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  1. #include <sys/types.h>
  2. #include <linux/ipc.h>
  3. #include <linux/sem.h>
  4. #include <stdio.h>
  5. #include <stdlib.h>
  6.  
  7. #define SEM_NUM 10
  8. #define SEM_MODE (IPC_CREAT|0660)
  9.  
  10. void printf_stat(union semun *arg);
  11.  
  12. int main(void)
  13. {
  14.     int semid;
  15.     union semun semopts;
  16.     struct semid_ds semds;
  17.     if((semid=semget(IPC_PRIVATE,SEM_NUM,SEM_MODE))==-1)
  18.     {
  19.         fprintf(stderr,"semget error!\n");
  20.         exit(1);
  21.     }
  22.     semopts.buf=&semds;
  23.     if(semctl(semid,IPC_STAT,semopts)==-1)
  24.     {
  25.         fprintf(stderr,"get semid_ds error!\n");
  26.         exit(1);
  27.     }
  28.     printfmode(&semopts);
  29.     changemode(semid,0600);
  30.     if(semctl(semid,IPC_STAT,semopts)==-1)
  31.     {
  32.         fprintf(stderr,"get semid_ds error!\n");
  33.         exit(1);
  34.     }
  35.     printfmode(&semopts);
  36.     if(semctl(semid,IPC_RMID,0)<0)
  37.     {
  38.         fprintf(stderr,"semctl error\n");
  39.         exit(1);
  40.     }
  41.     exit(0);
  42. }
  43. void printfmode (union semun *arg)
  44. {
  45.     printf(" mode=%d:\n",arg->buf->sem_perm.mode);
  46.     return;
  47. }
  48. void changemode(int sid,char *mode)
  49. {
  50.     int rc;
  51.     union semun semopts;
  52.     struct semid_ds mysemds;
  53.     semopts.buf=&mysemds;
  54.     rc=semctl(sid,0,IPC_STAT,semopts);
  55.     if(rc==-1)
  56.     {
  57.         printf("semctl error!\n");
  58.         exit(1);
  59.     }
  60.     sscanf(mode,"%ho",&semopts.buf->sem_perm.mode);
  61.     semctl(sid,0,IPC_SET,semopts);
  62.     return;
  63. }
  64.  
Runtime error #stdin #stdout #stderr 0s 1784KB
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Standard input is empty
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Standard output is empty
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get semid_ds error!
https://ideone.com/PvqhDE
language:
C (gcc 8.3)
created:
12 years ago
visibility:
public

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