2 * proc/fs/generic.c --- generic routines for the proc-fs
4 * This file contains generic proc-fs routines for handling
5 * directories and files.
7 * Copyright (C) 1991, 1992 Linus Torvalds.
8 * Copyright (C) 1997 Theodore Ts'o
11 #include <linux/errno.h>
12 #include <linux/time.h>
13 #include <linux/proc_fs.h>
14 #include <linux/stat.h>
15 #include <linux/module.h>
16 #include <linux/mount.h>
17 #include <linux/smp_lock.h>
18 #include <linux/init.h>
19 #include <linux/idr.h>
20 #include <linux/namei.h>
21 #include <linux/bitops.h>
22 #include <linux/spinlock.h>
23 #include <asm/uaccess.h>
27 static ssize_t proc_file_read(struct file *file, char __user *buf,
28 size_t nbytes, loff_t *ppos);
29 static ssize_t proc_file_write(struct file *file, const char __user *buffer,
30 size_t count, loff_t *ppos);
31 static loff_t proc_file_lseek(struct file *, loff_t, int);
33 DEFINE_SPINLOCK(proc_subdir_lock);
35 static int proc_match(int len, const char *name, struct proc_dir_entry *de)
37 if (de->namelen != len)
39 return !memcmp(name, de->name, len);
42 static const struct file_operations proc_file_operations = {
43 .llseek = proc_file_lseek,
44 .read = proc_file_read,
45 .write = proc_file_write,
48 /* buffer size is one page but our output routines use some slack for overruns */
49 #define PROC_BLOCK_SIZE (PAGE_SIZE - 1024)
52 proc_file_read(struct file *file, char __user *buf, size_t nbytes,
55 struct inode * inode = file->f_path.dentry->d_inode;
61 struct proc_dir_entry * dp;
62 unsigned long long pos;
65 * Gaah, please just use "seq_file" instead. The legacy /proc
66 * interfaces cut loff_t down to off_t for reads, and ignore
67 * the offset entirely for writes..
70 if (pos > MAX_NON_LFS)
72 if (nbytes > MAX_NON_LFS - pos)
73 nbytes = MAX_NON_LFS - pos;
76 if (!(page = (char*) __get_free_page(GFP_KERNEL)))
79 while ((nbytes > 0) && !eof) {
80 count = min_t(size_t, PROC_BLOCK_SIZE, nbytes);
84 /* Handle old net routines */
85 n = dp->get_info(page, &start, *ppos, count);
88 } else if (dp->read_proc) {
90 * How to be a proc read function
91 * ------------------------------
93 * int f(char *buffer, char **start, off_t offset,
94 * int count, int *peof, void *dat)
96 * Assume that the buffer is "count" bytes in size.
98 * If you know you have supplied all the data you
101 * You have three ways to return data:
102 * 0) Leave *start = NULL. (This is the default.)
103 * Put the data of the requested offset at that
104 * offset within the buffer. Return the number (n)
105 * of bytes there are from the beginning of the
106 * buffer up to the last byte of data. If the
107 * number of supplied bytes (= n - offset) is
108 * greater than zero and you didn't signal eof
109 * and the reader is prepared to take more data
110 * you will be called again with the requested
111 * offset advanced by the number of bytes
112 * absorbed. This interface is useful for files
113 * no larger than the buffer.
114 * 1) Set *start = an unsigned long value less than
115 * the buffer address but greater than zero.
116 * Put the data of the requested offset at the
117 * beginning of the buffer. Return the number of
118 * bytes of data placed there. If this number is
119 * greater than zero and you didn't signal eof
120 * and the reader is prepared to take more data
121 * you will be called again with the requested
122 * offset advanced by *start. This interface is
123 * useful when you have a large file consisting
124 * of a series of blocks which you want to count
125 * and return as wholes.
126 * (Hack by Paul.Russell@rustcorp.com.au)
127 * 2) Set *start = an address within the buffer.
128 * Put the data of the requested offset at *start.
129 * Return the number of bytes of data placed there.
130 * If this number is greater than zero and you
131 * didn't signal eof and the reader is prepared to
132 * take more data you will be called again with the
133 * requested offset advanced by the number of bytes
136 n = dp->read_proc(page, &start, *ppos,
137 count, &eof, dp->data);
141 if (n == 0) /* end of file */
143 if (n < 0) { /* error */
152 "proc_file_read: Apparent buffer overflow!\n");
160 start = page + *ppos;
161 } else if (start < page) {
164 "proc_file_read: Apparent buffer overflow!\n");
169 * Don't reduce n because doing so might
170 * cut off part of a data block.
173 "proc_file_read: Read count exceeded\n");
175 } else /* start >= page */ {
176 unsigned long startoff = (unsigned long)(start - page);
177 if (n > (PAGE_SIZE - startoff)) {
179 "proc_file_read: Apparent buffer overflow!\n");
180 n = PAGE_SIZE - startoff;
186 n -= copy_to_user(buf, start < page ? page : start, n);
193 *ppos += start < page ? (unsigned long)start : n;
198 free_page((unsigned long) page);
203 proc_file_write(struct file *file, const char __user *buffer,
204 size_t count, loff_t *ppos)
206 struct inode *inode = file->f_path.dentry->d_inode;
207 struct proc_dir_entry * dp;
214 /* FIXME: does this routine need ppos? probably... */
215 return dp->write_proc(file, buffer, count, dp->data);
220 proc_file_lseek(struct file *file, loff_t offset, int orig)
222 loff_t retval = -EINVAL;
225 offset += file->f_pos;
228 if (offset < 0 || offset > MAX_NON_LFS)
230 file->f_pos = retval = offset;
235 static int proc_notify_change(struct dentry *dentry, struct iattr *iattr)
237 struct inode *inode = dentry->d_inode;
238 struct proc_dir_entry *de = PDE(inode);
241 error = inode_change_ok(inode, iattr);
245 error = inode_setattr(inode, iattr);
249 de->uid = inode->i_uid;
250 de->gid = inode->i_gid;
251 de->mode = inode->i_mode;
256 static int proc_getattr(struct vfsmount *mnt, struct dentry *dentry,
259 struct inode *inode = dentry->d_inode;
260 struct proc_dir_entry *de = PROC_I(inode)->pde;
262 inode->i_nlink = de->nlink;
264 generic_fillattr(inode, stat);
268 static const struct inode_operations proc_file_inode_operations = {
269 .setattr = proc_notify_change,
273 * This function parses a name such as "tty/driver/serial", and
274 * returns the struct proc_dir_entry for "/proc/tty/driver", and
275 * returns "serial" in residual.
277 static int xlate_proc_name(const char *name,
278 struct proc_dir_entry **ret, const char **residual)
280 const char *cp = name, *next;
281 struct proc_dir_entry *de;
285 spin_lock(&proc_subdir_lock);
288 next = strchr(cp, '/');
293 for (de = de->subdir; de ; de = de->next) {
294 if (proc_match(len, cp, de))
306 spin_unlock(&proc_subdir_lock);
310 static DEFINE_IDR(proc_inum_idr);
311 static DEFINE_SPINLOCK(proc_inum_lock); /* protects the above */
313 #define PROC_DYNAMIC_FIRST 0xF0000000UL
316 * Return an inode number between PROC_DYNAMIC_FIRST and
317 * 0xffffffff, or zero on failure.
319 static unsigned int get_inode_number(void)
325 if (idr_pre_get(&proc_inum_idr, GFP_KERNEL) == 0)
328 spin_lock(&proc_inum_lock);
329 error = idr_get_new(&proc_inum_idr, NULL, &i);
330 spin_unlock(&proc_inum_lock);
331 if (error == -EAGAIN)
336 inum = (i & MAX_ID_MASK) + PROC_DYNAMIC_FIRST;
338 /* inum will never be more than 0xf0ffffff, so no check
345 static void release_inode_number(unsigned int inum)
347 int id = (inum - PROC_DYNAMIC_FIRST) | ~MAX_ID_MASK;
349 spin_lock(&proc_inum_lock);
350 idr_remove(&proc_inum_idr, id);
351 spin_unlock(&proc_inum_lock);
354 static void *proc_follow_link(struct dentry *dentry, struct nameidata *nd)
356 nd_set_link(nd, PDE(dentry->d_inode)->data);
360 static const struct inode_operations proc_link_inode_operations = {
361 .readlink = generic_readlink,
362 .follow_link = proc_follow_link,
366 * As some entries in /proc are volatile, we want to
367 * get rid of unused dentries. This could be made
368 * smarter: we could keep a "volatile" flag in the
369 * inode to indicate which ones to keep.
371 static int proc_delete_dentry(struct dentry * dentry)
376 static struct dentry_operations proc_dentry_operations =
378 .d_delete = proc_delete_dentry,
382 * Don't create negative dentries here, return -ENOENT by hand
385 struct dentry *proc_lookup(struct inode * dir, struct dentry *dentry, struct nameidata *nd)
387 struct inode *inode = NULL;
388 struct proc_dir_entry * de;
392 spin_lock(&proc_subdir_lock);
395 for (de = de->subdir; de ; de = de->next) {
396 if (de->namelen != dentry->d_name.len)
398 if (!memcmp(dentry->d_name.name, de->name, de->namelen)) {
399 unsigned int ino = de->low_ino;
401 spin_unlock(&proc_subdir_lock);
403 inode = proc_get_inode(dir->i_sb, ino, de);
404 spin_lock(&proc_subdir_lock);
409 spin_unlock(&proc_subdir_lock);
413 dentry->d_op = &proc_dentry_operations;
414 d_add(dentry, inode);
417 return ERR_PTR(error);
421 * This returns non-zero if at EOF, so that the /proc
422 * root directory can use this and check if it should
423 * continue with the <pid> entries..
425 * Note that the VFS-layer doesn't care about the return
426 * value of the readdir() call, as long as it's non-negative
429 int proc_readdir(struct file * filp,
430 void * dirent, filldir_t filldir)
432 struct proc_dir_entry * de;
435 struct inode *inode = filp->f_path.dentry->d_inode;
449 if (filldir(dirent, ".", 1, i, ino, DT_DIR) < 0)
455 if (filldir(dirent, "..", 2, i,
456 parent_ino(filp->f_path.dentry),
463 spin_lock(&proc_subdir_lock);
469 spin_unlock(&proc_subdir_lock);
479 /* filldir passes info to user space */
480 spin_unlock(&proc_subdir_lock);
481 if (filldir(dirent, de->name, de->namelen, filp->f_pos,
482 de->low_ino, de->mode >> 12) < 0)
484 spin_lock(&proc_subdir_lock);
488 spin_unlock(&proc_subdir_lock);
491 out: unlock_kernel();
496 * These are the generic /proc directory operations. They
497 * use the in-memory "struct proc_dir_entry" tree to parse
498 * the /proc directory.
500 static const struct file_operations proc_dir_operations = {
501 .read = generic_read_dir,
502 .readdir = proc_readdir,
506 * proc directories can do almost nothing..
508 static const struct inode_operations proc_dir_inode_operations = {
509 .lookup = proc_lookup,
510 .getattr = proc_getattr,
511 .setattr = proc_notify_change,
514 static int proc_register(struct proc_dir_entry * dir, struct proc_dir_entry * dp)
518 i = get_inode_number();
523 spin_lock(&proc_subdir_lock);
524 dp->next = dir->subdir;
527 spin_unlock(&proc_subdir_lock);
529 if (S_ISDIR(dp->mode)) {
530 if (dp->proc_iops == NULL) {
531 dp->proc_fops = &proc_dir_operations;
532 dp->proc_iops = &proc_dir_inode_operations;
535 } else if (S_ISLNK(dp->mode)) {
536 if (dp->proc_iops == NULL)
537 dp->proc_iops = &proc_link_inode_operations;
538 } else if (S_ISREG(dp->mode)) {
539 if (dp->proc_fops == NULL)
540 dp->proc_fops = &proc_file_operations;
541 if (dp->proc_iops == NULL)
542 dp->proc_iops = &proc_file_inode_operations;
548 * Kill an inode that got unregistered..
550 static void proc_kill_inodes(struct proc_dir_entry *de)
553 struct super_block *sb = proc_mnt->mnt_sb;
556 * Actually it's a partial revoke().
559 list_for_each(p, &sb->s_files) {
560 struct file * filp = list_entry(p, struct file, f_u.fu_list);
561 struct dentry * dentry = filp->f_path.dentry;
562 struct inode * inode;
563 const struct file_operations *fops;
565 if (dentry->d_op != &proc_dentry_operations)
567 inode = dentry->d_inode;
568 if (PDE(inode) != de)
577 static struct proc_dir_entry *proc_create(struct proc_dir_entry **parent,
582 struct proc_dir_entry *ent = NULL;
583 const char *fn = name;
586 /* make sure name is valid */
587 if (!name || !strlen(name)) goto out;
589 if (!(*parent) && xlate_proc_name(name, parent, &fn) != 0)
592 /* At this point there must not be any '/' characters beyond *fn */
598 ent = kmalloc(sizeof(struct proc_dir_entry) + len + 1, GFP_KERNEL);
601 memset(ent, 0, sizeof(struct proc_dir_entry));
602 memcpy(((char *) ent) + sizeof(struct proc_dir_entry), fn, len + 1);
603 ent->name = ((char *) ent) + sizeof(*ent);
611 struct proc_dir_entry *proc_symlink(const char *name,
612 struct proc_dir_entry *parent, const char *dest)
614 struct proc_dir_entry *ent;
616 ent = proc_create(&parent,name,
617 (S_IFLNK | S_IRUGO | S_IWUGO | S_IXUGO),1);
620 ent->data = kmalloc((ent->size=strlen(dest))+1, GFP_KERNEL);
622 strcpy((char*)ent->data,dest);
623 if (proc_register(parent, ent) < 0) {
636 struct proc_dir_entry *proc_mkdir_mode(const char *name, mode_t mode,
637 struct proc_dir_entry *parent)
639 struct proc_dir_entry *ent;
641 ent = proc_create(&parent, name, S_IFDIR | mode, 2);
643 ent->proc_fops = &proc_dir_operations;
644 ent->proc_iops = &proc_dir_inode_operations;
646 if (proc_register(parent, ent) < 0) {
654 struct proc_dir_entry *proc_mkdir(const char *name,
655 struct proc_dir_entry *parent)
657 return proc_mkdir_mode(name, S_IRUGO | S_IXUGO, parent);
660 struct proc_dir_entry *create_proc_entry(const char *name, mode_t mode,
661 struct proc_dir_entry *parent)
663 struct proc_dir_entry *ent;
667 if ((mode & S_IALLUGO) == 0)
668 mode |= S_IRUGO | S_IXUGO;
671 if ((mode & S_IFMT) == 0)
673 if ((mode & S_IALLUGO) == 0)
678 ent = proc_create(&parent,name,mode,nlink);
681 ent->proc_fops = &proc_dir_operations;
682 ent->proc_iops = &proc_dir_inode_operations;
684 if (proc_register(parent, ent) < 0) {
692 void free_proc_entry(struct proc_dir_entry *de)
694 unsigned int ino = de->low_ino;
696 if (ino < PROC_DYNAMIC_FIRST)
699 release_inode_number(ino);
701 if (S_ISLNK(de->mode) && de->data)
707 * Remove a /proc entry and free it if it's not currently in use.
708 * If it is in use, we set the 'deleted' flag.
710 void remove_proc_entry(const char *name, struct proc_dir_entry *parent)
712 struct proc_dir_entry **p;
713 struct proc_dir_entry *de;
714 const char *fn = name;
717 if (!parent && xlate_proc_name(name, &parent, &fn) != 0)
721 spin_lock(&proc_subdir_lock);
722 for (p = &parent->subdir; *p; p=&(*p)->next ) {
723 if (!proc_match(len, fn, *p))
728 if (S_ISDIR(de->mode))
730 proc_kill_inodes(de);
733 if (!atomic_read(&de->count))
737 printk("remove_proc_entry: %s/%s busy, count=%d\n",
738 parent->name, de->name, atomic_read(&de->count));
742 spin_unlock(&proc_subdir_lock);