blob: 563abd09b5c84b882cbe6f47e56d05e80e5db4b6 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * linux/fs/read_write.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 */
6
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>
Robert Love0eeca282005-07-12 17:06:03 -040013#include <linux/fsnotify.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070014#include <linux/security.h>
15#include <linux/module.h>
16#include <linux/syscalls.h>
17
18#include <asm/uaccess.h>
19#include <asm/unistd.h>
20
21struct file_operations generic_ro_fops = {
22 .llseek = generic_file_llseek,
23 .read = generic_file_read,
24 .mmap = generic_file_readonly_mmap,
25 .sendfile = generic_file_sendfile,
26};
27
28EXPORT_SYMBOL(generic_ro_fops);
29
30loff_t generic_file_llseek(struct file *file, loff_t offset, int origin)
31{
32 long long retval;
33 struct inode *inode = file->f_mapping->host;
34
35 down(&inode->i_sem);
36 switch (origin) {
37 case 2:
38 offset += inode->i_size;
39 break;
40 case 1:
41 offset += file->f_pos;
42 }
43 retval = -EINVAL;
44 if (offset>=0 && offset<=inode->i_sb->s_maxbytes) {
45 if (offset != file->f_pos) {
46 file->f_pos = offset;
47 file->f_version = 0;
48 }
49 retval = offset;
50 }
51 up(&inode->i_sem);
52 return retval;
53}
54
55EXPORT_SYMBOL(generic_file_llseek);
56
57loff_t remote_llseek(struct file *file, loff_t offset, int origin)
58{
59 long long retval;
60
61 lock_kernel();
62 switch (origin) {
63 case 2:
64 offset += i_size_read(file->f_dentry->d_inode);
65 break;
66 case 1:
67 offset += file->f_pos;
68 }
69 retval = -EINVAL;
70 if (offset>=0 && offset<=file->f_dentry->d_inode->i_sb->s_maxbytes) {
71 if (offset != file->f_pos) {
72 file->f_pos = offset;
73 file->f_version = 0;
74 }
75 retval = offset;
76 }
77 unlock_kernel();
78 return retval;
79}
80EXPORT_SYMBOL(remote_llseek);
81
82loff_t no_llseek(struct file *file, loff_t offset, int origin)
83{
84 return -ESPIPE;
85}
86EXPORT_SYMBOL(no_llseek);
87
88loff_t default_llseek(struct file *file, loff_t offset, int origin)
89{
90 long long retval;
91
92 lock_kernel();
93 switch (origin) {
94 case 2:
95 offset += i_size_read(file->f_dentry->d_inode);
96 break;
97 case 1:
98 offset += file->f_pos;
99 }
100 retval = -EINVAL;
101 if (offset >= 0) {
102 if (offset != file->f_pos) {
103 file->f_pos = offset;
104 file->f_version = 0;
105 }
106 retval = offset;
107 }
108 unlock_kernel();
109 return retval;
110}
111EXPORT_SYMBOL(default_llseek);
112
113loff_t vfs_llseek(struct file *file, loff_t offset, int origin)
114{
115 loff_t (*fn)(struct file *, loff_t, int);
116
117 fn = no_llseek;
118 if (file->f_mode & FMODE_LSEEK) {
119 fn = default_llseek;
120 if (file->f_op && file->f_op->llseek)
121 fn = file->f_op->llseek;
122 }
123 return fn(file, offset, origin);
124}
125EXPORT_SYMBOL(vfs_llseek);
126
127asmlinkage off_t sys_lseek(unsigned int fd, off_t offset, unsigned int origin)
128{
129 off_t retval;
130 struct file * file;
131 int fput_needed;
132
133 retval = -EBADF;
134 file = fget_light(fd, &fput_needed);
135 if (!file)
136 goto bad;
137
138 retval = -EINVAL;
139 if (origin <= 2) {
140 loff_t res = vfs_llseek(file, offset, origin);
141 retval = res;
142 if (res != (loff_t)retval)
143 retval = -EOVERFLOW; /* LFS: should only happen on 32 bit platforms */
144 }
145 fput_light(file, fput_needed);
146bad:
147 return retval;
148}
149
150#ifdef __ARCH_WANT_SYS_LLSEEK
151asmlinkage long sys_llseek(unsigned int fd, unsigned long offset_high,
152 unsigned long offset_low, loff_t __user * result,
153 unsigned int origin)
154{
155 int retval;
156 struct file * file;
157 loff_t offset;
158 int fput_needed;
159
160 retval = -EBADF;
161 file = fget_light(fd, &fput_needed);
162 if (!file)
163 goto bad;
164
165 retval = -EINVAL;
166 if (origin > 2)
167 goto out_putf;
168
169 offset = vfs_llseek(file, ((loff_t) offset_high << 32) | offset_low,
170 origin);
171
172 retval = (int)offset;
173 if (offset >= 0) {
174 retval = -EFAULT;
175 if (!copy_to_user(result, &offset, sizeof(offset)))
176 retval = 0;
177 }
178out_putf:
179 fput_light(file, fput_needed);
180bad:
181 return retval;
182}
183#endif
184
185
186int rw_verify_area(int read_write, struct file *file, loff_t *ppos, size_t count)
187{
188 struct inode *inode;
189 loff_t pos;
190
191 if (unlikely(count > file->f_maxcount))
192 goto Einval;
193 pos = *ppos;
194 if (unlikely((pos < 0) || (loff_t) (pos + count) < 0))
195 goto Einval;
196
197 inode = file->f_dentry->d_inode;
198 if (inode->i_flock && MANDATORY_LOCK(inode))
199 return locks_mandatory_area(read_write == READ ? FLOCK_VERIFY_READ : FLOCK_VERIFY_WRITE, inode, file, pos, count);
200 return 0;
201
202Einval:
203 return -EINVAL;
204}
205
Benjamin LaHaise63e68802005-06-23 00:10:27 -0700206static void wait_on_retry_sync_kiocb(struct kiocb *iocb)
207{
208 set_current_state(TASK_UNINTERRUPTIBLE);
209 if (!kiocbIsKicked(iocb))
210 schedule();
211 else
212 kiocbClearKicked(iocb);
213 __set_current_state(TASK_RUNNING);
214}
215
Linus Torvalds1da177e2005-04-16 15:20:36 -0700216ssize_t do_sync_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos)
217{
218 struct kiocb kiocb;
219 ssize_t ret;
220
221 init_sync_kiocb(&kiocb, filp);
222 kiocb.ki_pos = *ppos;
Benjamin LaHaise63e68802005-06-23 00:10:27 -0700223 while (-EIOCBRETRY ==
224 (ret = filp->f_op->aio_read(&kiocb, buf, len, kiocb.ki_pos)))
225 wait_on_retry_sync_kiocb(&kiocb);
226
Linus Torvalds1da177e2005-04-16 15:20:36 -0700227 if (-EIOCBQUEUED == ret)
228 ret = wait_on_sync_kiocb(&kiocb);
229 *ppos = kiocb.ki_pos;
230 return ret;
231}
232
233EXPORT_SYMBOL(do_sync_read);
234
235ssize_t vfs_read(struct file *file, char __user *buf, size_t count, loff_t *pos)
236{
237 ssize_t ret;
238
239 if (!(file->f_mode & FMODE_READ))
240 return -EBADF;
241 if (!file->f_op || (!file->f_op->read && !file->f_op->aio_read))
242 return -EINVAL;
243 if (unlikely(!access_ok(VERIFY_WRITE, buf, count)))
244 return -EFAULT;
245
246 ret = rw_verify_area(READ, file, pos, count);
247 if (!ret) {
248 ret = security_file_permission (file, MAY_READ);
249 if (!ret) {
250 if (file->f_op->read)
251 ret = file->f_op->read(file, buf, count, pos);
252 else
253 ret = do_sync_read(file, buf, count, pos);
254 if (ret > 0) {
Robert Love0eeca282005-07-12 17:06:03 -0400255 fsnotify_access(file->f_dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700256 current->rchar += ret;
257 }
258 current->syscr++;
259 }
260 }
261
262 return ret;
263}
264
265EXPORT_SYMBOL(vfs_read);
266
267ssize_t do_sync_write(struct file *filp, const char __user *buf, size_t len, loff_t *ppos)
268{
269 struct kiocb kiocb;
270 ssize_t ret;
271
272 init_sync_kiocb(&kiocb, filp);
273 kiocb.ki_pos = *ppos;
Benjamin LaHaise63e68802005-06-23 00:10:27 -0700274 while (-EIOCBRETRY ==
275 (ret = filp->f_op->aio_write(&kiocb, buf, len, kiocb.ki_pos)))
276 wait_on_retry_sync_kiocb(&kiocb);
277
Linus Torvalds1da177e2005-04-16 15:20:36 -0700278 if (-EIOCBQUEUED == ret)
279 ret = wait_on_sync_kiocb(&kiocb);
280 *ppos = kiocb.ki_pos;
281 return ret;
282}
283
284EXPORT_SYMBOL(do_sync_write);
285
286ssize_t vfs_write(struct file *file, const char __user *buf, size_t count, loff_t *pos)
287{
288 ssize_t ret;
289
290 if (!(file->f_mode & FMODE_WRITE))
291 return -EBADF;
292 if (!file->f_op || (!file->f_op->write && !file->f_op->aio_write))
293 return -EINVAL;
294 if (unlikely(!access_ok(VERIFY_READ, buf, count)))
295 return -EFAULT;
296
297 ret = rw_verify_area(WRITE, file, pos, count);
298 if (!ret) {
299 ret = security_file_permission (file, MAY_WRITE);
300 if (!ret) {
301 if (file->f_op->write)
302 ret = file->f_op->write(file, buf, count, pos);
303 else
304 ret = do_sync_write(file, buf, count, pos);
305 if (ret > 0) {
Robert Love0eeca282005-07-12 17:06:03 -0400306 fsnotify_modify(file->f_dentry);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700307 current->wchar += ret;
308 }
309 current->syscw++;
310 }
311 }
312
313 return ret;
314}
315
316EXPORT_SYMBOL(vfs_write);
317
318static inline loff_t file_pos_read(struct file *file)
319{
320 return file->f_pos;
321}
322
323static inline void file_pos_write(struct file *file, loff_t pos)
324{
325 file->f_pos = pos;
326}
327
328asmlinkage ssize_t sys_read(unsigned int fd, char __user * buf, size_t count)
329{
330 struct file *file;
331 ssize_t ret = -EBADF;
332 int fput_needed;
333
334 file = fget_light(fd, &fput_needed);
335 if (file) {
336 loff_t pos = file_pos_read(file);
337 ret = vfs_read(file, buf, count, &pos);
338 file_pos_write(file, pos);
339 fput_light(file, fput_needed);
340 }
341
342 return ret;
343}
344EXPORT_SYMBOL_GPL(sys_read);
345
346asmlinkage ssize_t sys_write(unsigned int fd, const char __user * buf, size_t count)
347{
348 struct file *file;
349 ssize_t ret = -EBADF;
350 int fput_needed;
351
352 file = fget_light(fd, &fput_needed);
353 if (file) {
354 loff_t pos = file_pos_read(file);
355 ret = vfs_write(file, buf, count, &pos);
356 file_pos_write(file, pos);
357 fput_light(file, fput_needed);
358 }
359
360 return ret;
361}
362
363asmlinkage ssize_t sys_pread64(unsigned int fd, char __user *buf,
364 size_t count, loff_t pos)
365{
366 struct file *file;
367 ssize_t ret = -EBADF;
368 int fput_needed;
369
370 if (pos < 0)
371 return -EINVAL;
372
373 file = fget_light(fd, &fput_needed);
374 if (file) {
375 ret = -ESPIPE;
376 if (file->f_mode & FMODE_PREAD)
377 ret = vfs_read(file, buf, count, &pos);
378 fput_light(file, fput_needed);
379 }
380
381 return ret;
382}
383
384asmlinkage ssize_t sys_pwrite64(unsigned int fd, const char __user *buf,
385 size_t count, loff_t pos)
386{
387 struct file *file;
388 ssize_t ret = -EBADF;
389 int fput_needed;
390
391 if (pos < 0)
392 return -EINVAL;
393
394 file = fget_light(fd, &fput_needed);
395 if (file) {
396 ret = -ESPIPE;
397 if (file->f_mode & FMODE_PWRITE)
398 ret = vfs_write(file, buf, count, &pos);
399 fput_light(file, fput_needed);
400 }
401
402 return ret;
403}
404
405/*
406 * Reduce an iovec's length in-place. Return the resulting number of segments
407 */
408unsigned long iov_shorten(struct iovec *iov, unsigned long nr_segs, size_t to)
409{
410 unsigned long seg = 0;
411 size_t len = 0;
412
413 while (seg < nr_segs) {
414 seg++;
415 if (len + iov->iov_len >= to) {
416 iov->iov_len = to - len;
417 break;
418 }
419 len += iov->iov_len;
420 iov++;
421 }
422 return seg;
423}
424
425EXPORT_SYMBOL(iov_shorten);
426
427/* A write operation does a read from user space and vice versa */
428#define vrfy_dir(type) ((type) == READ ? VERIFY_WRITE : VERIFY_READ)
429
430static ssize_t do_readv_writev(int type, struct file *file,
431 const struct iovec __user * uvector,
432 unsigned long nr_segs, loff_t *pos)
433{
434 typedef ssize_t (*io_fn_t)(struct file *, char __user *, size_t, loff_t *);
435 typedef ssize_t (*iov_fn_t)(struct file *, const struct iovec *, unsigned long, loff_t *);
436
437 size_t tot_len;
438 struct iovec iovstack[UIO_FASTIOV];
439 struct iovec *iov=iovstack, *vector;
440 ssize_t ret;
441 int seg;
442 io_fn_t fn;
443 iov_fn_t fnv;
444
445 /*
446 * SuS says "The readv() function *may* fail if the iovcnt argument
447 * was less than or equal to 0, or greater than {IOV_MAX}. Linux has
448 * traditionally returned zero for zero segments, so...
449 */
450 ret = 0;
451 if (nr_segs == 0)
452 goto out;
453
454 /*
455 * First get the "struct iovec" from user memory and
456 * verify all the pointers
457 */
458 ret = -EINVAL;
459 if ((nr_segs > UIO_MAXIOV) || (nr_segs <= 0))
460 goto out;
461 if (!file->f_op)
462 goto out;
463 if (nr_segs > UIO_FASTIOV) {
464 ret = -ENOMEM;
465 iov = kmalloc(nr_segs*sizeof(struct iovec), GFP_KERNEL);
466 if (!iov)
467 goto out;
468 }
469 ret = -EFAULT;
470 if (copy_from_user(iov, uvector, nr_segs*sizeof(*uvector)))
471 goto out;
472
473 /*
474 * Single unix specification:
475 * We should -EINVAL if an element length is not >= 0 and fitting an
476 * ssize_t. The total length is fitting an ssize_t
477 *
478 * Be careful here because iov_len is a size_t not an ssize_t
479 */
480 tot_len = 0;
481 ret = -EINVAL;
482 for (seg = 0; seg < nr_segs; seg++) {
483 void __user *buf = iov[seg].iov_base;
484 ssize_t len = (ssize_t)iov[seg].iov_len;
485
Linus Torvalds1da177e2005-04-16 15:20:36 -0700486 if (len < 0) /* size_t not fitting an ssize_t .. */
487 goto out;
Dave Hansen1f08ad02005-04-16 15:25:49 -0700488 if (unlikely(!access_ok(vrfy_dir(type), buf, len)))
489 goto Efault;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700490 tot_len += len;
491 if ((ssize_t)tot_len < 0) /* maths overflow on the ssize_t */
492 goto out;
493 }
494 if (tot_len == 0) {
495 ret = 0;
496 goto out;
497 }
498
499 ret = rw_verify_area(type, file, pos, tot_len);
500 if (ret)
501 goto out;
502
503 fnv = NULL;
504 if (type == READ) {
505 fn = file->f_op->read;
506 fnv = file->f_op->readv;
507 } else {
508 fn = (io_fn_t)file->f_op->write;
509 fnv = file->f_op->writev;
510 }
511 if (fnv) {
512 ret = fnv(file, iov, nr_segs, pos);
513 goto out;
514 }
515
516 /* Do it by hand, with file-ops */
517 ret = 0;
518 vector = iov;
519 while (nr_segs > 0) {
520 void __user * base;
521 size_t len;
522 ssize_t nr;
523
524 base = vector->iov_base;
525 len = vector->iov_len;
526 vector++;
527 nr_segs--;
528
529 nr = fn(file, base, len, pos);
530
531 if (nr < 0) {
532 if (!ret) ret = nr;
533 break;
534 }
535 ret += nr;
536 if (nr != len)
537 break;
538 }
539out:
540 if (iov != iovstack)
541 kfree(iov);
Robert Love0eeca282005-07-12 17:06:03 -0400542 if ((ret + (type == READ)) > 0) {
543 if (type == READ)
544 fsnotify_access(file->f_dentry);
545 else
546 fsnotify_modify(file->f_dentry);
547 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700548 return ret;
549Efault:
550 ret = -EFAULT;
551 goto out;
552}
553
554ssize_t vfs_readv(struct file *file, const struct iovec __user *vec,
555 unsigned long vlen, loff_t *pos)
556{
557 if (!(file->f_mode & FMODE_READ))
558 return -EBADF;
559 if (!file->f_op || (!file->f_op->readv && !file->f_op->read))
560 return -EINVAL;
561
562 return do_readv_writev(READ, file, vec, vlen, pos);
563}
564
565EXPORT_SYMBOL(vfs_readv);
566
567ssize_t vfs_writev(struct file *file, const struct iovec __user *vec,
568 unsigned long vlen, loff_t *pos)
569{
570 if (!(file->f_mode & FMODE_WRITE))
571 return -EBADF;
572 if (!file->f_op || (!file->f_op->writev && !file->f_op->write))
573 return -EINVAL;
574
575 return do_readv_writev(WRITE, file, vec, vlen, pos);
576}
577
578EXPORT_SYMBOL(vfs_writev);
579
580asmlinkage ssize_t
581sys_readv(unsigned long fd, const struct iovec __user *vec, unsigned long vlen)
582{
583 struct file *file;
584 ssize_t ret = -EBADF;
585 int fput_needed;
586
587 file = fget_light(fd, &fput_needed);
588 if (file) {
589 loff_t pos = file_pos_read(file);
590 ret = vfs_readv(file, vec, vlen, &pos);
591 file_pos_write(file, pos);
592 fput_light(file, fput_needed);
593 }
594
595 if (ret > 0)
596 current->rchar += ret;
597 current->syscr++;
598 return ret;
599}
600
601asmlinkage ssize_t
602sys_writev(unsigned long fd, const struct iovec __user *vec, unsigned long vlen)
603{
604 struct file *file;
605 ssize_t ret = -EBADF;
606 int fput_needed;
607
608 file = fget_light(fd, &fput_needed);
609 if (file) {
610 loff_t pos = file_pos_read(file);
611 ret = vfs_writev(file, vec, vlen, &pos);
612 file_pos_write(file, pos);
613 fput_light(file, fput_needed);
614 }
615
616 if (ret > 0)
617 current->wchar += ret;
618 current->syscw++;
619 return ret;
620}
621
622static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos,
623 size_t count, loff_t max)
624{
625 struct file * in_file, * out_file;
626 struct inode * in_inode, * out_inode;
627 loff_t pos;
628 ssize_t retval;
629 int fput_needed_in, fput_needed_out;
630
631 /*
632 * Get input file, and verify that it is ok..
633 */
634 retval = -EBADF;
635 in_file = fget_light(in_fd, &fput_needed_in);
636 if (!in_file)
637 goto out;
638 if (!(in_file->f_mode & FMODE_READ))
639 goto fput_in;
640 retval = -EINVAL;
641 in_inode = in_file->f_dentry->d_inode;
642 if (!in_inode)
643 goto fput_in;
644 if (!in_file->f_op || !in_file->f_op->sendfile)
645 goto fput_in;
646 retval = -ESPIPE;
647 if (!ppos)
648 ppos = &in_file->f_pos;
649 else
650 if (!(in_file->f_mode & FMODE_PREAD))
651 goto fput_in;
652 retval = rw_verify_area(READ, in_file, ppos, count);
653 if (retval)
654 goto fput_in;
655
656 retval = security_file_permission (in_file, MAY_READ);
657 if (retval)
658 goto fput_in;
659
660 /*
661 * Get output file, and verify that it is ok..
662 */
663 retval = -EBADF;
664 out_file = fget_light(out_fd, &fput_needed_out);
665 if (!out_file)
666 goto fput_in;
667 if (!(out_file->f_mode & FMODE_WRITE))
668 goto fput_out;
669 retval = -EINVAL;
670 if (!out_file->f_op || !out_file->f_op->sendpage)
671 goto fput_out;
672 out_inode = out_file->f_dentry->d_inode;
673 retval = rw_verify_area(WRITE, out_file, &out_file->f_pos, count);
674 if (retval)
675 goto fput_out;
676
677 retval = security_file_permission (out_file, MAY_WRITE);
678 if (retval)
679 goto fput_out;
680
681 if (!max)
682 max = min(in_inode->i_sb->s_maxbytes, out_inode->i_sb->s_maxbytes);
683
684 pos = *ppos;
685 retval = -EINVAL;
686 if (unlikely(pos < 0))
687 goto fput_out;
688 if (unlikely(pos + count > max)) {
689 retval = -EOVERFLOW;
690 if (pos >= max)
691 goto fput_out;
692 count = max - pos;
693 }
694
695 retval = in_file->f_op->sendfile(in_file, ppos, count, file_send_actor, out_file);
696
697 if (retval > 0) {
698 current->rchar += retval;
699 current->wchar += retval;
700 }
701 current->syscr++;
702 current->syscw++;
703
704 if (*ppos > max)
705 retval = -EOVERFLOW;
706
707fput_out:
708 fput_light(out_file, fput_needed_out);
709fput_in:
710 fput_light(in_file, fput_needed_in);
711out:
712 return retval;
713}
714
715asmlinkage ssize_t sys_sendfile(int out_fd, int in_fd, off_t __user *offset, size_t count)
716{
717 loff_t pos;
718 off_t off;
719 ssize_t ret;
720
721 if (offset) {
722 if (unlikely(get_user(off, offset)))
723 return -EFAULT;
724 pos = off;
725 ret = do_sendfile(out_fd, in_fd, &pos, count, MAX_NON_LFS);
726 if (unlikely(put_user(pos, offset)))
727 return -EFAULT;
728 return ret;
729 }
730
731 return do_sendfile(out_fd, in_fd, NULL, count, 0);
732}
733
734asmlinkage ssize_t sys_sendfile64(int out_fd, int in_fd, loff_t __user *offset, size_t count)
735{
736 loff_t pos;
737 ssize_t ret;
738
739 if (offset) {
740 if (unlikely(copy_from_user(&pos, offset, sizeof(loff_t))))
741 return -EFAULT;
742 ret = do_sendfile(out_fd, in_fd, &pos, count, 0);
743 if (unlikely(put_user(pos, offset)))
744 return -EFAULT;
745 return ret;
746 }
747
748 return do_sendfile(out_fd, in_fd, NULL, count, 0);
749}