svsem/event_flags.h

This is svsem/event_flags.h, an example to accompany the book, The Linux Programming Interface.

This file is not printed in the book; it is the solution to Exercise 47-5:b (page 995).

In the listing below, the names of Linux system calls and C library functions are hyperlinked to manual pages from the Linux man-pages project, and the names of functions implemented in the book are hyperlinked to the implementations of those functions.

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/* event_flags.h

   Header file for event_flags.c.

   The event flags operations are:

        set a flag:              setEventFlag(semId, semNum)
        clear a flag:            clearEventFlag(semId, semNum)
        wait for flag to be set: waitForEventFlag(semId, semNum)
        read a flag's value:     getFlagState(semId, semNum, &isSet)

   NB: The semantics of System V semaphores require that the "set"
   value for a flag is 0 and the "clear" value is 1.
*/
#ifndef EVENT_FLAGS_H
#define EVENT_FLAGS_H           /* Prevent accidental double inclusion */

#include "tlpi_hdr.h"

int waitForEventFlag(int semId, int semNum);

int clearEventFlag(int semId, int semNum);

int setEventFlag(int semId, int semNum);

int getFlagState(int semId, int semNum, Boolean *isSet);

#endif

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