1SIGSTACK(2)                   System Calls Manual                  SIGSTACK(2)
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NAME

6       sigstack - set and/or get signal stack context
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SYNOPSIS

9       #include <signal.h>
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11       struct sigstack {
12       caddr_t   ss_sp;
13       int  ss_onstack;
14       };
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16       sigstack(ss, oss);
17       struct sigstack *ss, *oss;
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DESCRIPTION

20       This interface has been made obsolete by: sigaltstack(2).
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22       Sigstack allows users to define an alternate stack on which signals are
23       to be processed.  If ss is non-zero, it specifies  a  signal  stack  on
24       which  to  deliver  signals and tells the system if the process is cur‐
25       rently executing on that stack.  When a signal's action  indicates  its
26       handler  should execute on the signal stack (specified with a sigvec(2)
27       call), the system checks to see if the process is  currently  executing
28       on that stack.  If the process is not currently executing on the signal
29       stack, the system arranges a switch to the signal stack for  the  dura‐
30       tion  of  the signal handler's execution.  If oss is non-zero, the cur‐
31       rent signal stack state is returned.
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NOTES

34       Signal stacks are not ``grown'' automatically, as is done for the  nor‐
35       mal stack.  If the stack overflows unpredictable results may occur.
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RETURN VALUE

38       Upon  successful  completion,  a  value of 0 is returned.  Otherwise, a
39       value of -1 is returned and errno is set to indicate the error.
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ERRORS

42       Sigstack will fail and the signal stack context will  remain  unchanged
43       if one of the following occurs.
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45       [EFAULT]       Either  ss  or  oss points to memory that is not a valid
46                      part of the process address space.
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SEE ALSO

49       sigvec(2), setjmp(3)
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HISTORY

52       The sigstack function call appeared in 4.2BSD and has been deprecated.
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564.2 Berkeley Distribution      September 3, 1997                   SIGSTACK(2)
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