sigstack(2)
Name
sigstack − set or get signal stack context
Syntax
#include <signal.h>
struct sigstack {
caddr_tss_sp;
intss_onstack;
};
sigstack(ss, oss)
struct sigstack *ss, *oss;
Description
The sigstack system call allows users to define an alternate stack on which signals are to be processed. If ss is nonzero, it specifies a signal stack on which to deliver signals and tells the system if the process is currently executing on that stack. When a signal’s action indicates its handler should execute on the signal stack (specified with a sigvec 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 duration of the signal handler’s execution. If oss is nonzero, the current signal stack state is returned.
Signal stacks are not grown’automatically, as is done for the normal stack. If the stack overflows, unpredictable results may occur.
Return Values
Upon successful completion, a value of zero (0) is returned. Otherwise, a value of −1 is returned and errno is set to indicate the error.
Diagnostics
The sigstack system call fails and the signal stack context remains 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.