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/* Attach shared memory segment.  */
extern void *shmat (int __shmid, __const void *__shmaddr, int __shmflg)
     __THROW;

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/* Get semaphore.  */
extern int semget (key_t __key, int __nsems, int __semflg) __THROW;

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/* Operate on semaphore.  */
extern int semop (int __semid, struct sembuf *__sops, size_t __nsops) __THROW;

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/* Detach shared memory segment.  */
extern int shmdt (__const void *__shmaddr) __THROW;

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/* Semaphore control operation.  */
extern int semctl (int __semid, int __semnum, int __cmd, ...) __THROW;

/* Commands for `semctl'.  */
#define GETPID          11              /* get sempid */
#define GETVAL          12              /* get semval */
#define GETALL          13              /* get all semval's */
#define GETNCNT         14              /* get semncnt */
#define GETZCNT         15              /* get semzcnt */
#define SETVAL          16              /* set semval */
#define SETALL          17              /* set all semval's */

/* The user should define a union like the following to use it for arguments
   for `semctl'.

   union semun
   {
     int val;                           <= value for SETVAL
     struct semid_ds *buf;              <= buffer for IPC_STAT & IPC_SET
     unsigned short int *array;         <= array for GETALL & SETALL
     struct seminfo *__buf;             <= buffer for IPC_INFO
   };

   Previous versions of this file used to define this union but this is
   incorrect.  One can test the macro _SEM_SEMUN_UNDEFINED to see whether
   one must define the union or not.  */

/* Data structure describing a set of semaphores.  */
struct semid_ds
{
  struct ipc_perm sem_perm;             /* operation permission struct */
  __time_t sem_otime;                   /* last semop() time */
  unsigned long int __unused1;
  __time_t sem_ctime;                   /* last time changed by semctl() */
  unsigned long int __unused2;
  unsigned long int sem_nsems;          /* number of semaphores in set */
  unsigned long int __unused3;
  unsigned long int __unused4;
};

struct  seminfo
{
  int semmap;
  int semmni;
  int semmns;
  int semmnu;
  int semmsl;
  int semopm;
  int semume;
  int semusz;
  int semvmx;
  int semaem;
};

/* Shared memory control operation.  */
extern int shmctl (int __shmid, int __cmd, struct shmid_ds *__buf) __THROW;

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/* Control commands for `msgctl', `semctl', and `shmctl'.  */
#define IPC_RMID        0               /* Remove identifier.  */
#define IPC_SET         1               /* Set `ipc_perm' options.  */
#define IPC_STAT        2               /* Get `ipc_perm' options.  */
#ifdef __USE_GNU
# define IPC_INFO       3               /* See ipcs.  */
#endif

/* Data structure describing a shared memory segment.  */
struct shmid_ds
  {
    struct ipc_perm shm_perm;           /* operation permission struct */
    size_t shm_segsz;                   /* size of segment in bytes */
    __time_t shm_atime;                 /* time of last shmat() */
#if __WORDSIZE == 32
    unsigned long int __unused1;
#endif
    __time_t shm_dtime;                 /* time of last shmdt() */
#if __WORDSIZE == 32
    unsigned long int __unused2;
#endif
    __time_t shm_ctime;                 /* time of last change by shmctl() */
#if __WORDSIZE == 32
    unsigned long int __unused3;
#endif
    __pid_t shm_cpid;                   /* pid of creator */
    __pid_t shm_lpid;                   /* pid of last shmop */
    shmatt_t shm_nattch;                /* number of current attaches */
    unsigned long int __unused4;
    unsigned long int __unused5;
  };

/* Data structure used to pass permission information to IPC operations.  */
struct ipc_perm
  {
    __key_t __key;                      /* Key.  */
    __uid_t uid;                        /* Owner's user ID.  */
    __gid_t gid;                        /* Owner's group ID.  */
    __uid_t cuid;                       /* Creator's user ID.  */
    __gid_t cgid;                       /* Creator's group ID.  */
    unsigned short int mode;            /* Read/write permission.  */
    unsigned short int __pad1;
    unsigned short int __seq;           /* Sequence number.  */
    unsigned short int __pad2;
    unsigned long int __unused1;
    unsigned long int __unused2;
  };