SIGRETURN(2) — UNIX Programmer’s Manual

NAME

sigreturn − return from signal

SYNOPSIS

#include <signal.h>
struct sigcontext {
intsc_onstack;/∗ sigstack state to restore ∗/
intsc_mask;/∗ signal mask to restore ∗/
intsc_cpu_regs[16];/∗ ARM cpu registers ∗/
structfp_regs sc_fp_regs; /∗ floating point registers ∗/
};
sigreturn(scp);
struct sigcontext ∗scp;

DESCRIPTION

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 4.2BSD, hence it should not be used if backward compatibility is needed. The format of the “sigcontext” structure varies according to the machine architecture on which the program runs. The above description only applies to the ARM.

RETURN VALUE

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

ERRORS

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.

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