shm.h

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#ifndef _UAPI_LINUX_SHM_H_
#define _UAPI_LINUX_SHM_H_

#include <linux/ipc.h>
#include <linux/errno.h>
#ifndef __KERNEL__
#include <unistd.h>
#endif

/*
 * SHMMAX, SHMMNI and SHMALL are upper limits are defaults which can
 * be increased by sysctl
 */

#define SHMMAX 0x2000000         /* max shared seg size (bytes) */
#define SHMMIN 1             /* min shared seg size (bytes) */
#define SHMMNI 4096          /* max num of segs system wide */
#ifndef __KERNEL__
#define SHMALL (SHMMAX/getpagesize()*(SHMMNI/16))
#endif
#define SHMSEG SHMMNI            /* max shared segs per process */


/* Obsolete, used only for backwards compatibility and libc5 compiles */
struct shmid_ds {
    struct ipc_perm     shm_perm;   /* operation perms */
    int         shm_segsz;  /* size of segment (bytes) */
    __kernel_time_t     shm_atime;  /* last attach time */
    __kernel_time_t     shm_dtime;  /* last detach time */
    __kernel_time_t     shm_ctime;  /* last change time */
    __kernel_ipc_pid_t  shm_cpid;   /* pid of creator */
    __kernel_ipc_pid_t  shm_lpid;   /* pid of last operator */
    unsigned short      shm_nattch; /* no. of current attaches */
    unsigned short      shm_unused; /* compatibility */
    void            *shm_unused2;   /* ditto - used by DIPC */
    void            *shm_unused3;   /* unused */
};

/* Include the definition of shmid64_ds and shminfo64 */
#include <asm/shmbuf.h>

/* permission flag for shmget */
#define SHM_R       0400    /* or S_IRUGO from <linux/stat.h> */
#define SHM_W       0200    /* or S_IWUGO from <linux/stat.h> */

/* mode for attach */
#define SHM_RDONLY  010000  /* read-only access */
#define SHM_RND     020000  /* round attach address to SHMLBA boundary */
#define SHM_REMAP   040000  /* take-over region on attach */
#define SHM_EXEC    0100000 /* execution access */

/* super user shmctl commands */
#define SHM_LOCK    11
#define SHM_UNLOCK  12

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

/* Obsolete, used only for backwards compatibility */
struct  shminfo {
    int shmmax;
    int shmmin;
    int shmmni;
    int shmseg;
    int shmall;
};

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


#endif /* _UAPI_LINUX_SHM_H_ */