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dm_handle_to_path() will now work in most cases, and in the other cases
there's just a little more grunt work that has to be done in the library.  If
the directory that contains some component of the path has never had a lookup
performed on it, then the kernel won't have that dir in its dcache.  In that
case it'll create an anonymous dentry for the filesystem's root dir, and the
library detects that this happened.

If the library detects that an anonymous dentry was created, then it returns
an error indicating that it didn't find the path.  Before I take this another
step, I'd like to know if this scenario happens in actual practice.  I'm
betting the directory of interest has almost always been loaded into the
dcache by a user process before the HSM uses dm_handle_to_path().  We'll see.

It seems that ioctl(XFS_IOC_OPEN_BY_HANDLE) would have the same restriction,
though it looks like it's never used in a case where the path hasn't already
been accessed.

This mod also removes libdm's dependence on libhandle.
cleanup junk

/*
 * Copyright (c) 1995-2001 Silicon Graphics, Inc.  All Rights Reserved.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of version 2.1 of the GNU Lesser General Public License
 * as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it would be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 *
 * Further, this software is distributed without any warranty that it is
 * free of the rightful claim of any third person regarding infringement
 * or the like.  Any license provided herein, whether implied or
 * otherwise, applies only to this software file.  Patent licenses, if
 * any, provided herein do not apply to combinations of this program with
 * other software, or any other product whatsoever.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this program; if not, write the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston MA 02111-1307,
 * USA.
 *
 * Contact information: Silicon Graphics, Inc., 1600 Amphitheatre Pkwy,
 * Mountain View, CA  94043, or:
 *
 * http://www.sgi.com
 *
 * For further information regarding this notice, see:
 *
 * http://oss.sgi.com/projects/GenInfo/SGIGPLNoticeExplan/
 */

#include <errno.h>
#include <stdlib.h>
#include <string.h>

#include <dmapi.h>
#include <dmapi_kern.h>
#include "dmapi_lib.h"

#ifdef linux
#include <xfs/xfs_fs.h>
#include <xfs/handle.h>
#else
#include <sys/handle.h>
#endif

typedef	enum	{
	DM_HANDLE_GLOBAL,
	DM_HANDLE_FILESYSTEM,
	DM_HANDLE_FILE,
	DM_HANDLE_BAD
} dm_handletype_t;


extern int
dm_path_to_handle (
	char		*path,
	void		**hanpp,
	size_t		*hlenp)
{
	char		hbuf[DM_MAX_HANDLE_SIZE];

	if (dmi(DM_PATH_TO_HANDLE, path, hbuf, hlenp))
		return(-1);

	if ((*hanpp = malloc(*hlenp)) == NULL) {	
		errno = ENOMEM;
		return -1;
	}
	memcpy(*hanpp, hbuf, *hlenp);
	return(0);
}


extern int
dm_path_to_fshandle (
	char		*path,
	void		**hanpp,
	size_t		*hlenp)
{
	char		hbuf[DM_MAX_HANDLE_SIZE];

	if (dmi(DM_PATH_TO_FSHANDLE, path, hbuf, hlenp))
		return(-1);

	if ((*hanpp = malloc(*hlenp)) == NULL) {	
		errno = ENOMEM;
		return -1;
	}
	memcpy(*hanpp, hbuf, *hlenp);
	return(0);
}


extern int
dm_fd_to_handle (
	int		fd,
	void		**hanpp,
	size_t		*hlenp)
{
	char		hbuf[DM_MAX_HANDLE_SIZE];

	if (dmi(DM_FD_TO_HANDLE, fd, hbuf, hlenp))
		return(-1);

	if ((*hanpp = malloc(*hlenp)) == NULL) {	
		errno = ENOMEM;
		return -1;
	}
	memcpy(*hanpp, hbuf, *hlenp);
	return(0);
}


extern int
dm_handle_to_fshandle (
	void		*hanp,
	size_t		hlen,
	void		**fshanp,
	size_t		*fshlen)
{
	dm_fsid_t	fsid;

	if (dm_handle_to_fsid(hanp, hlen, &fsid))
		return(-1);

	*fshlen = sizeof(fsid);
	if ((*fshanp = malloc(*fshlen)) == NULL) {
		errno = ENOMEM;
		return(-1);
	}
	memcpy(*fshanp, &fsid, *fshlen);
	return(0);
}


/* ARGSUSED */
extern void
dm_handle_free(
	void		*hanp,
	size_t		hlen)
{
	free(hanp);
}


static dm_handletype_t
parse_handle(
	void		*hanp,
	size_t		hlen,
	dm_fsid_t	*fsidp,
	dm_ino_t	*inop,
	dm_igen_t	*igenp)
{
	xfs_handle_t	handle;
	xfs_fid2_t	*xfid2;
	fid_t		*fidp;

	if (hanp == DM_GLOBAL_HANP && hlen == DM_GLOBAL_HLEN)
		return(DM_HANDLE_GLOBAL);

	if (hlen < sizeof(handle.ha_fsid) || hlen > sizeof(handle))
		return(DM_HANDLE_BAD);

	memcpy(&handle, hanp, hlen);
	if (!handle.ha_fsid.val[0] || !handle.ha_fsid.val[1])
		return(DM_HANDLE_BAD);
	if (fsidp)
		memcpy(fsidp, &handle.ha_fsid, sizeof(handle.ha_fsid));
	if (hlen == sizeof(handle.ha_fsid))
		return(DM_HANDLE_FILESYSTEM);

#ifdef linux
	fidp = (fid_t*)&handle.ha_fid;
	if (fidp->fid_len != (hlen - sizeof(handle.ha_fsid) - sizeof(fidp->fid_len)))
		return(DM_HANDLE_BAD);
#else
	if (handle.ha_fid.fid_len != (hlen - sizeof(handle.ha_fsid) - sizeof(handle.ha_fid.fid_len)))
		return(DM_HANDLE_BAD);
#endif

	xfid2 = (struct xfs_fid2 *)&handle.ha_fid;
	if (xfid2->fid_len == sizeof *xfid2 - sizeof xfid2->fid_len) {
		if (xfid2->fid_pad)
			return(DM_HANDLE_BAD);
		if (inop)
			*inop  = xfid2->fid_ino;
		if (igenp)
			*igenp = xfid2->fid_gen;
	} else {
		return(DM_HANDLE_BAD);
	}
	return(DM_HANDLE_FILE);
}


extern dm_boolean_t
dm_handle_is_valid(
	void		*hanp,
	size_t		hlen)
{
	if (parse_handle(hanp, hlen, NULL, NULL, NULL) != DM_HANDLE_BAD)
		return(DM_TRUE);
	return(DM_FALSE);
}


extern int
dm_handle_cmp(
	void		*hanp1,
	size_t		hlen1,
	void		*hanp2,
	size_t		hlen2)
{
	int		diff;

	/* If the handles don't have the same length, then this is an
	   apples-and-oranges comparison.  For lack of a better option,
	   use the handle lengths to sort them into an arbitrary order.
	*/
	if ((diff = (int)(hlen1 - hlen2)) != 0)
		return diff;
	return(memcmp(hanp1, hanp2, hlen1));
}


extern u_int
dm_handle_hash(
	void		*hanp,
	size_t		hlen)
{
	size_t		i;
	u_int		hash = 0;
	u_char		*ip = (u_char *)hanp;

	for (i = 0; i < hlen; i++) {
		hash += *ip++;
	}
	return(hash);
}


extern int
dm_handle_to_fsid(
	void		*hanp,
	size_t		hlen,
	dm_fsid_t	*fsidp)
{
	dm_handletype_t	htype;

	htype = parse_handle(hanp, hlen, fsidp, NULL, NULL);
	if (htype == DM_HANDLE_FILE || htype == DM_HANDLE_FILESYSTEM)
		return(0);
	errno = EBADF;
	return(-1);
}


extern int
dm_handle_to_ino(
	void		*hanp,
	size_t		hlen,
	dm_ino_t	*inop)
{
	if (parse_handle(hanp, hlen, NULL, inop, NULL) == DM_HANDLE_FILE)
		return(0);
	errno = EBADF;
	return(-1);
}


extern int
dm_handle_to_igen(
	void		*hanp,
	size_t		hlen,
	dm_igen_t	*igenp)
{
	if (parse_handle(hanp, hlen, NULL, NULL, igenp) == DM_HANDLE_FILE)
		return(0);
	errno = EBADF;
	return(-1);
}


extern int
dm_make_handle(
	dm_fsid_t	*fsidp,
	dm_ino_t	*inop,
	dm_igen_t	*igenp,
	void		**hanpp,
	size_t		*hlenp)
{
	xfs_fid2_t	*xfid2;
/* XXX */
	xfs_handle_t	handle;

	memcpy(&handle.ha_fsid, fsidp, sizeof(handle.ha_fsid));
	xfid2 = (struct xfs_fid2 *)&handle.ha_fid;
	xfid2->fid_pad = 0;
	xfid2->fid_gen = (__u32)*igenp;
	xfid2->fid_ino = *inop;
	xfid2->fid_len = sizeof(*xfid2) - sizeof(xfid2->fid_len);
	*hlenp = sizeof(*xfid2) + sizeof(handle.ha_fsid);
	if ((*hanpp = malloc(*hlenp)) == NULL) {	
		errno = ENOMEM;
		return -1;
	}
	memcpy(*hanpp, &handle, *hlenp);
	return(0);
}


extern int
dm_make_fshandle(
	dm_fsid_t	*fsidp,
	void		**hanpp,
	size_t		*hlenp)
{
/* XXX */
#if 0
	*hlenp = sizeof(fsid_t);
#else
	*hlenp = sizeof(__kernel_fsid_t);
#endif
	if ((*hanpp = malloc(*hlenp)) == NULL) {	
		errno = ENOMEM;
		return -1;
	}
	memcpy(*hanpp, fsidp, *hlenp);
	return(0);
}


extern int
dm_create_by_handle(
	dm_sessid_t	sid,
	void		*dirhanp,
	size_t		dirhlen,
	dm_token_t	token,
	void		*hanp,
	size_t		hlen,
	char		*cname)
{
	return dmi(DM_CREATE_BY_HANDLE, sid, dirhanp, dirhlen, token,
		hanp, hlen, cname);
}


extern int
dm_mkdir_by_handle(
	dm_sessid_t	sid,
	void		*dirhanp,
	size_t		dirhlen,
	dm_token_t	token,
	void		*hanp,
	size_t		hlen,
	char		*cname)
{
	return dmi(DM_MKDIR_BY_HANDLE, sid, dirhanp, dirhlen, token, hanp,
		hlen, cname);
}


extern int
dm_symlink_by_handle(
	dm_sessid_t	sid,
	void		*dirhanp,
	size_t		dirhlen,
	dm_token_t	token,
	void		*hanp,
	size_t		hlen,
	char		*cname,
	char		*path)
{
	return dmi(DM_SYMLINK_BY_HANDLE, sid, dirhanp, dirhlen, token, hanp,
		hlen, cname, path);
}