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.\" $FreeBSD$ 37.\" 38.Dd September 10, 2002 39.Dt UCONTEXT 3 40.Os 41.Sh NAME 42.Nm ucontext 43.Nd user thread context 44.Sh LIBRARY 45.Lb libc 46.Sh SYNOPSIS 47.In ucontext.h 48.Sh DESCRIPTION 49The 50.Vt ucontext_t 51type is a structure type suitable for holding the context for a user 52thread of execution. 53A thread's context includes its stack, saved registers, and list of 54blocked signals. 55.Pp 56The 57.Vt ucontext_t 58structure contains at least these fields: 59.Pp 60.Bl -tag -width ".Va mcontext_t\ \ uc_mcontext" -offset 3n -compact 61.It Va "ucontext_t *uc_link" 62context to assume when this one returns 63.It Va "sigset_t uc_sigmask" 64signals being blocked 65.It Va "stack_t uc_stack" 66stack area 67.It Va "mcontext_t uc_mcontext" 68saved registers 69.El 70.Pp 71The 72.Va uc_link 73field points to the context to resume when this context's entry point 74function returns. 75If 76.Va uc_link 77is equal to 78.Dv NULL , 79then the process exits when this context returns. 80.Pp 81The 82.Va uc_mcontext 83field is machine-dependent and should be treated as opaque by 84portable applications. 85.Pp 86The following functions are defined to manipulate 87.Vt ucontext_t 88structures: 89.Pp 90.Bl -item -offset 3n -compact 91.It 92.Ft int 93.Fn getcontext "ucontext_t *" ; 94.It 95.Ft int 96.Fn setcontext "const ucontext_t *" ; 97.It 98.Ft void 99.Fn makecontext "ucontext_t *" "void \*[lp]*\*[rp]\*[lp]void\*[rp]" int ... ; 100.It 101.Ft int 102.Fn swapcontext "ucontext_t *" "const ucontext_t *" ; 103.El 104.Sh SEE ALSO 105.Xr sigaltstack 2 , 106.Xr getcontext 3 , 107.Xr makecontext 3 108