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.\" %sccs.include.redist.man% 9.\" 10.\" @(#)setjmp.3 8.1 (Berkeley) 06/04/93 11.\" 12.Dd 13.Dt SETJMP 3 14.Os BSD 4 15.Sh NAME 16.Nm sigsetjmp , 17.Nm siglongjmp , 18.Nm setjmp , 19.Nm longjmp , 20.Nm _setjmp , 21.Nm _longjmp longjmperror 22.Nd non-local jumps 23.Sh SYNOPSIS 24.Fd #include <setjmp.h> 25.Ft int 26.Fn sigsetjmp "sigjmp_buf env" "int savemask" 27.Ft void 28.Fn siglongjmp "sigjmp_buf env" "int val" 29.Ft int 30.Fn setjmp "jmp_buf env" 31.Ft void 32.Fn longjmp "jmp_buf env" "int val" 33.Ft int 34.Fn _setjmp "jmp_buf env" 35.Ft void 36.Fn _longjmp "jmp_buf env" "int val" 37.Ft void 38.Fn longjmperror void 39.Sh DESCRIPTION 40The 41.Fn sigsetjmp , 42.Fn setjmp , 43and 44.Fn _setjmp 45functions save their calling environment in 46.Fa env . 47Each of these functions returns 0. 48.Pp 49The corresponding 50.Fn longjmp 51functions restore the environment saved by their most recent respective 52invocations 53of the 54.Fn setjmp 55function. 56They then return so that program execution continues as if the corresponding 57invocation of the 58.Fn setjmp 59call had just returned the value specified by 60.Fa val , 61instead of 0. 62.Pp 63Pairs of calls may be intermixed, i.e. both 64.Fn sigsetjmp 65and 66.Fn siglongjmp 67and 68.Fn setjmp 69and 70.Fn longjmp 71combinations may be used in the same program, however, individual 72calls may not, e.g. the 73.Fa env 74argument to 75.Fn setjmp 76may not be passed to 77.Fn siglongjmp . 78.Pp 79The 80.Fn longjmp 81routines may not be called after the routine which called the 82.Fn setjmp 83routines returns. 84.Pp 85All accessible objects have values as of the time 86.Fn longjmp 87routine was called, except that the values of objects of automatic storage 88invocation duration that do not have the 89.Em volatile 90type and have been changed between the 91.Fn setjmp 92invocation and 93.Fn longjmp 94call are indeterminate. 95.Pp 96The 97.Fn setjmp Ns / Ns Fn longjmp 98pairs save and restore the signal mask while 99.Fn _setjmp Ns / Ns Fn _longjmp 100pairs save and restore only the register set and the stack. 101(See 102.Fn sigmask 2 . ) 103.Pp 104The 105.Fn sigsetjmp Ns / Ns Fn siglongjmp 106function 107pairs save and restore the signal mask if the argument 108.Fa savemask 109is non-zero, otherwise only the register set and the stack are saved. 110.Sh ERRORS 111If the contents of the 112.Fa env 113are corrupted, or correspond to an environment that has already returned, 114the 115.Fn longjmp 116routine calls the routine 117.Fn longjmperror 3 . 118If 119.Fn longjmperror 120returns the program is aborted (see 121.Xr abort 2 ) . 122The default version of 123.Fn longjmperror 124prints the message 125.Dq Li longjmp botch 126to standard error and returns. 127User programs wishing to exit more gracefully should write their own 128versions of 129.Fn longjmperror . 130.Sh SEE ALSO 131.Xr sigaction 2 , 132.Xr sigaltstack 2 , 133.Xr signal 3 134.Sh STANDARDS 135The 136.Fn setjmp 137and 138.Fn longjmp 139functions conform to 140.St -ansiC . 141The 142.Fn sigsetjmp 143and 144.Fn siglongjmp 145functions conform to 146.St -p1003.1-88 . 147