stat.c

/*
 *  linux/fs/stat.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 */

#include <linux/config.h>
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/errno.h>
#include <linux/file.h>
#include <linux/smp_lock.h>
#include <linux/highuid.h>
#include <linux/fs.h>
#include <linux/namei.h>
#include <linux/security.h>
#include <linux/syscalls.h>

#include <asm/uaccess.h>
#include <asm/unistd.h>

void generic_fillattr(struct inode *inode, struct kstat *stat)
{
	stat->dev = inode->i_sb->s_dev;
	stat->ino = inode->i_ino;
	stat->mode = inode->i_mode;
	stat->nlink = inode->i_nlink;
	stat->uid = inode->i_uid;
	stat->gid = inode->i_gid;
	stat->rdev = inode->i_rdev;
	stat->atime = inode->i_atime;
	stat->mtime = inode->i_mtime;
	stat->ctime = inode->i_ctime;
	stat->size = i_size_read(inode);
	stat->blocks = inode->i_blocks;
	stat->blksize = inode->i_blksize;
}

EXPORT_SYMBOL(generic_fillattr);

int vfs_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
{
	struct inode *inode = dentry->d_inode;
	int retval;

	retval = security_inode_getattr(mnt, dentry);
	if (retval)
		return retval;

	if (inode->i_op->getattr)
		return inode->i_op->getattr(mnt, dentry, stat);

	generic_fillattr(inode, stat);
	if (!stat->blksize) {
		struct super_block *s = inode->i_sb;
		unsigned blocks;
		blocks = (stat->size+s->s_blocksize-1) >> s->s_blocksize_bits;
		stat->blocks = (s->s_blocksize / 512) * blocks;
		stat->blksize = s->s_blocksize;
	}
	return 0;
}

EXPORT_SYMBOL(vfs_getattr);

int vfs_stat_fd(int dfd, char __user *name, struct kstat *stat)
{
	struct nameidata nd;
	int error;

	error = __user_walk_fd(dfd, name, LOOKUP_FOLLOW, &nd);
	if (!error) {
		error = vfs_getattr(nd.mnt, nd.dentry, stat);
		path_release(&nd);
	}
	return error;
}

int vfs_stat(char __user *name, struct kstat *stat)
{
	return vfs_stat_fd(AT_FDCWD, name, stat);
}

EXPORT_SYMBOL(vfs_stat);

int vfs_lstat_fd(int dfd, char __user *name, struct kstat *stat)
{
	struct nameidata nd;
	int error;

	error = __user_walk_fd(dfd, name, 0, &nd);
	if (!error) {
		error = vfs_getattr(nd.mnt, nd.dentry, stat);
		path_release(&nd);
	}
	return error;
}

int vfs_lstat(char __user *name, struct kstat *stat)
{
	return vfs_lstat_fd(AT_FDCWD, name, stat);
}

EXPORT_SYMBOL(vfs_lstat);

int vfs_fstat(unsigned int fd, struct kstat *stat)
{
	struct file *f = fget(fd);
	int error = -EBADF;

	if (f) {
		error = vfs_getattr(f->f_vfsmnt, f->f_dentry, stat);
		fput(f);
	}
	return error;
}

EXPORT_SYMBOL(vfs_fstat);

#ifdef __ARCH_WANT_OLD_STAT

/*
 * For backward compatibility?  Maybe this should be moved
 * into arch/i386 instead?
 */
static int cp_old_stat(struct kstat *stat, struct __old_kernel_stat __user * statbuf)
{
	static int warncount = 5;
	struct __old_kernel_stat tmp;
	
	if (warncount > 0) {
		warncount--;
		printk(KERN_WARNING "VFS: Warning: %s using old stat() call. Recompile your binary.\n",
			current->comm);
	} else if (warncount < 0) {
		/* it's laughable, but... */
		warncount = 0;
	}

	memset(&tmp, 0, sizeof(struct __old_kernel_stat));
	tmp.st_dev = old_encode_dev(stat->dev);
	tmp.st_ino = stat->ino;
	tmp.st_mode = stat->mode;
	tmp.st_nlink = stat->nlink;
	if (tmp.st_nlink != stat->nlink)
		return -EOVERFLOW;
	SET_UID(tmp.st_uid, stat->uid);
	SET_GID(tmp.st_gid, stat->gid);
	tmp.st_rdev = old_encode_dev(stat->rdev);
#if BITS_PER_LONG == 32
	if (stat->size > MAX_NON_LFS)
		return -EOVERFLOW;
#endif	
	tmp.st_size = stat->size;
	tmp.st_atime = stat->atime.tv_sec;
	tmp.st_mtime = stat->mtime.tv_sec;
	tmp.st_ctime = stat->ctime.tv_sec;
	return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
}

asmlinkage long sys_stat(char __user * filename, struct __old_kernel_stat __user * statbuf)
{
	struct kstat stat;
	int error = vfs_stat_fd(AT_FDCWD, filename, &stat);

	if (!error)
		error = cp_old_stat(&stat, statbuf);

	return error;
}
asmlinkage long sys_lstat(char __user * filename, struct __old_kernel_stat __user * statbuf)
{
	struct kstat stat;
	int error = vfs_lstat_fd(AT_FDCWD, filename, &stat);

	if (!error)
		error = cp_old_stat(&stat, statbuf);

	return error;
}
asmlinkage long sys_fstat(unsigned int fd, struct __old_kernel_stat __user * statbuf)
{
	struct kstat stat;
	int error = vfs_fstat(fd, &stat);

	if (!error)
		error = cp_old_stat(&stat, statbuf);

	return error;
}

#endif /* __ARCH_WANT_OLD_STAT */

static int cp_new_stat(struct kstat *stat, struct stat __user *statbuf)
{
	struct stat tmp;

#if BITS_PER_LONG == 32
	if (!old_valid_dev(stat->dev) || !old_valid_dev(stat->rdev))
		return -EOVERFLOW;
#else
	if (!new_valid_dev(stat->dev) || !new_valid_dev(stat->rdev))
		return -EOVERFLOW;
#endif

	memset(&tmp, 0, sizeof(tmp));
#if BITS_PER_LONG == 32
	tmp.st_dev = old_encode_dev(stat->dev);
#else
	tmp.st_dev = new_encode_dev(stat->dev);
#endif
	tmp.st_ino = stat->ino;
	tmp.st_mode = stat->mode;
	tmp.st_nlink = stat->nlink;
	if (tmp.st_nlink != stat->nlink)
		return -EOVERFLOW;
	SET_UID(tmp.st_uid, stat->uid);
	SET_GID(tmp.st_gid, stat->gid);
#if BITS_PER_LONG == 32
	tmp.st_rdev = old_encode_dev(stat->rdev);
#else
	tmp.st_rdev = new_encode_dev(stat->rdev);
#endif
#if BITS_PER_LONG == 32
	if (stat->size > MAX_NON_LFS)
		return -EOVERFLOW;
#endif	
	tmp.st_size = stat->size;
	tmp.st_atime = stat->atime.tv_sec;
	tmp.st_mtime = stat->mtime.tv_sec;
	tmp.st_ctime = stat->ctime.tv_sec;
#ifdef STAT_HAVE_NSEC
	tmp.st_atime_nsec = stat->atime.tv_nsec;
	tmp.st_mtime_nsec = stat->mtime.tv_nsec;
	tmp.st_ctime_nsec = stat->ctime.tv_nsec;
#endif
	tmp.st_blocks = stat->blocks;
	tmp.st_blksize = stat->blksize;
	return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
}

asmlinkage long sys_newstat(char __user *filename, struct stat __user *statbuf)
{
	struct kstat stat;
	int error = vfs_stat_fd(AT_FDCWD, filename, &stat);

	if (!error)
		error = cp_new_stat(&stat, statbuf);

	return error;
}

asmlinkage long sys_newlstat(char __user *filename, struct stat __user *statbuf)
{
	struct kstat stat;
	int error = vfs_lstat_fd(AT_FDCWD, filename, &stat);

	if (!error)
		error = cp_new_stat(&stat, statbuf);

	return error;
}

asmlinkage long sys_newfstatat(int dfd, char __user *filename,
				struct stat __user *statbuf, int flag)
{
	struct kstat stat;
	int error = -EINVAL;

	if ((flag & ~AT_SYMLINK_NOFOLLOW) != 0)
		goto out;

	if (flag & AT_SYMLINK_NOFOLLOW)
		error = vfs_lstat_fd(dfd, filename, &stat);
	else
		error = vfs_stat_fd(dfd, filename, &stat);

	if (!error)
		error = cp_new_stat(&stat, statbuf);

out:
	return error;
}

asmlinkage long sys_newfstat(unsigned int fd, struct stat __user *statbuf)
{
	struct kstat stat;
	int error = vfs_fstat(fd, &stat);

	if (!error)
		error = cp_new_stat(&stat, statbuf);

	return error;
}

asmlinkage long sys_readlinkat(int dfd, const char __user *path,
				char __user *buf, int bufsiz)
{
	struct nameidata nd;
	int error;

	if (bufsiz <= 0)
		return -EINVAL;

	error = __user_walk_fd(dfd, path, 0, &nd);
	if (!error) {
		struct inode * inode = nd.dentry->d_inode;

		error = -EINVAL;
		if (inode->i_op && inode->i_op->readlink) {
			error = security_inode_readlink(nd.dentry);
			if (!error) {
				touch_atime(nd.mnt, nd.dentry);
				error = inode->i_op->readlink(nd.dentry, buf, bufsiz);
			}
		}
		path_release(&nd);
	}
	return error;
}

asmlinkage long sys_readlink(const char __user *path, char __user *buf,
				int bufsiz)
{
	return sys_readlinkat(AT_FDCWD, path, buf, bufsiz);
}


/* ---------- LFS-64 ----------- */
#ifdef __ARCH_WANT_STAT64

static long cp_new_stat64(struct kstat *stat, struct stat64 __user *statbuf)
{
	struct stat64 tmp;

	memset(&tmp, 0, sizeof(struct stat64));
#ifdef CONFIG_MIPS
	/* mips has weird padding, so we don't get 64 bits there */
	if (!new_valid_dev(stat->dev) || !new_valid_dev(stat->rdev))
		return -EOVERFLOW;
	tmp.st_dev = new_encode_dev(stat->dev);
	tmp.st_rdev = new_encode_dev(stat->rdev);
#else
	tmp.st_dev = huge_encode_dev(stat->dev);
	tmp.st_rdev = huge_encode_dev(stat->rdev);
#endif
	tmp.st_ino = stat->ino;
#ifdef STAT64_HAS_BROKEN_ST_INO
	tmp.__st_ino = stat->ino;
#endif
	tmp.st_mode = stat->mode;
	tmp.st_nlink = stat->nlink;
	tmp.st_uid = stat->uid;
	tmp.st_gid = stat->gid;
	tmp.st_atime = stat->atime.tv_sec;
	tmp.st_atime_nsec = stat->atime.tv_nsec;
	tmp.st_mtime = stat->mtime.tv_sec;
	tmp.st_mtime_nsec = stat->mtime.tv_nsec;
	tmp.st_ctime = stat->ctime.tv_sec;
	tmp.st_ctime_nsec = stat->ctime.tv_nsec;
	tmp.st_size = stat->size;
	tmp.st_blocks = stat->blocks;
	tmp.st_blksize = stat->blksize;
	return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
}

asmlinkage long sys_stat64(char __user * filename, struct stat64 __user * statbuf)
{
	struct kstat stat;
	int error = vfs_stat(filename, &stat);

	if (!error)
		error = cp_new_stat64(&stat, statbuf);

	return error;
}
asmlinkage long sys_lstat64(char __user * filename, struct stat64 __user * statbuf)
{
	struct kstat stat;
	int error = vfs_lstat(filename, &stat);

	if (!error)
		error = cp_new_stat64(&stat, statbuf);

	return error;
}
asmlinkage long sys_fstat64(unsigned long fd, struct stat64 __user * statbuf)
{
	struct kstat stat;
	int error = vfs_fstat(fd, &stat);

	if (!error)
		error = cp_new_stat64(&stat, statbuf);

	return error;
}

#endif /* __ARCH_WANT_STAT64 */

void inode_add_bytes(struct inode *inode, loff_t bytes)
{
	spin_lock(&inode->i_lock);
	inode->i_blocks += bytes >> 9;
	bytes &= 511;
	inode->i_bytes += bytes;
	if (inode->i_bytes >= 512) {
		inode->i_blocks++;
		inode->i_bytes -= 512;
	}
	spin_unlock(&inode->i_lock);
}

EXPORT_SYMBOL(inode_add_bytes);

void inode_sub_bytes(struct inode *inode, loff_t bytes)
{
	spin_lock(&inode->i_lock);
	inode->i_blocks -= bytes >> 9;
	bytes &= 511;
	if (inode->i_bytes < bytes) {
		inode->i_blocks--;
		inode->i_bytes += 512;
	}
	inode->i_bytes -= bytes;
	spin_unlock(&inode->i_lock);
}

EXPORT_SYMBOL(inode_sub_bytes);

loff_t inode_get_bytes(struct inode *inode)
{
	loff_t ret;

	spin_lock(&inode->i_lock);
	ret = (((loff_t)inode->i_blocks) << 9) + inode->i_bytes;
	spin_unlock(&inode->i_lock);
	return ret;
}

EXPORT_SYMBOL(inode_get_bytes);

void inode_set_bytes(struct inode *inode, loff_t bytes)
{
	/* Caller is here responsible for sufficient locking
	 * (ie. inode->i_lock) */
	inode->i_blocks = bytes >> 9;
	inode->i_bytes = bytes & 511;
}

EXPORT_SYMBOL(inode_set_bytes);