2 * linux/fs/read_write.c
4 * Copyright (C) 1991, 1992 Linus Torvalds
7 #include <linux/slab.h>
8 #include <linux/stat.h>
9 #include <linux/fcntl.h>
10 #include <linux/file.h>
11 #include <linux/uio.h>
12 #include <linux/smp_lock.h>
13 #include <linux/fsnotify.h>
14 #include <linux/security.h>
15 #include <linux/module.h>
16 #include <linux/syscalls.h>
17 #include <linux/pagemap.h>
18 #include <linux/splice.h>
19 #include "read_write.h"
21 #include <asm/uaccess.h>
22 #include <asm/unistd.h>
24 const struct file_operations generic_ro_fops
= {
25 .llseek
= generic_file_llseek
,
27 .aio_read
= generic_file_aio_read
,
28 .mmap
= generic_file_readonly_mmap
,
29 .splice_read
= generic_file_splice_read
,
32 EXPORT_SYMBOL(generic_ro_fops
);
35 generic_file_llseek_unlocked(struct file
*file
, loff_t offset
, int origin
)
38 struct inode
*inode
= file
->f_mapping
->host
;
42 offset
+= inode
->i_size
;
45 offset
+= file
->f_pos
;
48 if (offset
>=0 && offset
<=inode
->i_sb
->s_maxbytes
) {
49 /* Special lock needed here? */
50 if (offset
!= file
->f_pos
) {
58 EXPORT_SYMBOL(generic_file_llseek_unlocked
);
60 loff_t
generic_file_llseek(struct file
*file
, loff_t offset
, int origin
)
63 mutex_lock(&file
->f_dentry
->d_inode
->i_mutex
);
64 n
= generic_file_llseek_unlocked(file
, offset
, origin
);
65 mutex_unlock(&file
->f_dentry
->d_inode
->i_mutex
);
68 EXPORT_SYMBOL(generic_file_llseek
);
70 loff_t
no_llseek(struct file
*file
, loff_t offset
, int origin
)
74 EXPORT_SYMBOL(no_llseek
);
76 loff_t
default_llseek(struct file
*file
, loff_t offset
, int origin
)
83 offset
+= i_size_read(file
->f_path
.dentry
->d_inode
);
86 offset
+= file
->f_pos
;
90 if (offset
!= file
->f_pos
) {
99 EXPORT_SYMBOL(default_llseek
);
101 loff_t
vfs_llseek(struct file
*file
, loff_t offset
, int origin
)
103 loff_t (*fn
)(struct file
*, loff_t
, int);
106 if (file
->f_mode
& FMODE_LSEEK
) {
108 if (file
->f_op
&& file
->f_op
->llseek
)
109 fn
= file
->f_op
->llseek
;
111 return fn(file
, offset
, origin
);
113 EXPORT_SYMBOL(vfs_llseek
);
115 asmlinkage off_t
sys_lseek(unsigned int fd
, off_t offset
, unsigned int origin
)
122 file
= fget_light(fd
, &fput_needed
);
127 if (origin
<= SEEK_MAX
) {
128 loff_t res
= vfs_llseek(file
, offset
, origin
);
130 if (res
!= (loff_t
)retval
)
131 retval
= -EOVERFLOW
; /* LFS: should only happen on 32 bit platforms */
133 fput_light(file
, fput_needed
);
138 #ifdef __ARCH_WANT_SYS_LLSEEK
139 asmlinkage
long sys_llseek(unsigned int fd
, unsigned long offset_high
,
140 unsigned long offset_low
, loff_t __user
* result
,
149 file
= fget_light(fd
, &fput_needed
);
154 if (origin
> SEEK_MAX
)
157 offset
= vfs_llseek(file
, ((loff_t
) offset_high
<< 32) | offset_low
,
160 retval
= (int)offset
;
163 if (!copy_to_user(result
, &offset
, sizeof(offset
)))
167 fput_light(file
, fput_needed
);
174 * rw_verify_area doesn't like huge counts. We limit
175 * them to something that fits in "int" so that others
176 * won't have to do range checks all the time.
178 #define MAX_RW_COUNT (INT_MAX & PAGE_CACHE_MASK)
180 int rw_verify_area(int read_write
, struct file
*file
, loff_t
*ppos
, size_t count
)
184 int retval
= -EINVAL
;
186 inode
= file
->f_path
.dentry
->d_inode
;
187 if (unlikely((ssize_t
) count
< 0))
190 if (unlikely((pos
< 0) || (loff_t
) (pos
+ count
) < 0))
193 if (unlikely(inode
->i_flock
&& mandatory_lock(inode
))) {
194 retval
= locks_mandatory_area(
195 read_write
== READ
? FLOCK_VERIFY_READ
: FLOCK_VERIFY_WRITE
,
196 inode
, file
, pos
, count
);
200 retval
= security_file_permission(file
,
201 read_write
== READ
? MAY_READ
: MAY_WRITE
);
204 return count
> MAX_RW_COUNT
? MAX_RW_COUNT
: count
;
207 static void wait_on_retry_sync_kiocb(struct kiocb
*iocb
)
209 set_current_state(TASK_UNINTERRUPTIBLE
);
210 if (!kiocbIsKicked(iocb
))
213 kiocbClearKicked(iocb
);
214 __set_current_state(TASK_RUNNING
);
217 ssize_t
do_sync_read(struct file
*filp
, char __user
*buf
, size_t len
, loff_t
*ppos
)
219 struct iovec iov
= { .iov_base
= buf
, .iov_len
= len
};
223 init_sync_kiocb(&kiocb
, filp
);
224 kiocb
.ki_pos
= *ppos
;
228 ret
= filp
->f_op
->aio_read(&kiocb
, &iov
, 1, kiocb
.ki_pos
);
229 if (ret
!= -EIOCBRETRY
)
231 wait_on_retry_sync_kiocb(&kiocb
);
234 if (-EIOCBQUEUED
== ret
)
235 ret
= wait_on_sync_kiocb(&kiocb
);
236 *ppos
= kiocb
.ki_pos
;
240 EXPORT_SYMBOL(do_sync_read
);
242 ssize_t
vfs_read(struct file
*file
, char __user
*buf
, size_t count
, loff_t
*pos
)
246 if (!(file
->f_mode
& FMODE_READ
))
248 if (!file
->f_op
|| (!file
->f_op
->read
&& !file
->f_op
->aio_read
))
250 if (unlikely(!access_ok(VERIFY_WRITE
, buf
, count
)))
253 ret
= rw_verify_area(READ
, file
, pos
, count
);
256 if (file
->f_op
->read
)
257 ret
= file
->f_op
->read(file
, buf
, count
, pos
);
259 ret
= do_sync_read(file
, buf
, count
, pos
);
261 fsnotify_access(file
->f_path
.dentry
);
262 add_rchar(current
, ret
);
270 EXPORT_SYMBOL(vfs_read
);
272 ssize_t
do_sync_write(struct file
*filp
, const char __user
*buf
, size_t len
, loff_t
*ppos
)
274 struct iovec iov
= { .iov_base
= (void __user
*)buf
, .iov_len
= len
};
278 init_sync_kiocb(&kiocb
, filp
);
279 kiocb
.ki_pos
= *ppos
;
283 ret
= filp
->f_op
->aio_write(&kiocb
, &iov
, 1, kiocb
.ki_pos
);
284 if (ret
!= -EIOCBRETRY
)
286 wait_on_retry_sync_kiocb(&kiocb
);
289 if (-EIOCBQUEUED
== ret
)
290 ret
= wait_on_sync_kiocb(&kiocb
);
291 *ppos
= kiocb
.ki_pos
;
295 EXPORT_SYMBOL(do_sync_write
);
297 ssize_t
vfs_write(struct file
*file
, const char __user
*buf
, size_t count
, loff_t
*pos
)
301 if (!(file
->f_mode
& FMODE_WRITE
))
303 if (!file
->f_op
|| (!file
->f_op
->write
&& !file
->f_op
->aio_write
))
305 if (unlikely(!access_ok(VERIFY_READ
, buf
, count
)))
308 ret
= rw_verify_area(WRITE
, file
, pos
, count
);
311 if (file
->f_op
->write
)
312 ret
= file
->f_op
->write(file
, buf
, count
, pos
);
314 ret
= do_sync_write(file
, buf
, count
, pos
);
316 fsnotify_modify(file
->f_path
.dentry
);
317 add_wchar(current
, ret
);
325 EXPORT_SYMBOL(vfs_write
);
327 static inline loff_t
file_pos_read(struct file
*file
)
332 static inline void file_pos_write(struct file
*file
, loff_t pos
)
337 asmlinkage ssize_t
sys_read(unsigned int fd
, char __user
* buf
, size_t count
)
340 ssize_t ret
= -EBADF
;
343 file
= fget_light(fd
, &fput_needed
);
345 loff_t pos
= file_pos_read(file
);
346 ret
= vfs_read(file
, buf
, count
, &pos
);
347 file_pos_write(file
, pos
);
348 fput_light(file
, fput_needed
);
354 asmlinkage ssize_t
sys_write(unsigned int fd
, const char __user
* buf
, size_t count
)
357 ssize_t ret
= -EBADF
;
360 file
= fget_light(fd
, &fput_needed
);
362 loff_t pos
= file_pos_read(file
);
363 ret
= vfs_write(file
, buf
, count
, &pos
);
364 file_pos_write(file
, pos
);
365 fput_light(file
, fput_needed
);
371 asmlinkage ssize_t
sys_pread64(unsigned int fd
, char __user
*buf
,
372 size_t count
, loff_t pos
)
375 ssize_t ret
= -EBADF
;
381 file
= fget_light(fd
, &fput_needed
);
384 if (file
->f_mode
& FMODE_PREAD
)
385 ret
= vfs_read(file
, buf
, count
, &pos
);
386 fput_light(file
, fput_needed
);
392 asmlinkage ssize_t
sys_pwrite64(unsigned int fd
, const char __user
*buf
,
393 size_t count
, loff_t pos
)
396 ssize_t ret
= -EBADF
;
402 file
= fget_light(fd
, &fput_needed
);
405 if (file
->f_mode
& FMODE_PWRITE
)
406 ret
= vfs_write(file
, buf
, count
, &pos
);
407 fput_light(file
, fput_needed
);
414 * Reduce an iovec's length in-place. Return the resulting number of segments
416 unsigned long iov_shorten(struct iovec
*iov
, unsigned long nr_segs
, size_t to
)
418 unsigned long seg
= 0;
421 while (seg
< nr_segs
) {
423 if (len
+ iov
->iov_len
>= to
) {
424 iov
->iov_len
= to
- len
;
432 EXPORT_SYMBOL(iov_shorten
);
434 ssize_t
do_sync_readv_writev(struct file
*filp
, const struct iovec
*iov
,
435 unsigned long nr_segs
, size_t len
, loff_t
*ppos
, iov_fn_t fn
)
440 init_sync_kiocb(&kiocb
, filp
);
441 kiocb
.ki_pos
= *ppos
;
443 kiocb
.ki_nbytes
= len
;
446 ret
= fn(&kiocb
, iov
, nr_segs
, kiocb
.ki_pos
);
447 if (ret
!= -EIOCBRETRY
)
449 wait_on_retry_sync_kiocb(&kiocb
);
452 if (ret
== -EIOCBQUEUED
)
453 ret
= wait_on_sync_kiocb(&kiocb
);
454 *ppos
= kiocb
.ki_pos
;
458 /* Do it by hand, with file-ops */
459 ssize_t
do_loop_readv_writev(struct file
*filp
, struct iovec
*iov
,
460 unsigned long nr_segs
, loff_t
*ppos
, io_fn_t fn
)
462 struct iovec
*vector
= iov
;
465 while (nr_segs
> 0) {
470 base
= vector
->iov_base
;
471 len
= vector
->iov_len
;
475 nr
= fn(filp
, base
, len
, ppos
);
490 /* A write operation does a read from user space and vice versa */
491 #define vrfy_dir(type) ((type) == READ ? VERIFY_WRITE : VERIFY_READ)
493 ssize_t
rw_copy_check_uvector(int type
, const struct iovec __user
* uvector
,
494 unsigned long nr_segs
, unsigned long fast_segs
,
495 struct iovec
*fast_pointer
,
496 struct iovec
**ret_pointer
)
500 struct iovec
*iov
= fast_pointer
;
503 * SuS says "The readv() function *may* fail if the iovcnt argument
504 * was less than or equal to 0, or greater than {IOV_MAX}. Linux has
505 * traditionally returned zero for zero segments, so...
513 * First get the "struct iovec" from user memory and
514 * verify all the pointers
516 if (nr_segs
> UIO_MAXIOV
) {
520 if (nr_segs
> fast_segs
) {
521 iov
= kmalloc(nr_segs
*sizeof(struct iovec
), GFP_KERNEL
);
527 if (copy_from_user(iov
, uvector
, nr_segs
*sizeof(*uvector
))) {
533 * According to the Single Unix Specification we should return EINVAL
534 * if an element length is < 0 when cast to ssize_t or if the
535 * total length would overflow the ssize_t return value of the
539 for (seg
= 0; seg
< nr_segs
; seg
++) {
540 void __user
*buf
= iov
[seg
].iov_base
;
541 ssize_t len
= (ssize_t
)iov
[seg
].iov_len
;
543 /* see if we we're about to use an invalid len or if
544 * it's about to overflow ssize_t */
545 if (len
< 0 || (ret
+ len
< ret
)) {
549 if (unlikely(!access_ok(vrfy_dir(type
), buf
, len
))) {
561 static ssize_t
do_readv_writev(int type
, struct file
*file
,
562 const struct iovec __user
* uvector
,
563 unsigned long nr_segs
, loff_t
*pos
)
566 struct iovec iovstack
[UIO_FASTIOV
];
567 struct iovec
*iov
= iovstack
;
577 ret
= rw_copy_check_uvector(type
, uvector
, nr_segs
,
578 ARRAY_SIZE(iovstack
), iovstack
, &iov
);
583 ret
= rw_verify_area(type
, file
, pos
, tot_len
);
589 fn
= file
->f_op
->read
;
590 fnv
= file
->f_op
->aio_read
;
592 fn
= (io_fn_t
)file
->f_op
->write
;
593 fnv
= file
->f_op
->aio_write
;
597 ret
= do_sync_readv_writev(file
, iov
, nr_segs
, tot_len
,
600 ret
= do_loop_readv_writev(file
, iov
, nr_segs
, pos
, fn
);
605 if ((ret
+ (type
== READ
)) > 0) {
607 fsnotify_access(file
->f_path
.dentry
);
609 fsnotify_modify(file
->f_path
.dentry
);
614 ssize_t
vfs_readv(struct file
*file
, const struct iovec __user
*vec
,
615 unsigned long vlen
, loff_t
*pos
)
617 if (!(file
->f_mode
& FMODE_READ
))
619 if (!file
->f_op
|| (!file
->f_op
->aio_read
&& !file
->f_op
->read
))
622 return do_readv_writev(READ
, file
, vec
, vlen
, pos
);
625 EXPORT_SYMBOL(vfs_readv
);
627 ssize_t
vfs_writev(struct file
*file
, const struct iovec __user
*vec
,
628 unsigned long vlen
, loff_t
*pos
)
630 if (!(file
->f_mode
& FMODE_WRITE
))
632 if (!file
->f_op
|| (!file
->f_op
->aio_write
&& !file
->f_op
->write
))
635 return do_readv_writev(WRITE
, file
, vec
, vlen
, pos
);
638 EXPORT_SYMBOL(vfs_writev
);
641 sys_readv(unsigned long fd
, const struct iovec __user
*vec
, unsigned long vlen
)
644 ssize_t ret
= -EBADF
;
647 file
= fget_light(fd
, &fput_needed
);
649 loff_t pos
= file_pos_read(file
);
650 ret
= vfs_readv(file
, vec
, vlen
, &pos
);
651 file_pos_write(file
, pos
);
652 fput_light(file
, fput_needed
);
656 add_rchar(current
, ret
);
662 sys_writev(unsigned long fd
, const struct iovec __user
*vec
, unsigned long vlen
)
665 ssize_t ret
= -EBADF
;
668 file
= fget_light(fd
, &fput_needed
);
670 loff_t pos
= file_pos_read(file
);
671 ret
= vfs_writev(file
, vec
, vlen
, &pos
);
672 file_pos_write(file
, pos
);
673 fput_light(file
, fput_needed
);
677 add_wchar(current
, ret
);
682 static ssize_t
do_sendfile(int out_fd
, int in_fd
, loff_t
*ppos
,
683 size_t count
, loff_t max
)
685 struct file
* in_file
, * out_file
;
686 struct inode
* in_inode
, * out_inode
;
689 int fput_needed_in
, fput_needed_out
, fl
;
692 * Get input file, and verify that it is ok..
695 in_file
= fget_light(in_fd
, &fput_needed_in
);
698 if (!(in_file
->f_mode
& FMODE_READ
))
701 in_inode
= in_file
->f_path
.dentry
->d_inode
;
704 if (!in_file
->f_op
|| !in_file
->f_op
->splice_read
)
708 ppos
= &in_file
->f_pos
;
710 if (!(in_file
->f_mode
& FMODE_PREAD
))
712 retval
= rw_verify_area(READ
, in_file
, ppos
, count
);
718 * Get output file, and verify that it is ok..
721 out_file
= fget_light(out_fd
, &fput_needed_out
);
724 if (!(out_file
->f_mode
& FMODE_WRITE
))
727 if (!out_file
->f_op
|| !out_file
->f_op
->sendpage
)
729 out_inode
= out_file
->f_path
.dentry
->d_inode
;
730 retval
= rw_verify_area(WRITE
, out_file
, &out_file
->f_pos
, count
);
736 max
= min(in_inode
->i_sb
->s_maxbytes
, out_inode
->i_sb
->s_maxbytes
);
740 if (unlikely(pos
< 0))
742 if (unlikely(pos
+ count
> max
)) {
752 * We need to debate whether we can enable this or not. The
753 * man page documents EAGAIN return for the output at least,
754 * and the application is arguably buggy if it doesn't expect
755 * EAGAIN on a non-blocking file descriptor.
757 if (in_file
->f_flags
& O_NONBLOCK
)
758 fl
= SPLICE_F_NONBLOCK
;
760 retval
= do_splice_direct(in_file
, ppos
, out_file
, count
, fl
);
763 add_rchar(current
, retval
);
764 add_wchar(current
, retval
);
773 fput_light(out_file
, fput_needed_out
);
775 fput_light(in_file
, fput_needed_in
);
780 asmlinkage ssize_t
sys_sendfile(int out_fd
, int in_fd
, off_t __user
*offset
, size_t count
)
787 if (unlikely(get_user(off
, offset
)))
790 ret
= do_sendfile(out_fd
, in_fd
, &pos
, count
, MAX_NON_LFS
);
791 if (unlikely(put_user(pos
, offset
)))
796 return do_sendfile(out_fd
, in_fd
, NULL
, count
, 0);
799 asmlinkage ssize_t
sys_sendfile64(int out_fd
, int in_fd
, loff_t __user
*offset
, size_t count
)
805 if (unlikely(copy_from_user(&pos
, offset
, sizeof(loff_t
))))
807 ret
= do_sendfile(out_fd
, in_fd
, &pos
, count
, 0);
808 if (unlikely(put_user(pos
, offset
)))
813 return do_sendfile(out_fd
, in_fd
, NULL
, count
, 0);