLE h) { #ifdef DEBUGGING const char *what; if (h == read_ready) what = "reader"; else what = "writer"; #endif /* Set the wait to zero for non-blocking I/O-related events. */ DWORD wait = ((h == read_ready || h == write_ready) && get_flags () & O_NONBLOCK) ? 0 : INFINITE; debug_only_printf ("waiting for %s", what); /* Wait for the event. Set errno, as appropriate if something goes wrong. */ switch (cygwait (h, wait)) { case WAIT_OBJECT_0: debug_only_printf ("successfully waited for %s", what); return true; case WAIT_SIGNALED: debug_only_printf ("interrupted by signal while waiting for %s", what); set_errno (EINTR); return false; case WAIT_CANCELED: debug_only_printf ("cancellable interruption while waiting for %s", what); pthread::static_cancel_self (); /* never returns */ break; case WAIT_TIMEOUT: if (h == write_ready) { debug_only_printf ("wait timed out waiting for write but will still open reader since non-blocking mode"); return true; } else { set_errno (ENXIO); return false; } break; default: debug_only_printf ("unknown error while waiting for %s", what); __seterrno (); return false; } } ssize_t __reg3 fhandler_fifo::raw_write (const void *ptr, size_t len) { ssize_t ret = -1; size_t nbytes = 0, chunk; NTSTATUS status = STATUS_SUCCESS; IO_STATUS_BLOCK io; HANDLE evt = NULL; if (len <= max_atomic_write) chunk = len; else if (is_nonblocking ()) chunk = len = max_atomic_write; else chunk = max_atomic_write; /* Create a wait event if the FIFO is in blocking mode. */ if (!is_nonblocking () && !(evt = CreateEvent (NULL, false, false, NULL))) return -1; /* Write in chunks, accumulating a total. If there's an error, just return the accumulated total unless the first write fails, in which case return -1. */ while (nbytes < len) { ULONG_PTR nbytes_now = 0; size_t left = len - nbytes; size_t len1; if (left > chunk) len1 = chunk; else len1 = left; nbytes_now = 0; status = NtWriteFile (get_handle (), evt, NULL, NULL, &io, (PVOID) ptr, len1, NULL, NULL); if (evt && status == STATUS_PENDING) { DWORD waitret = cygwait (evt, cw_infinite, cw_cancel | cw_sig_eintr); switch (waitret) { case WAIT_OBJECT_0: status = io.Status; break; case WAIT_SIGNALED: status = STATUS_THREAD_SIGNALED; break; case WAIT_CANCELED: status = STATUS_THREAD_CANCELED; break; default: break; } } if (NT_SUCCESS (status)) { nbytes_now = io.Information; /* NtWriteFile returns success with # of bytes written == 0 if writing on a non-blocking pipe fails because the pipe buffer doesn't have sufficient space. */ if (nbytes_now == 0) set_errno (EAGAIN); ptr = ((char *) ptr) + chunk; nbytes += nbytes_now; } else if (STATUS_PIPE_IS_CLOSED (status)) { set_errno (EPIPE); raise (SIGPIPE); } else __seterrno_from_nt_status (status); if (nbytes_now == 0) len = 0; /* Terminate loop. */ if (nbytes > 0) ret = nbytes; } if (evt) CloseHandle (evt); if (status == STATUS_THREAD_SIGNALED && !_my_tls.call_signal_handler ()) set_errno (EINTR); else if (status == STATUS_THREAD_CANCELED) pthread::static_cancel_self (); return ret; } /* A FIFO open for reading is at EOF if no process has it open for writing. We test this by checking nconnected. But we must take account of the possible delay from the time of connection to the time the connection is recorded by the listen_client thread. */ bool fhandler_fifo::hit_eof () { bool eof; bool retry = true; retry: fifo_client_lock (); eof = (nconnected == 0); fifo_client_unlock (); if (eof && retry) { retry = false; /* Give the listen_client thread time to catch up. */ Sleep (1); goto retry; } return eof; } /* Is the lct running? */ int fhandler_fifo::check_listen_client_thread () { int ret = 0; if (listen_client_thr) { DWORD waitret = WaitForSingleObject (listen_client_thr, 0); switch (waitret) { case WAIT_OBJECT_0: CloseHandle (listen_client_thr); break; case WAIT_TIMEOUT: ret = 1; break; default: debug_printf ("WaitForSingleObject failed, %E"); ret = -1; __seterrno (); CloseHandle (listen_client_thr); break; } } return ret; } void __reg3 fhandler_fifo::raw_read (void *in_ptr, size_t& len) { size_t orig_len = len; /* Make sure the lct is running. */ int res = check_listen_client_thread (); debug_printf ("lct status %d", res); if (res < 0 || (res == 0 && !listen_client ())) goto errout; while (1) { if (hit_eof ()) { len = 0; return; } /* Poll the connected clients for input. */ fifo_client_lock (); for (int i = 0; i < nhandlers; i++) if (fc_handler[i].state == fc_connected) { len = orig_len; fc_handler[i].fh->fhandler_base::raw_read (in_ptr, len); ssize_t nread = (ssize_t) len; if (nread > 0) { fifo_client_unlock (); return; } /* If the pipe is empty, we get nread == -1 with ERROR_NO_DATA. */ else if (nread < 0 && GetLastError () != ERROR_NO_DATA) { fifo_client_unlock (); goto errout; } else if (nread == 0) /* Client has disconnected. */ { fc_handler[i].state = fc_invalid; nconnected--; } } fifo_client_unlock (); if (is_nonblocking ()) { set_errno (EAGAIN); goto errout; } else { /* Allow interruption. Copied from fhandler_socket_unix::open_reparse_point. */ pthread_testcancel (); if (cygwait (NULL, cw_nowait, cw_sig_eintr) == WAIT_SIGNALED && !_my_tls.call_signal_handler ()) { set_errno (EINTR); goto errout; } /* Don't hog the CPU. */ Sleep (1); } } errout: len = -1; } int __reg2 fhandler_fifo::fstatvfs (struct statvfs *sfs) { fhandler_disk_file fh (pc); fh.get_device () = FH_FS; return fh.fstatvfs (sfs); } int fifo_client_handler::close () { int res = 0; HANDLE evt = InterlockedExchangePointer (&connect_evt, NULL); if (evt) CloseHandle (evt); if (fh) { res = fh->fhandler_base::close (); delete fh; } return res; } int fhandler_fifo::stop_listen_client () { int ret = 0; HANDLE thr, evt; thr = InterlockedExchangePointer (&listen_client_thr, NULL); if (thr) { if (lct_termination_evt) SetEvent (lct_termination_evt); WaitForSingleObject (thr, INFINITE); DWORD err; GetExitCodeThread (thr, &err); if (err) { ret = -1; debug_printf ("listen_client_thread exited with error"); } CloseHandle (thr); } evt = InterlockedExchangePointer (&lct_termination_evt, NULL); if (evt) CloseHandle (evt); return ret; } int fhandler_fifo::close () { int ret = stop_listen_client (); if (read_ready) CloseHandle (read_ready); if (write_ready) CloseHandle (write_ready); for (int i = 0; i < nhandlers; i++) if (fc_handler[i].close () < 0) ret = -1; return fhandler_base::close () || ret; } /* If we have a write handle (i.e., we're a duplexer or a writer), keep the nonblocking state of the windows pipe in sync with our nonblocking state. */ int fhandler_fifo::fcntl (int cmd, intptr_t arg) { if (cmd != F_SETFL || nohandle ()) return fhandler_base::fcntl (cmd, arg); const bool was_nonblocking = is_nonblocking (); int res = fhandler_base::fcntl (cmd, arg); const bool now_nonblocking = is_nonblocking (); if (now_nonblocking != was_nonblocking) set_pipe_non_blocking (get_handle (), now_nonblocking); return res; } int fhandler_fifo::dup (fhandler_base *child, int flags) { int ret = -1; fhandler_fifo *fhf = NULL; if (fhandler_base::dup (child, flags)) goto out; fhf = (fhandler_fifo *) child; if (!DuplicateHandle (GetCurrentProcess (), read_ready, GetCurrentProcess (), &fhf->read_ready, 0, true, DUPLICATE_SAME_ACCESS)) { fhf->close (); __seterrno (); goto out; } if (!DuplicateHandle (GetCurrentProcess (), write_ready, GetCurrentProcess (), &fhf->write_ready, 0, true, DUPLICATE_SAME_ACCESS)) { CloseHandle (fhf->read_ready); fhf->close (); __seterrno (); goto out; } for (int i = 0; i < nhandlers; i++) { if (!DuplicateHandle (GetCurrentProcess (), fc_handler[i].fh->get_handle (), GetCurrentProcess (), &fhf->fc_handler[i].fh->get_handle (), 0, true, DUPLICATE_SAME_ACCESS)) { CloseHandle (fhf->read_ready); CloseHandle (fhf->write_ready); fhf->close (); __seterrno (); goto out; } } if (!reader || fhf->listen_client ()) ret = 0; if (reader) fhf->init_fixup_before (); out: return ret; } void fhandler_fifo::init_fixup_before () { cygheap->fdtab.inc_need_fixup_before (); } void fhandler_fifo::fixup_after_fork (HANDLE parent) { fhandler_base::fixup_after_fork (parent); fork_fixup (parent, read_ready, "read_ready"); fork_fixup (parent, write_ready, "write_ready"); for (int i = 0; i < nhandlers; i++) fc_handler[i].fh->fhandler_base::fixup_after_fork (parent); if (reader && !listen_client ()) debug_printf ("failed to start lct, %E"); } void fhandler_fifo::fixup_after_exec () { fhandler_base::fixup_after_exec (); if (reader && !listen_client ()) debug_printf ("failed to start lct, %E"); } void fhandler_fifo::set_close_on_exec (bool val) { fhandler_base::set_close_on_exec (val); set_no_inheritance (read_ready, val); set_no_inheritance (write_ready, val); for (int i = 0; i < nhandlers; i++) fc_handler[i].fh->fhandler_base::set_close_on_exec (val); }