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@(#)setjmp.3 8.1 (Berkeley) 6/4/93
$FreeBSD: releng/11.0/lib/libc/gen/setjmp.3 165903 2007-01-09 00:28:16Z imp $
.Dd June 4, 1993 .Dt SETJMP 3 .Os .Sh NAME .Nm sigsetjmp , .Nm siglongjmp , .Nm setjmp , .Nm longjmp , .Nm _setjmp , .Nm _longjmp , .Nm longjmperror .Nd non-local jumps .Sh LIBRARY .Lb libc .Sh SYNOPSIS n setjmp.h .Ft int .Fn sigsetjmp "sigjmp_buf env" "int savemask" .Ft void .Fn siglongjmp "sigjmp_buf env" "int val" .Ft int .Fn setjmp "jmp_buf env" .Ft void .Fn longjmp "jmp_buf env" "int val" .Ft int .Fn _setjmp "jmp_buf env" .Ft void .Fn _longjmp "jmp_buf env" "int val" .Ft void .Fn longjmperror void .Sh DESCRIPTION The .Fn sigsetjmp , .Fn setjmp , and .Fn _setjmp functions save their calling environment in .Fa env . Each of these functions returns 0.
p The corresponding .Fn longjmp functions restore the environment saved by their most recent respective invocations of the .Fn setjmp function. They then return so that program execution continues as if the corresponding invocation of the .Fn setjmp call had just returned the value specified by .Fa val , instead of 0.
p Pairs of calls may be intermixed, i.e., both .Fn sigsetjmp and .Fn siglongjmp and .Fn setjmp and .Fn longjmp combinations may be used in the same program, however, individual calls may not, e.g. the .Fa env argument to .Fn setjmp may not be passed to .Fn siglongjmp .
p The .Fn longjmp routines may not be called after the routine which called the .Fn setjmp routines returns.
p All accessible objects have values as of the time .Fn longjmp routine was called, except that the values of objects of automatic storage invocation duration that do not have the .Vt volatile type and have been changed between the .Fn setjmp invocation and .Fn longjmp call are indeterminate.
p The .Fn setjmp Ns / Ns Fn longjmp pairs save and restore the signal mask while .Fn _setjmp Ns / Ns Fn _longjmp pairs save and restore only the register set and the stack. (See .Fn sigprocmask 2 . )
p The .Fn sigsetjmp Ns / Ns Fn siglongjmp function pairs save and restore the signal mask if the argument .Fa savemask is non-zero, otherwise only the register set and the stack are saved. .Sh ERRORS If the contents of the .Fa env are corrupted, or correspond to an environment that has already returned, the .Fn longjmp routine calls the routine .Fn longjmperror 3 . If .Fn longjmperror returns the program is aborted (see .Xr abort 3 ) . The default version of .Fn longjmperror prints the message .Dq Li longjmp botch to standard error and returns. User programs wishing to exit more gracefully should write their own versions of .Fn longjmperror . .Sh SEE ALSO .Xr sigaction 2 , .Xr sigaltstack 2 , .Xr signal 3 .Sh STANDARDS The .Fn setjmp and .Fn longjmp functions conform to .St -isoC . The .Fn sigsetjmp and .Fn siglongjmp functions conform to .St -p1003.1-88 .