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/*

 *  linux/fs/file.c

 *

 *  Copyright (C) 1998-1999, Stephen Tweedie and Bill Hawes

 *

 *  Manage the dynamic fd arrays in the process files_struct.

 */

#include <linux/fs.h>

#include <linux/mm.h>

#include <linux/sched.h>

#include <linux/slab.h>

#include <linux/vmalloc.h>

#include <asm/bitops.h>

/*

 * Allocate an fd array, using kmalloc or vmalloc.

 * Note: the array isn't cleared at allocation time.

 */

struct file ** alloc_fd_array(int num)

{

        struct file **new_fds;

        int size = num * sizeof(struct file *);

        if (size <= PAGE_SIZE)

                new_fds = (struct file **) kmalloc(size, GFP_KERNEL);

        else

                new_fds = (struct file **) vmalloc(size);

        return new_fds;

}

void free_fd_array(struct file **array, int num)

{

        int size = num * sizeof(struct file *);

        if (!array) {

                printk(KERN_ERR "%s array = 0 (num = %d)\n",

                                __FUNCTION__, num);

                return;

        }

        if (num <= NR_OPEN_DEFAULT) /* Don't free the embedded fd array! */

                return;

        else if (size <= PAGE_SIZE)

                kfree(array);

        else

                vfree(array);

}

/*

 * Expand the fd array in the files_struct.  Called with the files

 * spinlock held for write.

 */

int expand_fd_array(struct files_struct *files, int nr)

{

        struct file **new_fds;

        int error, nfds;

        error = -EMFILE;

        if (files->max_fds >= NR_OPEN || nr >= NR_OPEN)

                goto out;

        nfds = files->max_fds;

        write_unlock(&files->file_lock);

        /*

         * Expand to the max in easy steps, and keep expanding it until

         * we have enough for the requested fd array size.

         */

        do {

#if NR_OPEN_DEFAULT < 256

                if (nfds < 256)

                        nfds = 256;

                else

#endif

                if (nfds < (PAGE_SIZE / sizeof(struct file *)))

                        nfds = PAGE_SIZE / sizeof(struct file *);

                else {

                        nfds = nfds * 2;

                        if (nfds > NR_OPEN)

                                nfds = NR_OPEN;

                }

        } while (nfds <= nr);

        error = -ENOMEM;

        new_fds = alloc_fd_array(nfds);

        write_lock(&files->file_lock);

        if (!new_fds)

                goto out;

        /* Copy the existing array and install the new pointer */

        if (nfds > files->max_fds) {

                struct file **old_fds;

                int i;

                old_fds = xchg(&files->fd, new_fds);

                i = xchg(&files->max_fds, nfds);

                /* Don't copy/clear the array if we are creating a new

                   fd array for fork() */

                if (i) {

                        memcpy(new_fds, old_fds, i * sizeof(struct file *));

                        /* clear the remainder of the array */

                        memset(&new_fds[i], 0,

                               (nfds-i) * sizeof(struct file *));

                        write_unlock(&files->file_lock);

                        free_fd_array(old_fds, i);

                        write_lock(&files->file_lock);

                }

        } else {

                /* Somebody expanded the array while we slept ... */

                write_unlock(&files->file_lock);

                free_fd_array(new_fds, nfds);

                write_lock(&files->file_lock);

        }

        error = 0;

out:

        return error;

}

/*

 * Allocate an fdset array, using kmalloc or vmalloc.

 * Note: the array isn't cleared at allocation time.

 */

fd_set * alloc_fdset(int num)

{

        fd_set *new_fdset;

        int size = num / 8;

        if (size <= PAGE_SIZE)

                new_fdset = (fd_set *) kmalloc(size, GFP_KERNEL);

        else

                new_fdset = (fd_set *) vmalloc(size);

        return new_fdset;

}

void free_fdset(fd_set *array, int num)

{

        int size = num / 8;

        if (!array) {

                printk(KERN_ERR "%s array = 0 (num = %d)\n",

                                __FUNCTION__, num);

                return;

        }

        if (num <= __FD_SETSIZE) /* Don't free an embedded fdset */

                return;

        else if (size <= PAGE_SIZE)

                kfree(array);

        else

                vfree(array);

}

/*

 * Expand the fdset in the files_struct.  Called with the files spinlock

 * held for write.

 */

int expand_fdset(struct files_struct *files, int nr)

{

        fd_set *new_openset = 0, *new_execset = 0;

        int error, nfds = 0;

        error = -EMFILE;

        if (files->max_fdset >= NR_OPEN || nr >= NR_OPEN)

                goto out;

        nfds = files->max_fdset;

        write_unlock(&files->file_lock);

        /* Expand to the max in easy steps */

        do {

                if (nfds < (PAGE_SIZE * 8))

                        nfds = PAGE_SIZE * 8;

                else {

                        nfds = nfds * 2;

                        if (nfds > NR_OPEN)

                                nfds = NR_OPEN;

                }

        } while (nfds <= nr);

        error = -ENOMEM;

        new_openset = alloc_fdset(nfds);

        new_execset = alloc_fdset(nfds);

        write_lock(&files->file_lock);

        if (!new_openset || !new_execset)

                goto out;

        error = 0;

        /* Copy the existing tables and install the new pointers */

        if (nfds > files->max_fdset) {

                int i = files->max_fdset / (sizeof(unsigned long) * 8);

                int count = (nfds - files->max_fdset) / 8;

                /*

                 * Don't copy the entire array if the current fdset is

                 * not yet initialised.

                 */

                if (i) {

                        memcpy (new_openset, files->open_fds, files->max_fdset/8);

                        memcpy (new_execset, files->close_on_exec, files->max_fdset/8);

                        memset (&new_openset->fds_bits[i], 0, count);

                        memset (&new_execset->fds_bits[i], 0, count);

                }

                nfds = xchg(&files->max_fdset, nfds);

                new_openset = xchg(&files->open_fds, new_openset);

                new_execset = xchg(&files->close_on_exec, new_execset);

                write_unlock(&files->file_lock);

                free_fdset (new_openset, nfds);

                free_fdset (new_execset, nfds);

                write_lock(&files->file_lock);

                return 0;

        }

        /* Somebody expanded the array while we slept ... */

out:

        write_unlock(&files->file_lock);

        if (new_openset)

                free_fdset(new_openset, nfds);

        if (new_execset)

                free_fdset(new_execset, nfds);

        write_lock(&files->file_lock);

        return error;

}