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/* Replacement for mach_msg used in interruptible Hurd RPCs.
Copyright (C) 1995, 1996 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If
not, write to the Free Software Foundation, Inc., 675 Mass Ave,
Cambridge, MA 02139, USA. */
#include <mach.h>
#include <mach/mig_errors.h>
#include <mach/mig_support.h>
#include <hurd/signal.h>
#include "intr-msg.h"
error_t
_hurd_intr_rpc_mach_msg (mach_msg_header_t *msg,
mach_msg_option_t option,
mach_msg_size_t send_size,
mach_msg_size_t rcv_size,
mach_port_t rcv_name,
mach_msg_timeout_t timeout,
mach_port_t notify)
{
struct hurd_sigstate *ss = _hurd_self_sigstate ();
error_t err;
/* Notice now if the user requested a timeout. OPTION may have the bit
added by interruption semantics, and we must distinguish. */
int user_timeout = option & MACH_RCV_TIMEOUT;
/* Tell the signal thread that we are doing an interruptible RPC on
this port. If we get a signal and should return EINTR, the signal
thread will set this variable to MACH_PORT_NULL. The RPC might
return EINTR when some other thread gets a signal, in which case we
want to restart our call. */
ss->intr_port = msg->msgh_remote_port;
/* A signal may arrive here, after intr_port is set, but before
the mach_msg system call. The signal handler might do an
interruptible RPC, and clobber intr_port; then it would not be
set properly when we actually did send the RPC, and a later
signal wouldn't interrupt that RPC. So,
_hurd_setup_sighandler saves intr_port in the sigcontext, and
sigreturn restores it. */
message:
if (ss->cancel)
{
ss->cancel = 0;
return EINTR;
}
err = INTR_MSG_TRAP (msg, option, send_size,
rcv_size, rcv_name, timeout, notify);
switch (err)
{
case MACH_RCV_TIMED_OUT:
if (user_timeout)
/* The real user RPC timed out. */
break;
else
/* The operation was supposedly interrupted, but still has
not returned. Declare it interrupted. */
goto interrupted;
case MACH_SEND_INTERRUPTED: /* RPC didn't get out. */
case EINTR: /* Server not cooperating with interrupt. */
if (ss->intr_port != MACH_PORT_NULL)
/* If this signal was for us and it should interrupt calls, the
signal thread will have cleared SS->intr_port.
Since it's not cleared, the signal was for another thread,
or SA_RESTART is set. Restart the interrupted call. */
{
restart:
if (rcv_name != MACH_PORT_NULL)
/* Make sure we have a valid reply port. The one we were using
may have been destroyed by interruption. */
msg->msgh_local_port = rcv_name = __mig_get_reply_port ();
goto message;
}
/* FALLTHROUGH */
case MACH_RCV_PORT_DIED:
/* Server didn't respond to interrupt_operation,
so the signal thread destroyed the reply port. */
/* FALLTHROUGH */
interrupted:
err = EINTR;
/* The EINTR return indicates cancellation, so clear the flag. */
ss->cancel = 0;
break;
case MACH_RCV_INTERRUPTED: /* RPC sent; no reply. */
option &= ~MACH_SEND_MSG; /* Don't send again. */
if (ss->intr_port == MACH_PORT_NULL)
{
/* This signal or cancellation was for us. We need to wait for
the reply, but not hang forever. */
option |= MACH_RCV_TIMEOUT;
/* Never decrease the user's timeout. */
if (!user_timeout || timeout > _hurd_interrupted_rpc_timeout)
timeout = _hurd_interrupted_rpc_timeout;
}
goto message; /* Retry the receive. */
case MACH_MSG_SUCCESS:
if (option & MACH_RCV_MSG)
{
/* We got a reply. Was it EINTR? */
mig_reply_header_t *const reply = (void *) msg;
const union
{
mach_msg_type_t t;
int i;
} check =
{ t: {
MACH_MSG_TYPE_INTEGER_32,
32,
1,
TRUE,
FALSE,
FALSE,
0
} };
if (msg->msgh_size == sizeof *reply &&
!(msg->msgh_bits & MACH_MSGH_BITS_COMPLEX) &&
*(int *) &reply->RetCodeType == check.i &&
reply->RetCode == EINTR)
{
/* It is indeed EINTR. Is the interrupt for us? */
if (ss->intr_port != MACH_PORT_NULL)
/* Nope; repeat the RPC.
XXX Resources moved? */
goto restart;
else
/* The EINTR return indicates cancellation, so clear the
flag. */
ss->cancel = 0;
}
}
break;
default: /* Quiet -Wswitch-enum. */
}
ss->intr_port = MACH_PORT_NULL;
return err;
}
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