sigstack(3ucb) [opensolaris man page]
sigstack(3UCB) SunOS/BSD Compatibility Library Functions sigstack(3UCB) NAME
sigstack - set and/or get signal stack context SYNOPSIS
/usr/ucb/cc [ flag ... ] file ... #include <signal.h> int sigstack(nss, oss) struct sigstack *nss, *oss; DESCRIPTION
The sigstack() function allows users to define an alternate stack, called the "signal stack", on which signals are to be processed. When a signal's action indicates its handler should execute on the signal stack (specified with a sigvec(3UCB) 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. A signal stack is specified by a sigstack() structure, which includes the following members: char *ss_sp; /* signal stack pointer */ int ss_onstack; /* current status */ The ss_sp member is the initial value to be assigned to the stack pointer when the system switches the process to the signal stack. Note that, on machines where the stack grows downwards in memory, this is not the address of the beginning of the signal stack area. The ss_onstack member is zero or non-zero depending on whether the process is currently executing on the signal stack or not. If nss is not a null pointer, sigstack() sets the signal stack state to the value in the sigstack() structure pointed to by nss. If nss is a null pointer, the signal stack state will be unchanged. If oss is not a null pointer, the current signal stack state is stored in the sigstack() structure pointed to by oss. RETURN VALUES
Upon successful completion, 0 is returned. Otherwise, -1 is returned and errno is set to indicate the error. ERRORS
The sigstack() function will fail and the signal stack context will remain unchanged if one of the following occurs. EFAULT Either nss or oss points to memory that is not a valid part of the process address space. SEE ALSO
cc(1B), sigaltstack(2), sigvec(3UCB), signal(3C) WARNINGS
Signal stacks are not "grown" automatically, as is done for the normal stack. If the stack overflows unpredictable results may occur. NOTES
Use of these interfaces should be restricted to only applications written on BSD platforms. Use of these interfaces with any of the system libraries or in multi-threaded applications is unsupported. SunOS 5.11 30 Oct 2007 sigstack(3UCB)
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sigstack(3C) Standard C Library Functions sigstack(3C) NAME
sigstack - set and/or get alternate signal stack context SYNOPSIS
#include <signal.h> int sigstack(struct sigstack *ss, struct sigstack *oss); DESCRIPTION
The sigstack() function allows the calling process to indicate to the system an area of its address space to be used for processing signals received by the process. If the ss argument is not a null pointer, it must point to a sigstack structure. The length of the application-supplied stack must be at least SIGSTKSZ bytes. If the alternate signal stack overflows, the resulting behavior is undefined. (See USAGE below.) o The value of the ss_onstack member indicates whether the process wants the system to use an alternate signal stack when delivering signals. o The value of the ss_sp member indicates the desired location of the alternate signal stack area in the process' address space. o If the ss argument is a null pointer, the current alternate signal stack context is not changed. If the oss argument is not a null pointer, it points to a sigstack structure in which the current alternate signal stack context is placed. The value stored in the ss_onstack member of oss will be non-zero if the process is currently executing on the alternate signal stack. If the oss argument is a null pointer, the current alternate signal stack context is not returned. When a signal's action indicates its handler should execute on the alternate signal stack (specified by calling sigaction(2)), sigstack() checks to see if the process is currently executing on that stack. If the process is not currently executing on the alternate signal stack, the system arranges a switch to the alternate signal stack for the duration of the signal handler's execution. After a successful call to one of the exec functions, there are no alternate signal stacks in the new process image. RETURN VALUES
Upon successful completion, sigstack() returns 0. Otherwise, it returns -1 and sets errno to indicate the error. ERRORS
The sigstack() function will fail if: EPERM An attempt was made to modify an active stack. USAGE
A portable application, when being written or rewritten, should use sigaltstack(2) instead of sigstack(). The direction of stack growth is not indicated in the historical definition of struct sigstack. The only way to portably establish a stack pointer is for the application to determine stack growth direction, or to allocate a block of storage and set the stack pointer to the mid- dle. sigstack() may assume that the size of the signal stack is SIGSTKSZ as found in <signal.h>. An application that would like to specify a signal stack size other than SIGSTKSZ should use sigaltstack(2). Applications should not use longjmp(3C) to leave a signal handler that is running on a stack established with sigstack(). Doing so may dis- able future use of the signal stack. For abnormal exit from a signal handler, siglongjmp(3C), setcontext(2), or swapcontext(3C) may be used. These functions fully support switching from one stack to another. The sigstack() function requires the application to have knowledge of the underlying system's stack architecture. For this reason, sigalt- stack(2) is recommended over this function. SEE ALSO
fork(2), _longjmp(3C), longjmp(3C), setjmp(3C), sigaltstack(2), siglongjmp(3C), sigsetjmp(3C) SunOS 5.10 28 Feb 1996 sigstack(3C)