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

#include <linux/mm.h>
#include <linux/errno.h>
#include <linux/file.h>
#include <linux/smp_lock.h>

#include <asm/uaccess.h>

/*
 * Revalidate the inode. This is required for proper NFS attribute caching.
 */
static __inline__ int
do_revalidate(struct dentry *dentry)
{
        struct inode * inode = dentry->d_inode;
        if (inode->i_op && inode->i_op->revalidate)
                return inode->i_op->revalidate(dentry);
        return 0;
}


#if !defined(__alpha__) && !defined(__sparc__)

/*
 * For backward compatibility?  Maybe this should be moved
 * into arch/i386 instead?
 */
static int cp_old_stat(struct inode * inode, struct __old_kernel_stat * statbuf)
{
        static int warncount = 5;
        struct __old_kernel_stat tmp;

        if (warncount) {
                warncount--;
                printk("VFS: Warning: %s using old stat() call. Recompile your binary.\n",
                        current->comm);
        }

        tmp.st_dev = kdev_t_to_nr(inode->i_dev);
        tmp.st_ino = inode->i_ino;
        tmp.st_mode = inode->i_mode;
        tmp.st_nlink = inode->i_nlink;
        tmp.st_uid = inode->i_uid;
        tmp.st_gid = inode->i_gid;
        tmp.st_rdev = kdev_t_to_nr(inode->i_rdev);
        tmp.st_size = inode->i_size;
        tmp.st_atime = inode->i_atime;
        tmp.st_mtime = inode->i_mtime;
        tmp.st_ctime = inode->i_ctime;
        return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
}

#endif

static int cp_new_stat(struct inode * inode, struct stat * statbuf)
{
        struct stat tmp;
        unsigned int blocks, indirect;

        memset(&tmp, 0, sizeof(tmp));
        tmp.st_dev = kdev_t_to_nr(inode->i_dev);
        tmp.st_ino = inode->i_ino;
        tmp.st_mode = inode->i_mode;
        tmp.st_nlink = inode->i_nlink;
        tmp.st_uid = inode->i_uid;
        tmp.st_gid = inode->i_gid;
        tmp.st_rdev = kdev_t_to_nr(inode->i_rdev);
        tmp.st_size = inode->i_size;
        tmp.st_atime = inode->i_atime;
        tmp.st_mtime = inode->i_mtime;
        tmp.st_ctime = inode->i_ctime;
/*
 * st_blocks and st_blksize are approximated with a simple algorithm if
 * they aren't supported directly by the filesystem. The minix and msdos
 * filesystems don't keep track of blocks, so they would either have to
 * be counted explicitly (by delving into the file itself), or by using
 * this simple algorithm to get a reasonable (although not 100% accurate)
 * value.
 */

/*
 * Use minix fs values for the number of direct and indirect blocks.  The
 * count is now exact for the minix fs except that it counts zero blocks.
 * Everything is in units of BLOCK_SIZE until the assignment to
 * tmp.st_blksize.
 */
#define D_B   7
#define I_B   (BLOCK_SIZE / sizeof(unsigned short))

        if (!inode->i_blksize) {
                blocks = (tmp.st_size + BLOCK_SIZE - 1) / BLOCK_SIZE;
                if (blocks > D_B) {
                        indirect = (blocks - D_B + I_B - 1) / I_B;
                        blocks += indirect;
                        if (indirect > 1) {
                                indirect = (indirect - 1 + I_B - 1) / I_B;
                                blocks += indirect;
                                if (indirect > 1)
                                        blocks++;
                        }
                }
                tmp.st_blocks = (BLOCK_SIZE / 512) * blocks;
                tmp.st_blksize = BLOCK_SIZE;
        } else {
                tmp.st_blocks = inode->i_blocks;
                tmp.st_blksize = inode->i_blksize;
        }
        return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
}


#if !defined(__alpha__) && !defined(__sparc__)
/*
 * For backward compatibility?  Maybe this should be moved
 * into arch/i386 instead?
 */
asmlinkage int sys_stat(char * filename, struct __old_kernel_stat * statbuf)
{
        struct dentry * dentry;
        int error;

        lock_kernel();
        dentry = namei(filename);

        error = PTR_ERR(dentry);
        if (!IS_ERR(dentry)) {
                error = do_revalidate(dentry);
                if (!error)
                        error = cp_old_stat(dentry->d_inode, statbuf);

                dput(dentry);
        }
        unlock_kernel();
        return error;
}
#endif

asmlinkage int sys_newstat(char * filename, struct stat * statbuf)
{
        struct dentry * dentry;
        int error;

        lock_kernel();
        dentry = namei(filename);

        error = PTR_ERR(dentry);
        if (!IS_ERR(dentry)) {
                error = do_revalidate(dentry);
                if (!error)
                        error = cp_new_stat(dentry->d_inode, statbuf);

                dput(dentry);
        }
        unlock_kernel();
        return error;
}

#if !defined(__alpha__) && !defined(__sparc__)

/*
 * For backward compatibility?  Maybe this should be moved
 * into arch/i386 instead?
 */
asmlinkage int sys_lstat(char * filename, struct __old_kernel_stat * statbuf)
{
        struct dentry * dentry;
        int error;

        lock_kernel();
        dentry = lnamei(filename);

        error = PTR_ERR(dentry);
        if (!IS_ERR(dentry)) {
                error = do_revalidate(dentry);
                if (!error)
                        error = cp_old_stat(dentry->d_inode, statbuf);

                dput(dentry);
        }
        unlock_kernel();
        return error;
}

#endif

asmlinkage int sys_newlstat(char * filename, struct stat * statbuf)
{
        struct dentry * dentry;
        int error;

        lock_kernel();
        dentry = lnamei(filename);

        error = PTR_ERR(dentry);
        if (!IS_ERR(dentry)) {
                error = do_revalidate(dentry);
                if (!error)
                        error = cp_new_stat(dentry->d_inode, statbuf);

                dput(dentry);
        }
        unlock_kernel();
        return error;
}

#if !defined(__alpha__) && !defined(__sparc__)

/*
 * For backward compatibility?  Maybe this should be moved
 * into arch/i386 instead?
 */
asmlinkage int sys_fstat(unsigned int fd, struct __old_kernel_stat * statbuf)
{
        struct file * f;
        int err = -EBADF;

        lock_kernel();
        f = fget(fd);
        if (f) {
                struct dentry * dentry = f->f_dentry;

                err = do_revalidate(dentry);
                if (!err)
                        err = cp_old_stat(dentry->d_inode, statbuf);
                fput(f);
        }
        unlock_kernel();
        return err;
}

#endif

asmlinkage int sys_newfstat(unsigned int fd, struct stat * statbuf)
{
        struct file * f;
        int err = -EBADF;

        lock_kernel();
        f = fget(fd);
        if (f) {
                struct dentry * dentry = f->f_dentry;

                err = do_revalidate(dentry);
                if (!err)
                        err = cp_new_stat(dentry->d_inode, statbuf);
                fput(f);
        }
        unlock_kernel();
        return err;
}

asmlinkage int sys_readlink(const char * path, char * buf, int bufsiz)
{
        struct dentry * dentry;
        int error;

        if (bufsiz <= 0)
                return -EINVAL;

        lock_kernel();
        dentry = lnamei(path);

        error = PTR_ERR(dentry);
        if (!IS_ERR(dentry)) {
                struct inode * inode = dentry->d_inode;

                error = -EINVAL;
                if (inode->i_op && inode->i_op->readlink &&
                    !(error = do_revalidate(dentry))) {
                        UPDATE_ATIME(inode);
                        error = inode->i_op->readlink(dentry, buf, bufsiz);
                }
                dput(dentry);
        }
        unlock_kernel();
        return error;
}