libc/winsup/cygwin/pipe.cc

/* pipe.cc: pipe for Cygwin.

   Copyright 1996, 1998, 1999, 2000, 2001, 2002, 2003 Red Hat, Inc.

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. */

/* FIXME: Should this really be fhandler_pipe.cc? */

#include "winsup.h"
#include <unistd.h>
#include <sys/socket.h>
#include "cygerrno.h"
#include "security.h"
#include "fhandler.h"
#include "path.h"
#include "dtable.h"
#include "cygheap.h"
#include "thread.h"
#include "pinfo.h"
#include "cygthread.h"

static unsigned pipecount;
static const NO_COPY char pipeid_fmt[] = "stupid_pipe.%u.%u";

fhandler_pipe::fhandler_pipe (DWORD devtype)
  : fhandler_base (devtype), guard (NULL), broken_pipe (false), writepipe_exists(0),
    orig_pid (0), id (0)
{
}

_off64_t
fhandler_pipe::lseek (_off64_t offset, int whence)
{
  debug_printf ("(%d, %d)", offset, whence);
  set_errno (ESPIPE);
  return -1;
}

void
fhandler_pipe::set_close_on_exec (int val)
{
  fhandler_base::set_close_on_exec (val);
  if (guard)
    set_inheritance (guard, val);
  if (writepipe_exists)
    set_inheritance (writepipe_exists, val);
}

struct pipeargs
{
  fhandler_base *fh;
  void *ptr;
  size_t *len;
};

static DWORD WINAPI
read_pipe (void *arg)
{
  pipeargs *pi = (pipeargs *) arg;
  pi->fh->fhandler_base::read (pi->ptr, *pi->len);
  return 0;
}

void __stdcall
fhandler_pipe::read (void *in_ptr, size_t& in_len)
{
  if (broken_pipe)
    in_len = 0;
  else
    {
      pipeargs pi = {this, in_ptr, &in_len};
      ResetEvent (read_state);
      cygthread *th = new cygthread (read_pipe, &pi, "read_pipe");
      if (th->detach (read_state) && !in_len)
	(ssize_t) in_len = -1;	/* received a signal */
    }
  (void) ReleaseMutex (guard);
  return;
}

int fhandler_pipe::close ()
{
  int res = fhandler_base::close ();
#undef guard
  if (guard)
    CloseHandle (guard);
  if (writepipe_exists)
    CloseHandle (writepipe_exists);
  if (read_state && !cygheap->fdtab.in_vfork_cleanup ())
    CloseHandle (read_state);
  return res;
}

bool
fhandler_pipe::hit_eof ()
{
  char buf[80];
  HANDLE ev;
  if (broken_pipe)
    return 1;
  if (!orig_pid)
    return false;
  __small_sprintf (buf, pipeid_fmt, orig_pid, id);
  if ((ev = OpenEvent (EVENT_ALL_ACCESS, FALSE, buf)))
    CloseHandle (ev);
  debug_printf ("%s %p", buf, ev);
  return ev == NULL;
}

void
fhandler_pipe::fixup_after_exec (HANDLE parent)
{
  if (read_state)
    read_state = CreateEvent (&sec_none_nih, FALSE, FALSE, NULL);
}

void
fhandler_pipe::fixup_after_fork (HANDLE parent)
{
  fhandler_base::fixup_after_fork (parent);
  if (guard)
    fork_fixup (parent, guard, "guard");
  if (writepipe_exists)
    fork_fixup (parent, writepipe_exists, "guard");
  fixup_after_exec (parent);
}

int
fhandler_pipe::dup (fhandler_base *child)
{
  if (get_handle ())
    {
      int res = fhandler_base::dup (child);
      if (res)
	return res;
    }

  fhandler_pipe *ftp = (fhandler_pipe *) child;

  /* FIXME: This leaks handles in the failing condition */
  if (guard == NULL)
    ftp->guard = NULL;
  else if (!DuplicateHandle (hMainProc, guard, hMainProc, &ftp->guard, 0, 1,
			     DUPLICATE_SAME_ACCESS))
    {
      debug_printf ("couldn't duplicate guard %p, %E", guard);
      return -1;
    }

  if (writepipe_exists == NULL)
    ftp->writepipe_exists = NULL;
  else if (!DuplicateHandle (hMainProc, writepipe_exists, hMainProc,
			     &ftp->writepipe_exists, 0, 1,
			     DUPLICATE_SAME_ACCESS))
    {
      debug_printf ("couldn't duplicate writepipe_exists %p, %E", writepipe_exists);
      return -1;
    }

  if (read_state == NULL)
    ftp->read_state = NULL;
  else if (!DuplicateHandle (hMainProc, read_state, hMainProc,
			     &ftp->read_state, 0, 1,
			     DUPLICATE_SAME_ACCESS))
    {
      debug_printf ("couldn't duplicate read_state %p, %E", writepipe_exists);
      return -1;
    }

  ftp->id = id;
  ftp->orig_pid = orig_pid;
  return 0;
}

int
make_pipe (int fildes[2], unsigned int psize, int mode)
{
  HANDLE r, w;
  SECURITY_ATTRIBUTES *sa = (mode & O_NOINHERIT) ?  &sec_none_nih : &sec_none;
  int res = -1;

  cygheap_fdnew fdr;
  if (fdr >= 0)
    {
      cygheap_fdnew fdw (fdr, false);
      if (fdw < 0)
	/* out of fds? */;
      else if (!CreatePipe (&r, &w, sa, psize))
	__seterrno ();
      else
	{
	  fhandler_pipe *fhr = (fhandler_pipe *) cygheap->fdtab.build_fhandler (fdr, FH_PIPER, "/dev/piper");
	  fhandler_pipe *fhw = (fhandler_pipe *) cygheap->fdtab.build_fhandler (fdw, FH_PIPEW, "/dev/pipew");

	  int binmode = mode & O_TEXT ?: O_BINARY;
	  fhr->init (r, GENERIC_READ, binmode);
	  fhw->init (w, GENERIC_WRITE, binmode);
	  if (mode & O_NOINHERIT)
	   {
	     fhr->set_close_on_exec_flag (1);
	     fhw->set_close_on_exec_flag (1);
	   }

	  fildes[0] = fdr;
	  fildes[1] = fdw;
	  fhr->read_state = CreateEvent (&sec_none_nih, FALSE, FALSE, NULL);
	  fhr->set_need_fork_fixup ();

	  res = 0;
	  fhr->create_guard (sa);
	  if (wincap.has_unreliable_pipes ())
	    {
	      char buf[80];
	      int count = pipecount++;	/* FIXME: Should this be InterlockedIncrement? */
	      __small_sprintf (buf, pipeid_fmt, myself->pid, count);
	      fhw->writepipe_exists = CreateEvent (sa, TRUE, FALSE, buf);
	      fhr->orig_pid = myself->pid;
	      fhr->id = count;
	    }
	}
    }

  syscall_printf ("%d = make_pipe ([%d, %d], %d, %p)", res, fildes[0],
		  fildes[1], psize, mode);
  return res;
}

int
fhandler_pipe::ioctl (unsigned int cmd, void *p)
{
  int n;

  switch (cmd)
    {
    case FIONREAD:
      if (get_device () == FH_PIPEW)
	{
	  set_errno (EINVAL);
	  return -1;
	}
      if (!PeekNamedPipe (get_handle (), NULL, 0, NULL, (DWORD *) &n, NULL))
	{
	  __seterrno ();
	  return -1;
	}
      break;
    default:
      return fhandler_base::ioctl (cmd, p);
      break;
    }
  *(int *) p = n;
  return 0;
}

extern "C" int
pipe (int filedes[2])
{
  extern DWORD binmode;
  return make_pipe (filedes, 16384, (!binmode || binmode == O_BINARY) ? O_BINARY : O_TEXT);
}

extern "C" int
_pipe (int filedes[2], unsigned int psize, int mode)
{
  int res = make_pipe (filedes, psize, mode);
  /* This type of pipe is not interruptible so set the appropriate flag. */
  if (!res)
    cygheap->fdtab[filedes[0]]->set_r_no_interrupt (1);
  return res;
}