343 lines
10 KiB
Groff
343 lines
10 KiB
Groff
.\" Copyright (c) 1980, 1991, 1993
|
|
.\" The Regents of the University of California. All rights reserved.
|
|
.\"
|
|
.\" Redistribution and use in source and binary forms, with or without
|
|
.\" modification, are permitted provided that the following conditions
|
|
.\" are met:
|
|
.\" 1. Redistributions of source code must retain the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer.
|
|
.\" 2. Redistributions in binary form must reproduce the above copyright
|
|
.\" notice, this list of conditions and the following disclaimer in the
|
|
.\" documentation and/or other materials provided with the distribution.
|
|
.\" 4. Neither the name of the University nor the names of its contributors
|
|
.\" may be used to endorse or promote products derived from this software
|
|
.\" without specific prior written permission.
|
|
.\"
|
|
.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
|
|
.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
|
|
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
|
|
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
|
|
.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
|
|
.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
|
|
.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
|
|
.\" SUCH DAMAGE.
|
|
.\"
|
|
.\" @(#)sigvec.2 8.2 (Berkeley) 4/19/94
|
|
.\" $FreeBSD$
|
|
.\"
|
|
.Dd April 19, 1994
|
|
.Dt SIGVEC 2
|
|
.Os
|
|
.Sh NAME
|
|
.Nm sigvec
|
|
.Nd software signal facilities
|
|
.Sh LIBRARY
|
|
.Lb libc
|
|
.Sh SYNOPSIS
|
|
.In signal.h
|
|
.Bd -literal
|
|
struct sigvec {
|
|
void (*sv_handler)();
|
|
int sv_mask;
|
|
int sv_flags;
|
|
};
|
|
.Ed
|
|
.Ft int
|
|
.Fn sigvec "int sig" "struct sigvec *vec" "struct sigvec *ovec"
|
|
.Sh DESCRIPTION
|
|
.Bf -symbolic
|
|
This interface is made obsolete by
|
|
.Xr sigaction 2 .
|
|
.Ef
|
|
.Pp
|
|
The system defines a set of signals that may be delivered to a process.
|
|
Signal delivery resembles the occurrence of a hardware interrupt:
|
|
the signal is blocked from further occurrence, the current process
|
|
context is saved, and a new one is built.
|
|
A process may specify a
|
|
.Em handler
|
|
to which a signal is delivered, or specify that a signal is to be
|
|
.Em blocked
|
|
or
|
|
.Em ignored .
|
|
A process may also specify that a default action is to be taken
|
|
by the system when a signal occurs.
|
|
Normally, signal handlers execute on the current stack
|
|
of the process.
|
|
This may be changed, on a per-handler basis,
|
|
so that signals are taken on a special
|
|
.Em "signal stack" .
|
|
.Pp
|
|
All signals have the same
|
|
.Em priority .
|
|
Signal routines execute with the signal that caused their
|
|
invocation
|
|
.Em blocked ,
|
|
but other signals may yet occur.
|
|
A global
|
|
.Em "signal mask"
|
|
defines the set of signals currently blocked from delivery
|
|
to a process.
|
|
The signal mask for a process is initialized
|
|
from that of its parent (normally 0).
|
|
It
|
|
may be changed with a
|
|
.Xr sigblock 2
|
|
or
|
|
.Xr sigsetmask 2
|
|
call, or when a signal is delivered to the process.
|
|
.Pp
|
|
When a signal
|
|
condition arises for a process, the signal is added to a set of
|
|
signals pending for the process.
|
|
If the signal is not currently
|
|
.Em blocked
|
|
by the process then it is delivered to the process.
|
|
When a signal
|
|
is delivered, the current state of the process is saved,
|
|
a new signal mask is calculated (as described below),
|
|
and the signal handler is invoked.
|
|
The call to the handler
|
|
is arranged so that if the signal handling routine returns
|
|
normally the process will resume execution in the context
|
|
from before the signal's delivery.
|
|
If the process wishes to resume in a different context, then it
|
|
must arrange to restore the previous context itself.
|
|
.Pp
|
|
When a signal is delivered to a process a new signal mask is
|
|
installed for the duration of the process' signal handler
|
|
(or until a
|
|
.Xr sigblock 2
|
|
or
|
|
.Xr sigsetmask 2
|
|
call is made).
|
|
This mask is formed by taking the current signal mask,
|
|
adding the signal to be delivered, and
|
|
.Em or Ns 'ing
|
|
in the signal mask associated with the handler to be invoked.
|
|
.Pp
|
|
The
|
|
.Fn sigvec
|
|
function
|
|
assigns a handler for a specific signal.
|
|
If
|
|
.Fa vec
|
|
is non-zero, it
|
|
specifies a handler routine and mask
|
|
to be used when delivering the specified signal.
|
|
Further, if the
|
|
.Dv SV_ONSTACK
|
|
bit is set in
|
|
.Fa sv_flags ,
|
|
the system will deliver the signal to the process on a
|
|
.Em "signal stack" ,
|
|
specified with
|
|
.Xr sigaltstack 2 .
|
|
If
|
|
.Fa ovec
|
|
is non-zero, the previous handling information for the signal
|
|
is returned to the user.
|
|
.Pp
|
|
The following is a list of all signals
|
|
with names as in the include file
|
|
.In signal.h :
|
|
.Bl -column SIGVTALARMXX "create core imagexxx"
|
|
.It Sy "NAME Default Action Description"
|
|
.It Dv SIGHUP No " terminate process" " terminal line hangup"
|
|
.It Dv SIGINT No " terminate process" " interrupt program"
|
|
.It Dv SIGQUIT No " create core image" " quit program"
|
|
.It Dv SIGILL No " create core image" " illegal instruction"
|
|
.It Dv SIGTRAP No " create core image" " trace trap"
|
|
.It Dv SIGABRT No " create core image" Ta Xr abort 3
|
|
call (formerly
|
|
.Dv SIGIOT )
|
|
.It Dv SIGEMT No " create core image" " emulate instruction executed"
|
|
.It Dv SIGFPE No " create core image" " floating-point exception"
|
|
.It Dv SIGKILL No " terminate process" " kill program"
|
|
.It Dv SIGBUS No " create core image" " bus error"
|
|
.It Dv SIGSEGV No " create core image" " segmentation violation"
|
|
.It Dv SIGSYS No " create core image" " non-existent system call invoked"
|
|
.It Dv SIGPIPE No " terminate process" " write on a pipe with no reader"
|
|
.It Dv SIGALRM No " terminate process" " real-time timer expired"
|
|
.It Dv SIGTERM No " terminate process" " software termination signal"
|
|
.It Dv SIGURG No " discard signal" " urgent condition present on socket"
|
|
.It Dv SIGSTOP No " stop process" " stop (cannot be caught or ignored)"
|
|
.It Dv SIGTSTP No " stop process" " stop signal generated from keyboard"
|
|
.It Dv SIGCONT No " discard signal" " continue after stop"
|
|
.It Dv SIGCHLD No " discard signal" " child status has changed"
|
|
.It Dv SIGTTIN No " stop process" " background read attempted from control terminal"
|
|
.It Dv SIGTTOU No " stop process" " background write attempted to control terminal"
|
|
.It Dv SIGIO No " discard signal" Tn " I/O"
|
|
is possible on a descriptor (see
|
|
.Xr fcntl 2 )
|
|
.It Dv SIGXCPU No " terminate process" " cpu time limit exceeded (see"
|
|
.Xr setrlimit 2 )
|
|
.It Dv SIGXFSZ No " terminate process" " file size limit exceeded (see"
|
|
.Xr setrlimit 2 )
|
|
.It Dv SIGVTALRM No " terminate process" " virtual time alarm (see"
|
|
.Xr setitimer 2 )
|
|
.It Dv SIGPROF No " terminate process" " profiling timer alarm (see"
|
|
.Xr setitimer 2 )
|
|
.It Dv SIGWINCH No " discard signal" " Window size change"
|
|
.It Dv SIGINFO No " discard signal" " status request from keyboard"
|
|
.It Dv SIGUSR1 No " terminate process" " User defined signal 1"
|
|
.It Dv SIGUSR2 No " terminate process" " User defined signal 2"
|
|
.El
|
|
.Pp
|
|
Once a signal handler is installed, it remains installed
|
|
until another
|
|
.Fn sigvec
|
|
call is made, or an
|
|
.Xr execve 2
|
|
is performed.
|
|
A signal-specific default action may be reset by
|
|
setting
|
|
.Fa sv_handler
|
|
to
|
|
.Dv SIG_DFL .
|
|
The defaults are process termination, possibly with core dump;
|
|
no action; stopping the process; or continuing the process.
|
|
See the above signal list for each signal's default action.
|
|
If
|
|
.Fa sv_handler
|
|
is
|
|
.Dv SIG_IGN
|
|
current and pending instances
|
|
of the signal are ignored and discarded.
|
|
.Pp
|
|
If a signal is caught during the system calls listed below,
|
|
the call is normally restarted.
|
|
The call can be forced to terminate prematurely with an
|
|
.Er EINTR
|
|
error return by setting the
|
|
.Dv SV_INTERRUPT
|
|
bit in
|
|
.Fa sv_flags .
|
|
The affected system calls include
|
|
.Xr read 2 ,
|
|
.Xr write 2 ,
|
|
.Xr sendto 2 ,
|
|
.Xr recvfrom 2 ,
|
|
.Xr sendmsg 2
|
|
and
|
|
.Xr recvmsg 2
|
|
on a communications channel or a slow device (such as a terminal,
|
|
but not a regular file)
|
|
and during a
|
|
.Xr wait 2
|
|
or
|
|
.Xr ioctl 2 .
|
|
However, calls that have already committed are not restarted,
|
|
but instead return a partial success (for example, a short read count).
|
|
.Pp
|
|
After a
|
|
.Xr fork 2
|
|
or
|
|
.Xr vfork 2
|
|
all signals, the signal mask, the signal stack,
|
|
and the restart/interrupt flags are inherited by the child.
|
|
.Pp
|
|
The
|
|
.Xr execve 2
|
|
system call reinstates the default
|
|
action for all signals which were caught and
|
|
resets all signals to be caught on the user stack.
|
|
Ignored signals remain ignored;
|
|
the signal mask remains the same;
|
|
signals that interrupt system calls continue to do so.
|
|
.Sh NOTES
|
|
The mask specified in
|
|
.Fa vec
|
|
is not allowed to block
|
|
.Dv SIGKILL
|
|
or
|
|
.Dv SIGSTOP .
|
|
This is done silently by the system.
|
|
.Pp
|
|
The
|
|
.Dv SV_INTERRUPT
|
|
flag is not available in
|
|
.Bx 4.2 ,
|
|
hence it should not be used if backward compatibility is needed.
|
|
.Sh RETURN VALUES
|
|
.Rv -std sigvec
|
|
.Sh EXAMPLES
|
|
On the
|
|
.Tn VAX\-11
|
|
The handler routine can be declared:
|
|
.Bd -literal -offset indent
|
|
void handler(sig, code, scp)
|
|
int sig, code;
|
|
struct sigcontext *scp;
|
|
.Ed
|
|
.Pp
|
|
Here
|
|
.Fa sig
|
|
is the signal number, into which the hardware faults and traps are
|
|
mapped as defined below.
|
|
The
|
|
.Fa code
|
|
argument
|
|
is either a constant
|
|
as given below or, for compatibility mode faults, the code provided by
|
|
the hardware (Compatibility mode faults are distinguished from the
|
|
other
|
|
.Dv SIGILL
|
|
traps by having
|
|
.Dv PSL_CM
|
|
set in the psl).
|
|
The
|
|
.Fa scp
|
|
argument
|
|
is a pointer to the
|
|
.Fa sigcontext
|
|
structure (defined in
|
|
.In signal.h ) ,
|
|
used to restore the context from before the signal.
|
|
.Sh ERRORS
|
|
The
|
|
.Fn sigvec
|
|
function
|
|
will fail and no new signal handler will be installed if one
|
|
of the following occurs:
|
|
.Bl -tag -width Er
|
|
.It Bq Er EFAULT
|
|
Either
|
|
.Fa vec
|
|
or
|
|
.Fa ovec
|
|
points to memory that is not a valid part of the process
|
|
address space.
|
|
.It Bq Er EINVAL
|
|
The
|
|
.Fa sig
|
|
argument
|
|
is not a valid signal number.
|
|
.It Bq Er EINVAL
|
|
An attempt is made to ignore or supply a handler for
|
|
.Dv SIGKILL
|
|
or
|
|
.Dv SIGSTOP .
|
|
.El
|
|
.Sh SEE ALSO
|
|
.Xr kill 1 ,
|
|
.Xr kill 2 ,
|
|
.Xr ptrace 2 ,
|
|
.Xr sigaction 2 ,
|
|
.Xr sigaltstack 2 ,
|
|
.Xr sigblock 2 ,
|
|
.Xr sigpause 2 ,
|
|
.Xr sigprocmask 2 ,
|
|
.Xr sigsetmask 2 ,
|
|
.Xr sigsuspend 2 ,
|
|
.Xr setjmp 3 ,
|
|
.Xr siginterrupt 3 ,
|
|
.Xr signal 3 ,
|
|
.Xr sigsetops 3 ,
|
|
.Xr tty 4
|
|
.Sh BUGS
|
|
This manual page is still confusing.
|