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) {
80 EXPORT_SYMBOL(remote_llseek);
82 loff_t no_llseek(struct file *file, loff_t offset, int origin)
87 EXPORT_SYMBOL(no_llseek);
89 loff_t default_llseek(struct file *file, loff_t offset, int origin)
96 offset += i_size_read(file->f_dentry->d_inode);
99 offset += file->f_pos;
103 if (offset != file->f_pos) {
104 file->f_pos = offset;
113 EXPORT_SYMBOL(default_llseek);
115 static inline loff_t llseek(struct file *file, loff_t offset, int origin)
117 loff_t (*fn)(struct file *, loff_t, int);
120 if (file->f_op && file->f_op->llseek)
121 fn = file->f_op->llseek;
122 return fn(file, offset, origin);
125 asmlinkage off_t sys_lseek(unsigned int fd, off_t offset, unsigned int origin)
132 file = fget_light(fd, &fput_needed);
138 loff_t res = llseek(file, offset, origin);
140 if (res != (loff_t)retval)
141 retval = -EOVERFLOW; /* LFS: should only happen on 32 bit platforms */
143 fput_light(file, fput_needed);
148 #ifdef __ARCH_WANT_SYS_LLSEEK
149 asmlinkage long sys_llseek(unsigned int fd, unsigned long offset_high,
150 unsigned long offset_low, loff_t __user * result,
159 file = fget_light(fd, &fput_needed);
167 offset = llseek(file, ((loff_t) offset_high << 32) | offset_low,
170 retval = (int)offset;
173 if (!copy_to_user(result, &offset, sizeof(offset)))
177 fput_light(file, fput_needed);
183 ssize_t do_sync_read(struct file *filp, char __user *buf, size_t len, loff_t *ppos)
188 init_sync_kiocb(&kiocb, filp);
189 kiocb.ki_pos = *ppos;
190 ret = filp->f_op->aio_read(&kiocb, buf, len, kiocb.ki_pos);
191 if (-EIOCBQUEUED == ret)
192 ret = wait_on_sync_kiocb(&kiocb);
193 *ppos = kiocb.ki_pos;
197 EXPORT_SYMBOL(do_sync_read);
199 ssize_t vfs_read(struct file *file, char __user *buf, size_t count, loff_t *pos)
201 struct inode *inode = file->f_dentry->d_inode;
204 if (!(file->f_mode & FMODE_READ))
206 if (!file->f_op || (!file->f_op->read && !file->f_op->aio_read))
209 ret = locks_verify_area(FLOCK_VERIFY_READ, inode, file, *pos, count);
211 ret = security_file_permission (file, MAY_READ);
213 if (file->f_op->read)
214 ret = file->f_op->read(file, buf, count, pos);
216 ret = do_sync_read(file, buf, count, pos);
218 dnotify_parent(file->f_dentry, DN_ACCESS);
225 EXPORT_SYMBOL(vfs_read);
227 ssize_t do_sync_write(struct file *filp, const char __user *buf, size_t len, loff_t *ppos)
232 init_sync_kiocb(&kiocb, filp);
233 kiocb.ki_pos = *ppos;
234 ret = filp->f_op->aio_write(&kiocb, buf, len, kiocb.ki_pos);
235 if (-EIOCBQUEUED == ret)
236 ret = wait_on_sync_kiocb(&kiocb);
237 *ppos = kiocb.ki_pos;
241 EXPORT_SYMBOL(do_sync_write);
243 ssize_t vfs_write(struct file *file, const char __user *buf, size_t count, loff_t *pos)
245 struct inode *inode = file->f_dentry->d_inode;
248 if (!(file->f_mode & FMODE_WRITE))
250 if (!file->f_op || (!file->f_op->write && !file->f_op->aio_write))
253 ret = locks_verify_area(FLOCK_VERIFY_WRITE, inode, file, *pos, count);
255 ret = security_file_permission (file, MAY_WRITE);
257 if (file->f_op->write)
258 ret = file->f_op->write(file, buf, count, pos);
260 ret = do_sync_write(file, buf, count, pos);
262 dnotify_parent(file->f_dentry, DN_MODIFY);
269 EXPORT_SYMBOL(vfs_write);
271 asmlinkage ssize_t sys_read(unsigned int fd, char __user * buf, size_t count)
274 ssize_t ret = -EBADF;
277 file = fget_light(fd, &fput_needed);
279 ret = vfs_read(file, buf, count, &file->f_pos);
280 fput_light(file, fput_needed);
286 asmlinkage ssize_t sys_write(unsigned int fd, const char __user * buf, size_t count)
289 ssize_t ret = -EBADF;
292 file = fget_light(fd, &fput_needed);
294 ret = vfs_write(file, buf, count, &file->f_pos);
295 fput_light(file, fput_needed);
301 asmlinkage ssize_t sys_pread64(unsigned int fd, char __user *buf,
302 size_t count, loff_t pos)
305 ssize_t ret = -EBADF;
311 file = fget_light(fd, &fput_needed);
313 ret = vfs_read(file, buf, count, &pos);
314 fput_light(file, fput_needed);
320 asmlinkage ssize_t sys_pwrite64(unsigned int fd, const char __user *buf,
321 size_t count, loff_t pos)
324 ssize_t ret = -EBADF;
330 file = fget_light(fd, &fput_needed);
332 ret = vfs_write(file, buf, count, &pos);
333 fput_light(file, fput_needed);
340 * Reduce an iovec's length in-place. Return the resulting number of segments
342 unsigned long iov_shorten(struct iovec *iov, unsigned long nr_segs, size_t to)
344 unsigned long seg = 0;
347 while (seg < nr_segs) {
349 if (len + iov->iov_len >= to) {
350 iov->iov_len = to - len;
359 EXPORT_SYMBOL(iov_shorten);
361 static ssize_t do_readv_writev(int type, struct file *file,
362 const struct iovec __user * uvector,
363 unsigned long nr_segs, loff_t *pos)
365 typedef ssize_t (*io_fn_t)(struct file *, char __user *, size_t, loff_t *);
366 typedef ssize_t (*iov_fn_t)(struct file *, const struct iovec *, unsigned long, loff_t *);
369 struct iovec iovstack[UIO_FASTIOV];
370 struct iovec *iov=iovstack, *vector;
378 * SuS says "The readv() function *may* fail if the iovcnt argument
379 * was less than or equal to 0, or greater than {IOV_MAX}. Linux has
380 * traditionally returned zero for zero segments, so...
387 * First get the "struct iovec" from user memory and
388 * verify all the pointers
391 if ((nr_segs > UIO_MAXIOV) || (nr_segs <= 0))
395 if (nr_segs > UIO_FASTIOV) {
397 iov = kmalloc(nr_segs*sizeof(struct iovec), GFP_KERNEL);
402 if (copy_from_user(iov, uvector, nr_segs*sizeof(*uvector)))
406 * Single unix specification:
407 * We should -EINVAL if an element length is not >= 0 and fitting an
408 * ssize_t. The total length is fitting an ssize_t
410 * Be careful here because iov_len is a size_t not an ssize_t
414 for (seg = 0; seg < nr_segs; seg++) {
415 ssize_t len = (ssize_t)iov[seg].iov_len;
417 if (len < 0) /* size_t not fitting an ssize_t .. */
420 if ((ssize_t)tot_len < 0) /* maths overflow on the ssize_t */
428 inode = file->f_dentry->d_inode;
429 /* VERIFY_WRITE actually means a read, as we write to user space */
430 ret = locks_verify_area((type == READ
431 ? FLOCK_VERIFY_READ : FLOCK_VERIFY_WRITE),
432 inode, file, *pos, tot_len);
438 fn = file->f_op->read;
439 fnv = file->f_op->readv;
441 fn = (io_fn_t)file->f_op->write;
442 fnv = file->f_op->writev;
445 ret = fnv(file, iov, nr_segs, pos);
449 /* Do it by hand, with file-ops */
452 while (nr_segs > 0) {
457 base = vector->iov_base;
458 len = vector->iov_len;
462 nr = fn(file, base, len, pos);
475 if ((ret + (type == READ)) > 0)
476 dnotify_parent(file->f_dentry,
477 (type == READ) ? DN_ACCESS : DN_MODIFY);
481 ssize_t vfs_readv(struct file *file, const struct iovec __user *vec,
482 unsigned long vlen, loff_t *pos)
484 if (!(file->f_mode & FMODE_READ))
486 if (!file->f_op || (!file->f_op->readv && !file->f_op->read))
489 return do_readv_writev(READ, file, vec, vlen, pos);
492 EXPORT_SYMBOL(vfs_readv);
494 ssize_t vfs_writev(struct file *file, const struct iovec __user *vec,
495 unsigned long vlen, loff_t *pos)
497 if (!(file->f_mode & FMODE_WRITE))
499 if (!file->f_op || (!file->f_op->writev && !file->f_op->write))
502 return do_readv_writev(WRITE, file, vec, vlen, pos);
505 EXPORT_SYMBOL(vfs_writev);
508 sys_readv(unsigned long fd, const struct iovec __user *vec, unsigned long vlen)
511 ssize_t ret = -EBADF;
514 file = fget_light(fd, &fput_needed);
516 ret = vfs_readv(file, vec, vlen, &file->f_pos);
517 fput_light(file, fput_needed);
524 sys_writev(unsigned long fd, const struct iovec __user *vec, unsigned long vlen)
527 ssize_t ret = -EBADF;
530 file = fget_light(fd, &fput_needed);
532 ret = vfs_writev(file, vec, vlen, &file->f_pos);
533 fput_light(file, fput_needed);
539 static ssize_t do_sendfile(int out_fd, int in_fd, loff_t *ppos,
540 size_t count, loff_t max)
542 struct file * in_file, * out_file;
543 struct inode * in_inode, * out_inode;
546 int fput_needed_in, fput_needed_out;
549 * Get input file, and verify that it is ok..
552 in_file = fget_light(in_fd, &fput_needed_in);
555 if (!(in_file->f_mode & FMODE_READ))
558 in_inode = in_file->f_dentry->d_inode;
561 if (!in_file->f_op || !in_file->f_op->sendfile)
564 ppos = &in_file->f_pos;
565 retval = locks_verify_area(FLOCK_VERIFY_READ, in_inode, in_file, *ppos, count);
569 retval = security_file_permission (in_file, MAY_READ);
574 * Get output file, and verify that it is ok..
577 out_file = fget_light(out_fd, &fput_needed_out);
580 if (!(out_file->f_mode & FMODE_WRITE))
583 if (!out_file->f_op || !out_file->f_op->sendpage)
585 out_inode = out_file->f_dentry->d_inode;
586 retval = locks_verify_area(FLOCK_VERIFY_WRITE, out_inode, out_file, out_file->f_pos, count);
590 retval = security_file_permission (out_file, MAY_WRITE);
595 max = min(in_inode->i_sb->s_maxbytes, out_inode->i_sb->s_maxbytes);
599 if (unlikely(pos < 0))
601 if (unlikely(pos + count > max)) {
608 retval = in_file->f_op->sendfile(in_file, ppos, count, file_send_actor, out_file);
614 fput_light(out_file, fput_needed_out);
616 fput_light(in_file, fput_needed_in);
621 asmlinkage ssize_t sys_sendfile(int out_fd, int in_fd, off_t __user *offset, size_t count)
628 if (unlikely(get_user(off, offset)))
631 ret = do_sendfile(out_fd, in_fd, &pos, count, MAX_NON_LFS);
632 if (unlikely(put_user(pos, offset)))
637 return do_sendfile(out_fd, in_fd, NULL, count, 0);
640 asmlinkage ssize_t sys_sendfile64(int out_fd, int in_fd, loff_t __user *offset, size_t count)
646 if (unlikely(copy_from_user(&pos, offset, sizeof(loff_t))))
648 ret = do_sendfile(out_fd, in_fd, &pos, count, 0);
649 if (unlikely(put_user(pos, offset)))
654 return do_sendfile(out_fd, in_fd, NULL, count, 0);