Initial revision

1 files changed, 182 insertions, 0 deletions

diff --git a/libdiskfs/dir-rename.c b/libdiskfs/dir-rename.c
new file mode 100644
index 00000000..e6985e10
--- /dev/null
+++ b/libdiskfs/dir-rename.c
@@ -0,0 +1,182 @@
+/* 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"
+
+/* 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;
+static int renamedirinit;
+
+/* 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;
+  volatile int isdir;
+  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 (readonly)
+    return EROFS;
+
+  fdp = fromcred->po->np;
+  tdp = tocred->po->np;
+
+ tryagain:
+  /* 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);
+      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 (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 (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 (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 == LINK_MAX - 1)
+    {
+      diskfs_drop_dirstat (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 (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 (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;
+}
+#endif