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/* libdiskfs implementation of fs.defs: dir_rename
Copyright (C) 1992, 1993, 1994 Free Software Foundation
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License as
published by the Free Software Foundation; either version 2, or (at
your option) any later version.
This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
#include "priv.h"
#include "fs_S.h"
/* To avoid races in checkpath, and to prevent a directory from being
simultaneously renamed by two processes, we serialize all renames of
directores with this lock */
static struct mutex renamedirlock = MUTEX_INITIALIZER;
/* Implement dir_rename as described in <hurd/fs.defs>. */
error_t
diskfs_S_dir_rename (struct protid *fromcred,
char *fromname,
struct protid *tocred,
char *toname)
{
struct node *fdp, *tdp, *fnp, *tnp, *tmpnp;
error_t err;
struct dirstat *ds = alloca (diskfs_dirstat_size);
if (!fromcred)
return EOPNOTSUPP;
/* Verify that tocred really is a port to us XXX */
if (!tocred)
return EXDEV;
if (diskfs_readonly)
return EROFS;
fdp = fromcred->po->np;
tdp = tocred->po->np;
try_again:
/* Acquire the source; hold a reference to it. This
will prevent anyone from deleting it before we create
the new link. */
mutex_lock (&fdp->lock);
err = diskfs_lookup (fdp, fromname, LOOKUP, &fnp, 0, fromcred);
mutex_unlock (&fdp->lock);
if (err)
return err;
if (S_ISDIR (fnp->dn_stat.st_mode))
{
mutex_unlock (&fnp->lock);
if (!mutex_try_lock (&renamedirlock))
{
diskfs_nrele (fnp);
mutex_lock (&renamedirlock);
goto try_again;
}
err = diskfs_rename_dir (fdp, fnp, fromname, tdp, toname, fromcred,
tocred);
diskfs_nrele (fnp);
mutex_unlock (&renamedirlock);
return err;
}
mutex_unlock (&fnp->lock);
/* We now hold no locks */
/* Link the node into the new directory. */
mutex_lock (&tdp->lock);
err = diskfs_lookup (tdp, toname, RENAME, &tnp, ds, tocred);
if (err && err != ENOENT)
{
diskfs_drop_dirstat (tdp, ds);
diskfs_nrele (fnp);
mutex_unlock (&tdp->lock);
return err;
}
/* rename("foo", "link-to-foo") is guaranteed to return 0 and
do nothing by Posix. */
if (tnp == fnp)
{
diskfs_drop_dirstat (tdp, ds);
diskfs_nrele (fnp);
diskfs_nput (tnp);
mutex_unlock (&tdp->lock);
return 0;
}
/* rename("foo", dir) should fail. */
if (tnp && S_ISDIR (tnp->dn_stat.st_mode))
{
diskfs_drop_dirstat (tdp, ds);
diskfs_nrele (fnp);
mutex_unlock (&tdp->lock);
return EISDIR;
}
mutex_lock (&fnp->lock);
/* Increment the link count for the upcoming link */
if (fnp->dn_stat.st_nlink == diskfs_link_max - 1)
{
diskfs_drop_dirstat (tdp, ds);
diskfs_nput (fnp);
mutex_unlock (&tdp->lock);
return EMLINK;
}
fnp->dn_stat.st_nlink++;
fnp->dn_set_ctime = 1;
diskfs_node_update (fnp, 1);
if (tnp)
{
err = diskfs_dirrewrite (tdp, fnp, ds);
if (!err)
{
tnp->dn_stat.st_nlink--;
tnp->dn_set_ctime = 1;
}
diskfs_nput (tnp);
}
else
err = diskfs_direnter (tdp, toname, fnp, ds, tocred);
mutex_unlock (&tdp->lock);
mutex_unlock (&fnp->lock);
if (err)
{
diskfs_nrele (fnp);
return err;
}
/* We now hold no locks */
/* Now we remove the source. Unfortunately, we haven't held
fdp locked (nor could we), so someone else might have already
removed it. */
mutex_lock (&fdp->lock);
err = diskfs_lookup (fdp, fromname, REMOVE, &tmpnp, ds, fromcred);
if (err)
{
diskfs_drop_dirstat (tdp, ds);
mutex_unlock (&fdp->lock);
diskfs_nrele (fnp);
return err;
}
if (tmpnp != fnp)
{
/* This is no longer the node being renamed, so just return. */
diskfs_drop_dirstat (tdp, ds);
diskfs_nput (tmpnp);
diskfs_nrele (fnp);
mutex_unlock (&fdp->lock);
return 0;
}
diskfs_nrele (tmpnp);
err = diskfs_dirremove (fdp, ds);
fnp->dn_stat.st_nlink--;
fnp->dn_set_ctime = 1;
diskfs_nput (fnp);
mutex_unlock (&fdp->lock);
return err;
}
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