Guardian Native C Library Calls Reference Manual (G06.28+, H06.05+)

alarm(3) Guardian Native C Library Calls Reference Manual

NAME

alarm - Sets or changes the timeout value for interval timers

LIBRARY

G-series native Guardian processes: system library

G-series native OSS processes: system library

H-series native Guardian processes: implicit libraries

H-series OSS processes: implicit libraries

SYNOPSIS

#include <unistd.h>

unsigned int alarm(

unsigned int seconds);

PARAMETERS

seconds Speciﬁes the number of real-time seconds before the timer

expires. Any value greater than the system maximum of

0x7FFFFFFF one-hundredths of a second is reduced to the sys-

tem maximum without informing the caller.

DESCRIPTION

The alarm() function is used to obtain notiﬁcation of a timeout after the number of real-time

seconds speciﬁed by the seconds parameter have elapsed.

When the number of seconds speciﬁed by the seconds parameter have elapsed, a SIGALRM sig-

nal is sent to the process. The receipt of this signal might be delayed because of scheduling

conﬂicts.

Each call to alarm() overrides any previous setting. Calling alarm() with the value 0 (zero) in

the seconds parameter cancels the timer.

Use From the Guardian Environment

The actions of this function are undeﬁned if it is called from a TNS or accelerated Guardian pro-

cess or from any privileged process.

RETURN VALUES

The alarm() function returns the number of seconds remaining from the previous alarm() call,

if any. Otherwise, the alarm( ) function returns 0 (zero).

ERRORS

The alarm() function never sets the value of errno. However, if the function call is unsuccess-

ful (for example, if the system has no time-list elements, or TLEs, available), then a nondeferr-

able SIGLIMIT signal is delivered to the process.

RELATED INFORMATION

Functions: sigaction(2), signal(3), sleep(3).

Files: signal(4).

STANDARDS CONFORMANCE

The following are HP extensions to the XPG4 Version 2 speciﬁcation:

• A SIGLIMIT signal is delivered to the process if the function call fails.

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