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+/* Wrapper for diskfs_lookup_hard
+ Copyright (C) 1996, 1997, 1998, 1999 Free Software Foundation, Inc.
+ Written by Michael I. Bushnell, p/BSG.
+
+ 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., 59 Temple Place - Suite 330, Boston, MA 02111, USA. */
+
+#include "priv.h"
+#include <string.h>
+
+static struct
+{
+ int present;
+ int absent;
+ int errors;
+ int dot;
+ int dotdot;
+} cache_misses;
+static spin_lock_t cm_lock = SPIN_LOCK_INITIALIZER;
+
+
+/* Lookup in directory DP (which is locked) the name NAME. TYPE will
+ either be LOOKUP, CREATE, RENAME, or REMOVE. CRED identifies the
+ user making the call.
+
+ NAME will have leading and trailing slashes stripped. It is an
+ error if there are internal slashes. NAME will be modified in
+ place if there are slashes in it; it is therefore an error to
+ specify a constant NAME which contains slashes.
+
+ If the name is found, return zero, and (if NP is nonzero) set *NP
+ to point to the node for it, locked. If the name is not found,
+ return ENOENT, and (if NP is nonzero) set *NP to zero. If NP is
+ zero, then the node found must not be locked, even transitorily.
+ Lookups for REMOVE and RENAME (which must often check permissions
+ on the node being found) will always set NP.
+
+ If DS is nonzero then:
+ For LOOKUP: set *DS to be ignored by diskfs_drop_dirstat.
+ For CREATE: on success, set *DS to be ignored by diskfs_drop_dirstat.
+ on failure, set *DS for a future call to diskfs_direnter.
+ For RENAME: on success, set *DS for a future call to diskfs_dirrewrite.
+ on failure, set *DS for a future call to diskfs_direnter.
+ For REMOVE: on success, set *DS for a future call to diskfs_dirremove.
+ on failure, set *DS to be ignored by diskfs_drop_dirstat.
+ The caller of this function guarantees that if DS is nonzero, then
+ either the appropriate call listed above or diskfs_drop_dirstat will
+ be called with DS before the directory DP is unlocked, and guarantees
+ that no lookup calls will be made on this directory between this
+ lookup and the use (or descruction) of *DS.
+
+ If you use the library's versions of diskfs_rename_dir,
+ diskfs_clear_directory, and diskfs_init_dir, then lookups for `..'
+ might have the flag SPEC_DOTDOT or'd in. This has the following special
+ meaning:
+ For LOOKUP: DP should be unlocked and its reference dropped before
+ returning.
+ For RENAME and REMOVE: The node being found (*NP) is already held
+ locked, so don't lock it or add a reference to it.
+ (SPEC_DOTDOT will not be given with CREATE.)
+
+ Return ENOTDIR if DP is not a directory.
+ Return EACCES if CRED isn't allowed to search DP.
+ Return EACCES if completing the operation will require writing
+ the directory and diskfs_checkdirmod won't allow the modification.
+ Return ENOENT if NAME isn't in the directory.
+ Return EAGAIN if NAME refers to the `..' of this filesystem's root.
+ Return EIO if appropriate.
+
+ This function is a wrapper for diskfs_lookup_hard. */
+error_t
+diskfs_lookup (struct node *dp, char *name, enum lookup_type type,
+ struct node **np, struct dirstat *ds, struct protid *cred)
+{
+ error_t err;
+ struct node *cached;
+
+ if (type == REMOVE || type == RENAME)
+ assert (np);
+
+ if (!S_ISDIR (dp->dn_stat.st_mode))
+ {
+ if (ds)
+ diskfs_null_dirstat (ds);
+ return ENOTDIR;
+ }
+
+ /* Strip leading and trailing slashes. */
+ while (*name == '/')
+ name++;
+
+ if (name[0] == '\0')
+ {
+ if (ds)
+ diskfs_null_dirstat (ds);
+ return EINVAL;
+ }
+ else
+ {
+ char *p = strchr (name, '/');
+ if (p != 0)
+ {
+ *p = '\0';
+ do
+ ++p;
+ while (*p == '/');
+ if (*p != '\0')
+ {
+ if (ds)
+ diskfs_null_dirstat (ds);
+ return EINVAL;
+ }
+ }
+ }
+
+
+ err = fshelp_access (&dp->dn_stat, S_IEXEC, cred->user);
+ if (err)
+ {
+ if (ds)
+ diskfs_null_dirstat (ds);
+ return err;
+ }
+
+ if (dp == cred->po->shadow_root
+ && name[0] == '.' && name[1] == '.' && name[2] == '\0')
+ /* Ran into the root. */
+ {
+ if (ds)
+ diskfs_null_dirstat (ds);
+ return EAGAIN;
+ }
+
+ if (type == LOOKUP)
+ /* Check the cache first */
+ cached = diskfs_check_lookup_cache (dp, name);
+ else
+ cached = 0;
+
+ if (cached == (struct node *)-1)
+ /* Negative lookup cached. */
+ {
+ if (np)
+ *np = 0;
+ return ENOENT;
+ }
+ else if (cached)
+ {
+ if (np)
+ *np = cached; /* Return what we found. */
+ else
+ /* Ick, the user doesn't want the result, we have to drop our
+ reference. */
+ if (cached == dp)
+ diskfs_nrele (cached);
+ else
+ diskfs_nput (cached);
+
+ if (ds)
+ diskfs_null_dirstat (ds);
+ }
+ else
+ {
+ err = diskfs_lookup_hard (dp, name, type, np, ds, cred);
+
+ spin_lock (&cm_lock);
+ if (type == LOOKUP)
+ {
+ if (err == ENOENT)
+ cache_misses.absent++;
+ else if (err)
+ cache_misses.errors++;
+ else
+ cache_misses.present++;
+ if (name[0] == '.')
+ {
+ if (name[1] == '\0')
+ cache_misses.dot++;
+ else if (name[1] == '.' && name[2] == '\0')
+ cache_misses.dotdot++;
+ }
+ }
+ spin_unlock (&cm_lock);
+
+ if (err && err != ENOENT)
+ return err;
+
+ if (type == RENAME
+ || (type == CREATE && err == ENOENT)
+ || (type == REMOVE && err != ENOENT))
+ {
+ error_t err2;
+
+ if (diskfs_name_max > 0 && strlen (name) > diskfs_name_max)
+ err2 = ENAMETOOLONG;
+ else
+ err2 = fshelp_checkdirmod (&dp->dn_stat,
+ (err || !np) ? 0 : &(*np)->dn_stat,
+ cred->user);
+ if (err2)
+ {
+ if (np && !err)
+ {
+ if (*np == dp)
+ diskfs_nrele (*np);
+ else
+ diskfs_nput (*np);
+ *np = 0;
+ }
+ return err2;
+ }
+ }
+
+ if ((type == LOOKUP || type == CREATE) && !err && np)
+ diskfs_enter_lookup_cache (dp, *np, name);
+ else if (type == LOOKUP && err == ENOENT)
+ diskfs_enter_lookup_cache (dp, 0, name);
+ }
+
+ return err;
+}
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