/*

* 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;

}