about summary refs log tree commit diff
path: root/hurd/intr-msg.c
blob: 6f670b538fdd216a676a59c320cff6af2b1a738a (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
/* Replacement for mach_msg used in interruptible Hurd RPCs.
Copyright (C) 1995 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 <hurd/signal.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;

  /* 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)
    {
      err = EINTR;
      ss->cancel = 0;
    }
  else 
  /*       err = intr_msg_trap (msg, option, send_size,
	   rcv_size, rcv_name, timeout, notify);
	   */
    asm (".globl _hurd_intr_rpc_msg_do_trap\n" 
	 ".globl _hurd_intr_rpc_msg_in_trap\n"
	 "				movl %%esp, %%ecx\n"
	 "				leal %1, %%esp\n"
	 "				movl $-25, %%eax\n"
	 "_hurd_intr_rpc_msg_do_trap:	lcall $7, $0 # status in %0\n"
	 "_hurd_intr_rpc_msg_in_trap:	movl %%ecx, %%esp"
	 : "=a" (err) : "m" ((&msg)[-1]) : "%ecx");

  switch (err)
    {
    case MACH_SEND_INTERRUPTED: /* RPC didn't get out.  */
      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.  */
	goto message;
      /* FALLTHROUGH */

    case MACH_RCV_PORT_DIED:
      /* Server didn't respond to interrupt_operation,
	 so the signal thread destroyed the reply port.  */
      /* FALLTHROUGH */

    case MACH_RCV_TIMED_OUT:
      /* The operation was supposedly interrupted, but still has
	 not returned.  Declare it 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;
	  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 message;
	      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;
}