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

#include <linux/mm.h>
#include <linux/utime.h>
#include <linux/file.h>
#include <linux/smp_lock.h>
#include <linux/quotaops.h>

#include <asm/uaccess.h>

asmlinkage int sys_statfs(const char * path, struct statfs * buf)
{
        struct dentry * dentry;
        int error;

        lock_kernel();
        dentry = namei(path);
        error = PTR_ERR(dentry);
        if (!IS_ERR(dentry)) {
                struct inode * inode = dentry->d_inode;
                struct super_block * sb = inode->i_sb;

                error = -ENODEV;
                if (sb && sb->s_op && sb->s_op->statfs)
                        error = sb->s_op->statfs(sb, buf, sizeof(struct statfs));

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

asmlinkage int sys_fstatfs(unsigned int fd, struct statfs * buf)
{
        struct file * file;
        struct inode * inode;
        struct dentry * dentry;
        struct super_block * sb;
        int error;

        lock_kernel();
        error = -EBADF;
        file = fget(fd);
        if (!file)
                goto out;
        error = -ENOENT;
        if (!(dentry = file->f_dentry))
                goto out_putf;
        if (!(inode = dentry->d_inode))
                goto out_putf;
        error = -ENODEV;
        sb = inode->i_sb;
        if (sb && sb->s_op && sb->s_op->statfs)
                error = sb->s_op->statfs(sb, buf, sizeof(struct statfs));
out_putf:
        fput(file);
out:
        unlock_kernel();
        return error;
}

int do_truncate(struct dentry *dentry, unsigned long length)
{
        struct inode *inode = dentry->d_inode;
        int error;
        struct iattr newattrs;

        /* Not pretty: "inode->i_size" shouldn't really be "off_t". But it is. */
        if ((off_t) length < 0)
                return -EINVAL;

        fs_down(&inode->i_sem);
        newattrs.ia_size = length;
        newattrs.ia_valid = ATTR_SIZE | ATTR_CTIME;
        error = notify_change(dentry, &newattrs);
        if (!error) {
                /* truncate virtual mappings of this file */
                vmtruncate(inode, length);
                if (inode->i_op && inode->i_op->truncate)
                        inode->i_op->truncate(inode);
        }
        fs_up(&inode->i_sem);
        return error;
}

asmlinkage int sys_truncate(const char * path, unsigned long length)
{
        struct dentry * dentry;
        struct inode * inode;
        int error;

        lock_kernel();
        dentry = namei(path);

        error = PTR_ERR(dentry);
        if (IS_ERR(dentry))
                goto out;
        inode = dentry->d_inode;

        error = -EACCES;
        if (S_ISDIR(inode->i_mode))
                goto dput_and_out;

        error = permission(inode,MAY_WRITE);
        if (error)
                goto dput_and_out;

        error = -EROFS;
        if (IS_RDONLY(inode))
                goto dput_and_out;

        error = -EPERM;
        if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
                goto dput_and_out;

        error = get_write_access(inode);
        if (error)
                goto dput_and_out;

        error = locks_verify_area(FLOCK_VERIFY_WRITE, inode, NULL,
                                  length < inode->i_size ? length : inode->i_size,
                                  abs(inode->i_size - length));
        if (!error) {
                DQUOT_INIT(inode);
                error = do_truncate(dentry, length);
        }
        put_write_access(inode);
dput_and_out:
        dput(dentry);
out:
        unlock_kernel();
        return error;
}

asmlinkage int sys_ftruncate(unsigned int fd, unsigned long length)
{
        struct inode * inode;
        struct dentry *dentry;
        struct file * file;
        int error;

        lock_kernel();
        error = -EBADF;
        file = fget(fd);
        if (!file)
                goto out;
        error = -ENOENT;
        if (!(dentry = file->f_dentry))
                goto out_putf;
        if (!(inode = dentry->d_inode))
                goto out_putf;
        error = -EACCES;
        if (S_ISDIR(inode->i_mode) || !(file->f_mode & FMODE_WRITE))
                goto out_putf;
        error = -EPERM;
        if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
                goto out_putf;
        error = locks_verify_area(FLOCK_VERIFY_WRITE, inode, file,
                                  length<inode->i_size ? length : inode->i_size,
                                  abs(inode->i_size - length));
        if (!error)
                error = do_truncate(dentry, length);
out_putf:
        fput(file);
out:
        unlock_kernel();
        return error;
}

#ifndef __alpha__

/*
 * sys_utime() can be implemented in user-level using sys_utimes().
 * Is this for backwards compatibility?  If so, why not move it
 * into the appropriate arch directory (for those architectures that
 * need it).
 */

/* If times==NULL, set access and modification to current time,
 * must be owner or have write permission.
 * Else, update from *times, must be owner or super user.
 */
asmlinkage int sys_utime(char * filename, struct utimbuf * times)
{
        int error;
        struct dentry * dentry;
        struct inode * inode;
        struct iattr newattrs;

        lock_kernel();
        dentry = namei(filename);

        error = PTR_ERR(dentry);
        if (IS_ERR(dentry))
                goto out;
        inode = dentry->d_inode;

        error = -EROFS;
        if (IS_RDONLY(inode))
                goto dput_and_out;

        /* Don't worry, the checks are done in inode_change_ok() */
        newattrs.ia_valid = ATTR_CTIME | ATTR_MTIME | ATTR_ATIME;
        if (times) {
                error = get_user(newattrs.ia_atime, &times->actime);
                if (!error) 
                        error = get_user(newattrs.ia_mtime, &times->modtime);
                if (error)
                        goto dput_and_out;

                newattrs.ia_valid |= ATTR_ATIME_SET | ATTR_MTIME_SET;
        } else {
                if (current->fsuid != inode->i_uid &&
                    (error = permission(inode,MAY_WRITE)) != 0)
                        goto dput_and_out;
        }
        error = notify_change(dentry, &newattrs);
dput_and_out:
        dput(dentry);
out:
        unlock_kernel();
        return error;
}

#endif

/* If times==NULL, set access and modification to current time,
 * must be owner or have write permission.
 * Else, update from *times, must be owner or super user.
 */
asmlinkage int sys_utimes(char * filename, struct timeval * utimes)
{
        int error;
        struct dentry * dentry;
        struct inode * inode;
        struct iattr newattrs;

        lock_kernel();
        dentry = namei(filename);

        error = PTR_ERR(dentry);
        if (IS_ERR(dentry))
                goto out;
        inode = dentry->d_inode;

        error = -EROFS;
        if (IS_RDONLY(inode))
                goto dput_and_out;

        /* Don't worry, the checks are done in inode_change_ok() */
        newattrs.ia_valid = ATTR_CTIME | ATTR_MTIME | ATTR_ATIME;
        if (utimes) {
                struct timeval times[2];
                error = -EFAULT;
                if (copy_from_user(&times, utimes, sizeof(times)))
                        goto dput_and_out;
                newattrs.ia_atime = times[0].tv_sec;
                newattrs.ia_mtime = times[1].tv_sec;
                newattrs.ia_valid |= ATTR_ATIME_SET | ATTR_MTIME_SET;
        } else {
                if ((error = permission(inode,MAY_WRITE)) != 0)
                        goto dput_and_out;
        }
        error = notify_change(dentry, &newattrs);
dput_and_out:
        dput(dentry);
out:
        unlock_kernel();
        return error;
}

/*
 * access() needs to use the real uid/gid, not the effective uid/gid.
 * We do this by temporarily clearing all FS-related capabilities and
 * switching the fsuid/fsgid around to the real ones.
 */
asmlinkage int sys_access(const char * filename, int mode)
{
        struct dentry * dentry;
        int old_fsuid, old_fsgid;
        kernel_cap_t old_cap;
        int res = -EINVAL;

        lock_kernel();
        if (mode != (mode & S_IRWXO))   /* where's F_OK, X_OK, W_OK, R_OK? */
                goto out;
        old_fsuid = current->fsuid;
        old_fsgid = current->fsgid;
        old_cap = current->cap_effective;

        current->fsuid = current->uid;
        current->fsgid = current->gid;

        /* Clear the capabilities if we switch to a non-root user */
        if (current->uid)
                cap_clear(current->cap_effective);
        else
                current->cap_effective = current->cap_permitted;
                
        dentry = namei(filename);
        res = PTR_ERR(dentry);
        if (!IS_ERR(dentry)) {
                res = permission(dentry->d_inode, mode);

                /* SUSv2 says to return EROFS for open() and access()
                   for files on a read-only filesystem, when writing
                   is requested.  Clearly, we want to be able to run
                   a system from read-only media, so should not
                   interpret this to mean that open("/dev/tty") should
                   fail when the device node lives on a CDROM.
                   In other words, no additional check is needed here. */

                dput(dentry);
        }

        current->fsuid = old_fsuid;
        current->fsgid = old_fsgid;
        current->cap_effective = old_cap;
out:
        unlock_kernel();
        return res;
}

asmlinkage int sys_chdir(const char * filename)
{
        int error;
        struct inode *inode;
        struct dentry *dentry, *tmp;

        lock_kernel();
        
        dentry = namei(filename);
        error = PTR_ERR(dentry);
        if (IS_ERR(dentry))
                goto out;

        inode = dentry->d_inode;

        error = -ENOTDIR;
        if (!S_ISDIR(inode->i_mode))
                goto dput_and_out;

        error = permission(inode,MAY_EXEC);
        if (error)
                goto dput_and_out;

        /* exchange dentries */
        tmp = current->fs->pwd;
        current->fs->pwd = dentry;
        dentry = tmp;

dput_and_out:
        dput(dentry);
out:
        unlock_kernel();
        return error;
}

asmlinkage int sys_fchdir(unsigned int fd)
{
        struct file *file;
        struct dentry *dentry;
        struct inode *inode;
        int error;

        lock_kernel();

        error = -EBADF;
        file = fget(fd);
        if (!file)
                goto out;

        error = -ENOENT;
        if (!(dentry = file->f_dentry))
                goto out_putf;
        if (!(inode = dentry->d_inode))
                goto out_putf;

        error = -ENOTDIR;
        if (!S_ISDIR(inode->i_mode))
                goto out_putf;

        error = permission(inode, MAY_EXEC);
        if (!error) {
                struct dentry *tmp = current->fs->pwd;
                current->fs->pwd = dget(dentry);
                dput(tmp);
        }
out_putf:
        fput(file);
out:
        unlock_kernel();
        return error;
}

asmlinkage int sys_chroot(const char * filename)
{
        int error;
        struct inode *inode;
        struct dentry *dentry, *tmp;

        lock_kernel();
        
        dentry = namei(filename);
        error = PTR_ERR(dentry);
        if (IS_ERR(dentry))
                goto out;

        inode = dentry->d_inode;

        error = -ENOTDIR;
        if (!S_ISDIR(inode->i_mode))
                goto dput_and_out;

        error = permission(inode,MAY_EXEC);
        if (error)
                goto dput_and_out;

        error = -EPERM;
        if (!capable(CAP_SYS_CHROOT))
                goto dput_and_out;

        /* exchange dentries */
        tmp = current->fs->root;
        current->fs->root = dentry;
        dentry = tmp;
        error = 0;

dput_and_out:
        dput(dentry);
out:
        unlock_kernel();
        return error;
}

asmlinkage int sys_fchmod(unsigned int fd, mode_t mode)
{
        struct inode * inode;
        struct dentry * dentry;
        struct file * file;
        int err = -EBADF;
        struct iattr newattrs;

        lock_kernel();
        file = fget(fd);
        if (!file)
                goto out;

        err = -ENOENT;
        if (!(dentry = file->f_dentry))
                goto out_putf;
        if (!(inode = dentry->d_inode))
                goto out_putf;

        err = -EROFS;
        if (IS_RDONLY(inode))
                goto out_putf;
        err = -EPERM;
        if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
                goto out_putf;
        if (mode == (mode_t) -1)
                mode = inode->i_mode;
        newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
        newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
        err = notify_change(dentry, &newattrs);

out_putf:
        fput(file);
out:
        unlock_kernel();
        return err;
}

asmlinkage int sys_chmod(const char * filename, mode_t mode)
{
        struct dentry * dentry;
        struct inode * inode;
        int error;
        struct iattr newattrs;

        lock_kernel();
        dentry = namei(filename);

        error = PTR_ERR(dentry);
        if (IS_ERR(dentry))
                goto out;
        inode = dentry->d_inode;

        error = -EROFS;
        if (IS_RDONLY(inode))
                goto dput_and_out;

        error = -EPERM;
        if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
                goto dput_and_out;

        if (mode == (mode_t) -1)
                mode = inode->i_mode;
        newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
        newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
        error = notify_change(dentry, &newattrs);

dput_and_out:
        dput(dentry);
out:
        unlock_kernel();
        return error;
}

static int chown_common(struct dentry * dentry, uid_t user, gid_t group)
{
        struct inode * inode;
        int error;
        struct iattr newattrs;

        error = -ENOENT;
        if (!(inode = dentry->d_inode)) {
                printk("chown_common: NULL inode\n");
                goto out;
        }
        error = -EROFS;
        if (IS_RDONLY(inode))
                goto out;
        error = -EPERM;
        if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
                goto out;
        if (user == (uid_t) -1)
                user = inode->i_uid;
        if (group == (gid_t) -1)
                group = inode->i_gid;
        newattrs.ia_mode = inode->i_mode;
        newattrs.ia_uid = user;
        newattrs.ia_gid = group;
        newattrs.ia_valid =  ATTR_UID | ATTR_GID | ATTR_CTIME;
        /*
         * If the user or group of a non-directory has been changed by a
         * non-root user, remove the setuid bit.
         * 19981026     David C Niemi <niemi@tux.org>
         *
         * Changed this to apply to all users, including root, to avoid
         * some races. This is the behavior we had in 2.0. The check for
         * non-root was definitely wrong for 2.2 anyway, as it should
         * have been using CAP_FSETID rather than fsuid -- 19990830 SD.
         */
        if ((inode->i_mode & S_ISUID) == S_ISUID &&
                !S_ISDIR(inode->i_mode))
        {
                newattrs.ia_mode &= ~S_ISUID;
                newattrs.ia_valid |= ATTR_MODE;
        }
        /*
         * Likewise, if the user or group of a non-directory has been changed
         * by a non-root user, remove the setgid bit UNLESS there is no group
         * execute bit (this would be a file marked for mandatory locking).
         * 19981026     David C Niemi <niemi@tux.org>
         *
         * Removed the fsuid check (see the comment above) -- 19990830 SD.
         */
        if (((inode->i_mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP)) 
                && !S_ISDIR(inode->i_mode))
        {
                newattrs.ia_mode &= ~S_ISGID;
                newattrs.ia_valid |= ATTR_MODE;
        }
        error = DQUOT_TRANSFER(dentry, &newattrs);
out:
        return error;
}

asmlinkage int sys_chown(const char * filename, uid_t user, gid_t group)
{
        struct dentry * dentry;
        int error;

        lock_kernel();
        dentry = namei(filename);

        error = PTR_ERR(dentry);
        if (!IS_ERR(dentry)) {
                error = chown_common(dentry, user, group);
                dput(dentry);
        }
        unlock_kernel();
        return error;
}

asmlinkage int sys_lchown(const char * filename, uid_t user, gid_t group)
{
        struct dentry * dentry;
        int error;

        lock_kernel();
        dentry = lnamei(filename);

        error = PTR_ERR(dentry);
        if (!IS_ERR(dentry)) {
                error = chown_common(dentry, user, group);
                dput(dentry);
        }
        unlock_kernel();
        return error;
}


asmlinkage int sys_fchown(unsigned int fd, uid_t user, gid_t group)
{
        struct dentry * dentry;
        struct file * file;
        int error = -EBADF;

        lock_kernel();
        file = fget(fd);
        if (!file)
                goto out;
        error = -ENOENT;
        if ((dentry = file->f_dentry) != NULL)
                error = chown_common(dentry, user, group);
        fput(file);

out:
        unlock_kernel();
        return error;
}

/*
 * Note that while the flag value (low two bits) for sys_open means:
 *      00 - read-only
 *      01 - write-only
 *      10 - read-write
 *      11 - special
 * it is changed into
 *      00 - no permissions needed
 *      01 - read-permission
 *      10 - write-permission
 *      11 - read-write
 * for the internal routines (ie open_namei()/follow_link() etc). 00 is
 * used by symlinks.
 */
struct file *filp_open(const char * filename, int flags, int mode)
{
        struct inode * inode;
        struct dentry * dentry;
        struct file * f;
        int flag,error;

        error = -ENFILE;
        f = get_empty_filp();
        if (!f)
                goto out;
        f->f_flags = flag = flags;
        f->f_mode = (flag+1) & O_ACCMODE;
        if (f->f_mode)
                flag++;
        if (flag & O_TRUNC)
                flag |= 2;
        dentry = open_namei(filename,flag,mode);
        error = PTR_ERR(dentry);
        if (IS_ERR(dentry))
                goto cleanup_file;
        inode = dentry->d_inode;
        if (f->f_mode & FMODE_WRITE) {
                error = get_write_access(inode);
                if (error)
                        goto cleanup_dentry;
        }

        f->f_dentry = dentry;
        f->f_pos = 0;
        f->f_reada = 0;
        f->f_op = NULL;
        if (inode->i_op)
                f->f_op = inode->i_op->default_file_ops;
        if (f->f_op && f->f_op->open) {
                error = f->f_op->open(inode,f);
                if (error)
                        goto cleanup_all;
        }
        f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);

        return f;

cleanup_all:
        if (f->f_mode & FMODE_WRITE)
                put_write_access(inode);
cleanup_dentry:
        f->f_dentry = NULL;
        dput(dentry);
cleanup_file:
        put_filp(f);
out:
        return ERR_PTR(error);
}

/*
 * Find an empty file descriptor entry, and mark it busy.
 */
int get_unused_fd(void)
{
        struct files_struct * files = current->files;
        int fd, error;
        
repeat:
        error = -EMFILE;

        fd = find_next_zero_bit(files->open_fds, 
                                current->files->max_fdset, 
                                files->next_fd);
        /*
         * N.B. For clone tasks sharing a files structure, this test
         * will limit the total number of files that can be opened.
         */
        if (fd >= current->rlim[RLIMIT_NOFILE].rlim_cur)
                goto out;

        /* Do we need to expand the fdset array? */
        if (fd >= current->files->max_fdset) {
                error = expand_fdset(files, fd + 1);
                if (!error)
                        goto repeat;
                goto out;
        }
        
        /* 
         * Check whether we need to expand the fd array.
         */
        if (fd >= files->max_fds) {
                error = expand_fd_array(files, fd + 1);
                if (!error)
                        goto repeat;
                goto out;
        }

        FD_SET(fd, files->open_fds);
        FD_CLR(fd, files->close_on_exec);
        files->next_fd = fd + 1;
#if 1
        /* Sanity check */
        if (files->fd[fd] != NULL) {
                printk("get_unused_fd: slot %d not NULL!\n", fd);
                files->fd[fd] = NULL;
        }
#endif
        error = fd;

out:
#ifdef FDSET_DEBUG      
        if (error < 0)
                printk (KERN_ERR __FUNCTION__ ": return %d\n", error);
#endif
        return error;
}

asmlinkage int sys_open(const char * filename, int flags, int mode)
{
        char * tmp;
        int fd, error;

        tmp = getname(filename);
        fd = PTR_ERR(tmp);
        if (!IS_ERR(tmp)) {
                lock_kernel();
                fd = get_unused_fd();
                if (fd >= 0) {
                        struct file * f = filp_open(tmp, flags, mode);
                        error = PTR_ERR(f);
                        if (IS_ERR(f))
                                goto out_error;
                        fd_install(fd, f);
                }
out:
                unlock_kernel();
                putname(tmp);
        }
        return fd;

out_error:
        put_unused_fd(fd);
        fd = error;
        goto out;
}

#ifndef __alpha__

/*
 * For backward compatibility?  Maybe this should be moved
 * into arch/i386 instead?
 */
asmlinkage int sys_creat(const char * pathname, int mode)
{
        return sys_open(pathname, O_CREAT | O_WRONLY | O_TRUNC, mode);
}

#endif

/*
 * Called when retiring the last use of a file pointer.
 */
void __fput(struct file *filp)
{
        struct dentry * dentry = filp->f_dentry;
        struct inode * inode = dentry->d_inode;

        if (filp->f_op && filp->f_op->release)
                filp->f_op->release(inode, filp);
        filp->f_dentry = NULL;
        if (filp->f_mode & FMODE_WRITE)
                put_write_access(inode);
        dput(dentry);
}

/*
 * "id" is the POSIX thread ID. We use the
 * files pointer for this..
 */
int filp_close(struct file *filp, fl_owner_t id)
{
        int retval;
        struct dentry *dentry = filp->f_dentry;

        if (filp->f_count == 0) {
                printk("VFS: Close: file count is 0\n");
                return 0;
        }
        retval = 0;
        if (filp->f_op && filp->f_op->flush)
                retval = filp->f_op->flush(filp);
        if (dentry->d_inode)
                locks_remove_posix(filp, id);
        fput(filp);
        return retval;
}

/*
 * Careful here! We test whether the file pointer is NULL before
 * releasing the fd. This ensures that one clone task can't release
 * an fd while another clone is opening it.
 */
asmlinkage int sys_close(unsigned int fd)
{
        int error;
        struct file * filp;

        lock_kernel();
        error = -EBADF;
        filp = fcheck(fd);
        if (filp) {
                struct files_struct * files = current->files;
                files->fd[fd] = NULL;
                put_unused_fd(fd);
                FD_CLR(fd, files->close_on_exec);
                error = filp_close(filp, files);
        }
        unlock_kernel();
        return error;
}

/*
 * This routine simulates a hangup on the tty, to arrange that users
 * are given clean terminals at login time.
 */
asmlinkage int sys_vhangup(void)
{
        int ret = -EPERM;

        lock_kernel();
        if (!capable(CAP_SYS_TTY_CONFIG))
                goto out;
        /* If there is a controlling tty, hang it up */
        if (current->tty)
                tty_vhangup(current->tty);
        ret = 0;
out:
        unlock_kernel();
        return ret;
}