C language query process signal whether it is masked or shelved simple method _c language

C language Sigprocmask () function: query or set a signal mask
header file:

#include <signal.h>

To define a function:

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

Function Description: Sigprocmask () can be used to change the current signal mask, the operation depends on the parameters how to determine:
1, Sig_block new signal mask by the current signal mask and parameter set specified by the signal mask as a joint set
2. Sig_unblock the current signal mask to remove the signal mask specified by the parameter set
3, sig_setmask the current signal mask set to the parameter set specified by the signal mask. If the parameter oldset is not a null pointer, the current signal mask is returned by this pointer.

Return value: Returns 0 if the execution succeeds, or 1 if there is an error.

Error code:
1, efault parameter set, Oldset pointer address cannot be accessed.
2, Eintr this call is interrupted.

C language Sigpending () function: The query is placed on the signal
header file:

#include <signal.h>

To define a function:

int sigpending (sigset_t *set);

Function Description: sigpending () will return the set of signals being shelved by the parameter set pointer. Returns 0 if the return value is successful, or 1 if there is an error.

Error code:
1, efault parameter set pointer address cannot be accessed
2, Eintr this call is interrupted.