Mon Aug 14 16:51:13 1995 Roland McGrath <roland@churchy.gnu.ai.mit.edu>
[glibc.git] / hurd / intr-msg.c
blobcdcd8d51ea4c0a12da9d9a23ed7a80f4bd4efa12
1 /* Replacement for mach_msg used in interruptible Hurd RPCs.
2 Copyright (C) 1995 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Library General Public License as
7 published by the Free Software Foundation; either version 2 of the
8 License, or (at your option) any later version.
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Library General Public License for more details.
15 You should have received a copy of the GNU Library General Public
16 License along with the GNU C Library; see the file COPYING.LIB. If
17 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
18 Cambridge, MA 02139, USA. */
20 #include <mach.h>
21 #include <mach/mig_errors.h>
22 #include <hurd/signal.h>
24 error_t
25 _hurd_intr_rpc_mach_msg (mach_msg_header_t *msg,
26 mach_msg_option_t option,
27 mach_msg_size_t send_size,
28 mach_msg_size_t rcv_size,
29 mach_port_t rcv_name,
30 mach_msg_timeout_t timeout,
31 mach_port_t notify)
33 struct hurd_sigstate *ss = _hurd_self_sigstate ();
34 error_t err;
36 /* Tell the signal thread that we are doing an interruptible RPC on
37 this port. If we get a signal and should return EINTR, the signal
38 thread will set this variable to MACH_PORT_NULL. The RPC might
39 return EINTR when some other thread gets a signal, in which case we
40 want to restart our call. */
41 ss->intr_port = msg->msgh_remote_port;
43 /* A signal may arrive here, after intr_port is set, but before
44 the mach_msg system call. The signal handler might do an
45 interruptible RPC, and clobber intr_port; then it would not be
46 set properly when we actually did send the RPC, and a later
47 signal wouldn't interrupt that RPC. So,
48 _hurd_setup_sighandler saves intr_port in the sigcontext, and
49 sigreturn restores it. */
51 message:
53 if (ss->cancel)
55 err = EINTR;
56 ss->cancel = 0;
58 else
59 /* err = intr_msg_trap (msg, option, send_size,
60 rcv_size, rcv_name, timeout, notify);
62 asm (".globl _hurd_intr_rpc_msg_do_trap\n"
63 ".globl _hurd_intr_rpc_msg_in_trap\n"
64 " movl %%esp, %%ecx\n"
65 " leal %1, %%esp\n"
66 " movl $-25, %%eax\n"
67 "_hurd_intr_rpc_msg_do_trap: lcall $7, $0 # status in %0\n"
68 "_hurd_intr_rpc_msg_in_trap: movl %%ecx, %%esp"
69 : "=a" (err) : "m" ((&msg)[1]) : "%ecx");
71 switch (err)
73 case MACH_SEND_INTERRUPTED: /* RPC didn't get out. */
74 if (ss->intr_port != MACH_PORT_NULL)
75 /* If this signal was for us and it should interrupt calls, the
76 signal thread will have cleared SS->intr_port.
77 Since it's not cleared, the signal was for another thread,
78 or SA_RESTART is set. Restart the interrupted call. */
79 goto message;
80 /* FALLTHROUGH */
82 case MACH_RCV_PORT_DIED:
83 /* Server didn't respond to interrupt_operation,
84 so the signal thread destroyed the reply port. */
85 /* FALLTHROUGH */
87 case MACH_RCV_TIMED_OUT:
88 /* The operation was supposedly interrupted, but still has
89 not returned. Declare it interrupted. */
91 err = EINTR;
93 /* The EINTR return indicates cancellation, so clear the flag. */
94 ss->cancel = 0;
95 break;
97 case MACH_RCV_INTERRUPTED: /* RPC sent; no reply. */
98 option &= ~MACH_SEND_MSG; /* Don't send again. */
99 if (ss->intr_port == MACH_PORT_NULL)
101 /* This signal or cancellation was for us. We need to wait for
102 the reply, but not hang forever. */
103 option |= MACH_RCV_TIMEOUT;
104 timeout = _hurd_interrupted_rpc_timeout;
106 goto message; /* Retry the receive. */
108 case MACH_MSG_SUCCESS:
109 if (option & MACH_RCV_MSG)
111 /* We got a reply. Was it EINTR? */
112 mig_reply_header_t *const reply = (void *) msg;
113 const union
115 mach_msg_type_t t;
116 int i;
117 } check =
118 { t: {
119 MACH_MSG_TYPE_INTEGER_32,
122 TRUE,
123 FALSE,
124 FALSE,
126 } };
127 if (msg->msgh_size == sizeof *reply &&
128 !(msg->msgh_bits & MACH_MSGH_BITS_COMPLEX) &&
129 *(int *) &reply->RetCodeType == check.i &&
130 reply->RetCode == EINTR)
132 /* It is indeed EINTR. Is the interrupt for us? */
133 if (ss->intr_port != MACH_PORT_NULL)
134 /* Nope; repeat the RPC.
135 XXX Resources moved? */
136 goto message;
137 else
138 /* The EINTR return indicates cancellation, so clear the
139 flag. */
140 ss->cancel = 0;
143 break;
145 default: /* Quiet -Wswitch-enum. */
148 ss->intr_port = MACH_PORT_NULL;
150 return err;