SIGRETURNSection: Linux Programmer's Manual (2)
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NAMEsigreturn - return from signal handler and cleanup stack frame
SYNOPSISint sigreturn(unsigned long __unused);
DESCRIPTIONWhen the Linux kernel creates the stack frame for a signal handler, a call to sigreturn() is inserted into the stack frame so that upon return from the signal handler, sigreturn() will be called.
This sigreturn() call undoes everything that was done---changing the process's signal mask, switching stacks (see sigaltstack(2))---in order to invoke the signal handler: it restores the process's signal mask, switches stacks, and restores the process's context (registers, processor flags), so that the process directly resumes execution at the point where it was interrupted by the signal.
RETURN VALUEsigreturn() never returns.
CONFORMING TOsigreturn() is specific to Linux and should not be used in programs intended to be portable.
NOTESThe sigreturn() call is used by the kernel to implement signal handlers. It should never be called directly. Better yet, the specific use of the __unused argument varies depending on the architecture.
SEE ALSOkill(2), sigaltstack(2), signal(2), signal(7)
COLOPHONThis page is part of release 3.21 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at http://www.kernel.org/doc/man-pages/.