The sigvec() function is provided for compatibility to old UNIX systems; its function is a subset of that available with the sigaction() function. Like the sigaction() function, the sigvec() function allows the user to set the action to take upon the receipt of a signal and to specify a signal handler mask to block signals before calling the signal handler. However, only signals with values 1 to 31 can be masked on entry to a signal-handler set up with the sigvec() function.
The sigvec() structure has the following members:
void (*sv_handler)( );
The sv_handler field specifies the action for the signal, and can be SIG_DFL, SIG_IGN, or the address of a signal handler function. See the sigaction() function for a detailed description of the signal actions.
The sv_mask field specifies a mask which specifies signals to block (in addition to any signals already blocked at time of delivery) when the signal handler function is called for the signal. Signal i is blocked if the i-th bit of the mask is set. Only signals with values 1 to 31 can be masked with the sigvec() function. The sv_flags field contains flags that further specify signal behavior. If SV_ONSTACK is set, the signal handler runs on the signal stack specified by the sigstack() function; otherwise, the signal handler runs on the stack of the process receiving the signal. If SV_INTERRUPT is set, a system call that is interrupted by signal returns a value of -1 with errno set to [EINTR]; otherwise, a system call interrupted by signal is restarted.
If the value of the in_vec parameter is a null pointer, then the signal handler information is not set. If the value of the out_vec parameter is null, then the previous signal handler information is not returned.
Once a signal handler is assigned, it remains assigned until another call to the sigvec(), signal(), sigaction(), or exec function is made.
The sigvec() function is provided for compatibility only, and its use is not recommended. Programs should use the sigaction() function instead.
The sigvec() function does not check the validity of the sv_handler field pointer. If it points to a location outside of the process address space, the process receives a memory fault when the system attempts to call the signal handler. If the sv_handler field points to anything other than a function, the results are unpredictable.
The signal-handler function can be declared as follows:
void handler (
int signal );
Upon successful completion, a value of 0 (zero) is returned. If the sigvec() function fails, a value of -1 is returned and errno is set to indicate the error.
If the sigvec() function fails, no new signal handler is installed and errno may be set to one of the following values: The in_vec or out_vec parameter points to a location outside of the process' address space. The signal parameter is not a valid signal number. An attempt was made to ignore or supply a handler for the SIGKILL signal.
Functions: kill(2), ptrace(2), sigaction(2), sigblock(2), sigpause(3), sigstack(2) delim off