1.\" Copyright (c) 2002 Packet Design, LLC. 2.\" All rights reserved. 3.\" 4.\" Subject to the following obligations and disclaimer of warranty, 5.\" use and redistribution of this software, in source or object code 6.\" forms, with or without modifications are expressly permitted by 7.\" Packet Design; provided, however, that: 8.\" 9.\" (i) Any and all reproductions of the source or object code 10.\" must include the copyright notice above and the following 11.\" disclaimer of warranties; and 12.\" (ii) No rights are granted, in any manner or form, to use 13.\" Packet Design trademarks, including the mark "PACKET DESIGN" 14.\" on advertising, endorsements, or otherwise except as such 15.\" appears in the above copyright notice or in the software. 16.\" 17.\" THIS SOFTWARE IS BEING PROVIDED BY PACKET DESIGN "AS IS", AND 18.\" TO THE MAXIMUM EXTENT PERMITTED BY LAW, PACKET DESIGN MAKES NO 19.\" REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED, REGARDING 20.\" THIS SOFTWARE, INCLUDING WITHOUT LIMITATION, ANY AND ALL IMPLIED 21.\" WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, 22.\" OR NON-INFRINGEMENT. PACKET DESIGN DOES NOT WARRANT, GUARANTEE, 23.\" OR MAKE ANY REPRESENTATIONS REGARDING THE USE OF, OR THE RESULTS 24.\" OF THE USE OF THIS SOFTWARE IN TERMS OF ITS CORRECTNESS, ACCURACY, 25.\" RELIABILITY OR OTHERWISE. IN NO EVENT SHALL PACKET DESIGN BE 26.\" LIABLE FOR ANY DAMAGES RESULTING FROM OR ARISING OUT OF ANY USE 27.\" OF THIS SOFTWARE, INCLUDING WITHOUT LIMITATION, ANY DIRECT, 28.\" INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, PUNITIVE, OR CONSEQUENTIAL 29.\" DAMAGES, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES, LOSS OF 30.\" USE, DATA OR PROFITS, HOWEVER CAUSED AND UNDER ANY THEORY OF 31.\" LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 32.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF 33.\" THE USE OF THIS SOFTWARE, EVEN IF PACKET DESIGN IS ADVISED OF 34.\" THE POSSIBILITY OF SUCH DAMAGE. 35.\" 36.\" $FreeBSD: src/lib/libc/gen/ucontext.3,v 1.3 2004/07/03 22:30:08 ru Exp $ 37.\" $DragonFly: src/lib/libc/gen/ucontext.3,v 1.7 2007/08/30 17:47:08 swildner Exp $ 38.\" 39.Dd September 10, 2002 40.Dt UCONTEXT 3 41.Os 42.Sh NAME 43.Nm ucontext 44.Nd user thread context 45.Sh LIBRARY 46.Lb libc 47.Sh SYNOPSIS 48.In ucontext.h 49.Sh DESCRIPTION 50The 51.Vt ucontext_t 52type is a structure type suitable for holding the context for a user 53thread of execution. 54A thread's context includes its stack, saved registers, and list of 55blocked signals. 56.Pp 57The 58.Vt ucontext_t 59structure contains at least these fields: 60.Pp 61.Bl -tag -width ".Va mcontext_t\ \ uc_mcontext" -offset 3n -compact 62.It Va "ucontext_t *uc_link" 63context to assume when this one returns 64.It Va "sigset_t uc_sigmask" 65signals being blocked 66.It Va "stack_t uc_stack" 67stack area 68.It Va "mcontext_t uc_mcontext" 69saved registers 70.El 71.Pp 72The 73.Va uc_link 74field points to the context to resume when this context's entry point 75function returns. 76If 77.Va uc_link 78is equal to 79.Dv NULL , 80then the process exits when this context returns. 81.Pp 82The 83.Va uc_mcontext 84field is machine-dependent and should be treated as opaque by 85portable applications. 86.Pp 87The following functions are defined to manipulate 88.Vt ucontext_t 89structures: 90.Pp 91.Bl -item -offset 3n -compact 92.It 93.Ft int 94.Fn getcontext "ucontext_t *" ; 95.It 96.Ft int 97.Fn setcontext "const ucontext_t *" ; 98.It 99.Ft void 100.Fn makecontext "ucontext_t *" "void (*func)(void)" int ... ; 101.It 102.Ft int 103.Fn swapcontext "ucontext_t *" "const ucontext_t *" ; 104.El 105.Sh SEE ALSO 106.Xr sigaltstack 2 , 107.Xr getcontext 3 , 108.Xr makecontext 3 , 109.Xr setcontext 3 110