SIGRETURN

Section: System Calls (2)
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BSD mandoc
BSD 4.3

NAME

sigreturn - return from signal

SYNOPSIS

Fd #include <signal.h>

struct sigcontext {
        int sc_onstack;
        int sc_mask;
        int sc_sp;
        int sc_fp;
        int sc_ap;
        int sc_pc;
        int sc_ps;
};

Ft int Fn sigreturn struct sigcontext *scp

DESCRIPTION

Fn 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 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 4.2 BSD 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

Fn Sigreturn will fail and the process context will remain unchanged if one of the following occurs.

Bq Er EFAULT: Fa Scp points to memory that is not a valid part of the process address space.
Bq Er EINVAL: The process status longword is invalid or would improperly raise the privilege level of the process.

HISTORY

The Fn sigreturn function call appeared in BSD 4.3

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Time: 16:28:59 GMT, April 18, 2022