/*
   * linux/ipc/util.h
   * Copyright (C) 1999 Christoph Rohland
   *

   * ipc helper functions (c) 1999 Manfred Spraul <manfred@colorfullife.com>

   * namespaces support.      2006 OpenVZ, SWsoft Inc.
   *                               Pavel Emelianov <xemul@openvz.org>

   */
  
  #ifndef _IPC_UTIL_H
  #define _IPC_UTIL_H

  #include <linux/unistd.h>

  #include <linux/err.h>

  #define SEQ_MULTIPLIER	(IPCMNI)

  void sem_init(void);
  void msg_init(void);
  void shm_init(void);

  struct ipc_namespace;

  #ifdef CONFIG_POSIX_MQUEUE

  extern void mq_clear_sbinfo(struct ipc_namespace *ns);
  extern void mq_put_mnt(struct ipc_namespace *ns);

  #else

  static inline void mq_clear_sbinfo(struct ipc_namespace *ns) { }
  static inline void mq_put_mnt(struct ipc_namespace *ns) { }

  #endif
  
  #ifdef CONFIG_SYSVIPC

  void sem_init_ns(struct ipc_namespace *ns);
  void msg_init_ns(struct ipc_namespace *ns);
  void shm_init_ns(struct ipc_namespace *ns);

  
  void sem_exit_ns(struct ipc_namespace *ns);
  void msg_exit_ns(struct ipc_namespace *ns);
  void shm_exit_ns(struct ipc_namespace *ns);

  #else
  static inline void sem_init_ns(struct ipc_namespace *ns) { }
  static inline void msg_init_ns(struct ipc_namespace *ns) { }
  static inline void shm_init_ns(struct ipc_namespace *ns) { }
  
  static inline void sem_exit_ns(struct ipc_namespace *ns) { }
  static inline void msg_exit_ns(struct ipc_namespace *ns) { }
  static inline void shm_exit_ns(struct ipc_namespace *ns) { }
  #endif

  struct ipc_rcu {
  	struct rcu_head rcu;
  	atomic_t refcount;
  } ____cacheline_aligned_in_smp;
  
  #define ipc_rcu_to_struct(p)  ((void *)(p+1))

  /*
   * Structure that holds the parameters needed by the ipc operations
   * (see after)
   */
  struct ipc_params {
  	key_t key;
  	int flg;
  	union {
  		size_t size;	/* for shared memories */
  		int nsems;	/* for semaphores */
  	} u;			/* holds the getnew() specific param */
  };
  
  /*
   * Structure that holds some ipc operations. This structure is used to unify
   * the calls to sys_msgget(), sys_semget(), sys_shmget()
   *      . routine to call to create a new ipc object. Can be one of newque,
   *        newary, newseg

   *      . routine to call to check permissions for a new ipc object.

   *        Can be one of security_msg_associate, security_sem_associate,
   *        security_shm_associate
   *      . routine to call for an extra check if needed
   */
  struct ipc_ops {

  	int (*getnew)(struct ipc_namespace *, struct ipc_params *);
  	int (*associate)(struct kern_ipc_perm *, int);
  	int (*more_checks)(struct kern_ipc_perm *, struct ipc_params *);

  };

  struct seq_file;

  struct ipc_ids;

  void ipc_init_ids(struct ipc_ids *);

  #ifdef CONFIG_PROC_FS
  void __init ipc_init_proc_interface(const char *path, const char *header,

  		int ids, int (*show)(struct seq_file *, void *));

  #else
  #define ipc_init_proc_interface(path, header, ids, show) do {} while (0)
  #endif

  #define IPC_SEM_IDS	0
  #define IPC_MSG_IDS	1
  #define IPC_SHM_IDS	2

  #define ipcid_to_idx(id) ((id) % SEQ_MULTIPLIER)

  #define ipcid_to_seqx(id) ((id) / SEQ_MULTIPLIER)

  #define IPCID_SEQ_MAX min_t(int, INT_MAX/SEQ_MULTIPLIER, USHRT_MAX)

  /* must be called with ids->rwsem acquired for writing */

  int ipc_addid(struct ipc_ids *, struct kern_ipc_perm *, int);

  /* must be called with ids->rwsem acquired for reading */

  int ipc_get_maxid(struct ipc_ids *);

  
  /* must be called with both locks acquired. */

  void ipc_rmid(struct ipc_ids *, struct kern_ipc_perm *);

  /* must be called with ipcp locked */

  int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flg);

  
  /* for rare, potentially huge allocations.
   * both function can sleep
   */

  void *ipc_alloc(int size);

  void ipc_free(void *ptr);

  
  /*
   * For allocation that need to be freed by RCU.
   * Objects are reference counted, they start with reference count 1.
   * getref increases the refcount, the putref call that reduces the recount
   * to 0 schedules the rcu destruction. Caller must guarantee locking.
   */

  void *ipc_rcu_alloc(int size);

  int ipc_rcu_getref(void *ptr);

  void ipc_rcu_putref(void *ptr, void (*func)(struct rcu_head *head));
  void ipc_rcu_free(struct rcu_head *head);

  struct kern_ipc_perm *ipc_lock(struct ipc_ids *, int);

  struct kern_ipc_perm *ipc_obtain_object_idr(struct ipc_ids *ids, int id);

  
  void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out);
  void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out);

  int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out);

  struct kern_ipc_perm *ipcctl_pre_down_nolock(struct ipc_namespace *ns,
  					     struct ipc_ids *ids, int id, int cmd,
  					     struct ipc64_perm *perm, int extra_perm);

  #ifndef CONFIG_ARCH_WANT_IPC_PARSE_VERSION

  /* On IA-64, we always use the "64-bit version" of the IPC structures.  */

  # define ipc_parse_version(cmd)	IPC_64
  #else

  int ipc_parse_version(int *cmd);

  #endif
  
  extern void free_msg(struct msg_msg *msg);

  extern struct msg_msg *load_msg(const void __user *src, size_t len);

  extern struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst);

  extern int store_msg(void __user *dest, struct msg_msg *msg, size_t len);

  extern void recompute_msgmni(struct ipc_namespace *);

  static inline int ipc_buildid(int id, int seq)

  {
  	return SEQ_MULTIPLIER * seq + id;
  }

  static inline int ipc_checkid(struct kern_ipc_perm *ipcp, int uid)

  {

  	return uid / SEQ_MULTIPLIER != ipcp->seq;

  }

  static inline void ipc_lock_object(struct kern_ipc_perm *perm)

  {

  	spin_lock(&perm->lock);
  }

  static inline void ipc_unlock_object(struct kern_ipc_perm *perm)

  {
  	spin_unlock(&perm->lock);

  }

  static inline void ipc_assert_locked_object(struct kern_ipc_perm *perm)

  {

  	assert_spin_locked(&perm->lock);
  }

  static inline void ipc_unlock(struct kern_ipc_perm *perm)
  {

  	ipc_unlock_object(perm);

  	rcu_read_unlock();
  }

  /*
   * ipc_valid_object() - helper to sort out IPC_RMID races for codepaths
   * where the respective ipc_ids.rwsem is not being held down.
   * Checks whether the ipc object is still around or if it's gone already, as
   * ipc_rmid() may have already freed the ID while the ipc lock was spinning.
   * Needs to be called with kern_ipc_perm.lock held -- exception made for one
   * checkpoint case at sys_semtimedop() as noted in code commentary.
   */
  static inline bool ipc_valid_object(struct kern_ipc_perm *perm)
  {

  	return !perm->deleted;

  }

  struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id);

  int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,

  			const struct ipc_ops *ops, struct ipc_params *params);

  void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
  		void (*free)(struct ipc_namespace *, struct kern_ipc_perm *));

  #endif