1.\" Copyright (c) 1990, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" This code is derived from software contributed to Berkeley by 5.\" the American National Standards Committee X3, on Information 6.\" Processing Systems. 7.\" 8.\" Redistribution and use in source and binary forms, with or without 9.\" modification, are permitted provided that the following conditions 10.\" are met: 11.\" 1. Redistributions of source code must retain the above copyright 12.\" notice, this list of conditions and the following disclaimer. 13.\" 2. Redistributions in binary form must reproduce the above copyright 14.\" notice, this list of conditions and the following disclaimer in the 15.\" documentation and/or other materials provided with the distribution. 16.\" 3. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)setjmp.3 8.1 (Berkeley) 6/4/93 33.\" 34.Dd April 2, 2022 35.Dt SETJMP 3 36.Os 37.Sh NAME 38.Nm sigsetjmp , 39.Nm siglongjmp , 40.Nm setjmp , 41.Nm longjmp , 42.Nm _setjmp , 43.Nm _longjmp , 44.Nm longjmperror 45.Nd non-local jumps 46.Sh LIBRARY 47.Lb libc 48.Sh SYNOPSIS 49.In setjmp.h 50.Ft int 51.Fn sigsetjmp "sigjmp_buf env" "int savemask" 52.Ft void 53.Fn siglongjmp "sigjmp_buf env" "int val" 54.Ft int 55.Fn setjmp "jmp_buf env" 56.Ft void 57.Fn longjmp "jmp_buf env" "int val" 58.Ft int 59.Fn _setjmp "jmp_buf env" 60.Ft void 61.Fn _longjmp "jmp_buf env" "int val" 62.Ft void 63.Fn longjmperror void 64.Sh DESCRIPTION 65The 66.Fn sigsetjmp , 67.Fn setjmp , 68and 69.Fn _setjmp 70functions save their calling environment in 71.Fa env . 72Each of these functions returns 0. 73.Pp 74The corresponding 75.Fn longjmp 76functions restore the environment saved by their most recent respective 77invocations 78of the 79.Fn setjmp 80function. 81They then return so that program execution continues as if the corresponding 82invocation of the 83.Fn setjmp 84call had just returned the value specified by 85.Fa val , 86instead of 0. 87.Pp 88Pairs of calls may be intermixed, i.e., both 89.Fn sigsetjmp 90and 91.Fn siglongjmp 92and 93.Fn setjmp 94and 95.Fn longjmp 96combinations may be used in the same program, however, individual 97calls may not, e.g.\& the 98.Fa env 99argument to 100.Fn setjmp 101may not be passed to 102.Fn siglongjmp . 103.Pp 104The 105.Fn longjmp 106routines may not be called after the routine which called the 107.Fn setjmp 108routines returns. 109.Pp 110All accessible objects have values as of the time 111.Fn longjmp 112routine was called, except that the values of objects of automatic storage 113invocation duration that do not have the 114.Vt volatile 115type and have been changed between the 116.Fn setjmp 117invocation and 118.Fn longjmp 119call are indeterminate. 120.Pp 121The 122.Fn setjmp Ns / Ns Fn longjmp 123pairs save and restore the signal mask while 124.Fn _setjmp Ns / Ns Fn _longjmp 125pairs save and restore only the register set and the stack. 126(See 127.Fn sigprocmask 2 . ) 128.Pp 129The 130.Fn sigsetjmp Ns / Ns Fn siglongjmp 131function 132pairs save and restore the signal mask if the argument 133.Fa savemask 134is non-zero, otherwise only the register set and the stack are saved. 135.Sh ERRORS 136If the contents of the 137.Fa env 138are corrupted, or correspond to an environment that has already returned, 139the 140.Fn longjmp 141routine calls the routine 142.Fn longjmperror 3 . 143If 144.Fn longjmperror 145returns the program is aborted (see 146.Xr abort 3 ) . 147The default version of 148.Fn longjmperror 149prints the message 150.Dq Li longjmp botch 151to standard error and returns. 152User programs wishing to exit more gracefully should write their own 153versions of 154.Fn longjmperror . 155.Sh SEE ALSO 156.Xr sigaction 2 , 157.Xr sigaltstack 2 , 158.Xr signal 3 159.Sh STANDARDS 160The 161.Fn setjmp 162and 163.Fn longjmp 164functions conform to 165.St -isoC . 166The 167.Fn sigsetjmp 168and 169.Fn siglongjmp 170functions conform to 171.St -p1003.1-88 . 172.Sh HISTORY 173The 174.Fn setjmp 175and 176.Fn longjmp 177functions first appeared in the Programmer's Workbench (PWB/UNIX). 178