9.72 sigprogmask ¶

#define SIG_BLOCK   1
#define SIG_UNBLOCK 2
#define SIG_SETMASK 3

int sigprocmask(int how, sigset_t *set, sigset_t *oldset);

This syscall fetches and/or changes the signal mask of the calling process. The signal mask is the set of signals whose delivery is currently blocked.

If not NULL, set can be used for passing a new mask, if not NULL, oldset can be used for getting the existing mask.

The behaviour of the syscall will depend on the value passed to how, which can be one of:

SIG_BLOCK

The blocked signals will be a union of the current ones and the passed ones.

SIG_UNBLOCK

The blocked signals will be the current ones minus the passed ones.

SIG_SETMASK

The blocked signals will be the passed ones.

It returns 0 on success and -1 on failure, with the following errno:

EINVAL

how is not valid.

EFAULT

A non-NULL pointer points to not valid memory.