freebsd-nq/lib/libc/gen/ucontext.3
Archie Cobbs a892767bc4 Add man pages for getcontext()/setcontext(), makecontext()/swapcontext(),
and ucontext_t.

Reviewed by:	mini
MFC after:	3 days
2002-09-11 21:39:21 +00:00

99 lines
3.2 KiB
Groff

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.Dd Sep 10, 2002
.Dt UCONTEXT 3
.Os
.Sh NAME
.Nm ucontext
.Nd user thread context
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In ucontext.h
.Sh DESCRIPTION
The
.Vt ucontext_t
type is a structure type suitable for holding the context for a user
thread of execution.
A thread's context includes its stack, saved registers, and list of
blocked signals.
.Pp
The
.Vt ucontext_t
structure contains at least these fields:
.Bl -tag -compact -offset 3n -width "mcontext_t uc_mcontext"
.Pp
.It "ucontext_t *uc_link"
Context to assume when this one returns
.It "sigset_t uc_sigmask"
Signals being blocked
.It "stack_t uc_stack"
Stack area
.It "mcontext_t uc_mcontext"
Saved registers
.El
.Pp
The
.Fa uc_link
field points to the context to resume when this context's entry point
function returns.
If
.Fa uc_link
is equal to
.Dv NULL ,
then the process exits when this context returns.
.Pp
The
.Fa uc_mcontext
field is machine-dependent and should be treated as opaque by
portable applications.
.Pp
The following functions are defined to manipulate
.Vt ucontext_t
structures:
.Bd -literal -offset xxx
int getcontext(ucontext_t *);
int setcontext(const ucontext_t *);
void makecontext(ucontext_t *, void (*)(void), int, ...);
int swapcontext(ucontext_t *, const ucontext_t *);
.Ed
.Sh SEE ALSO
.Xr sigaltstack 2 ,
.Xr getcontext 3 ,
.Xr makecontext 3