semstat: A semtool companion program Next: 6.4.4 Shared Memory Up: 6.4.3 Semaphores Previous: The Sourcesemstat: A semtool companion programAs an added bonus, the source code to a companion program called semstat is provided next. The semstat program displays the values of each of the semaphores in the set created by semtool./***************************************************************************** Excerpt from "Linux Programmer's Guide - Chapter 6" (C)opyright 1994-1995, Scott Burkett ***************************************************************************** MODULE: semstat.c ***************************************************************************** A companion command line tool for the semtool package. semstat displays the current value of all semaphores in the set created by semtool. *****************************************************************************/ #include <stdio.h> #include <stdlib.h> #include <sys/types.h> #include <sys/ipc.h> #include <sys/sem.h> int get_sem_count(int sid); void show_sem_usage(int sid); int get_sem_count(int sid); void dispval(int sid); int main(int argc, char *argv[]) { key_t key; int semset_id; /* Create unique key via call to ftok() */ key = ftok(".", 's'); /* Open the semaphore set - do not create! */ if((semset_id = semget(key, 1, 0666)) == -1) { printf("Semaphore set does not exist\n"); exit(1); } show_sem_usage(semset_id); return(0); } void show_sem_usage(int sid) { int cntr=0, maxsems, semval; maxsems = get_sem_count(sid); while(cntr < maxsems) { semval = semctl(sid, cntr, GETVAL, 0); printf("Semaphore #%d: --> %d\n", cntr, semval); cntr++; } } int get_sem_count(int sid) { int rc; struct semid_ds mysemds; union semun semopts; /* Get current values for internal data structure */ semopts.buf = &mysemds; if((rc = semctl(sid, 0, IPC_STAT, semopts)) == -1) { perror("semctl"); exit(1); } /* return number of semaphores in set */ return(semopts.buf->sem_nsems); } void dispval(int sid) { int semval; semval = semctl(sid, 0, GETVAL, 0); printf("semval is %d\n", semval); }Converted on:Fri Mar 29 14:43:04 EST 1996

Wyszukiwarka

Podobne podstrony:
node64
node64
node64
node64 1
node64 23D247UZAFJK737ACWMMOTR7Y4SKWTRJ2C6VWFA
node64 M5YLGUH5SPJJCD4SJ4JGOWRCD3IC5ACVRLZVTWY
node64 N6SEZLE2MYJK7TQARQSTXG2BTUZD2FXTJDDKGBI

więcej podobnych podstron