SIGRETURN(2) MidnightBSD System Calls Manual SIGRETURN(2)

NAME

sigreturn — return from signal

LIBRARY

Standard C Library (libc, −lc)

SYNOPSIS

#include <signal.h>

int

sigreturn(const ucontext_t *scp);

DESCRIPTION

The sigreturn() system call allows users to atomically unmask, switch stacks, and return from a signal context. The processes signal mask and stack status are restored from the context structure pointed to by scp. The system call does not return; the users stack pointer, frame pointer, argument pointer, and processor status longword are restored from the context. Execution resumes at the specified pc. This system call is used by the trampoline code and longjmp(3) when returning from a signal to the previously executing program.

NOTES

This system call is not available in 4.2BSD hence it should not be used if backward compatibility is needed.

RETURN VALUES

If successful, the system call does not return. Otherwise, a value of -1 is returned and errno is set to indicate the error.

ERRORS

The sigreturn() system call will fail and the process context will remain unchanged if one of the following occurs.

[EFAULT]

The scp argument points to memory that is not a valid part of the process address space.

[EINVAL]

The process status longword is invalid or would improperly raise the privilege level of the process.

SEE ALSO

sigvec(2), setjmp(3), ucontext(3)

HISTORY

The sigreturn() system call appeared in 4.3BSD.

MidnightBSD 0.3 June 4, 1993 MidnightBSD 0.3