root/fs/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 <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(char __user *name, struct kstat *stat)
{
        struct nameidata nd;
        int error;

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

EXPORT_SYMBOL(vfs_stat);

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

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

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(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(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(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(filename, &stat);

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

        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_readlink(const char __user * path, char __user * buf, int bufsiz)
{
        struct nameidata nd;
        int error;

        if (bufsiz <= 0)
                return -EINVAL;

        error = user_path_walk_link(path, &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;
}


/* ---------- 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);