SIGSTACK(2) SIGSTACK(2) NAME sigstack - set and/or get signal stack context SYNOPSIS #include <signal.h> struct sigstack { caddr_t ss_sp; int ss_onstack; }; sigstack(ss, oss); struct sigstack *ss, *oss; DESCRIPTION Sigstack allows users to define an alternate stack on which signals are to be processed. If ss is non-zero, it specifies a signal stack on which to deliver signals and tells the system if the process is cur‐ rently executing on that stack. When a signal’s action indicates its handler should execute on the signal stack (specified with a sigvec(2) call), the system checks to see if the process is currently executing on that stack. If the process is not currently executing on the signal stack, the system arranges a switch to the signal stack for the dura‐ tion of the signal handler’s execution. If oss is non-zero, the cur‐ rent signal stack state is returned. NOTES Signal stacks are not ‘‘grown’’ automatically, as is done for the nor‐ mal stack. If the stack overflows unpredictable results may occur. RETURN VALUE Upon successful completion, a value of 0 is returned. Otherwise, a value of -1 is returned and errno is set to indicate the error. ERRORS Sigstack will fail and the signal stack context will remain unchanged if one of the following occurs. [EFAULT] Either ss or oss points to memory that is not a valid part of the process address space. SEE ALSO sigvec(2), setjmp(3) 4.2 Berkeley Distribution June 30, 1985 SIGSTACK(2)