diff options
| -rw-r--r-- | lib/libc/sys/sigaltstack.2 | 74 |
1 files changed, 40 insertions, 34 deletions
diff --git a/lib/libc/sys/sigaltstack.2 b/lib/libc/sys/sigaltstack.2 index f01e1c316aa..a0b26225d61 100644 --- a/lib/libc/sys/sigaltstack.2 +++ b/lib/libc/sys/sigaltstack.2 @@ -1,4 +1,4 @@ -.\" $OpenBSD: sigaltstack.2,v 1.14 2009/07/09 10:14:41 eric Exp $ +.\" $OpenBSD: sigaltstack.2,v 1.15 2012/11/17 09:19:16 guenther Exp $ .\" $NetBSD: sigaltstack.2,v 1.3 1995/02/27 10:41:52 cgd Exp $ .\" .\" Copyright (c) 1983, 1991, 1992, 1993 @@ -30,7 +30,7 @@ .\" .\" @(#)sigaltstack.2 8.1 (Berkeley) 6/4/93 .\" -.Dd $Mdocdate: July 9 2009 $ +.Dd $Mdocdate: November 17 2012 $ .Dt SIGALTSTACK 2 .Os .Sh NAME @@ -40,54 +40,48 @@ .Fd #include <sys/types.h> .Fd #include <signal.h> .Bd -literal - -struct sigaltstack { +typedef struct sigaltstack { void *ss_sp; size_t ss_size; int ss_flags; -}; +} stack_t; .Ed .Ft int -.Fn sigaltstack "const struct sigaltstack *ss" "struct sigaltstack *oss" +.Fn sigaltstack "const stack_t *ss" "stack_t *oss" .Sh DESCRIPTION .Fn sigaltstack allows users to define an alternate stack on which signals +delivered to this thread are to be processed. If .Fa ss -is non-zero, -it specifies a pointer to and the size of a -.Em "signal stack" -on which to deliver signals, -and tells the system if the process is currently executing -on that stack. -When a signal's action indicates its handler -should execute on the signal stack (specified with a -.Xr sigaction 2 -call), the system checks to see -if the process is currently executing on that stack. -If the process is not currently executing on the signal stack, -the system arranges a switch to the signal stack for the -duration of the signal handler's execution. -.Pp -If +is non-zero and .Dv SS_DISABLE is set in -.Fa ss_flags , -.Fa ss_sp -and -.Fa ss_size -are ignored and the signal stack will be disabled. +.Fa ss_flags +the signal stack will be disabled. +A disabled stack will cause all signals to be +taken on the regular user stack. Trying to disable an active stack will cause .Nm to return \-1 with .Va errno set to -.Er EINVAL . -A disabled stack will cause all signals to be -taken on the regular user stack. -If the stack is later re-enabled then all signals that were specified -to be processed on an alternate stack will resume doing so. +.Er EPERM . +.Pp +Otherwise, +.Fa ss_sp +specifies a pointer to a space to be used as the signal stack and +.Fa ss_size +specifies the size of that space. +When a signal's action indicates its handler +should execute on the signal stack (specified with a +.Xr sigaction 2 +call), the system checks to see +if the thread is currently executing on that stack. +If the thread is not currently executing on the signal stack, +the system arranges a switch to the signal stack for the +duration of the signal handler's execution. .Pp If .Fa oss @@ -96,7 +90,7 @@ The .Fa ss_flags field will contain the value .Dv SS_ONSTACK -if the process is currently on a signal stack and +if the thread is currently on a signal stack and .Dv SS_DISABLE if the signal stack is currently disabled. .Sh NOTES @@ -149,14 +143,26 @@ or points to memory that is not a valid part of the process address space. .It Bq Er EINVAL -An attempt was made to disable an active stack. +The +.Fa ss_flags +member pointed to by the +.Fa ss +argument contains flags other than +.Dv SS_DISABLE . .It Bq Er ENOMEM Size of alternate stack area is less than or equal to .Dv MINSIGSTKSZ . +.It Bq Er EPERM +An attempt was made to disable an active stack. .El .Sh SEE ALSO .Xr sigaction 2 , .Xr setjmp 3 +.Sh STANDARDS +The +.Nm +function conforms to +.St -p1003.1-2008 . .Sh HISTORY The predecessor to .Nm sigaltstack , |