SIGRETURN(2) BSD System Calls Manual SIGRETURN(2)
sigreturn -- return from signal
sigreturn(struct sigcontext *scp);
sigreturn() 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. 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 speci-
fied pc. This system call is used by the trampoline code and longjmp(3)
when returning from a signal to the previously executing program.
Note that sigcontext contains machine dependent information.
This system call is not available in 4.2BSD hence it should not be used
if backward compatibility is needed.
If successful, the system call does not return. Otherwise, a value of -1
is returned and errno is set to indicate the error.
sigreturn() will fail and the process context will remain unchanged if
one of the following occurs.
[EFAULT] scp 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.
The sigreturn() function call appeared in 4.3BSD.
BSD September 9, 2014 BSD