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 "read_write.h"
20 #include <asm/uaccess.h>
21 #include <asm/unistd.h>
23 const struct file_operations generic_ro_fops = {
24 .llseek = generic_file_llseek,
25 .read = generic_file_read,
26 .mmap = generic_file_readonly_mmap,
27 .sendfile = generic_file_sendfile,
30 EXPORT_SYMBOL(generic_ro_fops);
32 loff_t generic_file_llseek(struct file *file, loff_t offset, int origin)
35 struct inode *inode = file->f_mapping->host;
37 mutex_lock(&inode->i_mutex);
40 offset += inode->i_size;
43 offset += file->f_pos;
46 if (offset>=0 && offset<=inode->i_sb->s_maxbytes) {
47 if (offset != file->f_pos) {
53 mutex_unlock(&inode->i_mutex);
57 EXPORT_SYMBOL(generic_file_llseek);
59 loff_t remote_llseek(struct file *file, loff_t offset, int origin)
66 offset += i_size_read(file->f_dentry->d_inode);
69 offset += file->f_pos;
72 if (offset>=0 && offset<=file->f_dentry->d_inode->i_sb->s_maxbytes) {
73 if (offset != file->f_pos) {
82 EXPORT_SYMBOL(remote_llseek);
84 loff_t no_llseek(struct file *file, loff_t offset, int origin)
88 EXPORT_SYMBOL(no_llseek);
90 loff_t default_llseek(struct file *file, loff_t offset, int origin)
97 offset += i_size_read(file->f_dentry->d_inode);
100 offset += file->f_pos;
104 if (offset != file->f_pos) {
105 file->f_pos = offset;
113 EXPORT_SYMBOL(default_llseek);
115 loff_t vfs_llseek(struct file *file, loff_t offset, int origin)
117 loff_t (*fn)(struct file *, loff_t, int);
120 if (file->f_mode & FMODE_LSEEK) {
122 if (file->f_op && file->f_op->llseek)
123 fn = file->f_op->llseek;
125 return fn(file, offset, origin);
127 EXPORT_SYMBOL(vfs_llseek);
129 asmlinkage off_t sys_lseek(unsigned int fd, off_t offset, unsigned int origin)
136 file = fget_light(fd, &fput_needed);
142 loff_t res = vfs_llseek(file, offset, origin);
144 if (res != (loff_t)retval)
145 retval = -EOVERFLOW; /* LFS: should only happen on 32 bit platforms */
147 fput_light(file, fput_needed);
152 #ifdef __ARCH_WANT_SYS_LLSEEK
153 asmlinkage long sys_llseek(unsigned int fd, unsigned long offset_high,
154 unsigned long offset_low, loff_t __user * result,
163 file = fget_light(fd, &fput_needed);
171 offset = vfs_llseek(file, ((loff_t) offset_high << 32) | offset_low,
174 retval = (int)offset;
177 if (!copy_to_user(result, &offset, sizeof(offset)))
181 fput_light(file, fput_needed);
188 * rw_verify_area doesn't like huge counts. We limit
189 * them to something that fits in "int" so that others
190 * won't have to do range checks all the time.
192 #define MAX_RW_COUNT (INT_MAX & PAGE_CACHE_MASK)
194 int rw_verify_area(int read_write, struct file *file, loff_t *ppos, size_t count)
199 if (unlikely((ssize_t) count < 0))
202 if (unlikely((pos < 0) || (loff_t) (pos + count) < 0))
205 inode = file->f_dentry->d_inode;
206 if (unlikely(inode->i_flock && MANDATORY_LOCK(inode))) {
207 int retval = locks_mandatory_area(
208 read_write == READ ? FLOCK_VERIFY_READ : FLOCK_VERIFY_WRITE,
209 inode, file, pos, count);
213 return count > MAX_RW_COUNT ? MAX_RW_COUNT : count;
219 static void wait_on_retry_sync_kiocb(struct kiocb *iocb)
221 set_current_state(TASK_UNINTERRUPTIBLE);
222 if (!kiocbIsKicked(iocb))
225 kiocbClearKicked(iocb);
226 __set_current_state(TASK_RUNNING);
229 ssize_t do_sync_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos)
231 struct iovec iov = { .iov_base = buf, .iov_len = len };
235 init_sync_kiocb(&kiocb, filp);
236 kiocb.ki_pos = *ppos;
240 ret = filp->f_op->aio_read(&kiocb, &iov, 1, kiocb.ki_pos);
241 if (ret != -EIOCBRETRY)
243 wait_on_retry_sync_kiocb(&kiocb);
246 if (-EIOCBQUEUED == ret)
247 ret = wait_on_sync_kiocb(&kiocb);
248 *ppos = kiocb.ki_pos;
252 EXPORT_SYMBOL(do_sync_read);
254 ssize_t vfs_read(struct file *file, char __user *buf, size_t count, loff_t *pos)
258 if (!(file->f_mode & FMODE_READ))
260 if (!file->f_op || (!file->f_op->read && !file->f_op->aio_read))
262 if (unlikely(!access_ok(VERIFY_WRITE, buf, count)))
265 ret = rw_verify_area(READ, file, pos, count);
268 ret = security_file_permission (file, MAY_READ);
270 if (file->f_op->read)
271 ret = file->f_op->read(file, buf, count, pos);
273 ret = do_sync_read(file, buf, count, pos);
275 fsnotify_access(file->f_dentry);
276 current->rchar += ret;
285 EXPORT_SYMBOL(vfs_read);
287 ssize_t do_sync_write(struct file *filp, const char __user *buf, size_t len, loff_t *ppos)
289 struct iovec iov = { .iov_base = (void __user *)buf, .iov_len = len };
293 init_sync_kiocb(&kiocb, filp);
294 kiocb.ki_pos = *ppos;
298 ret = filp->f_op->aio_write(&kiocb, &iov, 1, kiocb.ki_pos);
299 if (ret != -EIOCBRETRY)
301 wait_on_retry_sync_kiocb(&kiocb);
304 if (-EIOCBQUEUED == ret)
305 ret = wait_on_sync_kiocb(&kiocb);
306 *ppos = kiocb.ki_pos;
310 EXPORT_SYMBOL(do_sync_write);
312 ssize_t vfs_write(struct file *file, const char __user *buf, size_t count, loff_t *pos)
316 if (!(file->f_mode & FMODE_WRITE))
318 if (!file->f_op || (!file->f_op->write && !file->f_op->aio_write))
320 if (unlikely(!access_ok(VERIFY_READ, buf, count)))
323 ret = rw_verify_area(WRITE, file, pos, count);
326 ret = security_file_permission (file, MAY_WRITE);
328 if (file->f_op->write)
329 ret = file->f_op->write(file, buf, count, pos);
331 ret = do_sync_write(file, buf, count, pos);
333 fsnotify_modify(file->f_dentry);
334 current->wchar += ret;
343 EXPORT_SYMBOL(vfs_write);
345 static inline loff_t file_pos_read(struct file *file)
350 static inline void file_pos_write(struct file *file, loff_t pos)
355 asmlinkage ssize_t sys_read(unsigned int fd, char __user * buf, size_t count)
358 ssize_t ret = -EBADF;
361 file = fget_light(fd, &fput_needed);
363 loff_t pos = file_pos_read(file);
364 ret = vfs_read(file, buf, count, &pos);
365 file_pos_write(file, pos);
366 fput_light(file, fput_needed);
371 EXPORT_SYMBOL_GPL(sys_read);
373 asmlinkage ssize_t sys_write(unsigned int fd, const char __user * buf, size_t count)
376 ssize_t ret = -EBADF;
379 file = fget_light(fd, &fput_needed);
381 loff_t pos = file_pos_read(file);
382 ret = vfs_write(file, buf, count, &pos);
383 file_pos_write(file, pos);
384 fput_light(file, fput_needed);
390 asmlinkage ssize_t sys_pread64(unsigned int fd, char __user *buf,
391 size_t count, loff_t pos)
394 ssize_t ret = -EBADF;
400 file = fget_light(fd, &fput_needed);
403 if (file->f_mode & FMODE_PREAD)
404 ret = vfs_read(file, buf, count, &pos);
405 fput_light(file, fput_needed);
411 asmlinkage ssize_t sys_pwrite64(unsigned int fd, const char __user *buf,
412 size_t count, loff_t pos)
415 ssize_t ret = -EBADF;
421 file = fget_light(fd, &fput_needed);
424 if (file->f_mode & FMODE_PWRITE)
425 ret = vfs_write(file, buf, count, &pos);
426 fput_light(file, fput_needed);
433 * Reduce an iovec's length in-place. Return the resulting number of segments
435 unsigned long iov_shorten(struct iovec *iov, unsigned long nr_segs, size_t to)
437 unsigned long seg = 0;
440 while (seg < nr_segs) {
442 if (len + iov->iov_len >= to) {
443 iov->iov_len = to - len;
452 EXPORT_UNUSED_SYMBOL(iov_shorten); /* June 2006 */
454 ssize_t do_sync_readv_writev(struct file *filp, const struct iovec *iov,
455 unsigned long nr_segs, size_t len, loff_t *ppos, iov_fn_t fn)
460 init_sync_kiocb(&kiocb, filp);
461 kiocb.ki_pos = *ppos;
463 kiocb.ki_nbytes = len;
466 ret = fn(&kiocb, iov, nr_segs, kiocb.ki_pos);
467 if (ret != -EIOCBRETRY)
469 wait_on_retry_sync_kiocb(&kiocb);
472 if (ret == -EIOCBQUEUED)
473 ret = wait_on_sync_kiocb(&kiocb);
474 *ppos = kiocb.ki_pos;
478 /* Do it by hand, with file-ops */
479 ssize_t do_loop_readv_writev(struct file *filp, struct iovec *iov,
480 unsigned long nr_segs, loff_t *ppos, io_fn_t fn)
482 struct iovec *vector = iov;
485 while (nr_segs > 0) {
490 base = vector->iov_base;
491 len = vector->iov_len;
495 nr = fn(filp, base, len, ppos);
510 /* A write operation does a read from user space and vice versa */
511 #define vrfy_dir(type) ((type) == READ ? VERIFY_WRITE : VERIFY_READ)
513 static ssize_t do_readv_writev(int type, struct file *file,
514 const struct iovec __user * uvector,
515 unsigned long nr_segs, loff_t *pos)
518 struct iovec iovstack[UIO_FASTIOV];
519 struct iovec *iov = iovstack;
526 * SuS says "The readv() function *may* fail if the iovcnt argument
527 * was less than or equal to 0, or greater than {IOV_MAX}. Linux has
528 * traditionally returned zero for zero segments, so...
535 * First get the "struct iovec" from user memory and
536 * verify all the pointers
539 if (nr_segs > UIO_MAXIOV)
543 if (nr_segs > UIO_FASTIOV) {
545 iov = kmalloc(nr_segs*sizeof(struct iovec), GFP_KERNEL);
550 if (copy_from_user(iov, uvector, nr_segs*sizeof(*uvector)))
554 * Single unix specification:
555 * We should -EINVAL if an element length is not >= 0 and fitting an
556 * ssize_t. The total length is fitting an ssize_t
558 * Be careful here because iov_len is a size_t not an ssize_t
562 for (seg = 0; seg < nr_segs; seg++) {
563 void __user *buf = iov[seg].iov_base;
564 ssize_t len = (ssize_t)iov[seg].iov_len;
566 if (len < 0) /* size_t not fitting an ssize_t .. */
568 if (unlikely(!access_ok(vrfy_dir(type), buf, len)))
571 if ((ssize_t)tot_len < 0) /* maths overflow on the ssize_t */
579 ret = rw_verify_area(type, file, pos, tot_len);
582 ret = security_file_permission(file, type == READ ? MAY_READ : MAY_WRITE);
588 fn = file->f_op->read;
589 fnv = file->f_op->aio_read;
591 fn = (io_fn_t)file->f_op->write;
592 fnv = file->f_op->aio_write;
596 ret = do_sync_readv_writev(file, iov, nr_segs, tot_len,
599 ret = do_loop_readv_writev(file, iov, nr_segs, pos, fn);
604 if ((ret + (type == READ)) > 0) {
606 fsnotify_access(file->f_dentry);
608 fsnotify_modify(file->f_dentry);
616 ssize_t vfs_readv(struct file *file, const struct iovec __user *vec,
617 unsigned long vlen, loff_t *pos)
619 if (!(file->f_mode & FMODE_READ))
621 if (!file->f_op || (!file->f_op->aio_read && !file->f_op->read))
624 return do_readv_writev(READ, file, vec, vlen, pos);
627 EXPORT_SYMBOL(vfs_readv);
629 ssize_t vfs_writev(struct file *file, const struct iovec __user *vec,
630 unsigned long vlen, loff_t *pos)
632 if (!(file->f_mode & FMODE_WRITE))
634 if (!file->f_op || (!file->f_op->aio_write && !file->f_op->write))
637 return do_readv_writev(WRITE, file, vec, vlen, pos);
640 EXPORT_SYMBOL(vfs_writev);
643 sys_readv(unsigned long fd, const struct iovec __user *vec, unsigned long vlen)
646 ssize_t ret = -EBADF;
649 file = fget_light(fd, &fput_needed);
651 loff_t pos = file_pos_read(file);
652 ret = vfs_readv(file, vec, vlen, &pos);
653 file_pos_write(file, pos);
654 fput_light(file, fput_needed);
658 current->rchar += ret;
664 sys_writev(unsigned long fd, const struct iovec __user *vec, unsigned long vlen)
667 ssize_t ret = -EBADF;
670 file = fget_light(fd, &fput_needed);
672 loff_t pos = file_pos_read(file);
673 ret = vfs_writev(file, vec, vlen, &pos);
674 file_pos_write(file, pos);
675 fput_light(file, fput_needed);
679 current->wchar += ret;
684 static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos,
685 size_t count, loff_t max)
687 struct file * in_file, * out_file;
688 struct inode * in_inode, * out_inode;
691 int fput_needed_in, fput_needed_out;
694 * Get input file, and verify that it is ok..
697 in_file = fget_light(in_fd, &fput_needed_in);
700 if (!(in_file->f_mode & FMODE_READ))
703 in_inode = in_file->f_dentry->d_inode;
706 if (!in_file->f_op || !in_file->f_op->sendfile)
710 ppos = &in_file->f_pos;
712 if (!(in_file->f_mode & FMODE_PREAD))
714 retval = rw_verify_area(READ, in_file, ppos, count);
719 retval = security_file_permission (in_file, MAY_READ);
724 * Get output file, and verify that it is ok..
727 out_file = fget_light(out_fd, &fput_needed_out);
730 if (!(out_file->f_mode & FMODE_WRITE))
733 if (!out_file->f_op || !out_file->f_op->sendpage)
735 out_inode = out_file->f_dentry->d_inode;
736 retval = rw_verify_area(WRITE, out_file, &out_file->f_pos, count);
741 retval = security_file_permission (out_file, MAY_WRITE);
746 max = min(in_inode->i_sb->s_maxbytes, out_inode->i_sb->s_maxbytes);
750 if (unlikely(pos < 0))
752 if (unlikely(pos + count > max)) {
759 retval = in_file->f_op->sendfile(in_file, ppos, count, file_send_actor, out_file);
762 current->rchar += retval;
763 current->wchar += retval;
772 fput_light(out_file, fput_needed_out);
774 fput_light(in_file, fput_needed_in);
779 asmlinkage ssize_t sys_sendfile(int out_fd, int in_fd, off_t __user *offset, size_t count)
786 if (unlikely(get_user(off, offset)))
789 ret = do_sendfile(out_fd, in_fd, &pos, count, MAX_NON_LFS);
790 if (unlikely(put_user(pos, offset)))
795 return do_sendfile(out_fd, in_fd, NULL, count, 0);
798 asmlinkage ssize_t sys_sendfile64(int out_fd, int in_fd, loff_t __user *offset, size_t count)
804 if (unlikely(copy_from_user(&pos, offset, sizeof(loff_t))))
806 ret = do_sendfile(out_fd, in_fd, &pos, count, 0);
807 if (unlikely(put_user(pos, offset)))
812 return do_sendfile(out_fd, in_fd, NULL, count, 0);