C++ OPEN_FMODE函数代码示例

static int au_conv_oflags(int flags)
{
	int mask = 0;

#ifdef CONFIG_IMA
	fmode_t fmode;

	/* mask = MAY_OPEN; */
	fmode = OPEN_FMODE(flags);
	if (fmode & FMODE_READ)
		mask |= MAY_READ;
	if ((fmode & FMODE_WRITE)
	    || (flags & O_TRUNC))
		mask |= MAY_WRITE;
	/*
	 * if (flags & O_APPEND)
	 *	mask |= MAY_APPEND;
	 */
	if (flags & vfsub_fmode_to_uint(FMODE_EXEC))
		mask |= MAY_EXEC;

	AuDbg("flags 0x%x, mask 0x%x\n", flags, mask);
#endif

	return mask;
}

/**
 * anon_inode_getfd - creates a new file instance by hooking it up to an
 *                    anonymous inode, and a dentry that describe the "class"
 *                    of the file
 *
 * @name:    [in]    name of the "class" of the new file
 * @fops:    [in]    file operations for the new file
 * @priv:    [in]    private data for the new file (will be file's private_data)
 * @flags:   [in]    flags
 *
 * Creates a new file by hooking it on a single inode. This is useful for files
 * that do not need to have a full-fledged inode in order to operate correctly.
 * All the files created with anon_inode_getfile() will share a single inode,
 * hence saving memory and avoiding code duplication for the file/inode/dentry
 * setup.  Returns the newly created file* or an error pointer.
 */
struct file *anon_inode_getfile(const char *name,
				const struct file_operations *fops,
				void *priv, int flags)
{
	struct qstr this;
	struct path path;
	struct file *file;
	int error;

	if (IS_ERR(anon_inode_inode))
		return ERR_PTR(-ENODEV);

	if (fops->owner && !try_module_get(fops->owner))
		return ERR_PTR(-ENOENT);

	/*
	 * Link the inode to a directory entry by creating a unique name
	 * using the inode sequence number.
	 */
	error = -ENOMEM;
	this.name = name;
	this.len = strlen(name);
	this.hash = 0;
	path.dentry = d_alloc(anon_inode_mnt->mnt_sb->s_root, &this);
	if (!path.dentry)
		goto err_module;

	path.mnt = mntget(anon_inode_mnt);
	/*
	 * We know the anon_inode inode count is always greater than zero,
	 * so we can avoid doing an igrab() and we can use an open-coded
	 * atomic_inc().
	 */
	atomic_inc(&anon_inode_inode->i_count);

	path.dentry->d_op = &anon_inodefs_dentry_operations;
	d_instantiate(path.dentry, anon_inode_inode);

	error = -ENFILE;
	file = alloc_file(&path, OPEN_FMODE(flags), fops);
	if (!file)
		goto err_dput;
	file->f_mapping = anon_inode_inode->i_mapping;

	file->f_pos = 0;
	file->f_flags = flags & (O_ACCMODE | O_NONBLOCK);
	file->f_version = 0;
	file->private_data = priv;

	return file;

err_dput:
	path_put(&path);
err_module:
	module_put(fops->owner);
	return ERR_PTR(error);
}

/**
 * anon_inode_getfile - creates a new file instance by hooking it up to an
 *                      anonymous inode, and a dentry that describe the "class"
 *                      of the file
 *
 * @name:    [in]    name of the "class" of the new file
 * @fops:    [in]    file operations for the new file
 * @priv:    [in]    private data for the new file (will be file's private_data)
 * @flags:   [in]    flags
 *
 * Creates a new file by hooking it on a single inode. This is useful for files
 * that do not need to have a full-fledged inode in order to operate correctly.
 * All the files created with anon_inode_getfile() will share a single inode,
 * hence saving memory and avoiding code duplication for the file/inode/dentry
 * setup.  Returns the newly created file* or an error pointer.
 */
struct file *anon_inode_getfile(const char *name,
				const struct file_operations *fops,
				void *priv, int flags)
{
	struct qstr this;
	struct path path;
	struct file *file;

	if (IS_ERR(anon_inode_inode))
		return ERR_PTR(-ENODEV);

	if (fops->owner && !try_module_get(fops->owner))
		return ERR_PTR(-ENOENT);

	/*
	 * Link the inode to a directory entry by creating a unique name
	 * using the inode sequence number.
	 */
	file = ERR_PTR(-ENOMEM);
	this.name = name;
	this.len = strlen(name);
	this.hash = 0;
	path.dentry = d_alloc_pseudo(anon_inode_mnt->mnt_sb, &this);
	if (!path.dentry)
		goto err_module;

	path.mnt = mntget(anon_inode_mnt);
	/*
	 * We know the anon_inode inode count is always greater than zero,
	 * so ihold() is safe.
	 */
	ihold(anon_inode_inode);

	d_instantiate(path.dentry, anon_inode_inode);

	file = alloc_file(&path, OPEN_FMODE(flags), fops);
	if (IS_ERR(file))
		goto err_dput;
	file->f_mapping = anon_inode_inode->i_mapping;

	file->f_flags = flags & (O_ACCMODE | O_NONBLOCK);
	file->private_data = priv;

	return file;

err_dput:
	path_put(&path);
err_module:
	module_put(fops->owner);
	return file;
}

static bool ovl_open_need_copy_up(int flags, enum ovl_path_type type,
				  struct dentry *realdentry)
{
	if (type != OVL_PATH_LOWER)
		return false;

	if (special_file(realdentry->d_inode->i_mode))
		return false;

	if (!(OPEN_FMODE(flags) & FMODE_WRITE) && !(flags & O_TRUNC))
		return false;

	return true;
}

static bool ovl_open_need_copy_up(struct dentry *dentry, int flags)
{
	if (ovl_dentry_upper(dentry) &&
	    ovl_dentry_has_upper_alias(dentry))
		return false;

	if (special_file(d_inode(dentry)->i_mode))
		return false;

	if (!(OPEN_FMODE(flags) & FMODE_WRITE) && !(flags & O_TRUNC))
		return false;

	return true;
}

struct file *anon_inode_getfile(const char *name,
				const struct file_operations *fops,
				void *priv, int flags)
{
	struct qstr this;
	struct path path;
	struct file *file;
	int error;

	if (IS_ERR(anon_inode_inode))
		return ERR_PTR(-ENODEV);

	if (fops->owner && !try_module_get(fops->owner))
		return ERR_PTR(-ENOENT);

	error = -ENOMEM;
	this.name = name;
	this.len = strlen(name);
	this.hash = 0;
	path.dentry = d_alloc_pseudo(anon_inode_mnt->mnt_sb, &this);
	if (!path.dentry)
		goto err_module;

	path.mnt = mntget(anon_inode_mnt);
	ihold(anon_inode_inode);

	d_instantiate(path.dentry, anon_inode_inode);

	error = -ENFILE;
	file = alloc_file(&path, OPEN_FMODE(flags), fops);
	if (!file)
		goto err_dput;
	file->f_mapping = anon_inode_inode->i_mapping;

	file->f_pos = 0;
	file->f_flags = flags & (O_ACCMODE | O_NONBLOCK);
	file->f_version = 0;
	file->private_data = priv;

	return file;

err_dput:
	path_put(&path);
err_module:
	module_put(fops->owner);
	return ERR_PTR(error);
}

int
xfs_open_by_handle(
	struct file		*parfilp,
	xfs_fsop_handlereq_t	*hreq)
{
	const struct cred	*cred = current_cred();
	int			error;
	int			fd;
	int			permflag;
	struct file		*filp;
	struct inode		*inode;
	struct dentry		*dentry;
	fmode_t			fmode;
	struct path		path;

	if (!capable(CAP_SYS_ADMIN))
		return -EPERM;

	dentry = xfs_handlereq_to_dentry(parfilp, hreq);
	if (IS_ERR(dentry))
		return PTR_ERR(dentry);
	inode = d_inode(dentry);

	/* Restrict xfs_open_by_handle to directories & regular files. */
	if (!(S_ISREG(inode->i_mode) || S_ISDIR(inode->i_mode))) {
		error = -EPERM;
		goto out_dput;
	}

#if BITS_PER_LONG != 32
	hreq->oflags |= O_LARGEFILE;
#endif

	permflag = hreq->oflags;
	fmode = OPEN_FMODE(permflag);
	if ((!(permflag & O_APPEND) || (permflag & O_TRUNC)) &&
	    (fmode & FMODE_WRITE) && IS_APPEND(inode)) {
		error = -EPERM;
		goto out_dput;
	}

	if ((fmode & FMODE_WRITE) && IS_IMMUTABLE(inode)) {
		error = -EACCES;
		goto out_dput;
	}

	/* Can't write directories. */
	if (S_ISDIR(inode->i_mode) && (fmode & FMODE_WRITE)) {
		error = -EISDIR;
		goto out_dput;
	}

	fd = get_unused_fd_flags(0);
	if (fd < 0) {
		error = fd;
		goto out_dput;
	}

	path.mnt = parfilp->f_path.mnt;
	path.dentry = dentry;
	filp = dentry_open(&path, hreq->oflags, cred);
	dput(dentry);
	if (IS_ERR(filp)) {
		put_unused_fd(fd);
		return PTR_ERR(filp);
	}

	if (S_ISREG(inode->i_mode)) {
		filp->f_flags |= O_NOATIME;
		filp->f_mode |= FMODE_NOCMTIME;
	}

	fd_install(fd, filp);
	return fd;

 out_dput:
	dput(dentry);
	return error;
}

static struct file *__dentry_open(struct dentry *dentry, struct vfsmount *mnt,
					struct file *f,
					int (*open)(struct inode *, struct file *),
					const struct cred *cred)
{
	static const struct file_operations empty_fops = {};
	struct inode *inode;
	int error;

	f->f_mode = OPEN_FMODE(f->f_flags) | FMODE_LSEEK |
				FMODE_PREAD | FMODE_PWRITE;

	if (unlikely(f->f_flags & O_PATH))
		f->f_mode = FMODE_PATH;

	inode = dentry->d_inode;
	if (f->f_mode & FMODE_WRITE) {
		error = __get_file_write_access(inode, mnt);
		if (error)
			goto cleanup_file;
		if (!special_file(inode->i_mode))
			file_take_write(f);
	}

	f->f_mapping = inode->i_mapping;
	f->f_path.dentry = dentry;
	f->f_path.mnt = mnt;
	f->f_pos = 0;
	file_sb_list_add(f, inode->i_sb);

	if (unlikely(f->f_mode & FMODE_PATH)) {
		f->f_op = &empty_fops;
		return f;
	}

	f->f_op = fops_get(inode->i_fop);

	error = security_dentry_open(f, cred);
	if (error)
		goto cleanup_all;

	error = break_lease(inode, f->f_flags);
	if (error)
		goto cleanup_all;

	if (!open && f->f_op)
		open = f->f_op->open;
	if (open) {
		error = open(inode, f);
		if (error)
			goto cleanup_all;
	}
	if ((f->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
		i_readcount_inc(inode);

	f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);

	file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping);

	/* NB: we're sure to have correct a_ops only after f_op->open */
	if (f->f_flags & O_DIRECT) {
		if (!f->f_mapping->a_ops ||
		    ((!f->f_mapping->a_ops->direct_IO) &&
		    (!f->f_mapping->a_ops->get_xip_mem))) {
			fput(f);
			f = ERR_PTR(-EINVAL);
		}
	}

	return f;

cleanup_all:
	fops_put(f->f_op);
	if (f->f_mode & FMODE_WRITE) {
		put_write_access(inode);
		if (!special_file(inode->i_mode)) {
			/*
			 * We don't consider this a real
			 * mnt_want/drop_write() pair
			 * because it all happenend right
			 * here, so just reset the state.
			 */
			file_reset_write(f);
			mnt_drop_write(mnt);
		}
	}
	file_sb_list_del(f);
	f->f_path.dentry = NULL;
	f->f_path.mnt = NULL;
cleanup_file:
	put_filp(f);
	dput(dentry);
	mntput(mnt);
	return ERR_PTR(error);
}

static int
cifs_do_create(struct inode *inode, struct dentry *direntry, unsigned int xid,
	       struct tcon_link *tlink, unsigned oflags, umode_t mode,
	       __u32 *oplock, struct cifs_fid *fid, int *created)
{
	int rc = -ENOENT;
	int create_options = CREATE_NOT_DIR;
	int desired_access;
	struct cifs_sb_info *cifs_sb = CIFS_SB(inode->i_sb);
	struct cifs_tcon *tcon = tlink_tcon(tlink);
	char *full_path = NULL;
	FILE_ALL_INFO *buf = NULL;
	struct inode *newinode = NULL;
	int disposition;
	struct TCP_Server_Info *server = tcon->ses->server;

	*oplock = 0;
	if (tcon->ses->server->oplocks)
		*oplock = REQ_OPLOCK;

	full_path = build_path_from_dentry(direntry);
	if (full_path == NULL) {
		rc = -ENOMEM;
		goto out;
	}

	if (tcon->unix_ext && cap_unix(tcon->ses) && !tcon->broken_posix_open &&
	    (CIFS_UNIX_POSIX_PATH_OPS_CAP &
			le64_to_cpu(tcon->fsUnixInfo.Capability))) {
		rc = cifs_posix_open(full_path, &newinode, inode->i_sb, mode,
				     oflags, oplock, &fid->netfid, xid);
		switch (rc) {
		case 0:
			if (newinode == NULL) {
				/* query inode info */
				goto cifs_create_get_file_info;
			}

			if (S_ISDIR(newinode->i_mode)) {
				CIFSSMBClose(xid, tcon, fid->netfid);
				iput(newinode);
				rc = -EISDIR;
				goto out;
			}

			if (!S_ISREG(newinode->i_mode)) {
				/*
				 * The server may allow us to open things like
				 * FIFOs, but the client isn't set up to deal
				 * with that. If it's not a regular file, just
				 * close it and proceed as if it were a normal
				 * lookup.
				 */
				CIFSSMBClose(xid, tcon, fid->netfid);
				goto cifs_create_get_file_info;
			}
			/* success, no need to query */
			goto cifs_create_set_dentry;

		case -ENOENT:
			goto cifs_create_get_file_info;

		case -EIO:
		case -EINVAL:
			/*
			 * EIO could indicate that (posix open) operation is not
			 * supported, despite what server claimed in capability
			 * negotiation.
			 *
			 * POSIX open in samba versions 3.3.1 and earlier could
			 * incorrectly fail with invalid parameter.
			 */
			tcon->broken_posix_open = true;
			break;

		case -EREMOTE:
		case -EOPNOTSUPP:
			/*
			 * EREMOTE indicates DFS junction, which is not handled
			 * in posix open.  If either that or op not supported
			 * returned, follow the normal lookup.
			 */
			break;

		default:
			goto out;
		}
		/*
		 * fallthrough to retry, using older open call, this is case
		 * where server does not support this SMB level, and falsely
		 * claims capability (also get here for DFS case which should be
		 * rare for path not covered on files)
		 */
	}

	desired_access = 0;
	if (OPEN_FMODE(oflags) & FMODE_READ)
		desired_access |= GENERIC_READ; /* is this too little? */
	if (OPEN_FMODE(oflags) & FMODE_WRITE)
		desired_access |= GENERIC_WRITE;
//.........这里部分代码省略.........

static int do_dentry_open(struct file *f,
			  int (*open)(struct inode *, struct file *),
			  const struct cred *cred)
{
	static const struct file_operations empty_fops = {};
	struct inode *inode;
	int error;

	f->f_mode = OPEN_FMODE(f->f_flags) | FMODE_LSEEK |
				FMODE_PREAD | FMODE_PWRITE;

	if (unlikely(f->f_flags & O_PATH))
		f->f_mode = FMODE_PATH;

	path_get(&f->f_path);
	inode = f->f_inode = f->f_path.dentry->d_inode;
	if (f->f_mode & FMODE_WRITE) {
		error = __get_file_write_access(inode, f->f_path.mnt);
		if (error)
			goto cleanup_file;
		if (!special_file(inode->i_mode))
			file_take_write(f);
	}

	f->f_mapping = inode->i_mapping;
	file_sb_list_add(f, inode->i_sb);

	if (unlikely(f->f_mode & FMODE_PATH)) {
		f->f_op = &empty_fops;
		return 0;
	}

	f->f_op = fops_get(inode->i_fop);

	error = security_file_open(f, cred);
	if (error)
		goto cleanup_all;

	error = break_lease(inode, f->f_flags);
	if (error)
		goto cleanup_all;

	if (!open && f->f_op)
		open = f->f_op->open;
	if (open) {
		error = open(inode, f);
		if (error)
			goto cleanup_all;
	}
	if ((f->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
		i_readcount_inc(inode);

	f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);

	file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping);

	return 0;

cleanup_all:
	fops_put(f->f_op);
	file_sb_list_del(f);
	if (f->f_mode & FMODE_WRITE) {
		put_write_access(inode);
		if (!special_file(inode->i_mode)) {
			/*
			 * We don't consider this a real
			 * mnt_want/drop_write() pair
			 * because it all happenend right
			 * here, so just reset the state.
			 */
			file_reset_write(f);
			__mnt_drop_write(f->f_path.mnt);
		}
	}
cleanup_file:
	path_put(&f->f_path);
	f->f_path.mnt = NULL;
	f->f_path.dentry = NULL;
	f->f_inode = NULL;
	return error;
}

int
cifs_create(struct inode *inode, struct dentry *direntry, int mode,
		struct nameidata *nd)
{
	int rc = -ENOENT;
	int xid;
	int create_options = CREATE_NOT_DIR;
	__u32 oplock = 0;
	int oflags;
	/*
	 * BB below access is probably too much for mknod to request
	 *    but we have to do query and setpathinfo so requesting
	 *    less could fail (unless we want to request getatr and setatr
	 *    permissions (only).  At least for POSIX we do not have to
	 *    request so much.
	 */
	int desiredAccess = GENERIC_READ | GENERIC_WRITE;
	__u16 fileHandle;
	struct cifs_sb_info *cifs_sb;
	struct tcon_link *tlink;
	struct cifs_tcon *tcon;
	char *full_path = NULL;
	FILE_ALL_INFO *buf = NULL;
	struct inode *newinode = NULL;
	int disposition = FILE_OVERWRITE_IF;

	xid = GetXid();

	cifs_sb = CIFS_SB(inode->i_sb);
	tlink = cifs_sb_tlink(cifs_sb);
	if (IS_ERR(tlink)) {
		FreeXid(xid);
		return PTR_ERR(tlink);
	}
	tcon = tlink_tcon(tlink);

	if (oplockEnabled)
		oplock = REQ_OPLOCK;

	if (nd)
		oflags = nd->intent.open.file->f_flags;
	else
		oflags = O_RDONLY | O_CREAT;

	full_path = build_path_from_dentry(direntry);
	if (full_path == NULL) {
		rc = -ENOMEM;
		goto cifs_create_out;
	}

	if (tcon->unix_ext && (tcon->ses->capabilities & CAP_UNIX) &&
	    (CIFS_UNIX_POSIX_PATH_OPS_CAP &
			le64_to_cpu(tcon->fsUnixInfo.Capability))) {
		rc = cifs_posix_open(full_path, &newinode,
			inode->i_sb, mode, oflags, &oplock, &fileHandle, xid);
		/* EIO could indicate that (posix open) operation is not
		   supported, despite what server claimed in capability
		   negotiation.  EREMOTE indicates DFS junction, which is not
		   handled in posix open */

		if (rc == 0) {
			if (newinode == NULL) /* query inode info */
				goto cifs_create_get_file_info;
			else /* success, no need to query */
				goto cifs_create_set_dentry;
		} else if ((rc != -EIO) && (rc != -EREMOTE) &&
			 (rc != -EOPNOTSUPP) && (rc != -EINVAL))
			goto cifs_create_out;
		/* else fallthrough to retry, using older open call, this is
		   case where server does not support this SMB level, and
		   falsely claims capability (also get here for DFS case
		   which should be rare for path not covered on files) */
	}

	if (nd) {
		/* if the file is going to stay open, then we
		   need to set the desired access properly */
		desiredAccess = 0;
		if (OPEN_FMODE(oflags) & FMODE_READ)
			desiredAccess |= GENERIC_READ; /* is this too little? */
		if (OPEN_FMODE(oflags) & FMODE_WRITE)
			desiredAccess |= GENERIC_WRITE;

		if ((oflags & (O_CREAT | O_EXCL)) == (O_CREAT | O_EXCL))
			disposition = FILE_CREATE;
		else if ((oflags & (O_CREAT | O_TRUNC)) == (O_CREAT | O_TRUNC))
			disposition = FILE_OVERWRITE_IF;
		else if ((oflags & O_CREAT) == O_CREAT)
			disposition = FILE_OPEN_IF;
		else
			cFYI(1, "Create flag not set in create function");
	}

	/* BB add processing to set equivalent of mode - e.g. via CreateX with
	   ACLs */

	buf = kmalloc(sizeof(FILE_ALL_INFO), GFP_KERNEL);
	if (buf == NULL) {
		rc = -ENOMEM;
		goto cifs_create_out;
//.........这里部分代码省略.........

static int do_dentry_open(struct file *f,
			  int (*open)(struct inode *, struct file *),
			  const struct cred *cred)
{
	static const struct file_operations empty_fops = {};
	struct inode *inode;
	int error;

	f->f_mode = OPEN_FMODE(f->f_flags) | FMODE_LSEEK |
				FMODE_PREAD | FMODE_PWRITE;

	path_get(&f->f_path);
	inode = f->f_inode = f->f_path.dentry->d_inode;
	f->f_mapping = inode->i_mapping;

	if (unlikely(f->f_flags & O_PATH)) {
		f->f_mode = FMODE_PATH;
		f->f_op = &empty_fops;
		return 0;
	}

	if (f->f_mode & FMODE_WRITE && !special_file(inode->i_mode)) {
		error = get_write_access(inode);
		if (unlikely(error))
			goto cleanup_file;
		error = __mnt_want_write(f->f_path.mnt);
		if (unlikely(error)) {
			put_write_access(inode);
			goto cleanup_file;
		}
		f->f_mode |= FMODE_WRITER;
	}

	/* POSIX.1-2008/SUSv4 Section XSI 2.9.7 */
	if (S_ISREG(inode->i_mode))
		f->f_mode |= FMODE_ATOMIC_POS;

	f->f_op = fops_get(inode->i_fop);
	if (unlikely(WARN_ON(!f->f_op))) {
		error = -ENODEV;
		goto cleanup_all;
	}

	error = security_file_open(f, cred);
	if (error)
		goto cleanup_all;

	error = break_lease(inode, f->f_flags);
	if (error)
		goto cleanup_all;

	if (!open)
		open = f->f_op->open;
	if (open) {
		error = open(inode, f);
		if (error)
			goto cleanup_all;
	}
	if ((f->f_mode & (FMODE_READ | FMODE_WRITE)) == FMODE_READ)
		i_readcount_inc(inode);
	if ((f->f_mode & FMODE_READ) &&
	     likely(f->f_op->read || f->f_op->aio_read || f->f_op->read_iter))
		f->f_mode |= FMODE_CAN_READ;
	if ((f->f_mode & FMODE_WRITE) &&
	     likely(f->f_op->write || f->f_op->aio_write || f->f_op->write_iter))
		f->f_mode |= FMODE_CAN_WRITE;

	f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);

	file_ra_state_init(&f->f_ra, f->f_mapping->host->i_mapping);

	return 0;

cleanup_all:
	fops_put(f->f_op);
	if (f->f_mode & FMODE_WRITER) {
		put_write_access(inode);
		__mnt_drop_write(f->f_path.mnt);
	}
cleanup_file:
	path_put(&f->f_path);
	f->f_path.mnt = NULL;
	f->f_path.dentry = NULL;
	f->f_inode = NULL;
	return error;
}