sigignore(3c) [hpux man page]
sigset(3C) sigset(3C) NAME
sigset(), sighold(), sigrelse(), sigignore() - signal management SYNOPSIS
DESCRIPTION
The system defines a set of signals that can be delivered to a process. The set of signals is defined in signal(5), along with the meaning and side effects of each signal. An alternate mechanism for handling these signals is defined here. The facilities described here should not be used in conjunction with the other facilities described under signal(2) and sigspace(2). allows the calling process to choose one of four ways to handle the receipt of a specific signal. sig specifies the signal and func speci- fies the action handler. sig can be any one of the signals described under signal(5) except or func is assigned one of four values: or a function address. The actions prescribed by and are described under signal(5). The action pre- scribed by and function address are described below: Hold signal. The signal sig is held upon receipt. Any pending signal of this signal type remains held. Only one signal of each type is held. Note: the signals and cannot be held. function address Catch signal. func must be a pointer to a function, the signal-catching handler, that is called when signal sig occurs. specifies that the process calls this function upon receipt of signal sig. Any pending signal of this type is released. This handler address is retained across calls to the other signal management functions listed here. Upon receipt of signal sig, the receiving process executes the signal-catching function pointed to by func as described under signal(5) with the follow- ing differences: Before calling the signal-catching handler, the defined action of sig is set to During a normal return from the signal- catching handler, the defined action is restored to func and any held signal of this type is released. If a non-local goto (longjmp(3C)) is taken, must be called to restore the defined action to func and release any held signal of this type. holds the signal sig. restores the defined action of sig to that specified previously by and are used to establish critical regions of code. is analogous to raising the priority level and deferring or holding a signal until the priority is lowered by sets the action for signal sig to (see signal(5)). RETURN VALUE
Upon successful completion, returns the previous value of the defined action for the specified signal sig. Otherwise, a value of is returned and is set to indicate the error. is defined in For the other functions, a 0 value indicates that the call succeeded. A -1 return value indicates an error occurred and is set to indicate the reason. ERRORS
fails and the defined action for sig is not changed if any of the following occur: The func argument points to memory that is not a valid part of the process address space. Reliable detection of this error is implementation dependent. and and fail and the defined action for sig is not changed if any of the following occur: sig is not a valid signal number. An attempt is made to ignore, hold, or supply a handler for a signal that cannot be ignored, held, or caught; see signal(5). WARNINGS
These signal facilities should not be used in conjunction with signal(2) and sigspace(2). SEE ALSO
kill(1), kill(2), pause(2), signal(2), sigspace(2), wait(2), abort(3C), setjmp(3C), sigpause(3C), signal(5). STANDARDS CONFORMANCE
sigset(3C)
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signal(3C) Standard C Library Functions signal(3C) NAME
signal, sigset, sighold, sigrelse, sigignore, sigpause - simplified signal management for application processes SYNOPSIS
#include <signal.h> void (*signal(int sig, void (*disp)(int)))(int); void (*sigset(int sig, void (*disp)(int)))(int); int sighold(int sig); int sigrelse(int sig); int sigignore(int sig); int sigpause(int sig); DESCRIPTION
These functions provide simplified signal management for application processes. See signal.h(3HEAD) for an explanation of general signal concepts. The signal() and sigset() functions modify signal dispositions. The sig argument specifies the signal, which may be any signal except SIGKILL and SIGSTOP. The disp argument specifies the signal's disposition, which may be SIG_DFL, SIG_IGN, or the address of a signal han- dler. If signal() is used, disp is the address of a signal handler, and sig is not SIGILL, SIGTRAP, or SIGPWR, the system first sets the signal's disposition to SIG_DFL before executing the signal handler. If sigset() is used and disp is the address of a signal handler, the system adds sig to the calling process's signal mask before executing the signal handler; when the signal handler returns, the system restores the calling process's signal mask to its state prior to the delivery of the signal. In addition, if sigset() is used and disp is equal to SIG_HOLD, sig is added to the calling process's signal mask and the signal's disposition remains unchanged. The sighold() function adds sig to the calling process's signal mask. The sigrelse() function removes sig from the calling process's signal mask. The sigignore() function sets the disposition of sig to SIG_IGN. The sigpause() function removes sig from the calling process's signal mask and suspends the calling process until a signal is received. RETURN VALUES
Upon successful completion, signal() returns the signal's previous disposition. Otherwise, it returns SIG_ERR and sets errno to indicate the error. Upon successful completion, sigset() returns SIG_HOLD if the signal had been blocked or the signal's previous disposition if it had not been blocked. Otherwise, it returns SIG_ERR and sets errno to indicate the error. Upon successful completion, sighold(), sigrelse(), sigignore(), and sigpause(), return 0. Otherwise, they return -1 and set errno to indicate the error. ERRORS
These functions fail if: EINTR A signal was caught during the execution sigpause(). EINVAL The value of the sig argument is not a valid signal or is equal to SIGKILL or SIGSTOP. USAGE
The sighold() function used in conjunction with sigrelse() or sigpause() may be used to establish critical regions of code that require the delivery of a signal to be temporarily deferred. If signal() or sigset() is used to set SIGCHLD's disposition to a signal handler, SIGCHLD will not be sent when the calling process's children are stopped or continued. If any of the above functions are used to set SIGCHLD's disposition to SIG_IGN, the calling process's child processes will not create zom- bie processes when they terminate (see exit(2)). If the calling process subsequently waits for its children, it blocks until all of its children terminate; it then returns -1 with errno set to ECHILD (see wait(3C) and waitid(2)). The system guarantees that if more than one instance of the same signal is generated to a process, at least one signal will be received. It does not guarantee the reception of every generated signal. ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Interface Stability |Standard | +-----------------------------+-----------------------------+ |MT-Level |MT-Safe | +-----------------------------+-----------------------------+ SEE ALSO
exit(2), kill(2), pause(2), sigaction(2), sigsend(2), waitid(2), signal.h(3HEAD), wait(3C), attributes(5), standards(5) SunOS 5.11 6 Sep 2007 signal(3C)