Initial revision

1 files changed, 169 insertions, 0 deletions

diff --git a/sutils/clookup.c b/sutils/clookup.c
new file mode 100644
index 00000000..8db06295
--- /dev/null
+++ b/sutils/clookup.c
@@ -0,0 +1,169 @@
+/* Careful filename lookup
+
+   Copyright (C) 1996 Free Software Foundation, Inc.
+
+   Written by Miles Bader <miles@gnu.ai.mit.edu>
+
+   This file is part of the GNU Hurd.
+
+   The GNU Hurd 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.
+
+   The GNU Hurd 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 <unistd.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <hurd.h>
+#include <hurd/lookup.h>
+#include <hurd/id.h>
+#include <hurd/fsys.h>
+
+extern int __getuids (int num, gid_t *buf); /* XXX */
+
+/* This function is like file_name_lookup, but tries hard to avoid starting
+   any passive translators.  If a node with an unstarted passive translator
+   is encountered, ENXIO is returned in ERRNO; other errors are as for
+   file_name_lookup.  Note that checking for an active translator currently
+   requires fetching the control port, which is a priveleged operation.  */
+file_t
+file_name_lookup_carefully (const char *name, int flags, mode_t mode)
+{
+  error_t err;
+  file_t node;
+  uid_t *uids;			/* Authentication of the current process.  */
+  gid_t *gids;
+  size_t num_uids, num_gids;
+
+  /* Do the actual directory lookup.  We only do the first pathname element
+     of NAME, appending the rest to any RETRY_NAME returned.  We then make
+     sure the result node doesn't have a passive translator with no active
+     translator started (but we make an exception for symlinks) -- if it
+     does, we just return ENXIO.  */
+  error_t lookup (file_t dir, char *name, int flags, mode_t mode,
+		  retry_type *retry, string_t retry_name,
+		  mach_port_t *node)
+    {
+      error_t err;
+      char *head, *tail;
+      char *slash = index (name, '/');
+
+      if (slash)
+	{
+	  *stpncpy (head = alloca (slash - name + 1), name, slash - name) = 0;
+	  tail = slash + 1;
+	}
+      else
+	{
+	  head = name;
+	  tail = 0;
+	}
+
+      err = dir_lookup (dir, head, flags | O_NOTRANS, mode,
+			retry, retry_name, node);
+      if (err)
+	return err;
+
+      if (*node != MACH_PORT_NULL
+	  && (!(flags & O_NOTRANS) || tail || *retry_name))
+	/* The dir_lookup has returned a node to use for the next stage of
+	   the lookup.  Unless it's the last element of the path and FLAGS
+	   has O_NOTRANS set (in which case we just return what we got as
+	   is), we have to simulate the above lookup being done without
+	   O_NOTRANS.  Do this being careful not to start any translators.  */
+	{
+	  char _ptrans[1024], *ptrans = _ptrans;
+	  size_t ptrans_len = sizeof _ptrans;
+
+	  err = file_get_translator (*node, &ptrans, &ptrans_len);
+	  if (! err)
+	    /* Has a passive translator, see if there's an active one too.  */
+	    {
+	      fsys_t fsys;	/* Active translator control port.  */
+
+	      if (ptrans != _ptrans)
+		/* Deallocate out-of-line memory from file_get_translator.  */
+		vm_deallocate (mach_task_self (),
+			       (vm_address_t)ptrans, ptrans_len);
+
+	      err = file_get_translator_cntl (*node, &fsys);
+	      if (! err)
+		/* There is!  Get its root node to use as the actual file.  */
+		{
+		  file_t unauth_dir; /* DIR unauthenticated.  */
+		  err = io_restrict_auth (dir, &unauth_dir, 0, 0, 0, 0);
+		  if (! err)
+		    {
+		      file_t old_node = *node;
+		      err = fsys_getroot (fsys,
+					  unauth_dir, MACH_MSG_TYPE_MOVE_SEND,
+					  uids, num_uids, gids, num_gids,
+					  flags & ~O_NOTRANS, retry,
+					  retry_name, node);
+		      if (! err)
+			mach_port_deallocate (mach_task_self (), old_node);
+		    }
+		  mach_port_deallocate (mach_task_self (), fsys);
+		}
+	    }
+	  else if (err == EINVAL)
+	    /* No passive translator.  */
+	    err = 0;
+
+	  if (!err && tail)
+	    /* Append TAIL to RETRY_NAME.  */
+	    {
+	      size_t rtn_len = strlen (retry_name);
+	      if (rtn_len + 1 + strlen (tail) + 1 > sizeof (string_t))
+		err = ENAMETOOLONG; /* Argh.  Lovely string_t. */
+	      else
+		{
+		  if (rtn_len > 0 && retry_name[rtn_len - 1] != '/')
+		    retry_name[rtn_len++] = '/';
+		  strcat (retry_name, tail);
+		}
+	    }
+
+	  if (err)
+	    mach_port_deallocate (mach_task_self (), *node);
+	}
+
+      return err;
+    }
+
+  /* Fetch uids for use with fsys_getroot.  */
+  num_uids = __getuids (0, 0);
+  if (num_uids < 0)
+    return errno;
+  uids = alloca (num_uids * sizeof (uid_t));
+  num_uids = __getuids (num_uids, uids);
+  if (num_uids < 0)
+    return errno;
+
+  /* ... and gids.  */
+  num_gids = getgroups (0, 0);
+  if (num_gids < 0)
+    return errno;
+  gids = alloca (num_gids * sizeof (gid_t));
+  num_gids = getgroups (num_gids, gids);
+  if (num_gids < 0)
+    return errno;
+  
+  /* Look things up ...  */
+  err = __hurd_file_name_lookup (&_hurd_ports_use, &__getdport, lookup,
+				 name, flags, mode & ~_hurd_umask,
+				 &node);
+
+  return err ? (__hurd_fail (err), MACH_PORT_NULL) : node;
+}