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.Dd March 23, 2020 37.Dt UCONTEXT 3 38.Os 39.Sh NAME 40.Nm ucontext 41.Nd user thread context 42.Sh LIBRARY 43.Lb libc 44.Sh SYNOPSIS 45.In ucontext.h 46.Sh DESCRIPTION 47The 48.Vt ucontext_t 49type is a structure type suitable for holding the context for a user 50thread of execution. 51A thread's context includes its stack, saved registers, and list of 52blocked signals. 53.Pp 54The 55.Vt ucontext_t 56structure contains at least these fields: 57.Pp 58.Bl -tag -width ".Va mcontext_t\ \ uc_mcontext" -offset 3n -compact 59.It Va "ucontext_t *uc_link" 60context to assume when this one returns 61.It Va "sigset_t uc_sigmask" 62signals being blocked 63.It Va "stack_t uc_stack" 64stack area 65.It Va "mcontext_t uc_mcontext" 66saved registers 67.El 68.Pp 69The 70.Va uc_link 71field points to the context to resume when this context's entry point 72function returns. 73If 74.Va uc_link 75is equal to 76.Dv NULL , 77then the process exits when this context returns. 78.Pp 79The 80.Va uc_mcontext 81field is machine-dependent and should be treated as opaque by 82portable applications. 83.Pp 84The following functions are defined to manipulate 85.Vt ucontext_t 86structures: 87.Pp 88.Bl -item -offset 3n -compact 89.It 90.Ft int 91.Fn getcontext "ucontext_t *" ; 92.It 93.Ft "ucontext_t *" 94.Fn getcontextx "void" ; 95.It 96.Ft int 97.Fn setcontext "const ucontext_t *" ; 98.It 99.Ft void 100.Fn makecontext "ucontext_t *" "void \*[lp]*\*[rp]\*[lp]void\*[rp]" 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 getcontextx 3 , 109.Xr makecontext 3 110.Sh STANDARDS 111The 112.Vt ucontext_t 113type conforms to 114.St -xsh5 115and 116.St -p1003.1-2001 . 117The 118.St -p1003.1-2008 119revision removed the 120.Vt ucontext_t 121from the specification. 122