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);
148 EXPORT_SYMBOL_GPL(sys_lseek);
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 asmlinkage ssize_t sys_pread64(unsigned int fd, char __user *buf,
319 size_t count, loff_t pos)
322 ssize_t ret = -EBADF;
328 file = fget_light(fd, &fput_needed);
331 if (file->f_mode & FMODE_PREAD)
332 ret = vfs_read(file, buf, count, &pos);
333 fput_light(file, fput_needed);
339 asmlinkage ssize_t sys_pwrite64(unsigned int fd, const char __user *buf,
340 size_t count, loff_t pos)
343 ssize_t ret = -EBADF;
349 file = fget_light(fd, &fput_needed);
352 if (file->f_mode & FMODE_PWRITE)
353 ret = vfs_write(file, buf, count, &pos);
354 fput_light(file, fput_needed);
361 * Reduce an iovec's length in-place. Return the resulting number of segments
363 unsigned long iov_shorten(struct iovec *iov, unsigned long nr_segs, size_t to)
365 unsigned long seg = 0;
368 while (seg < nr_segs) {
370 if (len + iov->iov_len >= to) {
371 iov->iov_len = to - len;
380 EXPORT_SYMBOL(iov_shorten);
382 static ssize_t do_readv_writev(int type, struct file *file,
383 const struct iovec __user * uvector,
384 unsigned long nr_segs, loff_t *pos)
386 typedef ssize_t (*io_fn_t)(struct file *, char __user *, size_t, loff_t *);
387 typedef ssize_t (*iov_fn_t)(struct file *, const struct iovec *, unsigned long, loff_t *);
390 struct iovec iovstack[UIO_FASTIOV];
391 struct iovec *iov=iovstack, *vector;
399 * SuS says "The readv() function *may* fail if the iovcnt argument
400 * was less than or equal to 0, or greater than {IOV_MAX}. Linux has
401 * traditionally returned zero for zero segments, so...
408 * First get the "struct iovec" from user memory and
409 * verify all the pointers
412 if ((nr_segs > UIO_MAXIOV) || (nr_segs <= 0))
416 if (nr_segs > UIO_FASTIOV) {
418 iov = kmalloc(nr_segs*sizeof(struct iovec), GFP_KERNEL);
423 if (copy_from_user(iov, uvector, nr_segs*sizeof(*uvector)))
427 * Single unix specification:
428 * We should -EINVAL if an element length is not >= 0 and fitting an
429 * ssize_t. The total length is fitting an ssize_t
431 * Be careful here because iov_len is a size_t not an ssize_t
435 for (seg = 0; seg < nr_segs; seg++) {
436 ssize_t len = (ssize_t)iov[seg].iov_len;
438 if (len < 0) /* size_t not fitting an ssize_t .. */
441 if ((ssize_t)tot_len < 0) /* maths overflow on the ssize_t */
449 inode = file->f_dentry->d_inode;
450 /* VERIFY_WRITE actually means a read, as we write to user space */
451 ret = locks_verify_area((type == READ
452 ? FLOCK_VERIFY_READ : FLOCK_VERIFY_WRITE),
453 inode, file, *pos, tot_len);
459 fn = file->f_op->read;
460 fnv = file->f_op->readv;
462 fn = (io_fn_t)file->f_op->write;
463 fnv = file->f_op->writev;
466 ret = fnv(file, iov, nr_segs, pos);
470 /* Do it by hand, with file-ops */
473 while (nr_segs > 0) {
478 base = vector->iov_base;
479 len = vector->iov_len;
483 nr = fn(file, base, len, pos);
496 if ((ret + (type == READ)) > 0)
497 dnotify_parent(file->f_dentry,
498 (type == READ) ? DN_ACCESS : DN_MODIFY);
502 ssize_t vfs_readv(struct file *file, const struct iovec __user *vec,
503 unsigned long vlen, loff_t *pos)
505 if (!(file->f_mode & FMODE_READ))
507 if (!file->f_op || (!file->f_op->readv && !file->f_op->read))
510 return do_readv_writev(READ, file, vec, vlen, pos);
513 EXPORT_SYMBOL(vfs_readv);
515 ssize_t vfs_writev(struct file *file, const struct iovec __user *vec,
516 unsigned long vlen, loff_t *pos)
518 if (!(file->f_mode & FMODE_WRITE))
520 if (!file->f_op || (!file->f_op->writev && !file->f_op->write))
523 return do_readv_writev(WRITE, file, vec, vlen, pos);
526 EXPORT_SYMBOL(vfs_writev);
529 sys_readv(unsigned long fd, const struct iovec __user *vec, unsigned long vlen)
532 ssize_t ret = -EBADF;
535 file = fget_light(fd, &fput_needed);
537 loff_t pos = file_pos_read(file);
538 ret = vfs_readv(file, vec, vlen, &pos);
539 file_pos_write(file, pos);
540 fput_light(file, fput_needed);
547 sys_writev(unsigned long fd, const struct iovec __user *vec, unsigned long vlen)
550 ssize_t ret = -EBADF;
553 file = fget_light(fd, &fput_needed);
555 loff_t pos = file_pos_read(file);
556 ret = vfs_writev(file, vec, vlen, &pos);
557 file_pos_write(file, pos);
558 fput_light(file, fput_needed);
564 static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos,
565 size_t count, loff_t max)
567 struct file * in_file, * out_file;
568 struct inode * in_inode, * out_inode;
571 int fput_needed_in, fput_needed_out;
574 * Get input file, and verify that it is ok..
577 in_file = fget_light(in_fd, &fput_needed_in);
580 if (!(in_file->f_mode & FMODE_READ))
583 in_inode = in_file->f_dentry->d_inode;
586 if (!in_file->f_op || !in_file->f_op->sendfile)
590 ppos = &in_file->f_pos;
592 if (!(in_file->f_mode & FMODE_PREAD))
594 retval = locks_verify_area(FLOCK_VERIFY_READ, in_inode, in_file, *ppos, count);
598 retval = security_file_permission (in_file, MAY_READ);
603 * Get output file, and verify that it is ok..
606 out_file = fget_light(out_fd, &fput_needed_out);
609 if (!(out_file->f_mode & FMODE_WRITE))
612 if (!out_file->f_op || !out_file->f_op->sendpage)
614 out_inode = out_file->f_dentry->d_inode;
615 retval = locks_verify_area(FLOCK_VERIFY_WRITE, out_inode, out_file, out_file->f_pos, count);
619 retval = security_file_permission (out_file, MAY_WRITE);
624 max = min(in_inode->i_sb->s_maxbytes, out_inode->i_sb->s_maxbytes);
628 if (unlikely(pos < 0))
630 if (unlikely(pos + count > max)) {
637 retval = in_file->f_op->sendfile(in_file, ppos, count, file_send_actor, out_file);
643 fput_light(out_file, fput_needed_out);
645 fput_light(in_file, fput_needed_in);
650 asmlinkage ssize_t sys_sendfile(int out_fd, int in_fd, off_t __user *offset, size_t count)
657 if (unlikely(get_user(off, offset)))
660 ret = do_sendfile(out_fd, in_fd, &pos, count, MAX_NON_LFS);
661 if (unlikely(put_user(pos, offset)))
666 return do_sendfile(out_fd, in_fd, NULL, count, 0);
669 asmlinkage ssize_t sys_sendfile64(int out_fd, int in_fd, loff_t __user *offset, size_t count)
675 if (unlikely(copy_from_user(&pos, offset, sizeof(loff_t))))
677 ret = do_sendfile(out_fd, in_fd, &pos, count, 0);
678 if (unlikely(put_user(pos, offset)))
683 return do_sendfile(out_fd, in_fd, NULL, count, 0);