sysdeps/mach/hurd/dup2.c

   1 /* Copyright (C) 1991, 92, 93, 94, 95, 97 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Library General Public License as
   6    published by the Free Software Foundation; either version 2 of the
   7    License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Library General Public License for more details.
  13
  14    You should have received a copy of the GNU Library General Public
  15    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  16    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  17    Boston, MA 02111-1307, USA.  */
  18
  19 #include <errno.h>
  20 #include <fcntl.h>
  21 #include <unistd.h>
  22 #include <hurd.h>
  23 #include <hurd/fd.h>
  24
  25
  26 /* Duplicate FD to FD2, closing the old FD2 and making FD2 be
  27    open on the same file as FD is.  Return FD2 or -1.  */
  28 int
  29 __dup2 (fd, fd2)
  30      int fd;
  31      int fd2;
  32 {
  33   struct hurd_fd *d;
  34
  35   /* Extract the ports and flags from FD.  */
  36   d = _hurd_fd_get (fd);
  37   if (d == NULL)
  38     {
  39       errno = EBADF;
  40       return -1;
  41     }
  42
  43   HURD_CRITICAL_BEGIN;
  44
  45   __spin_lock (&d->port.lock);
  46   if (d->port.port == MACH_PORT_NULL)
  47     {
  48       __spin_unlock (&d->port.lock);
  49       errno = EBADF;
  50       fd2 = -1;
  51     }
  52   else if (fd2 == fd)
  53     /* FD is valid and FD2 is already the same; just return it.  */
  54     __spin_unlock (&d->port.lock);
  55   else
  56     {
  57       struct hurd_userlink ulink, ctty_ulink;
  58       int flags = d->flags;
  59       io_t ctty = _hurd_port_get (&d->ctty, &ctty_ulink);
  60       io_t port = _hurd_port_locked_get (&d->port, &ulink); /* Unlocks D.  */
  61
  62       if (fd2 < 0)
  63         {
  64           errno = EBADF;
  65           fd2 = -1;
  66         }
  67       else
  68         {
  69           /* Get a hold of the destination descriptor.  */
  70           struct hurd_fd *d2;
  71
  72           if (fd2 >= _hurd_dtablesize)
  73             {
  74               /* The table is not large enough to hold the destination
  75                  descriptor.  Enlarge it as necessary to allocate this
  76                  descriptor.  */
  77               __mutex_unlock (&_hurd_dtable_lock);
  78               /* We still hold FD1's lock, but this is safe because
  79                  _hurd_alloc_fd will only examine the cells starting
  80                  at FD2.  */
  81               d2 = _hurd_alloc_fd (NULL, fd2);
  82               if (d2)
  83                 __spin_unlock (&d2->port.lock);
  84               __mutex_lock (&_hurd_dtable_lock);
  85             }
  86           else
  87             {
  88               d2 = _hurd_dtable[fd2];
  89               if (d2 == NULL)
  90                 {
  91                   /* Must allocate a new one.  We don't initialize the port
  92                      cells with this call so that if it fails (out of
  93                      memory), we will not have already added user
  94                      references for the ports, which we would then have to
  95                      deallocate.  */
  96                   d2 = _hurd_dtable[fd2] = _hurd_new_fd (MACH_PORT_NULL,
  97                                                          MACH_PORT_NULL);
  98                 }
  99             }
 100
 101           if (d2 == NULL)
 102             {
 103               fd2 = -1;
 104               if (errno == EINVAL)
 105                 errno = EBADF;  /* POSIX.1-1990 6.2.1.2 ll 54-55.  */
 106             }
 107           else
 108             {
 109               /* Give the ports each a user ref for the new descriptor.  */
 110               __mach_port_mod_refs (__mach_task_self (), port,
 111                                     MACH_PORT_RIGHT_SEND, 1);
 112               if (ctty != MACH_PORT_NULL)
 113                 __mach_port_mod_refs (__mach_task_self (), ctty,
 114                                       MACH_PORT_RIGHT_SEND, 1);
 115
 116               /* Install the ports and flags in the new descriptor slot.  */
 117               __spin_lock (&d2->port.lock);
 118               d2->flags = flags & ~FD_CLOEXEC; /* Dup clears FD_CLOEXEC. */
 119               _hurd_port_set (&d2->ctty, ctty);
 120               _hurd_port_locked_set (&d2->port, port); /* Unlocks D2.  */
 121             }
 122         }
 123       __mutex_unlock (&_hurd_dtable_lock);
 124
 125       _hurd_port_free (&d->port, &ulink, port);
 126       if (ctty != MACH_PORT_NULL)
 127         _hurd_port_free (&d->ctty, &ctty_ulink, port);
 128     }
 129
 130   HURD_CRITICAL_END;
 131
 132   return fd2;
 133 }
 134
 135 weak_alias (__dup2, dup2)