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/dnotify.h>
14 #include <linux/security.h>
15 #include <linux/module.h>
16 #include <linux/syscalls.h>
18 #include <asm/uaccess.h>
19 #include <asm/unistd.h>
21 struct 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,
28 EXPORT_SYMBOL(generic_ro_fops);
30 loff_t generic_file_llseek(struct file *file, loff_t offset, int origin)
33 struct inode *inode = file->f_mapping->host;
38 offset += inode->i_size;
41 offset += file->f_pos;
44 if (offset>=0 && offset<=inode->i_sb->s_maxbytes) {
45 if (offset != file->f_pos) {
55 EXPORT_SYMBOL(generic_file_llseek);
57 loff_t remote_llseek(struct file *file, loff_t offset, int origin)
64 offset += i_size_read(file->f_dentry->d_inode);
67 offset += file->f_pos;
70 if (offset>=0 && offset<=file->f_dentry->d_inode->i_sb->s_maxbytes) {
71 if (offset != file->f_pos) {
80 EXPORT_SYMBOL(remote_llseek);
82 loff_t no_llseek(struct file *file, loff_t offset, int origin)
86 EXPORT_SYMBOL(no_llseek);
88 loff_t default_llseek(struct file *file, loff_t offset, int origin)
95 offset += i_size_read(file->f_dentry->d_inode);
98 offset += file->f_pos;
102 if (offset != file->f_pos) {
103 file->f_pos = offset;
111 EXPORT_SYMBOL(default_llseek);
113 loff_t vfs_llseek(struct file *file, loff_t offset, int origin)
115 loff_t (*fn)(struct file *, loff_t, int);
118 if (file->f_mode & FMODE_LSEEK) {
120 if (file->f_op && file->f_op->llseek)
121 fn = file->f_op->llseek;
123 return fn(file, offset, origin);
125 EXPORT_SYMBOL(vfs_llseek);
127 asmlinkage off_t sys_lseek(unsigned int fd, off_t offset, unsigned int origin)
134 file = fget_light(fd, &fput_needed);
140 loff_t res = vfs_llseek(file, offset, origin);
142 if (res != (loff_t)retval)
143 retval = -EOVERFLOW; /* LFS: should only happen on 32 bit platforms */
145 fput_light(file, fput_needed);
150 #ifdef __ARCH_WANT_SYS_LLSEEK
151 asmlinkage long sys_llseek(unsigned int fd, unsigned long offset_high,
152 unsigned long offset_low, loff_t __user * result,
161 file = fget_light(fd, &fput_needed);
169 offset = vfs_llseek(file, ((loff_t) offset_high << 32) | offset_low,
172 retval = (int)offset;
175 if (!copy_to_user(result, &offset, sizeof(offset)))
179 fput_light(file, fput_needed);
185 ssize_t do_sync_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos)
190 init_sync_kiocb(&kiocb, filp);
191 kiocb.ki_pos = *ppos;
192 ret = filp->f_op->aio_read(&kiocb, buf, len, kiocb.ki_pos);
193 if (-EIOCBQUEUED == ret)
194 ret = wait_on_sync_kiocb(&kiocb);
195 *ppos = kiocb.ki_pos;
199 EXPORT_SYMBOL(do_sync_read);
201 ssize_t vfs_read(struct file *file, char __user *buf, size_t count, loff_t *pos)
203 struct inode *inode = file->f_dentry->d_inode;
206 if (!(file->f_mode & FMODE_READ))
208 if (!file->f_op || (!file->f_op->read && !file->f_op->aio_read))
211 ret = locks_verify_area(FLOCK_VERIFY_READ, inode, file, *pos, count);
213 ret = security_file_permission (file, MAY_READ);
215 if (file->f_op->read)
216 ret = file->f_op->read(file, buf, count, pos);
218 ret = do_sync_read(file, buf, count, pos);
220 dnotify_parent(file->f_dentry, DN_ACCESS);
227 EXPORT_SYMBOL(vfs_read);
229 ssize_t do_sync_write(struct file *filp, const char __user *buf, size_t len, loff_t *ppos)
234 init_sync_kiocb(&kiocb, filp);
235 kiocb.ki_pos = *ppos;
236 ret = filp->f_op->aio_write(&kiocb, buf, len, kiocb.ki_pos);
237 if (-EIOCBQUEUED == ret)
238 ret = wait_on_sync_kiocb(&kiocb);
239 *ppos = kiocb.ki_pos;
243 EXPORT_SYMBOL(do_sync_write);
245 ssize_t vfs_write(struct file *file, const char __user *buf, size_t count, loff_t *pos)
247 struct inode *inode = file->f_dentry->d_inode;
250 if (!(file->f_mode & FMODE_WRITE))
252 if (!file->f_op || (!file->f_op->write && !file->f_op->aio_write))
255 ret = locks_verify_area(FLOCK_VERIFY_WRITE, inode, file, *pos, count);
257 ret = security_file_permission (file, MAY_WRITE);
259 if (file->f_op->write)
260 ret = file->f_op->write(file, buf, count, pos);
262 ret = do_sync_write(file, buf, count, pos);
264 dnotify_parent(file->f_dentry, DN_MODIFY);
271 EXPORT_SYMBOL(vfs_write);
273 static inline loff_t file_pos_read(struct file *file)
278 static inline void file_pos_write(struct file *file, loff_t pos)
283 asmlinkage ssize_t sys_read(unsigned int fd, char __user * buf, size_t count)
286 ssize_t ret = -EBADF;
289 file = fget_light(fd, &fput_needed);
291 loff_t pos = file_pos_read(file);
292 ret = vfs_read(file, buf, count, &pos);
293 file_pos_write(file, pos);
294 fput_light(file, fput_needed);
299 EXPORT_SYMBOL_GPL(sys_read);
301 asmlinkage ssize_t sys_write(unsigned int fd, const char __user * buf, size_t count)
304 ssize_t ret = -EBADF;
307 file = fget_light(fd, &fput_needed);
309 loff_t pos = file_pos_read(file);
310 ret = vfs_write(file, buf, count, &pos);
311 file_pos_write(file, pos);
312 fput_light(file, fput_needed);
318 EXPORT_SYMBOL_GPL(sys_write);
320 asmlinkage ssize_t sys_pread64(unsigned int fd, char __user *buf,
321 size_t count, loff_t pos)
324 ssize_t ret = -EBADF;
330 file = fget_light(fd, &fput_needed);
333 if (file->f_mode & FMODE_PREAD)
334 ret = vfs_read(file, buf, count, &pos);
335 fput_light(file, fput_needed);
341 asmlinkage ssize_t sys_pwrite64(unsigned int fd, const char __user *buf,
342 size_t count, loff_t pos)
345 ssize_t ret = -EBADF;
351 file = fget_light(fd, &fput_needed);
354 if (file->f_mode & FMODE_PWRITE)
355 ret = vfs_write(file, buf, count, &pos);
356 fput_light(file, fput_needed);
363 * Reduce an iovec's length in-place. Return the resulting number of segments
365 unsigned long iov_shorten(struct iovec *iov, unsigned long nr_segs, size_t to)
367 unsigned long seg = 0;
370 while (seg < nr_segs) {
372 if (len + iov->iov_len >= to) {
373 iov->iov_len = to - len;
382 EXPORT_SYMBOL(iov_shorten);
384 static ssize_t do_readv_writev(int type, struct file *file,
385 const struct iovec __user * uvector,
386 unsigned long nr_segs, loff_t *pos)
388 typedef ssize_t (*io_fn_t)(struct file *, char __user *, size_t, loff_t *);
389 typedef ssize_t (*iov_fn_t)(struct file *, const struct iovec *, unsigned long, loff_t *);
392 struct iovec iovstack[UIO_FASTIOV];
393 struct iovec *iov=iovstack, *vector;
401 * SuS says "The readv() function *may* fail if the iovcnt argument
402 * was less than or equal to 0, or greater than {IOV_MAX}. Linux has
403 * traditionally returned zero for zero segments, so...
410 * First get the "struct iovec" from user memory and
411 * verify all the pointers
414 if ((nr_segs > UIO_MAXIOV) || (nr_segs <= 0))
418 if (nr_segs > UIO_FASTIOV) {
420 iov = kmalloc(nr_segs*sizeof(struct iovec), GFP_KERNEL);
425 if (copy_from_user(iov, uvector, nr_segs*sizeof(*uvector)))
429 * Single unix specification:
430 * We should -EINVAL if an element length is not >= 0 and fitting an
431 * ssize_t. The total length is fitting an ssize_t
433 * Be careful here because iov_len is a size_t not an ssize_t
437 for (seg = 0; seg < nr_segs; seg++) {
438 ssize_t len = (ssize_t)iov[seg].iov_len;
440 if (len < 0) /* size_t not fitting an ssize_t .. */
443 if ((ssize_t)tot_len < 0) /* maths overflow on the ssize_t */
451 inode = file->f_dentry->d_inode;
452 /* VERIFY_WRITE actually means a read, as we write to user space */
453 ret = locks_verify_area((type == READ
454 ? FLOCK_VERIFY_READ : FLOCK_VERIFY_WRITE),
455 inode, file, *pos, tot_len);
461 fn = file->f_op->read;
462 fnv = file->f_op->readv;
464 fn = (io_fn_t)file->f_op->write;
465 fnv = file->f_op->writev;
468 ret = fnv(file, iov, nr_segs, pos);
472 /* Do it by hand, with file-ops */
475 while (nr_segs > 0) {
480 base = vector->iov_base;
481 len = vector->iov_len;
485 nr = fn(file, base, len, pos);
498 if ((ret + (type == READ)) > 0)
499 dnotify_parent(file->f_dentry,
500 (type == READ) ? DN_ACCESS : DN_MODIFY);
504 ssize_t vfs_readv(struct file *file, const struct iovec __user *vec,
505 unsigned long vlen, loff_t *pos)
507 if (!(file->f_mode & FMODE_READ))
509 if (!file->f_op || (!file->f_op->readv && !file->f_op->read))
512 return do_readv_writev(READ, file, vec, vlen, pos);
515 EXPORT_SYMBOL(vfs_readv);
517 ssize_t vfs_writev(struct file *file, const struct iovec __user *vec,
518 unsigned long vlen, loff_t *pos)
520 if (!(file->f_mode & FMODE_WRITE))
522 if (!file->f_op || (!file->f_op->writev && !file->f_op->write))
525 return do_readv_writev(WRITE, file, vec, vlen, pos);
528 EXPORT_SYMBOL(vfs_writev);
531 sys_readv(unsigned long fd, const struct iovec __user *vec, unsigned long vlen)
534 ssize_t ret = -EBADF;
537 file = fget_light(fd, &fput_needed);
539 loff_t pos = file_pos_read(file);
540 ret = vfs_readv(file, vec, vlen, &pos);
541 file_pos_write(file, pos);
542 fput_light(file, fput_needed);
549 sys_writev(unsigned long fd, const struct iovec __user *vec, unsigned long vlen)
552 ssize_t ret = -EBADF;
555 file = fget_light(fd, &fput_needed);
557 loff_t pos = file_pos_read(file);
558 ret = vfs_writev(file, vec, vlen, &pos);
559 file_pos_write(file, pos);
560 fput_light(file, fput_needed);
566 static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos,
567 size_t count, loff_t max)
569 struct file * in_file, * out_file;
570 struct inode * in_inode, * out_inode;
573 int fput_needed_in, fput_needed_out;
576 * Get input file, and verify that it is ok..
579 in_file = fget_light(in_fd, &fput_needed_in);
582 if (!(in_file->f_mode & FMODE_READ))
585 in_inode = in_file->f_dentry->d_inode;
588 if (!in_file->f_op || !in_file->f_op->sendfile)
592 ppos = &in_file->f_pos;
594 if (!(in_file->f_mode & FMODE_PREAD))
596 retval = locks_verify_area(FLOCK_VERIFY_READ, in_inode, in_file, *ppos, count);
600 retval = security_file_permission (in_file, MAY_READ);
605 * Get output file, and verify that it is ok..
608 out_file = fget_light(out_fd, &fput_needed_out);
611 if (!(out_file->f_mode & FMODE_WRITE))
614 if (!out_file->f_op || !out_file->f_op->sendpage)
616 out_inode = out_file->f_dentry->d_inode;
617 retval = locks_verify_area(FLOCK_VERIFY_WRITE, out_inode, out_file, out_file->f_pos, count);
621 retval = security_file_permission (out_file, MAY_WRITE);
626 max = min(in_inode->i_sb->s_maxbytes, out_inode->i_sb->s_maxbytes);
630 if (unlikely(pos < 0))
632 if (unlikely(pos + count > max)) {
639 retval = in_file->f_op->sendfile(in_file, ppos, count, file_send_actor, out_file);
645 fput_light(out_file, fput_needed_out);
647 fput_light(in_file, fput_needed_in);
652 asmlinkage ssize_t sys_sendfile(int out_fd, int in_fd, off_t __user *offset, size_t count)
659 if (unlikely(get_user(off, offset)))
662 ret = do_sendfile(out_fd, in_fd, &pos, count, MAX_NON_LFS);
663 if (unlikely(put_user(pos, offset)))
668 return do_sendfile(out_fd, in_fd, NULL, count, 0);
671 asmlinkage ssize_t sys_sendfile64(int out_fd, int in_fd, loff_t __user *offset, size_t count)
677 if (unlikely(copy_from_user(&pos, offset, sizeof(loff_t))))
679 ret = do_sendfile(out_fd, in_fd, &pos, count, 0);
680 if (unlikely(put_user(pos, offset)))
685 return do_sendfile(out_fd, in_fd, NULL, count, 0);