src/include/sys/shm.h

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#ifndef _SYS_SHM_H
#define _SYS_SHM_H

#include <sys/types.h>
#include <sys/ipc.h>

#include <unistd.h>

typedef unsigned long int shmatt_t;

#define SHMLBA  getpagesize()
#define SHMMNI  4096
#define SHMSEG  32              /* max shared segs per process */

struct shmid_ds
{
        struct ipc_perm shm_perm;       /* Ownership and permissions */
        size_t  shm_segsz;                      /* Size of segment (bytes) */
        time_t  shm_atime;                      /* Last attach time */
        time_t  shm_dtime;                      /* Last detach time */
        time_t  shm_ctime;                      /* Last change time */
        pid_t   shm_cpid;                       /* PID of creator */
        pid_t   shm_lpid;                       /* PID of last shmat()/shmdt() */
        shmatt_t        shm_nattch;             /* No. of current attaches */
};

/* Permission flag for shmget. */
#define SHM_R   0400
#define SHM_W   0200

#define SHM_RDONLY 010000               /* attach read-only else read-write */
#define SHM_RND    020000               /* round attach address to SHMLBA */

/* shm_mode upper byte flags */
#define SHM_DEST 01000                  /* segment will be destroyed on last detach */
#define SHM_LOCKED 02000                /* segment will not be swapped */

/* ipcs ctl commands */
#define SHM_STAT        13
#define SHM_INFO        14

struct  shminfo
{
        unsigned long int shmmax;
        unsigned long int shmmin;
        unsigned long int shmmni;
        unsigned long int shmseg;
        unsigned long int shmall;
};

struct shm_info
{
        int used_ids;
        unsigned long int shm_tot;  /* total allocated shm */
        unsigned long int shm_rss;  /* total resident shm */
        unsigned long int shm_swp;  /* total swapped shm */
        unsigned long int swap_attempts;
        unsigned long int swap_successes;
};

/* The following System V style IPC functions implement a shared memory
 * facility.  The definition is found in XPG4.2.
 */

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

/* Get shared memory segment. */
_PROTOTYPE( int shmget, (key_t __key, size_t __size, int __shmflg));

/* Attach shared memory segment. */
_PROTOTYPE( void *shmat, (int __shmid, const void *__shmaddr, int __shmflg));

/* Deattach shared memory segment. */
_PROTOTYPE( int shmdt, (const void *__shmaddr));

#endif /* _SYS_SHM_H */

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