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SIGRETURN(2) FreeBSD 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 thread's 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.
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 thread 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
sigaction(2), setjmp(3), ucontext(3)
HISTORY
The sigreturn() system call appeared in 4.3BSD.
FreeBSD 14.0-RELEASE-p6 September 6, 2013 FreeBSD 14.0-RELEASE-p6