stat.c

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

#include <linux/export.h>
#include <linux/mm.h>
#include <linux/errno.h>
#include <linux/file.h>
#include <linux/highuid.h>
#include <linux/fs.h>
#include <linux/namei.h>
#include <linux/security.h>
#include <linux/syscalls.h>
#include <linux/pagemap.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->size = i_size_read(inode);
    stat->atime = inode->i_atime;
    stat->mtime = inode->i_mtime;
    stat->ctime = inode->i_ctime;
    stat->blksize = (1 << inode->i_blkbits);
    stat->blocks = inode->i_blocks;
}

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);
    return 0;
}

EXPORT_SYMBOL(vfs_getattr);

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

    if (f.file) {
        error = vfs_getattr(f.file->f_path.mnt, f.file->f_path.dentry,
                    stat);
        fdput(f);
    }
    return error;
}
EXPORT_SYMBOL(vfs_fstat);

int vfs_fstatat(int dfd, const char __user *filename, struct kstat *stat,
        int flag)
{
    struct path path;
    int error = -EINVAL;
    int lookup_flags = 0;

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

    if (!(flag & AT_SYMLINK_NOFOLLOW))
        lookup_flags |= LOOKUP_FOLLOW;
    if (flag & AT_EMPTY_PATH)
        lookup_flags |= LOOKUP_EMPTY;

    error = user_path_at(dfd, filename, lookup_flags, &path);
    if (error)
        goto out;

    error = vfs_getattr(path.mnt, path.dentry, stat);
    path_put(&path);
out:
    return error;
}
EXPORT_SYMBOL(vfs_fstatat);

int vfs_stat(const char __user *name, struct kstat *stat)
{
    return vfs_fstatat(AT_FDCWD, name, stat, 0);
}
EXPORT_SYMBOL(vfs_stat);

int vfs_lstat(const char __user *name, struct kstat *stat)
{
    return vfs_fstatat(AT_FDCWD, name, stat, AT_SYMLINK_NOFOLLOW);
}
EXPORT_SYMBOL(vfs_lstat);


#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;
    if (sizeof(tmp.st_ino) < sizeof(stat->ino) && tmp.st_ino != stat->ino)
        return -EOVERFLOW;
    tmp.st_mode = stat->mode;
    tmp.st_nlink = stat->nlink;
    if (tmp.st_nlink != stat->nlink)
        return -EOVERFLOW;
    SET_UID(tmp.st_uid, from_kuid_munged(current_user_ns(), stat->uid));
    SET_GID(tmp.st_gid, from_kgid_munged(current_user_ns(), 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;
}

SYSCALL_DEFINE2(stat, const char __user *, filename,
        struct __old_kernel_stat __user *, statbuf)
{
    struct kstat stat;
    int error;

    error = vfs_stat(filename, &stat);
    if (error)
        return error;

    return cp_old_stat(&stat, statbuf);
}

SYSCALL_DEFINE2(lstat, const char __user *, filename,
        struct __old_kernel_stat __user *, statbuf)
{
    struct kstat stat;
    int error;

    error = vfs_lstat(filename, &stat);
    if (error)
        return error;

    return cp_old_stat(&stat, statbuf);
}

SYSCALL_DEFINE2(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 */

#if BITS_PER_LONG == 32
#  define choose_32_64(a,b) a
#else
#  define choose_32_64(a,b) b
#endif

#define valid_dev(x)  choose_32_64(old_valid_dev,new_valid_dev)(x)
#define encode_dev(x) choose_32_64(old_encode_dev,new_encode_dev)(x)

#ifndef INIT_STRUCT_STAT_PADDING
#  define INIT_STRUCT_STAT_PADDING(st) memset(&st, 0, sizeof(st))
#endif

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

    if (!valid_dev(stat->dev) || !valid_dev(stat->rdev))
        return -EOVERFLOW;
#if BITS_PER_LONG == 32
    if (stat->size > MAX_NON_LFS)
        return -EOVERFLOW;
#endif

    INIT_STRUCT_STAT_PADDING(tmp);
    tmp.st_dev = encode_dev(stat->dev);
    tmp.st_ino = stat->ino;
    if (sizeof(tmp.st_ino) < sizeof(stat->ino) && tmp.st_ino != stat->ino)
        return -EOVERFLOW;
    tmp.st_mode = stat->mode;
    tmp.st_nlink = stat->nlink;
    if (tmp.st_nlink != stat->nlink)
        return -EOVERFLOW;
    SET_UID(tmp.st_uid, from_kuid_munged(current_user_ns(), stat->uid));
    SET_GID(tmp.st_gid, from_kgid_munged(current_user_ns(), stat->gid));
    tmp.st_rdev = encode_dev(stat->rdev);
    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;
}

SYSCALL_DEFINE2(newstat, const char __user *, filename,
        struct stat __user *, statbuf)
{
    struct kstat stat;
    int error = vfs_stat(filename, &stat);

    if (error)
        return error;
    return cp_new_stat(&stat, statbuf);
}

SYSCALL_DEFINE2(newlstat, const char __user *, filename,
        struct stat __user *, statbuf)
{
    struct kstat stat;
    int error;

    error = vfs_lstat(filename, &stat);
    if (error)
        return error;

    return cp_new_stat(&stat, statbuf);
}

#if !defined(__ARCH_WANT_STAT64) || defined(__ARCH_WANT_SYS_NEWFSTATAT)
SYSCALL_DEFINE4(newfstatat, int, dfd, const char __user *, filename,
        struct stat __user *, statbuf, int, flag)
{
    struct kstat stat;
    int error;

    error = vfs_fstatat(dfd, filename, &stat, flag);
    if (error)
        return error;
    return cp_new_stat(&stat, statbuf);
}
#endif

SYSCALL_DEFINE2(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;
}

SYSCALL_DEFINE4(readlinkat, int, dfd, const char __user *, pathname,
        char __user *, buf, int, bufsiz)
{
    struct path path;
    int error;
    int empty = 0;

    if (bufsiz <= 0)
        return -EINVAL;

    error = user_path_at_empty(dfd, pathname, LOOKUP_EMPTY, &path, &empty);
    if (!error) {
        struct inode *inode = path.dentry->d_inode;

        error = empty ? -ENOENT : -EINVAL;
        if (inode->i_op->readlink) {
            error = security_inode_readlink(path.dentry);
            if (!error) {
                touch_atime(&path);
                error = inode->i_op->readlink(path.dentry,
                                  buf, bufsiz);
            }
        }
        path_put(&path);
    }
    return error;
}

SYSCALL_DEFINE3(readlink, const char __user *, path, char __user *, buf,
        int, bufsiz)
{
    return sys_readlinkat(AT_FDCWD, path, buf, bufsiz);
}


/* ---------- LFS-64 ----------- */
#if defined(__ARCH_WANT_STAT64) || defined(__ARCH_WANT_COMPAT_STAT64)

#ifndef INIT_STRUCT_STAT64_PADDING
#  define INIT_STRUCT_STAT64_PADDING(st) memset(&st, 0, sizeof(st))
#endif

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

    INIT_STRUCT_STAT64_PADDING(tmp);
#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;
    if (sizeof(tmp.st_ino) < sizeof(stat->ino) && tmp.st_ino != stat->ino)
        return -EOVERFLOW;
#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 = from_kuid_munged(current_user_ns(), stat->uid);
    tmp.st_gid = from_kgid_munged(current_user_ns(), 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;
}

SYSCALL_DEFINE2(stat64, const 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;
}

SYSCALL_DEFINE2(lstat64, const 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;
}

SYSCALL_DEFINE2(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;
}

SYSCALL_DEFINE4(fstatat64, int, dfd, const char __user *, filename,
        struct stat64 __user *, statbuf, int, flag)
{
    struct kstat stat;
    int error;

    error = vfs_fstatat(dfd, filename, &stat, flag);
    if (error)
        return error;
    return cp_new_stat64(&stat, statbuf);
}
#endif /* __ARCH_WANT_STAT64 || __ARCH_WANT_COMPAT_STAT64 */

/* Caller is here responsible for sufficient locking (ie. inode->i_lock) */
void __inode_add_bytes(struct inode *inode, loff_t bytes)
{
    inode->i_blocks += bytes >> 9;
    bytes &= 511;
    inode->i_bytes += bytes;
    if (inode->i_bytes >= 512) {
        inode->i_blocks++;
        inode->i_bytes -= 512;
    }
}

void inode_add_bytes(struct inode *inode, loff_t bytes)
{
    spin_lock(&inode->i_lock);
    __inode_add_bytes(inode, bytes);
    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);