root/include/uapi/linux/shm.h

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INCLUDED FROM


#ifndef _UAPI_LINUX_SHM_H_
#define _UAPI_LINUX_SHM_H_

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

/*
 * SHMMNI, SHMMAX and SHMALL are default upper limits which can be
 * modified by sysctl. The SHMMAX and SHMALL values have been chosen to
 * be as large possible without facilitating scenarios where userspace
 * causes overflows when adjusting the limits via operations of the form
 * "retrieve current limit; add X; update limit". It is therefore not
 * advised to make SHMMAX and SHMALL any larger. These limits are
 * suitable for both 32 and 64-bit systems.
 */
#define SHMMIN 1                         /* min shared seg size (bytes) */
#define SHMMNI 4096                      /* max num of segs system wide */
#define SHMMAX (ULONG_MAX - (1UL << 24)) /* max shared seg size (bytes) */
#define SHMALL (ULONG_MAX - (1UL << 24)) /* max shm system wide (pages) */
#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;
        __kernel_ulong_t shm_tot;       /* total allocated shm */
        __kernel_ulong_t shm_rss;       /* total resident shm */
        __kernel_ulong_t shm_swp;       /* total swapped shm */
        __kernel_ulong_t swap_attempts;
        __kernel_ulong_t swap_successes;
};


#endif /* _UAPI_LINUX_SHM_H_ */

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