/*
 * linux/ipc/util.c
 * Copyright (C) 1992 Krishna Balasubramanian
 *
 * Sep 1997 - Call suser() last after "normal" permission checks so we
 *            get BSD style process accounting right.
 *            Occurs in several places in the IPC code.
 *            Chris Evans, <chris@ferret.lmh.ox.ac.uk>
 * Nov 1999 - ipc helper functions, unified SMP locking
 *            Manfred Spraul <manfreds@colorfullife.com>
 */

#include <linux/config.h>
#include <linux/mm.h>
#include <linux/shm.h>
#include <linux/init.h>
#include <linux/msg.h>
#include <linux/smp_lock.h>
#include <linux/vmalloc.h>
#include <linux/slab.h>
#include <linux/highuid.h>

#if defined(CONFIG_SYSVIPC)

#include "util.h"

/**
 *      ipc_init        -       initialise IPC subsystem
 *
 *      The various system5 IPC resources (semaphores, messages and shared
 *      memory are initialised
 */
 
void __init ipc_init (void)
{
        sem_init();
        msg_init();
        shm_init();
        return;
}

/**
 *      ipc_init_ids            -       initialise IPC identifiers
 *      @ids: Identifier set
 *      @size: Number of identifiers
 *
 *      Given a size for the ipc identifier range (limited below IPCMNI)
 *      set up the sequence range to use then allocate and initialise the
 *      array itself. 
 */
 
void __init ipc_init_ids(struct ipc_ids* ids, int size)
{
        int i;
        sema_init(&ids->sem,1);

        if(size > IPCMNI)
                size = IPCMNI;
        ids->size = size;
        ids->in_use = 0;
        ids->max_id = -1;
        ids->seq = 0;
        {
                int seq_limit = INT_MAX/SEQ_MULTIPLIER;
                if(seq_limit > USHRT_MAX)
                        ids->seq_max = USHRT_MAX;
                 else
                        ids->seq_max = seq_limit;
        }

        ids->entries = ipc_alloc(sizeof(struct ipc_id)*size);

        if(ids->entries == NULL) {
                printk(KERN_ERR "ipc_init_ids() failed, ipc service disabled.\n");
                ids->size = 0;
        }
        ids->ary = SPIN_LOCK_UNLOCKED;
        for(i=0;i<ids->size;i++)
                ids->entries[i].p = NULL;
}

/**
 *      ipc_findkey     -       find a key in an ipc identifier set     
 *      @ids: Identifier set
 *      @key: The key to find
 *
 *      Returns the identifier if found or -1 if not.
 */
 
int ipc_findkey(struct ipc_ids* ids, key_t key)
{
        int id;
        struct kern_ipc_perm* p;

        for (id = 0; id <= ids->max_id; id++) {
                p = ids->entries[id].p;
                if(p==NULL)
                        continue;
                if (key == p->key)
                        return id;
        }
        return -1;
}

static int grow_ary(struct ipc_ids* ids, int newsize)
{
        struct ipc_id* new;
        struct ipc_id* old;
        int i;

        if(newsize > IPCMNI)
                newsize = IPCMNI;
        if(newsize <= ids->size)
                return newsize;

        new = ipc_alloc(sizeof(struct ipc_id)*newsize);
        if(new == NULL)
                return ids->size;
        memcpy(new, ids->entries, sizeof(struct ipc_id)*ids->size);
        for(i=ids->size;i<newsize;i++) {
                new[i].p = NULL;
        }
        spin_lock(&ids->ary);

        old = ids->entries;
        ids->entries = new;
        i = ids->size;
        ids->size = newsize;
        spin_unlock(&ids->ary);
        ipc_free(old, sizeof(struct ipc_id)*i);
        return ids->size;
}

/**
 *      ipc_addid       -       add an IPC identifier
 *      @ids: IPC identifier set
 *      @new: new IPC permission set
 *      @size: new size limit for the id array
 *
 *      Add an entry 'new' to the IPC arrays. The permissions object is
 *      initialised and the first free entry is set up and the id assigned
 *      is returned. The list is returned in a locked state on success.
 *      On failure the list is not locked and -1 is returned.
 */
 
int ipc_addid(struct ipc_ids* ids, struct kern_ipc_perm* new, int size)
{
        int id;

        size = grow_ary(ids,size);
        for (id = 0; id < size; id++) {
                if(ids->entries[id].p == NULL)
                        goto found;
        }
        return -1;
found:
        ids->in_use++;
        if (id > ids->max_id)
                ids->max_id = id;

        new->cuid = new->uid = current->euid;
        new->gid = new->cgid = current->egid;

        new->seq = ids->seq++;
        if(ids->seq > ids->seq_max)
                ids->seq = 0;

        spin_lock(&ids->ary);
        ids->entries[id].p = new;
        return id;
}

/**
 *      ipc_rmid        -       remove an IPC identifier
 *      @ids: identifier set
 *      @id: Identifier to remove
 *
 *      The identifier must be valid, and in use. The kernel will panic if
 *      fed an invalid identifier. The entry is removed and internal
 *      variables recomputed. The object associated with the identifier
 *      is returned.
 */
 
struct kern_ipc_perm* ipc_rmid(struct ipc_ids* ids, int id)
{
        struct kern_ipc_perm* p;
        int lid = id % SEQ_MULTIPLIER;
        if(lid >= ids->size)
                BUG();
        p = ids->entries[lid].p;
        ids->entries[lid].p = NULL;
        if(p==NULL)
                BUG();
        ids->in_use--;

        if (lid == ids->max_id) {
                do {
                        lid--;
                        if(lid == -1)
                                break;
                } while (ids->entries[lid].p == NULL);
                ids->max_id = lid;
        }
        return p;
}

/**
 *      ipc_alloc       -       allocate ipc space
 *      @size: size desired
 *
 *      Allocate memory from the appropriate pools and return a pointer to it.
 *      NULL is returned if the allocation fails
 */
 
void* ipc_alloc(int size)
{
        void* out;
        if(size > PAGE_SIZE)
                out = vmalloc(size);
        else
                out = kmalloc(size, GFP_KERNEL);
        return out;
}

/**
 *      ipc_free        -       free ipc space
 *      @ptr: pointer returned by ipc_alloc
 *      @size: size of block
 *
 *      Free a block created with ipc_alloc. The caller must know the size
 *      used in the allocation call.
 */
 
void ipc_free(void* ptr, int size)
{
        if(size > PAGE_SIZE)
                vfree(ptr);
        else
                kfree(ptr);
}

/**
 *      ipcperms        -       check IPC permissions
 *      @ipcp: IPC permission set
 *      @flag: desired permission set.
 *
 *      Check user, group, other permissions for access
 *      to ipc resources. return 0 if allowed
 */
 
int ipcperms (struct kern_ipc_perm *ipcp, short flag)
{       /* flag will most probably be 0 or S_...UGO from <linux/stat.h> */
        int requested_mode, granted_mode;

        requested_mode = (flag >> 6) | (flag >> 3) | flag;
        granted_mode = ipcp->mode;
        if (current->euid == ipcp->cuid || current->euid == ipcp->uid)
                granted_mode >>= 6;
        else if (in_group_p(ipcp->cgid) || in_group_p(ipcp->gid))
                granted_mode >>= 3;
        /* is there some bit set in requested_mode but not in granted_mode? */
        if ((requested_mode & ~granted_mode & 0007) && 
            !capable(CAP_IPC_OWNER))
                return -1;

        return 0;
}

/*
 * Functions to convert between the kern_ipc_perm structure and the
 * old/new ipc_perm structures
 */

/**
 *      kernel_to_ipc64_perm    -       convert kernel ipc permissions to user
 *      @in: kernel permissions
 *      @out: new style IPC permissions
 *
 *      Turn the kernel object 'in' into a set of permissions descriptions
 *      for returning to userspace (out).
 */
 

void kernel_to_ipc64_perm (struct kern_ipc_perm *in, struct ipc64_perm *out)
{
        out->key        = in->key;
        out->uid        = in->uid;
        out->gid        = in->gid;
        out->cuid       = in->cuid;
        out->cgid       = in->cgid;
        out->mode       = in->mode;
        out->seq        = in->seq;
}

/**
 *      ipc64_perm_to_ipc_perm  -       convert old ipc permissions to new
 *      @in: new style IPC permissions
 *      @out: old style IPC permissions
 *
 *      Turn the new style permissions object in into a compatibility
 *      object and store it into the 'out' pointer.
 */
 
void ipc64_perm_to_ipc_perm (struct ipc64_perm *in, struct ipc_perm *out)
{
        out->key        = in->key;
        out->uid        = NEW_TO_OLD_UID(in->uid);
        out->gid        = NEW_TO_OLD_GID(in->gid);
        out->cuid       = NEW_TO_OLD_UID(in->cuid);
        out->cgid       = NEW_TO_OLD_GID(in->cgid);
        out->mode       = in->mode;
        out->seq        = in->seq;
}

#if !defined(__ia64__) && !defined(__hppa__)

/**
 *      ipc_parse_version       -       IPC call version
 *      @cmd: pointer to command
 *
 *      Return IPC_64 for new style IPC and IPC_OLD for old style IPC. 
 *      The cmd value is turned from an encoding command and version into
 *      just the command code.
 */
 
int ipc_parse_version (int *cmd)
{
#ifdef __x86_64__
        if (!(current->thread.flags & THREAD_IA32))
                return IPC_64; 
#endif
        if (*cmd & IPC_64) {
                *cmd ^= IPC_64;
                return IPC_64;
        } else {
                return IPC_OLD;
        }
}

#endif /* __ia64__ */

#else
/*
 * Dummy functions when SYSV IPC isn't configured
 */

void sem_exit (void)
{
    return;
}

asmlinkage long sys_semget (key_t key, int nsems, int semflg)
{
        return -ENOSYS;
}

asmlinkage long sys_semop (int semid, struct sembuf *sops, unsigned nsops)
{
        return -ENOSYS;
}

asmlinkage long sys_semtimedop(int semid, struct sembuf *sops, unsigned nsops,
                               const struct timespec *timeout)
{
        return -ENOSYS;
}

asmlinkage long sys_semctl (int semid, int semnum, int cmd, union semun arg)
{
        return -ENOSYS;
}

asmlinkage long sys_msgget (key_t key, int msgflg)
{
        return -ENOSYS;
}

asmlinkage long sys_msgsnd (int msqid, struct msgbuf *msgp, size_t msgsz, int msgflg)
{
        return -ENOSYS;
}

asmlinkage long sys_msgrcv (int msqid, struct msgbuf *msgp, size_t msgsz, long msgtyp,
                       int msgflg)
{
        return -ENOSYS;
}

asmlinkage long sys_msgctl (int msqid, int cmd, struct msqid_ds *buf)
{
        return -ENOSYS;
}

asmlinkage long sys_shmget (key_t key, size_t size, int shmflag)
{
        return -ENOSYS;
}

asmlinkage long sys_shmat (int shmid, char *shmaddr, int shmflg, ulong *addr)
{
        return -ENOSYS;
}

asmlinkage long sys_shmdt (char *shmaddr)
{
        return -ENOSYS;
}

asmlinkage long sys_shmctl (int shmid, int cmd, struct shmid_ds *buf)
{
        return -ENOSYS;
}

#endif /* CONFIG_SYSVIPC */