1 // SPDX-License-Identifier: GPL-2.0
5 * Copyright (C) 1998-1999, Stephen Tweedie and Bill Hawes
7 * Manage the dynamic fd arrays in the process files_struct.
10 #include <linux/syscalls.h>
11 #include <linux/export.h>
14 #include <linux/mmzone.h>
15 #include <linux/time.h>
16 #include <linux/sched/signal.h>
17 #include <linux/slab.h>
18 #include <linux/vmalloc.h>
19 #include <linux/file.h>
20 #include <linux/fdtable.h>
21 #include <linux/bitops.h>
22 #include <linux/interrupt.h>
23 #include <linux/spinlock.h>
24 #include <linux/rcupdate.h>
25 #include <linux/workqueue.h>
27 unsigned int sysctl_nr_open __read_mostly
= 1024*1024;
28 unsigned int sysctl_nr_open_min
= BITS_PER_LONG
;
29 /* our min() is unusable in constant expressions ;-/ */
30 #define __const_min(x, y) ((x) < (y) ? (x) : (y))
31 unsigned int sysctl_nr_open_max
=
32 __const_min(INT_MAX
, ~(size_t)0/sizeof(void *)) & -BITS_PER_LONG
;
34 static void __free_fdtable(struct fdtable
*fdt
)
37 kvfree(fdt
->open_fds
);
41 static void free_fdtable_rcu(struct rcu_head
*rcu
)
43 __free_fdtable(container_of(rcu
, struct fdtable
, rcu
));
46 #define BITBIT_NR(nr) BITS_TO_LONGS(BITS_TO_LONGS(nr))
47 #define BITBIT_SIZE(nr) (BITBIT_NR(nr) * sizeof(long))
50 * Copy 'count' fd bits from the old table to the new table and clear the extra
51 * space if any. This does not copy the file pointers. Called with the files
52 * spinlock held for write.
54 static void copy_fd_bitmaps(struct fdtable
*nfdt
, struct fdtable
*ofdt
,
57 unsigned int cpy
, set
;
59 cpy
= count
/ BITS_PER_BYTE
;
60 set
= (nfdt
->max_fds
- count
) / BITS_PER_BYTE
;
61 memcpy(nfdt
->open_fds
, ofdt
->open_fds
, cpy
);
62 memset((char *)nfdt
->open_fds
+ cpy
, 0, set
);
63 memcpy(nfdt
->close_on_exec
, ofdt
->close_on_exec
, cpy
);
64 memset((char *)nfdt
->close_on_exec
+ cpy
, 0, set
);
66 cpy
= BITBIT_SIZE(count
);
67 set
= BITBIT_SIZE(nfdt
->max_fds
) - cpy
;
68 memcpy(nfdt
->full_fds_bits
, ofdt
->full_fds_bits
, cpy
);
69 memset((char *)nfdt
->full_fds_bits
+ cpy
, 0, set
);
73 * Copy all file descriptors from the old table to the new, expanded table and
74 * clear the extra space. Called with the files spinlock held for write.
76 static void copy_fdtable(struct fdtable
*nfdt
, struct fdtable
*ofdt
)
78 unsigned int cpy
, set
;
80 BUG_ON(nfdt
->max_fds
< ofdt
->max_fds
);
82 cpy
= ofdt
->max_fds
* sizeof(struct file
*);
83 set
= (nfdt
->max_fds
- ofdt
->max_fds
) * sizeof(struct file
*);
84 memcpy(nfdt
->fd
, ofdt
->fd
, cpy
);
85 memset((char *)nfdt
->fd
+ cpy
, 0, set
);
87 copy_fd_bitmaps(nfdt
, ofdt
, ofdt
->max_fds
);
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_ACCOUNT
);
120 data
= kvmalloc_array(nr
, sizeof(struct file
*), GFP_KERNEL_ACCOUNT
);
125 data
= kvmalloc(max_t(size_t,
126 2 * nr
/ BITS_PER_BYTE
+ BITBIT_SIZE(nr
), L1_CACHE_BYTES
),
130 fdt
->open_fds
= data
;
131 data
+= nr
/ BITS_PER_BYTE
;
132 fdt
->close_on_exec
= data
;
133 data
+= nr
/ BITS_PER_BYTE
;
134 fdt
->full_fds_bits
= data
;
147 * Expand the file descriptor table.
148 * This function will allocate a new fdtable and both fd array and fdset, of
150 * Return <0 error code on error; 1 on successful completion.
151 * The files->file_lock should be held on entry, and will be held on exit.
153 static int expand_fdtable(struct files_struct
*files
, unsigned int nr
)
154 __releases(files
->file_lock
)
155 __acquires(files
->file_lock
)
157 struct fdtable
*new_fdt
, *cur_fdt
;
159 spin_unlock(&files
->file_lock
);
160 new_fdt
= alloc_fdtable(nr
);
162 /* make sure all __fd_install() have seen resize_in_progress
163 * or have finished their rcu_read_lock_sched() section.
165 if (atomic_read(&files
->count
) > 1)
168 spin_lock(&files
->file_lock
);
172 * extremely unlikely race - sysctl_nr_open decreased between the check in
173 * caller and alloc_fdtable(). Cheaper to catch it here...
175 if (unlikely(new_fdt
->max_fds
<= nr
)) {
176 __free_fdtable(new_fdt
);
179 cur_fdt
= files_fdtable(files
);
180 BUG_ON(nr
< cur_fdt
->max_fds
);
181 copy_fdtable(new_fdt
, cur_fdt
);
182 rcu_assign_pointer(files
->fdt
, new_fdt
);
183 if (cur_fdt
!= &files
->fdtab
)
184 call_rcu(&cur_fdt
->rcu
, free_fdtable_rcu
);
185 /* coupled with smp_rmb() in __fd_install() */
192 * This function will expand the file structures, if the requested size exceeds
193 * the current capacity and there is room for expansion.
194 * Return <0 error code on error; 0 when nothing done; 1 when files were
195 * expanded and execution may have blocked.
196 * The files->file_lock should be held on entry, and will be held on exit.
198 static int expand_files(struct files_struct
*files
, unsigned int nr
)
199 __releases(files
->file_lock
)
200 __acquires(files
->file_lock
)
206 fdt
= files_fdtable(files
);
208 /* Do we need to expand? */
209 if (nr
< fdt
->max_fds
)
213 if (nr
>= sysctl_nr_open
)
216 if (unlikely(files
->resize_in_progress
)) {
217 spin_unlock(&files
->file_lock
);
219 wait_event(files
->resize_wait
, !files
->resize_in_progress
);
220 spin_lock(&files
->file_lock
);
224 /* All good, so we try */
225 files
->resize_in_progress
= true;
226 expanded
= expand_fdtable(files
, nr
);
227 files
->resize_in_progress
= false;
229 wake_up_all(&files
->resize_wait
);
233 static inline void __set_close_on_exec(unsigned int fd
, struct fdtable
*fdt
)
235 __set_bit(fd
, fdt
->close_on_exec
);
238 static inline void __clear_close_on_exec(unsigned int fd
, struct fdtable
*fdt
)
240 if (test_bit(fd
, fdt
->close_on_exec
))
241 __clear_bit(fd
, fdt
->close_on_exec
);
244 static inline void __set_open_fd(unsigned int fd
, struct fdtable
*fdt
)
246 __set_bit(fd
, fdt
->open_fds
);
248 if (!~fdt
->open_fds
[fd
])
249 __set_bit(fd
, fdt
->full_fds_bits
);
252 static inline void __clear_open_fd(unsigned int fd
, struct fdtable
*fdt
)
254 __clear_bit(fd
, fdt
->open_fds
);
255 __clear_bit(fd
/ BITS_PER_LONG
, fdt
->full_fds_bits
);
258 static unsigned int count_open_files(struct fdtable
*fdt
)
260 unsigned int size
= fdt
->max_fds
;
263 /* Find the last open fd */
264 for (i
= size
/ BITS_PER_LONG
; i
> 0; ) {
265 if (fdt
->open_fds
[--i
])
268 i
= (i
+ 1) * BITS_PER_LONG
;
273 * Allocate a new files structure and copy contents from the
274 * passed in files structure.
275 * errorp will be valid only when the returned files_struct is NULL.
277 struct files_struct
*dup_fd(struct files_struct
*oldf
, int *errorp
)
279 struct files_struct
*newf
;
280 struct file
**old_fds
, **new_fds
;
281 unsigned int open_files
, i
;
282 struct fdtable
*old_fdt
, *new_fdt
;
285 newf
= kmem_cache_alloc(files_cachep
, GFP_KERNEL
);
289 atomic_set(&newf
->count
, 1);
291 spin_lock_init(&newf
->file_lock
);
292 newf
->resize_in_progress
= false;
293 init_waitqueue_head(&newf
->resize_wait
);
295 new_fdt
= &newf
->fdtab
;
296 new_fdt
->max_fds
= NR_OPEN_DEFAULT
;
297 new_fdt
->close_on_exec
= newf
->close_on_exec_init
;
298 new_fdt
->open_fds
= newf
->open_fds_init
;
299 new_fdt
->full_fds_bits
= newf
->full_fds_bits_init
;
300 new_fdt
->fd
= &newf
->fd_array
[0];
302 spin_lock(&oldf
->file_lock
);
303 old_fdt
= files_fdtable(oldf
);
304 open_files
= count_open_files(old_fdt
);
307 * Check whether we need to allocate a larger fd array and fd set.
309 while (unlikely(open_files
> new_fdt
->max_fds
)) {
310 spin_unlock(&oldf
->file_lock
);
312 if (new_fdt
!= &newf
->fdtab
)
313 __free_fdtable(new_fdt
);
315 new_fdt
= alloc_fdtable(open_files
- 1);
321 /* beyond sysctl_nr_open; nothing to do */
322 if (unlikely(new_fdt
->max_fds
< open_files
)) {
323 __free_fdtable(new_fdt
);
329 * Reacquire the oldf lock and a pointer to its fd table
330 * who knows it may have a new bigger fd table. We need
331 * the latest pointer.
333 spin_lock(&oldf
->file_lock
);
334 old_fdt
= files_fdtable(oldf
);
335 open_files
= count_open_files(old_fdt
);
338 copy_fd_bitmaps(new_fdt
, old_fdt
, open_files
);
340 old_fds
= old_fdt
->fd
;
341 new_fds
= new_fdt
->fd
;
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 /* clear the remainder */
361 memset(new_fds
, 0, (new_fdt
->max_fds
- open_files
) * sizeof(struct file
*));
363 rcu_assign_pointer(newf
->fdt
, new_fdt
);
368 kmem_cache_free(files_cachep
, newf
);
373 static struct fdtable
*close_files(struct files_struct
* files
)
376 * It is safe to dereference the fd table without RCU or
377 * ->file_lock because this is the last reference to the
380 struct fdtable
*fdt
= rcu_dereference_raw(files
->fdt
);
381 unsigned int i
, j
= 0;
385 i
= j
* BITS_PER_LONG
;
386 if (i
>= fdt
->max_fds
)
388 set
= fdt
->open_fds
[j
++];
391 struct file
* file
= xchg(&fdt
->fd
[i
], NULL
);
393 filp_close(file
, files
);
394 cond_resched_rcu_qs();
405 struct files_struct
*get_files_struct(struct task_struct
*task
)
407 struct files_struct
*files
;
412 atomic_inc(&files
->count
);
418 void put_files_struct(struct files_struct
*files
)
420 if (atomic_dec_and_test(&files
->count
)) {
421 struct fdtable
*fdt
= close_files(files
);
423 /* free the arrays if they are not embedded */
424 if (fdt
!= &files
->fdtab
)
426 kmem_cache_free(files_cachep
, files
);
430 void reset_files_struct(struct files_struct
*files
)
432 struct task_struct
*tsk
= current
;
433 struct files_struct
*old
;
439 put_files_struct(old
);
442 void exit_files(struct task_struct
*tsk
)
444 struct files_struct
* files
= tsk
->files
;
450 put_files_struct(files
);
454 struct files_struct init_files
= {
455 .count
= ATOMIC_INIT(1),
456 .fdt
= &init_files
.fdtab
,
458 .max_fds
= NR_OPEN_DEFAULT
,
459 .fd
= &init_files
.fd_array
[0],
460 .close_on_exec
= init_files
.close_on_exec_init
,
461 .open_fds
= init_files
.open_fds_init
,
462 .full_fds_bits
= init_files
.full_fds_bits_init
,
464 .file_lock
= __SPIN_LOCK_UNLOCKED(init_files
.file_lock
),
465 .resize_wait
= __WAIT_QUEUE_HEAD_INITIALIZER(init_files
.resize_wait
),
468 static unsigned int find_next_fd(struct fdtable
*fdt
, unsigned int start
)
470 unsigned int maxfd
= fdt
->max_fds
;
471 unsigned int maxbit
= maxfd
/ BITS_PER_LONG
;
472 unsigned int bitbit
= start
/ BITS_PER_LONG
;
474 bitbit
= find_next_zero_bit(fdt
->full_fds_bits
, maxbit
, bitbit
) * BITS_PER_LONG
;
479 return find_next_zero_bit(fdt
->open_fds
, maxfd
, start
);
483 * allocate a file descriptor, mark it busy.
485 int __alloc_fd(struct files_struct
*files
,
486 unsigned start
, unsigned end
, unsigned flags
)
492 spin_lock(&files
->file_lock
);
494 fdt
= files_fdtable(files
);
496 if (fd
< files
->next_fd
)
499 if (fd
< fdt
->max_fds
)
500 fd
= find_next_fd(fdt
, fd
);
503 * N.B. For clone tasks sharing a files structure, this test
504 * will limit the total number of files that can be opened.
510 error
= expand_files(files
, fd
);
515 * If we needed to expand the fs array we
516 * might have blocked - try again.
521 if (start
<= files
->next_fd
)
522 files
->next_fd
= fd
+ 1;
524 __set_open_fd(fd
, fdt
);
525 if (flags
& O_CLOEXEC
)
526 __set_close_on_exec(fd
, fdt
);
528 __clear_close_on_exec(fd
, fdt
);
532 if (rcu_access_pointer(fdt
->fd
[fd
]) != NULL
) {
533 printk(KERN_WARNING
"alloc_fd: slot %d not NULL!\n", fd
);
534 rcu_assign_pointer(fdt
->fd
[fd
], NULL
);
539 spin_unlock(&files
->file_lock
);
543 static int alloc_fd(unsigned start
, unsigned flags
)
545 return __alloc_fd(current
->files
, start
, rlimit(RLIMIT_NOFILE
), flags
);
548 int get_unused_fd_flags(unsigned flags
)
550 return __alloc_fd(current
->files
, 0, rlimit(RLIMIT_NOFILE
), flags
);
552 EXPORT_SYMBOL(get_unused_fd_flags
);
554 static void __put_unused_fd(struct files_struct
*files
, unsigned int fd
)
556 struct fdtable
*fdt
= files_fdtable(files
);
557 __clear_open_fd(fd
, fdt
);
558 if (fd
< files
->next_fd
)
562 void put_unused_fd(unsigned int fd
)
564 struct files_struct
*files
= current
->files
;
565 spin_lock(&files
->file_lock
);
566 __put_unused_fd(files
, fd
);
567 spin_unlock(&files
->file_lock
);
570 EXPORT_SYMBOL(put_unused_fd
);
573 * Install a file pointer in the fd array.
575 * The VFS is full of places where we drop the files lock between
576 * setting the open_fds bitmap and installing the file in the file
577 * array. At any such point, we are vulnerable to a dup2() race
578 * installing a file in the array before us. We need to detect this and
579 * fput() the struct file we are about to overwrite in this case.
581 * It should never happen - if we allow dup2() do it, _really_ bad things
584 * NOTE: __fd_install() variant is really, really low-level; don't
585 * use it unless you are forced to by truly lousy API shoved down
586 * your throat. 'files' *MUST* be either current->files or obtained
587 * by get_files_struct(current) done by whoever had given it to you,
588 * or really bad things will happen. Normally you want to use
589 * fd_install() instead.
592 void __fd_install(struct files_struct
*files
, unsigned int fd
,
597 rcu_read_lock_sched();
599 if (unlikely(files
->resize_in_progress
)) {
600 rcu_read_unlock_sched();
601 spin_lock(&files
->file_lock
);
602 fdt
= files_fdtable(files
);
603 BUG_ON(fdt
->fd
[fd
] != NULL
);
604 rcu_assign_pointer(fdt
->fd
[fd
], file
);
605 spin_unlock(&files
->file_lock
);
608 /* coupled with smp_wmb() in expand_fdtable() */
610 fdt
= rcu_dereference_sched(files
->fdt
);
611 BUG_ON(fdt
->fd
[fd
] != NULL
);
612 rcu_assign_pointer(fdt
->fd
[fd
], file
);
613 rcu_read_unlock_sched();
616 void fd_install(unsigned int fd
, struct file
*file
)
618 __fd_install(current
->files
, fd
, file
);
621 EXPORT_SYMBOL(fd_install
);
624 * The same warnings as for __alloc_fd()/__fd_install() apply here...
626 int __close_fd(struct files_struct
*files
, unsigned fd
)
631 spin_lock(&files
->file_lock
);
632 fdt
= files_fdtable(files
);
633 if (fd
>= fdt
->max_fds
)
638 rcu_assign_pointer(fdt
->fd
[fd
], NULL
);
639 __put_unused_fd(files
, fd
);
640 spin_unlock(&files
->file_lock
);
641 return filp_close(file
, files
);
644 spin_unlock(&files
->file_lock
);
648 void do_close_on_exec(struct files_struct
*files
)
653 /* exec unshares first */
654 spin_lock(&files
->file_lock
);
657 unsigned fd
= i
* BITS_PER_LONG
;
658 fdt
= files_fdtable(files
);
659 if (fd
>= fdt
->max_fds
)
661 set
= fdt
->close_on_exec
[i
];
664 fdt
->close_on_exec
[i
] = 0;
665 for ( ; set
; fd
++, set
>>= 1) {
672 rcu_assign_pointer(fdt
->fd
[fd
], NULL
);
673 __put_unused_fd(files
, fd
);
674 spin_unlock(&files
->file_lock
);
675 filp_close(file
, files
);
677 spin_lock(&files
->file_lock
);
681 spin_unlock(&files
->file_lock
);
684 static struct file
*__fget(unsigned int fd
, fmode_t mask
)
686 struct files_struct
*files
= current
->files
;
691 file
= fcheck_files(files
, fd
);
693 /* File object ref couldn't be taken.
694 * dup2() atomicity guarantee is the reason
695 * we loop to catch the new file (or NULL pointer)
697 if (file
->f_mode
& mask
)
699 else if (!get_file_rcu(file
))
707 struct file
*fget(unsigned int fd
)
709 return __fget(fd
, FMODE_PATH
);
713 struct file
*fget_raw(unsigned int fd
)
715 return __fget(fd
, 0);
717 EXPORT_SYMBOL(fget_raw
);
720 * Lightweight file lookup - no refcnt increment if fd table isn't shared.
722 * You can use this instead of fget if you satisfy all of the following
724 * 1) You must call fput_light before exiting the syscall and returning control
725 * to userspace (i.e. you cannot remember the returned struct file * after
726 * returning to userspace).
727 * 2) You must not call filp_close on the returned struct file * in between
728 * calls to fget_light and fput_light.
729 * 3) You must not clone the current task in between the calls to fget_light
732 * The fput_needed flag returned by fget_light should be passed to the
733 * corresponding fput_light.
735 static unsigned long __fget_light(unsigned int fd
, fmode_t mask
)
737 struct files_struct
*files
= current
->files
;
740 if (atomic_read(&files
->count
) == 1) {
741 file
= __fcheck_files(files
, fd
);
742 if (!file
|| unlikely(file
->f_mode
& mask
))
744 return (unsigned long)file
;
746 file
= __fget(fd
, mask
);
749 return FDPUT_FPUT
| (unsigned long)file
;
752 unsigned long __fdget(unsigned int fd
)
754 return __fget_light(fd
, FMODE_PATH
);
756 EXPORT_SYMBOL(__fdget
);
758 unsigned long __fdget_raw(unsigned int fd
)
760 return __fget_light(fd
, 0);
763 unsigned long __fdget_pos(unsigned int fd
)
765 unsigned long v
= __fdget(fd
);
766 struct file
*file
= (struct file
*)(v
& ~3);
768 if (file
&& (file
->f_mode
& FMODE_ATOMIC_POS
)) {
769 if (file_count(file
) > 1) {
770 v
|= FDPUT_POS_UNLOCK
;
771 mutex_lock(&file
->f_pos_lock
);
777 void __f_unlock_pos(struct file
*f
)
779 mutex_unlock(&f
->f_pos_lock
);
783 * We only lock f_pos if we have threads or if the file might be
784 * shared with another process. In both cases we'll have an elevated
785 * file count (done either by fdget() or by fork()).
788 void set_close_on_exec(unsigned int fd
, int flag
)
790 struct files_struct
*files
= current
->files
;
792 spin_lock(&files
->file_lock
);
793 fdt
= files_fdtable(files
);
795 __set_close_on_exec(fd
, fdt
);
797 __clear_close_on_exec(fd
, fdt
);
798 spin_unlock(&files
->file_lock
);
801 bool get_close_on_exec(unsigned int fd
)
803 struct files_struct
*files
= current
->files
;
807 fdt
= files_fdtable(files
);
808 res
= close_on_exec(fd
, fdt
);
813 static int do_dup2(struct files_struct
*files
,
814 struct file
*file
, unsigned fd
, unsigned flags
)
815 __releases(&files
->file_lock
)
821 * We need to detect attempts to do dup2() over allocated but still
822 * not finished descriptor. NB: OpenBSD avoids that at the price of
823 * extra work in their equivalent of fget() - they insert struct
824 * file immediately after grabbing descriptor, mark it larval if
825 * more work (e.g. actual opening) is needed and make sure that
826 * fget() treats larval files as absent. Potentially interesting,
827 * but while extra work in fget() is trivial, locking implications
828 * and amount of surgery on open()-related paths in VFS are not.
829 * FreeBSD fails with -EBADF in the same situation, NetBSD "solution"
830 * deadlocks in rather amusing ways, AFAICS. All of that is out of
831 * scope of POSIX or SUS, since neither considers shared descriptor
832 * tables and this condition does not arise without those.
834 fdt
= files_fdtable(files
);
835 tofree
= fdt
->fd
[fd
];
836 if (!tofree
&& fd_is_open(fd
, fdt
))
839 rcu_assign_pointer(fdt
->fd
[fd
], file
);
840 __set_open_fd(fd
, fdt
);
841 if (flags
& O_CLOEXEC
)
842 __set_close_on_exec(fd
, fdt
);
844 __clear_close_on_exec(fd
, fdt
);
845 spin_unlock(&files
->file_lock
);
848 filp_close(tofree
, files
);
853 spin_unlock(&files
->file_lock
);
857 int replace_fd(unsigned fd
, struct file
*file
, unsigned flags
)
860 struct files_struct
*files
= current
->files
;
863 return __close_fd(files
, fd
);
865 if (fd
>= rlimit(RLIMIT_NOFILE
))
868 spin_lock(&files
->file_lock
);
869 err
= expand_files(files
, fd
);
870 if (unlikely(err
< 0))
872 return do_dup2(files
, file
, fd
, flags
);
875 spin_unlock(&files
->file_lock
);
879 SYSCALL_DEFINE3(dup3
, unsigned int, oldfd
, unsigned int, newfd
, int, flags
)
883 struct files_struct
*files
= current
->files
;
885 if ((flags
& ~O_CLOEXEC
) != 0)
888 if (unlikely(oldfd
== newfd
))
891 if (newfd
>= rlimit(RLIMIT_NOFILE
))
894 spin_lock(&files
->file_lock
);
895 err
= expand_files(files
, newfd
);
896 file
= fcheck(oldfd
);
899 if (unlikely(err
< 0)) {
904 return do_dup2(files
, file
, newfd
, flags
);
909 spin_unlock(&files
->file_lock
);
913 SYSCALL_DEFINE2(dup2
, unsigned int, oldfd
, unsigned int, newfd
)
915 if (unlikely(newfd
== oldfd
)) { /* corner case */
916 struct files_struct
*files
= current
->files
;
920 if (!fcheck_files(files
, oldfd
))
925 return sys_dup3(oldfd
, newfd
, 0);
928 SYSCALL_DEFINE1(dup
, unsigned int, fildes
)
931 struct file
*file
= fget_raw(fildes
);
934 ret
= get_unused_fd_flags(0);
936 fd_install(ret
, file
);
943 int f_dupfd(unsigned int from
, struct file
*file
, unsigned flags
)
946 if (from
>= rlimit(RLIMIT_NOFILE
))
948 err
= alloc_fd(from
, flags
);
951 fd_install(err
, file
);
956 int iterate_fd(struct files_struct
*files
, unsigned n
,
957 int (*f
)(const void *, struct file
*, unsigned),
964 spin_lock(&files
->file_lock
);
965 for (fdt
= files_fdtable(files
); n
< fdt
->max_fds
; n
++) {
967 file
= rcu_dereference_check_fdtable(files
, fdt
->fd
[n
]);
974 spin_unlock(&files
->file_lock
);
977 EXPORT_SYMBOL(iterate_fd
);