4 * Copyright (C) 1998-1999, Stephen Tweedie and Bill Hawes
6 * Manage the dynamic fd arrays in the process files_struct.
9 #include <linux/syscalls.h>
10 #include <linux/export.h>
13 #include <linux/mmzone.h>
14 #include <linux/time.h>
15 #include <linux/sched.h>
16 #include <linux/slab.h>
17 #include <linux/vmalloc.h>
18 #include <linux/file.h>
19 #include <linux/fdtable.h>
20 #include <linux/bitops.h>
21 #include <linux/interrupt.h>
22 #include <linux/spinlock.h>
23 #include <linux/rcupdate.h>
24 #include <linux/workqueue.h>
26 int sysctl_nr_open __read_mostly
= 1024*1024;
27 int sysctl_nr_open_min
= BITS_PER_LONG
;
28 /* our max() is unusable in constant expressions ;-/ */
29 #define __const_max(x, y) ((x) < (y) ? (x) : (y))
30 int sysctl_nr_open_max
= __const_max(INT_MAX
, ~(size_t)0/sizeof(void *)) &
33 static void *alloc_fdmem(size_t size
)
36 * Very large allocations can stress page reclaim, so fall back to
37 * vmalloc() if the allocation size will be considered "large" by the VM.
39 if (size
<= (PAGE_SIZE
<< PAGE_ALLOC_COSTLY_ORDER
)) {
40 void *data
= kmalloc(size
, GFP_KERNEL
|__GFP_NOWARN
|__GFP_NORETRY
);
47 static void __free_fdtable(struct fdtable
*fdt
)
50 kvfree(fdt
->open_fds
);
54 static void free_fdtable_rcu(struct rcu_head
*rcu
)
56 __free_fdtable(container_of(rcu
, struct fdtable
, rcu
));
59 #define BITBIT_NR(nr) BITS_TO_LONGS(BITS_TO_LONGS(nr))
60 #define BITBIT_SIZE(nr) (BITBIT_NR(nr) * sizeof(long))
63 * Expand the fdset in the files_struct. Called with the files spinlock
66 static void copy_fdtable(struct fdtable
*nfdt
, struct fdtable
*ofdt
)
68 unsigned int cpy
, set
;
70 BUG_ON(nfdt
->max_fds
< ofdt
->max_fds
);
72 cpy
= ofdt
->max_fds
* sizeof(struct file
*);
73 set
= (nfdt
->max_fds
- ofdt
->max_fds
) * sizeof(struct file
*);
74 memcpy(nfdt
->fd
, ofdt
->fd
, cpy
);
75 memset((char *)(nfdt
->fd
) + cpy
, 0, set
);
77 cpy
= ofdt
->max_fds
/ BITS_PER_BYTE
;
78 set
= (nfdt
->max_fds
- ofdt
->max_fds
) / BITS_PER_BYTE
;
79 memcpy(nfdt
->open_fds
, ofdt
->open_fds
, cpy
);
80 memset((char *)(nfdt
->open_fds
) + cpy
, 0, set
);
81 memcpy(nfdt
->close_on_exec
, ofdt
->close_on_exec
, cpy
);
82 memset((char *)(nfdt
->close_on_exec
) + cpy
, 0, set
);
84 cpy
= BITBIT_SIZE(ofdt
->max_fds
);
85 set
= BITBIT_SIZE(nfdt
->max_fds
) - cpy
;
86 memcpy(nfdt
->full_fds_bits
, ofdt
->full_fds_bits
, cpy
);
87 memset(cpy
+(char *)nfdt
->full_fds_bits
, 0, set
);
90 static struct fdtable
* alloc_fdtable(unsigned int nr
)
96 * Figure out how many fds we actually want to support in this fdtable.
97 * Allocation steps are keyed to the size of the fdarray, since it
98 * grows far faster than any of the other dynamic data. We try to fit
99 * the fdarray into comfortable page-tuned chunks: starting at 1024B
100 * and growing in powers of two from there on.
102 nr
/= (1024 / sizeof(struct file
*));
103 nr
= roundup_pow_of_two(nr
+ 1);
104 nr
*= (1024 / sizeof(struct file
*));
106 * Note that this can drive nr *below* what we had passed if sysctl_nr_open
107 * had been set lower between the check in expand_files() and here. Deal
108 * with that in caller, it's cheaper that way.
110 * We make sure that nr remains a multiple of BITS_PER_LONG - otherwise
111 * bitmaps handling below becomes unpleasant, to put it mildly...
113 if (unlikely(nr
> sysctl_nr_open
))
114 nr
= ((sysctl_nr_open
- 1) | (BITS_PER_LONG
- 1)) + 1;
116 fdt
= kmalloc(sizeof(struct fdtable
), GFP_KERNEL
);
120 data
= alloc_fdmem(nr
* sizeof(struct file
*));
125 data
= alloc_fdmem(max_t(size_t,
126 2 * nr
/ BITS_PER_BYTE
+ BITBIT_SIZE(nr
), L1_CACHE_BYTES
));
129 fdt
->open_fds
= data
;
130 data
+= nr
/ BITS_PER_BYTE
;
131 fdt
->close_on_exec
= data
;
132 data
+= nr
/ BITS_PER_BYTE
;
133 fdt
->full_fds_bits
= data
;
146 * Expand the file descriptor table.
147 * This function will allocate a new fdtable and both fd array and fdset, of
149 * Return <0 error code on error; 1 on successful completion.
150 * The files->file_lock should be held on entry, and will be held on exit.
152 static int expand_fdtable(struct files_struct
*files
, int nr
)
153 __releases(files
->file_lock
)
154 __acquires(files
->file_lock
)
156 struct fdtable
*new_fdt
, *cur_fdt
;
158 spin_unlock(&files
->file_lock
);
159 new_fdt
= alloc_fdtable(nr
);
161 /* make sure all __fd_install() have seen resize_in_progress
162 * or have finished their rcu_read_lock_sched() section.
164 if (atomic_read(&files
->count
) > 1)
167 spin_lock(&files
->file_lock
);
171 * extremely unlikely race - sysctl_nr_open decreased between the check in
172 * caller and alloc_fdtable(). Cheaper to catch it here...
174 if (unlikely(new_fdt
->max_fds
<= nr
)) {
175 __free_fdtable(new_fdt
);
178 cur_fdt
= files_fdtable(files
);
179 BUG_ON(nr
< cur_fdt
->max_fds
);
180 copy_fdtable(new_fdt
, cur_fdt
);
181 rcu_assign_pointer(files
->fdt
, new_fdt
);
182 if (cur_fdt
!= &files
->fdtab
)
183 call_rcu(&cur_fdt
->rcu
, free_fdtable_rcu
);
184 /* coupled with smp_rmb() in __fd_install() */
191 * This function will expand the file structures, if the requested size exceeds
192 * the current capacity and there is room for expansion.
193 * Return <0 error code on error; 0 when nothing done; 1 when files were
194 * expanded and execution may have blocked.
195 * The files->file_lock should be held on entry, and will be held on exit.
197 static int expand_files(struct files_struct
*files
, int nr
)
198 __releases(files
->file_lock
)
199 __acquires(files
->file_lock
)
205 fdt
= files_fdtable(files
);
207 /* Do we need to expand? */
208 if (nr
< fdt
->max_fds
)
212 if (nr
>= sysctl_nr_open
)
215 if (unlikely(files
->resize_in_progress
)) {
216 spin_unlock(&files
->file_lock
);
218 wait_event(files
->resize_wait
, !files
->resize_in_progress
);
219 spin_lock(&files
->file_lock
);
223 /* All good, so we try */
224 files
->resize_in_progress
= true;
225 expanded
= expand_fdtable(files
, nr
);
226 files
->resize_in_progress
= false;
228 wake_up_all(&files
->resize_wait
);
232 static inline void __set_close_on_exec(int fd
, struct fdtable
*fdt
)
234 __set_bit(fd
, fdt
->close_on_exec
);
237 static inline void __clear_close_on_exec(int fd
, struct fdtable
*fdt
)
239 __clear_bit(fd
, fdt
->close_on_exec
);
242 static inline void __set_open_fd(unsigned int fd
, struct fdtable
*fdt
)
244 __set_bit(fd
, fdt
->open_fds
);
246 if (!~fdt
->open_fds
[fd
])
247 __set_bit(fd
, fdt
->full_fds_bits
);
250 static inline void __clear_open_fd(unsigned int fd
, struct fdtable
*fdt
)
252 __clear_bit(fd
, fdt
->open_fds
);
253 __clear_bit(fd
/ BITS_PER_LONG
, fdt
->full_fds_bits
);
256 static int count_open_files(struct fdtable
*fdt
)
258 int size
= fdt
->max_fds
;
261 /* Find the last open fd */
262 for (i
= size
/ BITS_PER_LONG
; i
> 0; ) {
263 if (fdt
->open_fds
[--i
])
266 i
= (i
+ 1) * BITS_PER_LONG
;
271 * Allocate a new files structure and copy contents from the
272 * passed in files structure.
273 * errorp will be valid only when the returned files_struct is NULL.
275 struct files_struct
*dup_fd(struct files_struct
*oldf
, int *errorp
)
277 struct files_struct
*newf
;
278 struct file
**old_fds
, **new_fds
;
279 int open_files
, size
, i
;
280 struct fdtable
*old_fdt
, *new_fdt
;
283 newf
= kmem_cache_alloc(files_cachep
, GFP_KERNEL
);
287 atomic_set(&newf
->count
, 1);
289 spin_lock_init(&newf
->file_lock
);
290 newf
->resize_in_progress
= false;
291 init_waitqueue_head(&newf
->resize_wait
);
293 new_fdt
= &newf
->fdtab
;
294 new_fdt
->max_fds
= NR_OPEN_DEFAULT
;
295 new_fdt
->close_on_exec
= newf
->close_on_exec_init
;
296 new_fdt
->open_fds
= newf
->open_fds_init
;
297 new_fdt
->full_fds_bits
= newf
->full_fds_bits_init
;
298 new_fdt
->fd
= &newf
->fd_array
[0];
300 spin_lock(&oldf
->file_lock
);
301 old_fdt
= files_fdtable(oldf
);
302 open_files
= count_open_files(old_fdt
);
305 * Check whether we need to allocate a larger fd array and fd set.
307 while (unlikely(open_files
> new_fdt
->max_fds
)) {
308 spin_unlock(&oldf
->file_lock
);
310 if (new_fdt
!= &newf
->fdtab
)
311 __free_fdtable(new_fdt
);
313 new_fdt
= alloc_fdtable(open_files
- 1);
319 /* beyond sysctl_nr_open; nothing to do */
320 if (unlikely(new_fdt
->max_fds
< open_files
)) {
321 __free_fdtable(new_fdt
);
327 * Reacquire the oldf lock and a pointer to its fd table
328 * who knows it may have a new bigger fd table. We need
329 * the latest pointer.
331 spin_lock(&oldf
->file_lock
);
332 old_fdt
= files_fdtable(oldf
);
333 open_files
= count_open_files(old_fdt
);
336 old_fds
= old_fdt
->fd
;
337 new_fds
= new_fdt
->fd
;
339 memcpy(new_fdt
->open_fds
, old_fdt
->open_fds
, open_files
/ 8);
340 memcpy(new_fdt
->close_on_exec
, old_fdt
->close_on_exec
, open_files
/ 8);
341 memcpy(new_fdt
->full_fds_bits
, old_fdt
->full_fds_bits
, BITBIT_SIZE(open_files
));
343 for (i
= open_files
; i
!= 0; i
--) {
344 struct file
*f
= *old_fds
++;
349 * The fd may be claimed in the fd bitmap but not yet
350 * instantiated in the files array if a sibling thread
351 * is partway through open(). So make sure that this
352 * fd is available to the new process.
354 __clear_open_fd(open_files
- i
, new_fdt
);
356 rcu_assign_pointer(*new_fds
++, f
);
358 spin_unlock(&oldf
->file_lock
);
360 /* compute the remainder to be cleared */
361 size
= (new_fdt
->max_fds
- open_files
) * sizeof(struct file
*);
363 /* This is long word aligned thus could use a optimized version */
364 memset(new_fds
, 0, size
);
366 if (new_fdt
->max_fds
> open_files
) {
367 int left
= (new_fdt
->max_fds
- open_files
) / 8;
368 int start
= open_files
/ BITS_PER_LONG
;
370 memset(&new_fdt
->open_fds
[start
], 0, left
);
371 memset(&new_fdt
->close_on_exec
[start
], 0, left
);
374 rcu_assign_pointer(newf
->fdt
, new_fdt
);
379 kmem_cache_free(files_cachep
, newf
);
384 static struct fdtable
*close_files(struct files_struct
* files
)
387 * It is safe to dereference the fd table without RCU or
388 * ->file_lock because this is the last reference to the
391 struct fdtable
*fdt
= rcu_dereference_raw(files
->fdt
);
396 i
= j
* BITS_PER_LONG
;
397 if (i
>= fdt
->max_fds
)
399 set
= fdt
->open_fds
[j
++];
402 struct file
* file
= xchg(&fdt
->fd
[i
], NULL
);
404 filp_close(file
, files
);
405 cond_resched_rcu_qs();
416 struct files_struct
*get_files_struct(struct task_struct
*task
)
418 struct files_struct
*files
;
423 atomic_inc(&files
->count
);
429 void put_files_struct(struct files_struct
*files
)
431 if (atomic_dec_and_test(&files
->count
)) {
432 struct fdtable
*fdt
= close_files(files
);
434 /* free the arrays if they are not embedded */
435 if (fdt
!= &files
->fdtab
)
437 kmem_cache_free(files_cachep
, files
);
441 void reset_files_struct(struct files_struct
*files
)
443 struct task_struct
*tsk
= current
;
444 struct files_struct
*old
;
450 put_files_struct(old
);
453 void exit_files(struct task_struct
*tsk
)
455 struct files_struct
* files
= tsk
->files
;
461 put_files_struct(files
);
465 struct files_struct init_files
= {
466 .count
= ATOMIC_INIT(1),
467 .fdt
= &init_files
.fdtab
,
469 .max_fds
= NR_OPEN_DEFAULT
,
470 .fd
= &init_files
.fd_array
[0],
471 .close_on_exec
= init_files
.close_on_exec_init
,
472 .open_fds
= init_files
.open_fds_init
,
473 .full_fds_bits
= init_files
.full_fds_bits_init
,
475 .file_lock
= __SPIN_LOCK_UNLOCKED(init_files
.file_lock
),
478 static unsigned long find_next_fd(struct fdtable
*fdt
, unsigned long start
)
480 unsigned long maxfd
= fdt
->max_fds
;
481 unsigned long maxbit
= maxfd
/ BITS_PER_LONG
;
482 unsigned long bitbit
= start
/ BITS_PER_LONG
;
484 bitbit
= find_next_zero_bit(fdt
->full_fds_bits
, maxbit
, bitbit
) * BITS_PER_LONG
;
489 return find_next_zero_bit(fdt
->open_fds
, maxfd
, start
);
493 * allocate a file descriptor, mark it busy.
495 int __alloc_fd(struct files_struct
*files
,
496 unsigned start
, unsigned end
, unsigned flags
)
502 spin_lock(&files
->file_lock
);
504 fdt
= files_fdtable(files
);
506 if (fd
< files
->next_fd
)
509 if (fd
< fdt
->max_fds
)
510 fd
= find_next_fd(fdt
, fd
);
513 * N.B. For clone tasks sharing a files structure, this test
514 * will limit the total number of files that can be opened.
520 error
= expand_files(files
, fd
);
525 * If we needed to expand the fs array we
526 * might have blocked - try again.
531 if (start
<= files
->next_fd
)
532 files
->next_fd
= fd
+ 1;
534 __set_open_fd(fd
, fdt
);
535 if (flags
& O_CLOEXEC
)
536 __set_close_on_exec(fd
, fdt
);
538 __clear_close_on_exec(fd
, fdt
);
542 if (rcu_access_pointer(fdt
->fd
[fd
]) != NULL
) {
543 printk(KERN_WARNING
"alloc_fd: slot %d not NULL!\n", fd
);
544 rcu_assign_pointer(fdt
->fd
[fd
], NULL
);
549 spin_unlock(&files
->file_lock
);
553 static int alloc_fd(unsigned start
, unsigned flags
)
555 return __alloc_fd(current
->files
, start
, rlimit(RLIMIT_NOFILE
), flags
);
558 int get_unused_fd_flags(unsigned flags
)
560 return __alloc_fd(current
->files
, 0, rlimit(RLIMIT_NOFILE
), flags
);
562 EXPORT_SYMBOL(get_unused_fd_flags
);
564 static void __put_unused_fd(struct files_struct
*files
, unsigned int fd
)
566 struct fdtable
*fdt
= files_fdtable(files
);
567 __clear_open_fd(fd
, fdt
);
568 if (fd
< files
->next_fd
)
572 void put_unused_fd(unsigned int fd
)
574 struct files_struct
*files
= current
->files
;
575 spin_lock(&files
->file_lock
);
576 __put_unused_fd(files
, fd
);
577 spin_unlock(&files
->file_lock
);
580 EXPORT_SYMBOL(put_unused_fd
);
583 * Install a file pointer in the fd array.
585 * The VFS is full of places where we drop the files lock between
586 * setting the open_fds bitmap and installing the file in the file
587 * array. At any such point, we are vulnerable to a dup2() race
588 * installing a file in the array before us. We need to detect this and
589 * fput() the struct file we are about to overwrite in this case.
591 * It should never happen - if we allow dup2() do it, _really_ bad things
594 * NOTE: __fd_install() variant is really, really low-level; don't
595 * use it unless you are forced to by truly lousy API shoved down
596 * your throat. 'files' *MUST* be either current->files or obtained
597 * by get_files_struct(current) done by whoever had given it to you,
598 * or really bad things will happen. Normally you want to use
599 * fd_install() instead.
602 void __fd_install(struct files_struct
*files
, unsigned int fd
,
608 rcu_read_lock_sched();
610 while (unlikely(files
->resize_in_progress
)) {
611 rcu_read_unlock_sched();
612 wait_event(files
->resize_wait
, !files
->resize_in_progress
);
613 rcu_read_lock_sched();
615 /* coupled with smp_wmb() in expand_fdtable() */
617 fdt
= rcu_dereference_sched(files
->fdt
);
618 BUG_ON(fdt
->fd
[fd
] != NULL
);
619 rcu_assign_pointer(fdt
->fd
[fd
], file
);
620 rcu_read_unlock_sched();
623 void fd_install(unsigned int fd
, struct file
*file
)
625 __fd_install(current
->files
, fd
, file
);
628 EXPORT_SYMBOL(fd_install
);
631 * The same warnings as for __alloc_fd()/__fd_install() apply here...
633 int __close_fd(struct files_struct
*files
, unsigned fd
)
638 spin_lock(&files
->file_lock
);
639 fdt
= files_fdtable(files
);
640 if (fd
>= fdt
->max_fds
)
645 rcu_assign_pointer(fdt
->fd
[fd
], NULL
);
646 __clear_close_on_exec(fd
, fdt
);
647 __put_unused_fd(files
, fd
);
648 spin_unlock(&files
->file_lock
);
649 return filp_close(file
, files
);
652 spin_unlock(&files
->file_lock
);
656 void do_close_on_exec(struct files_struct
*files
)
661 /* exec unshares first */
662 spin_lock(&files
->file_lock
);
665 unsigned fd
= i
* BITS_PER_LONG
;
666 fdt
= files_fdtable(files
);
667 if (fd
>= fdt
->max_fds
)
669 set
= fdt
->close_on_exec
[i
];
672 fdt
->close_on_exec
[i
] = 0;
673 for ( ; set
; fd
++, set
>>= 1) {
680 rcu_assign_pointer(fdt
->fd
[fd
], NULL
);
681 __put_unused_fd(files
, fd
);
682 spin_unlock(&files
->file_lock
);
683 filp_close(file
, files
);
685 spin_lock(&files
->file_lock
);
689 spin_unlock(&files
->file_lock
);
692 static struct file
*__fget(unsigned int fd
, fmode_t mask
)
694 struct files_struct
*files
= current
->files
;
699 file
= fcheck_files(files
, fd
);
701 /* File object ref couldn't be taken.
702 * dup2() atomicity guarantee is the reason
703 * we loop to catch the new file (or NULL pointer)
705 if (file
->f_mode
& mask
)
707 else if (!get_file_rcu(file
))
715 struct file
*fget(unsigned int fd
)
717 return __fget(fd
, FMODE_PATH
);
721 struct file
*fget_raw(unsigned int fd
)
723 return __fget(fd
, 0);
725 EXPORT_SYMBOL(fget_raw
);
728 * Lightweight file lookup - no refcnt increment if fd table isn't shared.
730 * You can use this instead of fget if you satisfy all of the following
732 * 1) You must call fput_light before exiting the syscall and returning control
733 * to userspace (i.e. you cannot remember the returned struct file * after
734 * returning to userspace).
735 * 2) You must not call filp_close on the returned struct file * in between
736 * calls to fget_light and fput_light.
737 * 3) You must not clone the current task in between the calls to fget_light
740 * The fput_needed flag returned by fget_light should be passed to the
741 * corresponding fput_light.
743 static unsigned long __fget_light(unsigned int fd
, fmode_t mask
)
745 struct files_struct
*files
= current
->files
;
748 if (atomic_read(&files
->count
) == 1) {
749 file
= __fcheck_files(files
, fd
);
750 if (!file
|| unlikely(file
->f_mode
& mask
))
752 return (unsigned long)file
;
754 file
= __fget(fd
, mask
);
757 return FDPUT_FPUT
| (unsigned long)file
;
760 unsigned long __fdget(unsigned int fd
)
762 return __fget_light(fd
, FMODE_PATH
);
764 EXPORT_SYMBOL(__fdget
);
766 unsigned long __fdget_raw(unsigned int fd
)
768 return __fget_light(fd
, 0);
771 unsigned long __fdget_pos(unsigned int fd
)
773 unsigned long v
= __fdget(fd
);
774 struct file
*file
= (struct file
*)(v
& ~3);
776 if (file
&& (file
->f_mode
& FMODE_ATOMIC_POS
)) {
777 if (file_count(file
) > 1) {
778 v
|= FDPUT_POS_UNLOCK
;
779 mutex_lock(&file
->f_pos_lock
);
786 * We only lock f_pos if we have threads or if the file might be
787 * shared with another process. In both cases we'll have an elevated
788 * file count (done either by fdget() or by fork()).
791 void set_close_on_exec(unsigned int fd
, int flag
)
793 struct files_struct
*files
= current
->files
;
795 spin_lock(&files
->file_lock
);
796 fdt
= files_fdtable(files
);
798 __set_close_on_exec(fd
, fdt
);
800 __clear_close_on_exec(fd
, fdt
);
801 spin_unlock(&files
->file_lock
);
804 bool get_close_on_exec(unsigned int fd
)
806 struct files_struct
*files
= current
->files
;
810 fdt
= files_fdtable(files
);
811 res
= close_on_exec(fd
, fdt
);
816 static int do_dup2(struct files_struct
*files
,
817 struct file
*file
, unsigned fd
, unsigned flags
)
818 __releases(&files
->file_lock
)
824 * We need to detect attempts to do dup2() over allocated but still
825 * not finished descriptor. NB: OpenBSD avoids that at the price of
826 * extra work in their equivalent of fget() - they insert struct
827 * file immediately after grabbing descriptor, mark it larval if
828 * more work (e.g. actual opening) is needed and make sure that
829 * fget() treats larval files as absent. Potentially interesting,
830 * but while extra work in fget() is trivial, locking implications
831 * and amount of surgery on open()-related paths in VFS are not.
832 * FreeBSD fails with -EBADF in the same situation, NetBSD "solution"
833 * deadlocks in rather amusing ways, AFAICS. All of that is out of
834 * scope of POSIX or SUS, since neither considers shared descriptor
835 * tables and this condition does not arise without those.
837 fdt
= files_fdtable(files
);
838 tofree
= fdt
->fd
[fd
];
839 if (!tofree
&& fd_is_open(fd
, fdt
))
842 rcu_assign_pointer(fdt
->fd
[fd
], file
);
843 __set_open_fd(fd
, fdt
);
844 if (flags
& O_CLOEXEC
)
845 __set_close_on_exec(fd
, fdt
);
847 __clear_close_on_exec(fd
, fdt
);
848 spin_unlock(&files
->file_lock
);
851 filp_close(tofree
, files
);
856 spin_unlock(&files
->file_lock
);
860 int replace_fd(unsigned fd
, struct file
*file
, unsigned flags
)
863 struct files_struct
*files
= current
->files
;
866 return __close_fd(files
, fd
);
868 if (fd
>= rlimit(RLIMIT_NOFILE
))
871 spin_lock(&files
->file_lock
);
872 err
= expand_files(files
, fd
);
873 if (unlikely(err
< 0))
875 return do_dup2(files
, file
, fd
, flags
);
878 spin_unlock(&files
->file_lock
);
882 SYSCALL_DEFINE3(dup3
, unsigned int, oldfd
, unsigned int, newfd
, int, flags
)
886 struct files_struct
*files
= current
->files
;
888 if ((flags
& ~O_CLOEXEC
) != 0)
891 if (unlikely(oldfd
== newfd
))
894 if (newfd
>= rlimit(RLIMIT_NOFILE
))
897 spin_lock(&files
->file_lock
);
898 err
= expand_files(files
, newfd
);
899 file
= fcheck(oldfd
);
902 if (unlikely(err
< 0)) {
907 return do_dup2(files
, file
, newfd
, flags
);
912 spin_unlock(&files
->file_lock
);
916 SYSCALL_DEFINE2(dup2
, unsigned int, oldfd
, unsigned int, newfd
)
918 if (unlikely(newfd
== oldfd
)) { /* corner case */
919 struct files_struct
*files
= current
->files
;
923 if (!fcheck_files(files
, oldfd
))
928 return sys_dup3(oldfd
, newfd
, 0);
931 SYSCALL_DEFINE1(dup
, unsigned int, fildes
)
934 struct file
*file
= fget_raw(fildes
);
937 ret
= get_unused_fd_flags(0);
939 fd_install(ret
, file
);
946 int f_dupfd(unsigned int from
, struct file
*file
, unsigned flags
)
949 if (from
>= rlimit(RLIMIT_NOFILE
))
951 err
= alloc_fd(from
, flags
);
954 fd_install(err
, file
);
959 int iterate_fd(struct files_struct
*files
, unsigned n
,
960 int (*f
)(const void *, struct file
*, unsigned),
967 spin_lock(&files
->file_lock
);
968 for (fdt
= files_fdtable(files
); n
< fdt
->max_fds
; n
++) {
970 file
= rcu_dereference_check_fdtable(files
, fdt
->fd
[n
]);
977 spin_unlock(&files
->file_lock
);
980 EXPORT_SYMBOL(iterate_fd
);