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>
17 #include <asm/uaccess.h>
18 #include <asm/unistd.h>
20 struct file_operations generic_ro_fops = {
21 .llseek = generic_file_llseek,
22 .read = generic_file_read,
23 .mmap = generic_file_readonly_mmap,
24 .sendfile = generic_file_sendfile,
27 EXPORT_SYMBOL(generic_ro_fops);
29 loff_t generic_file_llseek(struct file *file, loff_t offset, int origin)
32 struct inode *inode = file->f_mapping->host;
37 offset += inode->i_size;
40 offset += file->f_pos;
43 if (offset>=0 && offset<=inode->i_sb->s_maxbytes) {
44 if (offset != file->f_pos) {
54 EXPORT_SYMBOL(generic_file_llseek);
56 loff_t remote_llseek(struct file *file, loff_t offset, int origin)
63 offset += i_size_read(file->f_dentry->d_inode);
66 offset += file->f_pos;
69 if (offset>=0 && offset<=file->f_dentry->d_inode->i_sb->s_maxbytes) {
70 if (offset != file->f_pos) {
79 EXPORT_SYMBOL(remote_llseek);
81 loff_t no_llseek(struct file *file, loff_t offset, int origin)
85 EXPORT_SYMBOL(no_llseek);
87 loff_t default_llseek(struct file *file, loff_t offset, int origin)
94 offset += i_size_read(file->f_dentry->d_inode);
97 offset += file->f_pos;
101 if (offset != file->f_pos) {
102 file->f_pos = offset;
110 EXPORT_SYMBOL(default_llseek);
112 loff_t vfs_llseek(struct file *file, loff_t offset, int origin)
114 loff_t (*fn)(struct file *, loff_t, int);
117 if (file->f_mode & FMODE_LSEEK) {
119 if (file->f_op && file->f_op->llseek)
120 fn = file->f_op->llseek;
122 return fn(file, offset, origin);
124 EXPORT_SYMBOL(vfs_llseek);
126 asmlinkage off_t sys_lseek(unsigned int fd, off_t offset, unsigned int origin)
133 file = fget_light(fd, &fput_needed);
139 loff_t res = vfs_llseek(file, offset, origin);
141 if (res != (loff_t)retval)
142 retval = -EOVERFLOW; /* LFS: should only happen on 32 bit platforms */
144 fput_light(file, fput_needed);
149 #ifdef __ARCH_WANT_SYS_LLSEEK
150 asmlinkage long sys_llseek(unsigned int fd, unsigned long offset_high,
151 unsigned long offset_low, loff_t __user * result,
160 file = fget_light(fd, &fput_needed);
168 offset = vfs_llseek(file, ((loff_t) offset_high << 32) | offset_low,
171 retval = (int)offset;
174 if (!copy_to_user(result, &offset, sizeof(offset)))
178 fput_light(file, fput_needed);
184 ssize_t do_sync_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos)
189 init_sync_kiocb(&kiocb, filp);
190 kiocb.ki_pos = *ppos;
191 ret = filp->f_op->aio_read(&kiocb, buf, len, kiocb.ki_pos);
192 if (-EIOCBQUEUED == ret)
193 ret = wait_on_sync_kiocb(&kiocb);
194 *ppos = kiocb.ki_pos;
198 EXPORT_SYMBOL(do_sync_read);
200 ssize_t vfs_read(struct file *file, char __user *buf, size_t count, loff_t *pos)
202 struct inode *inode = file->f_dentry->d_inode;
205 if (!(file->f_mode & FMODE_READ))
207 if (!file->f_op || (!file->f_op->read && !file->f_op->aio_read))
210 ret = locks_verify_area(FLOCK_VERIFY_READ, inode, file, *pos, count);
212 ret = security_file_permission (file, MAY_READ);
214 if (file->f_op->read)
215 ret = file->f_op->read(file, buf, count, pos);
217 ret = do_sync_read(file, buf, count, pos);
219 dnotify_parent(file->f_dentry, DN_ACCESS);
226 EXPORT_SYMBOL(vfs_read);
228 ssize_t do_sync_write(struct file *filp, const char __user *buf, size_t len, loff_t *ppos)
233 init_sync_kiocb(&kiocb, filp);
234 kiocb.ki_pos = *ppos;
235 ret = filp->f_op->aio_write(&kiocb, buf, len, kiocb.ki_pos);
236 if (-EIOCBQUEUED == ret)
237 ret = wait_on_sync_kiocb(&kiocb);
238 *ppos = kiocb.ki_pos;
242 EXPORT_SYMBOL(do_sync_write);
244 ssize_t vfs_write(struct file *file, const char __user *buf, size_t count, loff_t *pos)
246 struct inode *inode = file->f_dentry->d_inode;
249 if (!(file->f_mode & FMODE_WRITE))
251 if (!file->f_op || (!file->f_op->write && !file->f_op->aio_write))
254 ret = locks_verify_area(FLOCK_VERIFY_WRITE, inode, file, *pos, count);
256 ret = security_file_permission (file, MAY_WRITE);
258 if (file->f_op->write)
259 ret = file->f_op->write(file, buf, count, pos);
261 ret = do_sync_write(file, buf, count, pos);
263 dnotify_parent(file->f_dentry, DN_MODIFY);
270 EXPORT_SYMBOL(vfs_write);
272 static inline loff_t file_pos_read(struct file *file)
277 static inline void file_pos_write(struct file *file, loff_t pos)
282 asmlinkage ssize_t sys_read(unsigned int fd, char __user * buf, size_t count)
285 ssize_t ret = -EBADF;
288 file = fget_light(fd, &fput_needed);
290 loff_t pos = file_pos_read(file);
291 ret = vfs_read(file, buf, count, &pos);
292 file_pos_write(file, pos);
293 fput_light(file, fput_needed);
299 asmlinkage ssize_t sys_write(unsigned int fd, const char __user * buf, size_t count)
302 ssize_t ret = -EBADF;
305 file = fget_light(fd, &fput_needed);
307 loff_t pos = file_pos_read(file);
308 ret = vfs_write(file, buf, count, &pos);
309 file_pos_write(file, pos);
310 fput_light(file, fput_needed);
316 asmlinkage ssize_t sys_pread64(unsigned int fd, char __user *buf,
317 size_t count, loff_t pos)
320 ssize_t ret = -EBADF;
326 file = fget_light(fd, &fput_needed);
329 if (file->f_mode & FMODE_PREAD)
330 ret = vfs_read(file, buf, count, &pos);
331 fput_light(file, fput_needed);
337 asmlinkage ssize_t sys_pwrite64(unsigned int fd, const char __user *buf,
338 size_t count, loff_t pos)
341 ssize_t ret = -EBADF;
347 file = fget_light(fd, &fput_needed);
350 if (file->f_mode & FMODE_PWRITE)
351 ret = vfs_write(file, buf, count, &pos);
352 fput_light(file, fput_needed);
359 * Reduce an iovec's length in-place. Return the resulting number of segments
361 unsigned long iov_shorten(struct iovec *iov, unsigned long nr_segs, size_t to)
363 unsigned long seg = 0;
366 while (seg < nr_segs) {
368 if (len + iov->iov_len >= to) {
369 iov->iov_len = to - len;
378 EXPORT_SYMBOL(iov_shorten);
380 static ssize_t do_readv_writev(int type, struct file *file,
381 const struct iovec __user * uvector,
382 unsigned long nr_segs, loff_t *pos)
384 typedef ssize_t (*io_fn_t)(struct file *, char __user *, size_t, loff_t *);
385 typedef ssize_t (*iov_fn_t)(struct file *, const struct iovec *, unsigned long, loff_t *);
388 struct iovec iovstack[UIO_FASTIOV];
389 struct iovec *iov=iovstack, *vector;
397 * SuS says "The readv() function *may* fail if the iovcnt argument
398 * was less than or equal to 0, or greater than {IOV_MAX}. Linux has
399 * traditionally returned zero for zero segments, so...
406 * First get the "struct iovec" from user memory and
407 * verify all the pointers
410 if ((nr_segs > UIO_MAXIOV) || (nr_segs <= 0))
414 if (nr_segs > UIO_FASTIOV) {
416 iov = kmalloc(nr_segs*sizeof(struct iovec), GFP_KERNEL);
421 if (copy_from_user(iov, uvector, nr_segs*sizeof(*uvector)))
425 * Single unix specification:
426 * We should -EINVAL if an element length is not >= 0 and fitting an
427 * ssize_t. The total length is fitting an ssize_t
429 * Be careful here because iov_len is a size_t not an ssize_t
433 for (seg = 0; seg < nr_segs; seg++) {
434 ssize_t len = (ssize_t)iov[seg].iov_len;
436 if (len < 0) /* size_t not fitting an ssize_t .. */
439 if ((ssize_t)tot_len < 0) /* maths overflow on the ssize_t */
447 inode = file->f_dentry->d_inode;
448 /* VERIFY_WRITE actually means a read, as we write to user space */
449 ret = locks_verify_area((type == READ
450 ? FLOCK_VERIFY_READ : FLOCK_VERIFY_WRITE),
451 inode, file, *pos, tot_len);
457 fn = file->f_op->read;
458 fnv = file->f_op->readv;
460 fn = (io_fn_t)file->f_op->write;
461 fnv = file->f_op->writev;
464 ret = fnv(file, iov, nr_segs, pos);
468 /* Do it by hand, with file-ops */
471 while (nr_segs > 0) {
476 base = vector->iov_base;
477 len = vector->iov_len;
481 nr = fn(file, base, len, pos);
494 if ((ret + (type == READ)) > 0)
495 dnotify_parent(file->f_dentry,
496 (type == READ) ? DN_ACCESS : DN_MODIFY);
500 ssize_t vfs_readv(struct file *file, const struct iovec __user *vec,
501 unsigned long vlen, loff_t *pos)
503 if (!(file->f_mode & FMODE_READ))
505 if (!file->f_op || (!file->f_op->readv && !file->f_op->read))
508 return do_readv_writev(READ, file, vec, vlen, pos);
511 EXPORT_SYMBOL(vfs_readv);
513 ssize_t vfs_writev(struct file *file, const struct iovec __user *vec,
514 unsigned long vlen, loff_t *pos)
516 if (!(file->f_mode & FMODE_WRITE))
518 if (!file->f_op || (!file->f_op->writev && !file->f_op->write))
521 return do_readv_writev(WRITE, file, vec, vlen, pos);
524 EXPORT_SYMBOL(vfs_writev);
527 sys_readv(unsigned long fd, const struct iovec __user *vec, unsigned long vlen)
530 ssize_t ret = -EBADF;
533 file = fget_light(fd, &fput_needed);
535 loff_t pos = file_pos_read(file);
536 ret = vfs_readv(file, vec, vlen, &pos);
537 file_pos_write(file, pos);
538 fput_light(file, fput_needed);
545 sys_writev(unsigned long fd, const struct iovec __user *vec, unsigned long vlen)
548 ssize_t ret = -EBADF;
551 file = fget_light(fd, &fput_needed);
553 loff_t pos = file_pos_read(file);
554 ret = vfs_writev(file, vec, vlen, &pos);
555 file_pos_write(file, pos);
556 fput_light(file, fput_needed);
562 static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos,
563 size_t count, loff_t max)
565 struct file * in_file, * out_file;
566 struct inode * in_inode, * out_inode;
569 int fput_needed_in, fput_needed_out;
572 * Get input file, and verify that it is ok..
575 in_file = fget_light(in_fd, &fput_needed_in);
578 if (!(in_file->f_mode & FMODE_READ))
581 in_inode = in_file->f_dentry->d_inode;
584 if (!in_file->f_op || !in_file->f_op->sendfile)
588 ppos = &in_file->f_pos;
590 if (!(in_file->f_mode & FMODE_PREAD))
592 retval = locks_verify_area(FLOCK_VERIFY_READ, in_inode, in_file, *ppos, count);
596 retval = security_file_permission (in_file, MAY_READ);
601 * Get output file, and verify that it is ok..
604 out_file = fget_light(out_fd, &fput_needed_out);
607 if (!(out_file->f_mode & FMODE_WRITE))
610 if (!out_file->f_op || !out_file->f_op->sendpage)
612 out_inode = out_file->f_dentry->d_inode;
613 retval = locks_verify_area(FLOCK_VERIFY_WRITE, out_inode, out_file, out_file->f_pos, count);
617 retval = security_file_permission (out_file, MAY_WRITE);
622 max = min(in_inode->i_sb->s_maxbytes, out_inode->i_sb->s_maxbytes);
626 if (unlikely(pos < 0))
628 if (unlikely(pos + count > max)) {
635 retval = in_file->f_op->sendfile(in_file, ppos, count, file_send_actor, out_file);
641 fput_light(out_file, fput_needed_out);
643 fput_light(in_file, fput_needed_in);
648 asmlinkage ssize_t sys_sendfile(int out_fd, int in_fd, off_t __user *offset, size_t count)
655 if (unlikely(get_user(off, offset)))
658 ret = do_sendfile(out_fd, in_fd, &pos, count, MAX_NON_LFS);
659 if (unlikely(put_user(pos, offset)))
664 return do_sendfile(out_fd, in_fd, NULL, count, 0);
667 asmlinkage ssize_t sys_sendfile64(int out_fd, int in_fd, loff_t __user *offset, size_t count)
673 if (unlikely(copy_from_user(&pos, offset, sizeof(loff_t))))
675 ret = do_sendfile(out_fd, in_fd, &pos, count, 0);
676 if (unlikely(put_user(pos, offset)))
681 return do_sendfile(out_fd, in_fd, NULL, count, 0);