[XFS] clean up some xfs_log_priv.h macros
[linux-2.6/mini2440.git] / fs / open.c
blob4932b4d1da05f72037b22ec04378edcf83fbc14f
1 /*
2 * linux/fs/open.c
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 */
7 #include <linux/string.h>
8 #include <linux/mm.h>
9 #include <linux/file.h>
10 #include <linux/quotaops.h>
11 #include <linux/fsnotify.h>
12 #include <linux/module.h>
13 #include <linux/slab.h>
14 #include <linux/tty.h>
15 #include <linux/namei.h>
16 #include <linux/backing-dev.h>
17 #include <linux/capability.h>
18 #include <linux/security.h>
19 #include <linux/mount.h>
20 #include <linux/vfs.h>
21 #include <linux/fcntl.h>
22 #include <asm/uaccess.h>
23 #include <linux/fs.h>
24 #include <linux/personality.h>
25 #include <linux/pagemap.h>
26 #include <linux/syscalls.h>
27 #include <linux/rcupdate.h>
28 #include <linux/audit.h>
29 #include <linux/falloc.h>
31 int vfs_statfs(struct dentry *dentry, struct kstatfs *buf)
33 int retval = -ENODEV;
35 if (dentry) {
36 retval = -ENOSYS;
37 if (dentry->d_sb->s_op->statfs) {
38 memset(buf, 0, sizeof(*buf));
39 retval = security_sb_statfs(dentry);
40 if (retval)
41 return retval;
42 retval = dentry->d_sb->s_op->statfs(dentry, buf);
43 if (retval == 0 && buf->f_frsize == 0)
44 buf->f_frsize = buf->f_bsize;
47 return retval;
50 EXPORT_SYMBOL(vfs_statfs);
52 static int vfs_statfs_native(struct dentry *dentry, struct statfs *buf)
54 struct kstatfs st;
55 int retval;
57 retval = vfs_statfs(dentry, &st);
58 if (retval)
59 return retval;
61 if (sizeof(*buf) == sizeof(st))
62 memcpy(buf, &st, sizeof(st));
63 else {
64 if (sizeof buf->f_blocks == 4) {
65 if ((st.f_blocks | st.f_bfree | st.f_bavail) &
66 0xffffffff00000000ULL)
67 return -EOVERFLOW;
69 * f_files and f_ffree may be -1; it's okay to stuff
70 * that into 32 bits
72 if (st.f_files != -1 &&
73 (st.f_files & 0xffffffff00000000ULL))
74 return -EOVERFLOW;
75 if (st.f_ffree != -1 &&
76 (st.f_ffree & 0xffffffff00000000ULL))
77 return -EOVERFLOW;
80 buf->f_type = st.f_type;
81 buf->f_bsize = st.f_bsize;
82 buf->f_blocks = st.f_blocks;
83 buf->f_bfree = st.f_bfree;
84 buf->f_bavail = st.f_bavail;
85 buf->f_files = st.f_files;
86 buf->f_ffree = st.f_ffree;
87 buf->f_fsid = st.f_fsid;
88 buf->f_namelen = st.f_namelen;
89 buf->f_frsize = st.f_frsize;
90 memset(buf->f_spare, 0, sizeof(buf->f_spare));
92 return 0;
95 static int vfs_statfs64(struct dentry *dentry, struct statfs64 *buf)
97 struct kstatfs st;
98 int retval;
100 retval = vfs_statfs(dentry, &st);
101 if (retval)
102 return retval;
104 if (sizeof(*buf) == sizeof(st))
105 memcpy(buf, &st, sizeof(st));
106 else {
107 buf->f_type = st.f_type;
108 buf->f_bsize = st.f_bsize;
109 buf->f_blocks = st.f_blocks;
110 buf->f_bfree = st.f_bfree;
111 buf->f_bavail = st.f_bavail;
112 buf->f_files = st.f_files;
113 buf->f_ffree = st.f_ffree;
114 buf->f_fsid = st.f_fsid;
115 buf->f_namelen = st.f_namelen;
116 buf->f_frsize = st.f_frsize;
117 memset(buf->f_spare, 0, sizeof(buf->f_spare));
119 return 0;
122 asmlinkage long sys_statfs(const char __user * path, struct statfs __user * buf)
124 struct nameidata nd;
125 int error;
127 error = user_path_walk(path, &nd);
128 if (!error) {
129 struct statfs tmp;
130 error = vfs_statfs_native(nd.dentry, &tmp);
131 if (!error && copy_to_user(buf, &tmp, sizeof(tmp)))
132 error = -EFAULT;
133 path_release(&nd);
135 return error;
139 asmlinkage long sys_statfs64(const char __user *path, size_t sz, struct statfs64 __user *buf)
141 struct nameidata nd;
142 long error;
144 if (sz != sizeof(*buf))
145 return -EINVAL;
146 error = user_path_walk(path, &nd);
147 if (!error) {
148 struct statfs64 tmp;
149 error = vfs_statfs64(nd.dentry, &tmp);
150 if (!error && copy_to_user(buf, &tmp, sizeof(tmp)))
151 error = -EFAULT;
152 path_release(&nd);
154 return error;
158 asmlinkage long sys_fstatfs(unsigned int fd, struct statfs __user * buf)
160 struct file * file;
161 struct statfs tmp;
162 int error;
164 error = -EBADF;
165 file = fget(fd);
166 if (!file)
167 goto out;
168 error = vfs_statfs_native(file->f_path.dentry, &tmp);
169 if (!error && copy_to_user(buf, &tmp, sizeof(tmp)))
170 error = -EFAULT;
171 fput(file);
172 out:
173 return error;
176 asmlinkage long sys_fstatfs64(unsigned int fd, size_t sz, struct statfs64 __user *buf)
178 struct file * file;
179 struct statfs64 tmp;
180 int error;
182 if (sz != sizeof(*buf))
183 return -EINVAL;
185 error = -EBADF;
186 file = fget(fd);
187 if (!file)
188 goto out;
189 error = vfs_statfs64(file->f_path.dentry, &tmp);
190 if (!error && copy_to_user(buf, &tmp, sizeof(tmp)))
191 error = -EFAULT;
192 fput(file);
193 out:
194 return error;
197 int do_truncate(struct dentry *dentry, loff_t length, unsigned int time_attrs,
198 struct file *filp)
200 int err;
201 struct iattr newattrs;
203 /* Not pretty: "inode->i_size" shouldn't really be signed. But it is. */
204 if (length < 0)
205 return -EINVAL;
207 newattrs.ia_size = length;
208 newattrs.ia_valid = ATTR_SIZE | time_attrs;
209 if (filp) {
210 newattrs.ia_file = filp;
211 newattrs.ia_valid |= ATTR_FILE;
214 /* Remove suid/sgid on truncate too */
215 newattrs.ia_valid |= should_remove_suid(dentry);
217 mutex_lock(&dentry->d_inode->i_mutex);
218 err = notify_change(dentry, &newattrs);
219 mutex_unlock(&dentry->d_inode->i_mutex);
220 return err;
223 static long do_sys_truncate(const char __user * path, loff_t length)
225 struct nameidata nd;
226 struct inode * inode;
227 int error;
229 error = -EINVAL;
230 if (length < 0) /* sorry, but loff_t says... */
231 goto out;
233 error = user_path_walk(path, &nd);
234 if (error)
235 goto out;
236 inode = nd.dentry->d_inode;
238 /* For directories it's -EISDIR, for other non-regulars - -EINVAL */
239 error = -EISDIR;
240 if (S_ISDIR(inode->i_mode))
241 goto dput_and_out;
243 error = -EINVAL;
244 if (!S_ISREG(inode->i_mode))
245 goto dput_and_out;
247 error = vfs_permission(&nd, MAY_WRITE);
248 if (error)
249 goto dput_and_out;
251 error = -EROFS;
252 if (IS_RDONLY(inode))
253 goto dput_and_out;
255 error = -EPERM;
256 if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
257 goto dput_and_out;
259 error = get_write_access(inode);
260 if (error)
261 goto dput_and_out;
264 * Make sure that there are no leases. get_write_access() protects
265 * against the truncate racing with a lease-granting setlease().
267 error = break_lease(inode, FMODE_WRITE);
268 if (error)
269 goto put_write_and_out;
271 error = locks_verify_truncate(inode, NULL, length);
272 if (!error) {
273 DQUOT_INIT(inode);
274 error = do_truncate(nd.dentry, length, 0, NULL);
277 put_write_and_out:
278 put_write_access(inode);
279 dput_and_out:
280 path_release(&nd);
281 out:
282 return error;
285 asmlinkage long sys_truncate(const char __user * path, unsigned long length)
287 /* on 32-bit boxen it will cut the range 2^31--2^32-1 off */
288 return do_sys_truncate(path, (long)length);
291 static long do_sys_ftruncate(unsigned int fd, loff_t length, int small)
293 struct inode * inode;
294 struct dentry *dentry;
295 struct file * file;
296 int error;
298 error = -EINVAL;
299 if (length < 0)
300 goto out;
301 error = -EBADF;
302 file = fget(fd);
303 if (!file)
304 goto out;
306 /* explicitly opened as large or we are on 64-bit box */
307 if (file->f_flags & O_LARGEFILE)
308 small = 0;
310 dentry = file->f_path.dentry;
311 inode = dentry->d_inode;
312 error = -EINVAL;
313 if (!S_ISREG(inode->i_mode) || !(file->f_mode & FMODE_WRITE))
314 goto out_putf;
316 error = -EINVAL;
317 /* Cannot ftruncate over 2^31 bytes without large file support */
318 if (small && length > MAX_NON_LFS)
319 goto out_putf;
321 error = -EPERM;
322 if (IS_APPEND(inode))
323 goto out_putf;
325 error = locks_verify_truncate(inode, file, length);
326 if (!error)
327 error = do_truncate(dentry, length, ATTR_MTIME|ATTR_CTIME, file);
328 out_putf:
329 fput(file);
330 out:
331 return error;
334 asmlinkage long sys_ftruncate(unsigned int fd, unsigned long length)
336 long ret = do_sys_ftruncate(fd, length, 1);
337 /* avoid REGPARM breakage on x86: */
338 prevent_tail_call(ret);
339 return ret;
342 /* LFS versions of truncate are only needed on 32 bit machines */
343 #if BITS_PER_LONG == 32
344 asmlinkage long sys_truncate64(const char __user * path, loff_t length)
346 return do_sys_truncate(path, length);
349 asmlinkage long sys_ftruncate64(unsigned int fd, loff_t length)
351 long ret = do_sys_ftruncate(fd, length, 0);
352 /* avoid REGPARM breakage on x86: */
353 prevent_tail_call(ret);
354 return ret;
356 #endif
358 asmlinkage long sys_fallocate(int fd, int mode, loff_t offset, loff_t len)
360 struct file *file;
361 struct inode *inode;
362 long ret = -EINVAL;
364 if (offset < 0 || len <= 0)
365 goto out;
367 /* Return error if mode is not supported */
368 ret = -EOPNOTSUPP;
369 if (mode && !(mode & FALLOC_FL_KEEP_SIZE))
370 goto out;
372 ret = -EBADF;
373 file = fget(fd);
374 if (!file)
375 goto out;
376 if (!(file->f_mode & FMODE_WRITE))
377 goto out_fput;
379 * Revalidate the write permissions, in case security policy has
380 * changed since the files were opened.
382 ret = security_file_permission(file, MAY_WRITE);
383 if (ret)
384 goto out_fput;
386 inode = file->f_path.dentry->d_inode;
388 ret = -ESPIPE;
389 if (S_ISFIFO(inode->i_mode))
390 goto out_fput;
392 ret = -ENODEV;
394 * Let individual file system decide if it supports preallocation
395 * for directories or not.
397 if (!S_ISREG(inode->i_mode) && !S_ISDIR(inode->i_mode))
398 goto out_fput;
400 ret = -EFBIG;
401 /* Check for wrap through zero too */
402 if (((offset + len) > inode->i_sb->s_maxbytes) || ((offset + len) < 0))
403 goto out_fput;
405 if (inode->i_op && inode->i_op->fallocate)
406 ret = inode->i_op->fallocate(inode, mode, offset, len);
407 else
408 ret = -EOPNOTSUPP;
410 out_fput:
411 fput(file);
412 out:
413 return ret;
417 * access() needs to use the real uid/gid, not the effective uid/gid.
418 * We do this by temporarily clearing all FS-related capabilities and
419 * switching the fsuid/fsgid around to the real ones.
421 asmlinkage long sys_faccessat(int dfd, const char __user *filename, int mode)
423 struct nameidata nd;
424 int old_fsuid, old_fsgid;
425 kernel_cap_t old_cap;
426 int res;
428 if (mode & ~S_IRWXO) /* where's F_OK, X_OK, W_OK, R_OK? */
429 return -EINVAL;
431 old_fsuid = current->fsuid;
432 old_fsgid = current->fsgid;
433 old_cap = current->cap_effective;
435 current->fsuid = current->uid;
436 current->fsgid = current->gid;
439 * Clear the capabilities if we switch to a non-root user
441 * FIXME: There is a race here against sys_capset. The
442 * capabilities can change yet we will restore the old
443 * value below. We should hold task_capabilities_lock,
444 * but we cannot because user_path_walk can sleep.
446 if (current->uid)
447 cap_clear(current->cap_effective);
448 else
449 current->cap_effective = current->cap_permitted;
451 res = __user_walk_fd(dfd, filename, LOOKUP_FOLLOW|LOOKUP_ACCESS, &nd);
452 if (res)
453 goto out;
455 res = vfs_permission(&nd, mode);
456 /* SuS v2 requires we report a read only fs too */
457 if(res || !(mode & S_IWOTH) ||
458 special_file(nd.dentry->d_inode->i_mode))
459 goto out_path_release;
461 if(IS_RDONLY(nd.dentry->d_inode))
462 res = -EROFS;
464 out_path_release:
465 path_release(&nd);
466 out:
467 current->fsuid = old_fsuid;
468 current->fsgid = old_fsgid;
469 current->cap_effective = old_cap;
471 return res;
474 asmlinkage long sys_access(const char __user *filename, int mode)
476 return sys_faccessat(AT_FDCWD, filename, mode);
479 asmlinkage long sys_chdir(const char __user * filename)
481 struct nameidata nd;
482 int error;
484 error = __user_walk(filename,
485 LOOKUP_FOLLOW|LOOKUP_DIRECTORY|LOOKUP_CHDIR, &nd);
486 if (error)
487 goto out;
489 error = vfs_permission(&nd, MAY_EXEC);
490 if (error)
491 goto dput_and_out;
493 set_fs_pwd(current->fs, nd.mnt, nd.dentry);
495 dput_and_out:
496 path_release(&nd);
497 out:
498 return error;
501 asmlinkage long sys_fchdir(unsigned int fd)
503 struct file *file;
504 struct dentry *dentry;
505 struct inode *inode;
506 struct vfsmount *mnt;
507 int error;
509 error = -EBADF;
510 file = fget(fd);
511 if (!file)
512 goto out;
514 dentry = file->f_path.dentry;
515 mnt = file->f_path.mnt;
516 inode = dentry->d_inode;
518 error = -ENOTDIR;
519 if (!S_ISDIR(inode->i_mode))
520 goto out_putf;
522 error = file_permission(file, MAY_EXEC);
523 if (!error)
524 set_fs_pwd(current->fs, mnt, dentry);
525 out_putf:
526 fput(file);
527 out:
528 return error;
531 asmlinkage long sys_chroot(const char __user * filename)
533 struct nameidata nd;
534 int error;
536 error = __user_walk(filename, LOOKUP_FOLLOW | LOOKUP_DIRECTORY | LOOKUP_NOALT, &nd);
537 if (error)
538 goto out;
540 error = vfs_permission(&nd, MAY_EXEC);
541 if (error)
542 goto dput_and_out;
544 error = -EPERM;
545 if (!capable(CAP_SYS_CHROOT))
546 goto dput_and_out;
548 set_fs_root(current->fs, nd.mnt, nd.dentry);
549 set_fs_altroot();
550 error = 0;
551 dput_and_out:
552 path_release(&nd);
553 out:
554 return error;
557 asmlinkage long sys_fchmod(unsigned int fd, mode_t mode)
559 struct inode * inode;
560 struct dentry * dentry;
561 struct file * file;
562 int err = -EBADF;
563 struct iattr newattrs;
565 file = fget(fd);
566 if (!file)
567 goto out;
569 dentry = file->f_path.dentry;
570 inode = dentry->d_inode;
572 audit_inode(NULL, dentry);
574 err = -EROFS;
575 if (IS_RDONLY(inode))
576 goto out_putf;
577 err = -EPERM;
578 if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
579 goto out_putf;
580 mutex_lock(&inode->i_mutex);
581 if (mode == (mode_t) -1)
582 mode = inode->i_mode;
583 newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
584 newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
585 err = notify_change(dentry, &newattrs);
586 mutex_unlock(&inode->i_mutex);
588 out_putf:
589 fput(file);
590 out:
591 return err;
594 asmlinkage long sys_fchmodat(int dfd, const char __user *filename,
595 mode_t mode)
597 struct nameidata nd;
598 struct inode * inode;
599 int error;
600 struct iattr newattrs;
602 error = __user_walk_fd(dfd, filename, LOOKUP_FOLLOW, &nd);
603 if (error)
604 goto out;
605 inode = nd.dentry->d_inode;
607 error = -EROFS;
608 if (IS_RDONLY(inode))
609 goto dput_and_out;
611 error = -EPERM;
612 if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
613 goto dput_and_out;
615 mutex_lock(&inode->i_mutex);
616 if (mode == (mode_t) -1)
617 mode = inode->i_mode;
618 newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
619 newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
620 error = notify_change(nd.dentry, &newattrs);
621 mutex_unlock(&inode->i_mutex);
623 dput_and_out:
624 path_release(&nd);
625 out:
626 return error;
629 asmlinkage long sys_chmod(const char __user *filename, mode_t mode)
631 return sys_fchmodat(AT_FDCWD, filename, mode);
634 static int chown_common(struct dentry * dentry, uid_t user, gid_t group)
636 struct inode * inode;
637 int error;
638 struct iattr newattrs;
640 error = -ENOENT;
641 if (!(inode = dentry->d_inode)) {
642 printk(KERN_ERR "chown_common: NULL inode\n");
643 goto out;
645 error = -EROFS;
646 if (IS_RDONLY(inode))
647 goto out;
648 error = -EPERM;
649 if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
650 goto out;
651 newattrs.ia_valid = ATTR_CTIME;
652 if (user != (uid_t) -1) {
653 newattrs.ia_valid |= ATTR_UID;
654 newattrs.ia_uid = user;
656 if (group != (gid_t) -1) {
657 newattrs.ia_valid |= ATTR_GID;
658 newattrs.ia_gid = group;
660 if (!S_ISDIR(inode->i_mode))
661 newattrs.ia_valid |=
662 ATTR_KILL_SUID | ATTR_KILL_SGID | ATTR_KILL_PRIV;
663 mutex_lock(&inode->i_mutex);
664 error = notify_change(dentry, &newattrs);
665 mutex_unlock(&inode->i_mutex);
666 out:
667 return error;
670 asmlinkage long sys_chown(const char __user * filename, uid_t user, gid_t group)
672 struct nameidata nd;
673 int error;
675 error = user_path_walk(filename, &nd);
676 if (error)
677 goto out;
678 error = chown_common(nd.dentry, user, group);
679 path_release(&nd);
680 out:
681 return error;
684 asmlinkage long sys_fchownat(int dfd, const char __user *filename, uid_t user,
685 gid_t group, int flag)
687 struct nameidata nd;
688 int error = -EINVAL;
689 int follow;
691 if ((flag & ~AT_SYMLINK_NOFOLLOW) != 0)
692 goto out;
694 follow = (flag & AT_SYMLINK_NOFOLLOW) ? 0 : LOOKUP_FOLLOW;
695 error = __user_walk_fd(dfd, filename, follow, &nd);
696 if (error)
697 goto out;
698 error = chown_common(nd.dentry, user, group);
699 path_release(&nd);
700 out:
701 return error;
704 asmlinkage long sys_lchown(const char __user * filename, uid_t user, gid_t group)
706 struct nameidata nd;
707 int error;
709 error = user_path_walk_link(filename, &nd);
710 if (error)
711 goto out;
712 error = chown_common(nd.dentry, user, group);
713 path_release(&nd);
714 out:
715 return error;
719 asmlinkage long sys_fchown(unsigned int fd, uid_t user, gid_t group)
721 struct file * file;
722 int error = -EBADF;
723 struct dentry * dentry;
725 file = fget(fd);
726 if (!file)
727 goto out;
729 dentry = file->f_path.dentry;
730 audit_inode(NULL, dentry);
731 error = chown_common(dentry, user, group);
732 fput(file);
733 out:
734 return error;
737 static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt,
738 int flags, struct file *f,
739 int (*open)(struct inode *, struct file *))
741 struct inode *inode;
742 int error;
744 f->f_flags = flags;
745 f->f_mode = ((flags+1) & O_ACCMODE) | FMODE_LSEEK |
746 FMODE_PREAD | FMODE_PWRITE;
747 inode = dentry->d_inode;
748 if (f->f_mode & FMODE_WRITE) {
749 error = get_write_access(inode);
750 if (error)
751 goto cleanup_file;
754 f->f_mapping = inode->i_mapping;
755 f->f_path.dentry = dentry;
756 f->f_path.mnt = mnt;
757 f->f_pos = 0;
758 f->f_op = fops_get(inode->i_fop);
759 file_move(f, &inode->i_sb->s_files);
761 error = security_dentry_open(f);
762 if (error)
763 goto cleanup_all;
765 if (!open && f->f_op)
766 open = f->f_op->open;
767 if (open) {
768 error = open(inode, f);
769 if (error)
770 goto cleanup_all;
773 f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
775 file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping);
777 /* NB: we're sure to have correct a_ops only after f_op->open */
778 if (f->f_flags & O_DIRECT) {
779 if (!f->f_mapping->a_ops ||
780 ((!f->f_mapping->a_ops->direct_IO) &&
781 (!f->f_mapping->a_ops->get_xip_page))) {
782 fput(f);
783 f = ERR_PTR(-EINVAL);
787 return f;
789 cleanup_all:
790 fops_put(f->f_op);
791 if (f->f_mode & FMODE_WRITE)
792 put_write_access(inode);
793 file_kill(f);
794 f->f_path.dentry = NULL;
795 f->f_path.mnt = NULL;
796 cleanup_file:
797 put_filp(f);
798 dput(dentry);
799 mntput(mnt);
800 return ERR_PTR(error);
804 * Note that while the flag value (low two bits) for sys_open means:
805 * 00 - read-only
806 * 01 - write-only
807 * 10 - read-write
808 * 11 - special
809 * it is changed into
810 * 00 - no permissions needed
811 * 01 - read-permission
812 * 10 - write-permission
813 * 11 - read-write
814 * for the internal routines (ie open_namei()/follow_link() etc). 00 is
815 * used by symlinks.
817 static struct file *do_filp_open(int dfd, const char *filename, int flags,
818 int mode)
820 int namei_flags, error;
821 struct nameidata nd;
823 namei_flags = flags;
824 if ((namei_flags+1) & O_ACCMODE)
825 namei_flags++;
827 error = open_namei(dfd, filename, namei_flags, mode, &nd);
828 if (!error)
829 return nameidata_to_filp(&nd, flags);
831 return ERR_PTR(error);
834 struct file *filp_open(const char *filename, int flags, int mode)
836 return do_filp_open(AT_FDCWD, filename, flags, mode);
838 EXPORT_SYMBOL(filp_open);
841 * lookup_instantiate_filp - instantiates the open intent filp
842 * @nd: pointer to nameidata
843 * @dentry: pointer to dentry
844 * @open: open callback
846 * Helper for filesystems that want to use lookup open intents and pass back
847 * a fully instantiated struct file to the caller.
848 * This function is meant to be called from within a filesystem's
849 * lookup method.
850 * Beware of calling it for non-regular files! Those ->open methods might block
851 * (e.g. in fifo_open), leaving you with parent locked (and in case of fifo,
852 * leading to a deadlock, as nobody can open that fifo anymore, because
853 * another process to open fifo will block on locked parent when doing lookup).
854 * Note that in case of error, nd->intent.open.file is destroyed, but the
855 * path information remains valid.
856 * If the open callback is set to NULL, then the standard f_op->open()
857 * filesystem callback is substituted.
859 struct file *lookup_instantiate_filp(struct nameidata *nd, struct dentry *dentry,
860 int (*open)(struct inode *, struct file *))
862 if (IS_ERR(nd->intent.open.file))
863 goto out;
864 if (IS_ERR(dentry))
865 goto out_err;
866 nd->intent.open.file = __dentry_open(dget(dentry), mntget(nd->mnt),
867 nd->intent.open.flags - 1,
868 nd->intent.open.file,
869 open);
870 out:
871 return nd->intent.open.file;
872 out_err:
873 release_open_intent(nd);
874 nd->intent.open.file = (struct file *)dentry;
875 goto out;
877 EXPORT_SYMBOL_GPL(lookup_instantiate_filp);
880 * nameidata_to_filp - convert a nameidata to an open filp.
881 * @nd: pointer to nameidata
882 * @flags: open flags
884 * Note that this function destroys the original nameidata
886 struct file *nameidata_to_filp(struct nameidata *nd, int flags)
888 struct file *filp;
890 /* Pick up the filp from the open intent */
891 filp = nd->intent.open.file;
892 /* Has the filesystem initialised the file for us? */
893 if (filp->f_path.dentry == NULL)
894 filp = __dentry_open(nd->dentry, nd->mnt, flags, filp, NULL);
895 else
896 path_release(nd);
897 return filp;
901 * dentry_open() will have done dput(dentry) and mntput(mnt) if it returns an
902 * error.
904 struct file *dentry_open(struct dentry *dentry, struct vfsmount *mnt, int flags)
906 int error;
907 struct file *f;
909 error = -ENFILE;
910 f = get_empty_filp();
911 if (f == NULL) {
912 dput(dentry);
913 mntput(mnt);
914 return ERR_PTR(error);
917 return __dentry_open(dentry, mnt, flags, f, NULL);
919 EXPORT_SYMBOL(dentry_open);
922 * Find an empty file descriptor entry, and mark it busy.
924 int get_unused_fd_flags(int flags)
926 struct files_struct * files = current->files;
927 int fd, error;
928 struct fdtable *fdt;
930 error = -EMFILE;
931 spin_lock(&files->file_lock);
933 repeat:
934 fdt = files_fdtable(files);
935 fd = find_next_zero_bit(fdt->open_fds->fds_bits, fdt->max_fds,
936 files->next_fd);
939 * N.B. For clone tasks sharing a files structure, this test
940 * will limit the total number of files that can be opened.
942 if (fd >= current->signal->rlim[RLIMIT_NOFILE].rlim_cur)
943 goto out;
945 /* Do we need to expand the fd array or fd set? */
946 error = expand_files(files, fd);
947 if (error < 0)
948 goto out;
950 if (error) {
952 * If we needed to expand the fs array we
953 * might have blocked - try again.
955 error = -EMFILE;
956 goto repeat;
959 FD_SET(fd, fdt->open_fds);
960 if (flags & O_CLOEXEC)
961 FD_SET(fd, fdt->close_on_exec);
962 else
963 FD_CLR(fd, fdt->close_on_exec);
964 files->next_fd = fd + 1;
965 #if 1
966 /* Sanity check */
967 if (fdt->fd[fd] != NULL) {
968 printk(KERN_WARNING "get_unused_fd: slot %d not NULL!\n", fd);
969 fdt->fd[fd] = NULL;
971 #endif
972 error = fd;
974 out:
975 spin_unlock(&files->file_lock);
976 return error;
979 int get_unused_fd(void)
981 return get_unused_fd_flags(0);
984 EXPORT_SYMBOL(get_unused_fd);
986 static void __put_unused_fd(struct files_struct *files, unsigned int fd)
988 struct fdtable *fdt = files_fdtable(files);
989 __FD_CLR(fd, fdt->open_fds);
990 if (fd < files->next_fd)
991 files->next_fd = fd;
994 void fastcall put_unused_fd(unsigned int fd)
996 struct files_struct *files = current->files;
997 spin_lock(&files->file_lock);
998 __put_unused_fd(files, fd);
999 spin_unlock(&files->file_lock);
1002 EXPORT_SYMBOL(put_unused_fd);
1005 * Install a file pointer in the fd array.
1007 * The VFS is full of places where we drop the files lock between
1008 * setting the open_fds bitmap and installing the file in the file
1009 * array. At any such point, we are vulnerable to a dup2() race
1010 * installing a file in the array before us. We need to detect this and
1011 * fput() the struct file we are about to overwrite in this case.
1013 * It should never happen - if we allow dup2() do it, _really_ bad things
1014 * will follow.
1017 void fastcall fd_install(unsigned int fd, struct file * file)
1019 struct files_struct *files = current->files;
1020 struct fdtable *fdt;
1021 spin_lock(&files->file_lock);
1022 fdt = files_fdtable(files);
1023 BUG_ON(fdt->fd[fd] != NULL);
1024 rcu_assign_pointer(fdt->fd[fd], file);
1025 spin_unlock(&files->file_lock);
1028 EXPORT_SYMBOL(fd_install);
1030 long do_sys_open(int dfd, const char __user *filename, int flags, int mode)
1032 char *tmp = getname(filename);
1033 int fd = PTR_ERR(tmp);
1035 if (!IS_ERR(tmp)) {
1036 fd = get_unused_fd_flags(flags);
1037 if (fd >= 0) {
1038 struct file *f = do_filp_open(dfd, tmp, flags, mode);
1039 if (IS_ERR(f)) {
1040 put_unused_fd(fd);
1041 fd = PTR_ERR(f);
1042 } else {
1043 fsnotify_open(f->f_path.dentry);
1044 fd_install(fd, f);
1047 putname(tmp);
1049 return fd;
1052 asmlinkage long sys_open(const char __user *filename, int flags, int mode)
1054 long ret;
1056 if (force_o_largefile())
1057 flags |= O_LARGEFILE;
1059 ret = do_sys_open(AT_FDCWD, filename, flags, mode);
1060 /* avoid REGPARM breakage on x86: */
1061 prevent_tail_call(ret);
1062 return ret;
1064 EXPORT_UNUSED_SYMBOL_GPL(sys_open); /* To be deleted for 2.6.25 */
1066 asmlinkage long sys_openat(int dfd, const char __user *filename, int flags,
1067 int mode)
1069 long ret;
1071 if (force_o_largefile())
1072 flags |= O_LARGEFILE;
1074 ret = do_sys_open(dfd, filename, flags, mode);
1075 /* avoid REGPARM breakage on x86: */
1076 prevent_tail_call(ret);
1077 return ret;
1080 #ifndef __alpha__
1083 * For backward compatibility? Maybe this should be moved
1084 * into arch/i386 instead?
1086 asmlinkage long sys_creat(const char __user * pathname, int mode)
1088 return sys_open(pathname, O_CREAT | O_WRONLY | O_TRUNC, mode);
1091 #endif
1094 * "id" is the POSIX thread ID. We use the
1095 * files pointer for this..
1097 int filp_close(struct file *filp, fl_owner_t id)
1099 int retval = 0;
1101 if (!file_count(filp)) {
1102 printk(KERN_ERR "VFS: Close: file count is 0\n");
1103 return 0;
1106 if (filp->f_op && filp->f_op->flush)
1107 retval = filp->f_op->flush(filp, id);
1109 dnotify_flush(filp, id);
1110 locks_remove_posix(filp, id);
1111 fput(filp);
1112 return retval;
1115 EXPORT_SYMBOL(filp_close);
1118 * Careful here! We test whether the file pointer is NULL before
1119 * releasing the fd. This ensures that one clone task can't release
1120 * an fd while another clone is opening it.
1122 asmlinkage long sys_close(unsigned int fd)
1124 struct file * filp;
1125 struct files_struct *files = current->files;
1126 struct fdtable *fdt;
1127 int retval;
1129 spin_lock(&files->file_lock);
1130 fdt = files_fdtable(files);
1131 if (fd >= fdt->max_fds)
1132 goto out_unlock;
1133 filp = fdt->fd[fd];
1134 if (!filp)
1135 goto out_unlock;
1136 rcu_assign_pointer(fdt->fd[fd], NULL);
1137 FD_CLR(fd, fdt->close_on_exec);
1138 __put_unused_fd(files, fd);
1139 spin_unlock(&files->file_lock);
1140 retval = filp_close(filp, files);
1142 /* can't restart close syscall because file table entry was cleared */
1143 if (unlikely(retval == -ERESTARTSYS ||
1144 retval == -ERESTARTNOINTR ||
1145 retval == -ERESTARTNOHAND ||
1146 retval == -ERESTART_RESTARTBLOCK))
1147 retval = -EINTR;
1149 return retval;
1151 out_unlock:
1152 spin_unlock(&files->file_lock);
1153 return -EBADF;
1156 EXPORT_SYMBOL(sys_close);
1159 * This routine simulates a hangup on the tty, to arrange that users
1160 * are given clean terminals at login time.
1162 asmlinkage long sys_vhangup(void)
1164 if (capable(CAP_SYS_TTY_CONFIG)) {
1165 /* XXX: this needs locking */
1166 tty_vhangup(current->signal->tty);
1167 return 0;
1169 return -EPERM;
1173 * Called when an inode is about to be open.
1174 * We use this to disallow opening large files on 32bit systems if
1175 * the caller didn't specify O_LARGEFILE. On 64bit systems we force
1176 * on this flag in sys_open.
1178 int generic_file_open(struct inode * inode, struct file * filp)
1180 if (!(filp->f_flags & O_LARGEFILE) && i_size_read(inode) > MAX_NON_LFS)
1181 return -EOVERFLOW;
1182 return 0;
1185 EXPORT_SYMBOL(generic_file_open);
1188 * This is used by subsystems that don't want seekable
1189 * file descriptors
1191 int nonseekable_open(struct inode *inode, struct file *filp)
1193 filp->f_mode &= ~(FMODE_LSEEK | FMODE_PREAD | FMODE_PWRITE);
1194 return 0;
1197 EXPORT_SYMBOL(nonseekable_open);