forked from rcore-os/zCore
49 lines
756 B
C
49 lines
756 B
C
#ifndef _XOPEN_SOURCE
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#define _XOPEN_SOURCE 700
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#endif
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#include <errno.h>
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#include <stdlib.h>
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#include <string.h>
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#include <time.h>
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#include <sys/types.h>
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#include <sys/sem.h>
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#include <sys/wait.h>
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#include <unistd.h>
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#include <assert.h>
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#include <stdio.h>
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static const char path[] = ".";
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static const int id = 's';
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#define T(f) assert((f) != -1)
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static void dec()
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{
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key_t k;
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int semid, semval;
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struct sembuf sops;
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T(k = ftok(path, id));
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T(semid = semget(k, 0, 0));
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/* test sem_op < 0 */
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sops.sem_num = 0;
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sops.sem_op = -1;
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sops.sem_flg = 0;
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T(semop(semid, &sops, 1));
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T(semval = semctl(semid, 0, GETVAL));
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assert(semval == 0);
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/* cleanup */
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T(semctl(semid, 0, IPC_RMID));
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}
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int main(void)
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{
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int p;
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int status;
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dec();
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return 0;
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}
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