Adding upstream version 2.4.38.upstream/2.4.38

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1211 insertions, 0 deletions

diff --git a/modules/dav/lock/locks.c b/modules/dav/lock/locks.c
new file mode 100644
index 0000000..17b9ee6
--- /dev/null
+++ b/modules/dav/lock/locks.c
@@ -0,0 +1,1211 @@
+/* Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/*
+ * Generic DAV lock implementation that a DAV provider can use.
+ */
+
+#include "apr.h"
+#include "apr_strings.h"
+#include "apr_file_io.h"
+#include "apr_uuid.h"
+
+#define APR_WANT_MEMFUNC
+#include "apr_want.h"
+
+#include "httpd.h"
+#include "http_log.h"
+
+#include "mod_dav.h"
+
+#include "locks.h"
+
+
+/* ---------------------------------------------------------------
+ *
+ * Lock database primitives
+ *
+ */
+
+/*
+ * LOCK DATABASES
+ *
+ * Lockdiscovery information is stored in the single lock database specified
+ * by the DAVGenericLockDB directive.  Information about this db is stored in
+ * the per-dir configuration.
+ *
+ * KEY
+ *
+ * The database is keyed by a key_type unsigned char (DAV_TYPE_FNAME)
+ * followed by full path.
+ *
+ * VALUE
+ *
+ * The value consists of a list of elements.
+ *    DIRECT LOCK:     [char      (DAV_LOCK_DIRECT),
+ *                      char      (dav_lock_scope),
+ *                      char      (dav_lock_type),
+ *                      int        depth,
+ *                      time_t     expires,
+ *                      apr_uuid_t locktoken,
+ *                      char[]     owner,
+ *                      char[]     auth_user]
+ *
+ *    INDIRECT LOCK:   [char      (DAV_LOCK_INDIRECT),
+ *                      apr_uuid_t locktoken,
+ *                      time_t     expires,
+ *                      int        key_size,
+ *                      char[]     key]
+ *       The key is to the collection lock that resulted in this indirect lock
+ */
+
+#define DAV_TRUE                    1
+#define DAV_FALSE                   0
+
+#define DAV_CREATE_LIST            23
+#define DAV_APPEND_LIST            24
+
+/* Stored lock_discovery prefix */
+#define DAV_LOCK_DIRECT             1
+#define DAV_LOCK_INDIRECT           2
+
+#define DAV_TYPE_FNAME             11
+
+/* Use the opaquelock scheme for locktokens */
+struct dav_locktoken {
+    apr_uuid_t uuid;
+};
+#define dav_compare_locktoken(plt1, plt2) \
+                memcmp(&(plt1)->uuid, &(plt2)->uuid, sizeof((plt1)->uuid))
+
+
+/* #################################################################
+ * ### keep these structures (internal) or move fully to dav_lock?
+ */
+
+/*
+ * We need to reliably size the fixed-length portion of
+ * dav_lock_discovery; best to separate it into another
+ * struct for a convenient sizeof, unless we pack lock_discovery.
+ */
+typedef struct dav_lock_discovery_fixed
+{
+    char scope;
+    char type;
+    int depth;
+    time_t timeout;
+} dav_lock_discovery_fixed;
+
+typedef struct dav_lock_discovery
+{
+    struct dav_lock_discovery_fixed f;
+
+    dav_locktoken *locktoken;
+    const char *owner;     /* owner field from activelock */
+    const char *auth_user; /* authenticated user who created the lock */
+    struct dav_lock_discovery *next;
+} dav_lock_discovery;
+
+/* Indirect locks represent locks inherited from containing collections.
+ * They reference the lock token for the collection the lock is
+ * inherited from. A lock provider may also define a key to the
+ * inherited lock, for fast datbase lookup. The key is opaque outside
+ * the lock provider.
+ */
+typedef struct dav_lock_indirect
+{
+    dav_locktoken *locktoken;
+    apr_datum_t key;
+    struct dav_lock_indirect *next;
+    time_t timeout;
+} dav_lock_indirect;
+
+/* ################################################################# */
+
+/*
+ * Stored direct lock info - full lock_discovery length:
+ * prefix + Fixed length + lock token + 2 strings + 2 nulls (one for each
+ * string)
+ */
+#define dav_size_direct(a)  (1 + sizeof(dav_lock_discovery_fixed) \
+                               + sizeof(apr_uuid_t) \
+                               + ((a)->owner ? strlen((a)->owner) : 0) \
+                               + ((a)->auth_user ? strlen((a)->auth_user) : 0) \
+                               + 2)
+
+/* Stored indirect lock info - lock token and apr_datum_t */
+#define dav_size_indirect(a) (1 + sizeof(apr_uuid_t) \
+                                + sizeof(time_t) \
+                                + sizeof(int) + (a)->key.dsize)
+
+/*
+ * The lockdb structure.
+ *
+ * The <db> field may be NULL, meaning one of two things:
+ * 1) That we have not actually opened the underlying database (yet). The
+ *    <opened> field should be false.
+ * 2) We opened it readonly and it wasn't present.
+ *
+ * The delayed opening (determined by <opened>) makes creating a lockdb
+ * quick, while deferring the underlying I/O until it is actually required.
+ *
+ * We export the notion of a lockdb, but hide the details of it. Most
+ * implementations will use a database of some kind, but it is certainly
+ * possible that alternatives could be used.
+ */
+struct dav_lockdb_private
+{
+    request_rec *r; /* for accessing the uuid state */
+    apr_pool_t *pool; /* a pool to use */
+    const char *lockdb_path; /* where is the lock database? */
+
+    int opened; /* we opened the database */
+    apr_dbm_t *db; /* if non-NULL, the lock database */
+};
+
+typedef struct
+{
+    dav_lockdb pub;
+    dav_lockdb_private priv;
+} dav_lockdb_combined;
+
+/*
+ * The private part of the lock structure.
+ */
+struct dav_lock_private
+{
+    apr_datum_t key;        /* key into the lock database */
+};
+typedef struct
+{
+    dav_lock pub;
+    dav_lock_private priv;
+    dav_locktoken token;
+} dav_lock_combined;
+
+/*
+ * This must be forward-declared so the open_lockdb function can use it.
+ */
+extern const dav_hooks_locks dav_hooks_locks_generic;
+
+static dav_error * dav_generic_dbm_new_error(apr_dbm_t *db, apr_pool_t *p,
+                                             apr_status_t status)
+{
+    int errcode;
+    const char *errstr;
+    dav_error *err;
+    char errbuf[200];
+
+    if (status == APR_SUCCESS) {
+        return NULL;
+    }
+
+    /* There might not be a <db> if we had problems creating it. */
+    if (db == NULL) {
+        errcode = 1;
+        errstr = "Could not open property database.";
+    }
+    else {
+        (void) apr_dbm_geterror(db, &errcode, errbuf, sizeof(errbuf));
+        errstr = apr_pstrdup(p, errbuf);
+    }
+
+    err = dav_new_error(p, HTTP_INTERNAL_SERVER_ERROR, errcode, status, errstr);
+    return err;
+}
+
+/* internal function for creating locks */
+static dav_lock *dav_generic_alloc_lock(dav_lockdb *lockdb, apr_datum_t key,
+                                        const dav_locktoken *locktoken)
+{
+    dav_lock_combined *comb;
+
+    comb = apr_pcalloc(lockdb->info->pool, sizeof(*comb));
+    comb->pub.rectype = DAV_LOCKREC_DIRECT;
+    comb->pub.info = &comb->priv;
+    comb->priv.key = key;
+
+    if (locktoken == NULL) {
+        comb->pub.locktoken = &comb->token;
+        apr_uuid_get(&comb->token.uuid);
+    }
+    else {
+        comb->pub.locktoken = locktoken;
+    }
+
+    return &comb->pub;
+}
+
+/*
+ * dav_generic_parse_locktoken
+ *
+ * Parse an opaquelocktoken URI into a locktoken.
+ */
+static dav_error * dav_generic_parse_locktoken(apr_pool_t *p,
+                                               const char *char_token,
+                                               dav_locktoken **locktoken_p)
+{
+    dav_locktoken *locktoken;
+
+    if (ap_strstr_c(char_token, "opaquelocktoken:") != char_token) {
+        return dav_new_error(p,
+                             HTTP_BAD_REQUEST, DAV_ERR_LOCK_UNK_STATE_TOKEN, 0,
+                             "The lock token uses an unknown State-token "
+                             "format and could not be parsed.");
+    }
+    char_token += 16;
+
+    locktoken = apr_pcalloc(p, sizeof(*locktoken));
+    if (apr_uuid_parse(&locktoken->uuid, char_token)) {
+        return dav_new_error(p, HTTP_BAD_REQUEST, DAV_ERR_LOCK_PARSE_TOKEN, 0,
+                             "The opaquelocktoken has an incorrect format "
+                             "and could not be parsed.");
+    }
+
+    *locktoken_p = locktoken;
+    return NULL;
+}
+
+/*
+ * dav_generic_format_locktoken
+ *
+ * Generate the URI for a locktoken
+ */
+static const char *dav_generic_format_locktoken(apr_pool_t *p,
+                                                const dav_locktoken *locktoken)
+{
+    char buf[APR_UUID_FORMATTED_LENGTH + 1];
+
+    apr_uuid_format(buf, &locktoken->uuid);
+    return apr_pstrcat(p, "opaquelocktoken:", buf, NULL);
+}
+
+/*
+ * dav_generic_compare_locktoken
+ *
+ * Determine whether two locktokens are the same
+ */
+static int dav_generic_compare_locktoken(const dav_locktoken *lt1,
+                                         const dav_locktoken *lt2)
+{
+    return dav_compare_locktoken(lt1, lt2);
+}
+
+/*
+ * dav_generic_really_open_lockdb:
+ *
+ * If the database hasn't been opened yet, then open the thing.
+ */
+static dav_error * dav_generic_really_open_lockdb(dav_lockdb *lockdb)
+{
+    dav_error *err;
+    apr_status_t status;
+
+    if (lockdb->info->opened) {
+        return NULL;
+    }
+
+    status = apr_dbm_open(&lockdb->info->db, lockdb->info->lockdb_path,
+                          lockdb->ro ? APR_DBM_READONLY : APR_DBM_RWCREATE,
+                          APR_OS_DEFAULT, lockdb->info->pool);
+
+    if (status) {
+        err = dav_generic_dbm_new_error(lockdb->info->db, lockdb->info->pool,
+                                        status);
+        return dav_push_error(lockdb->info->pool,
+                              HTTP_INTERNAL_SERVER_ERROR,
+                              DAV_ERR_LOCK_OPENDB,
+                              "Could not open the lock database.",
+                              err);
+    }
+
+    /* all right. it is opened now. */
+    lockdb->info->opened = 1;
+
+    return NULL;
+}
+
+/*
+ * dav_generic_open_lockdb:
+ *
+ * "open" the lock database, as specified in the global server configuration.
+ * If force is TRUE, then the database is opened now, rather than lazily.
+ *
+ * Note that only one can be open read/write.
+ */
+static dav_error * dav_generic_open_lockdb(request_rec *r, int ro, int force,
+                                           dav_lockdb **lockdb)
+{
+    dav_lockdb_combined *comb;
+
+    comb = apr_pcalloc(r->pool, sizeof(*comb));
+    comb->pub.hooks = &dav_hooks_locks_generic;
+    comb->pub.ro = ro;
+    comb->pub.info = &comb->priv;
+    comb->priv.r = r;
+    comb->priv.pool = r->pool;
+
+    comb->priv.lockdb_path = dav_generic_get_lockdb_path(r);
+    if (comb->priv.lockdb_path == NULL) {
+        return dav_new_error(r->pool, HTTP_INTERNAL_SERVER_ERROR,
+                             DAV_ERR_LOCK_NO_DB, 0,
+                             "A lock database was not specified with the "
+                             "DAVGenericLockDB directive. One must be "
+                             "specified to use the locking functionality.");
+    }
+
+    /* done initializing. return it. */
+    *lockdb = &comb->pub;
+
+    if (force) {
+        /* ### add a higher-level comment? */
+        return dav_generic_really_open_lockdb(*lockdb);
+    }
+
+    return NULL;
+}
+
+/*
+ * dav_generic_close_lockdb:
+ *
+ * Close it. Duh.
+ */
+static void dav_generic_close_lockdb(dav_lockdb *lockdb)
+{
+    if (lockdb->info->db != NULL) {
+        apr_dbm_close(lockdb->info->db);
+    }
+    lockdb->info->opened = 0;
+}
+
+/*
+ * dav_generic_build_key
+ *
+ * Given a pathname, build a DAV_TYPE_FNAME lock database key.
+ */
+static apr_datum_t dav_generic_build_key(apr_pool_t *p,
+                                         const dav_resource *resource)
+{
+    apr_datum_t key;
+    const char *pathname = resource->uri;
+
+    /* ### does this allocation have a proper lifetime? need to check */
+    /* ### can we use a buffer for this? */
+
+    /* size is TYPE + pathname + null */
+    key.dsize = strlen(pathname) + 2;
+    key.dptr = apr_palloc(p, key.dsize);
+    *key.dptr = DAV_TYPE_FNAME;
+    memcpy(key.dptr + 1, pathname, key.dsize - 1);
+    if (key.dptr[key.dsize - 2] == '/')
+        key.dptr[--key.dsize - 1] = '\0';
+    return key;
+}
+
+/*
+ * dav_generic_lock_expired:  return 1 (true) if the given timeout is in the
+ *    past or present (the lock has expired), or 0 (false) if in the future
+ *    (the lock has not yet expired).
+ */
+static int dav_generic_lock_expired(time_t expires)
+{
+    return expires != DAV_TIMEOUT_INFINITE && time(NULL) >= expires;
+}
+
+/*
+ * dav_generic_save_lock_record:  Saves the lock information specified in the
+ *    direct and indirect lock lists about path into the lock database.
+ *    If direct and indirect == NULL, the key is removed.
+ */
+static dav_error * dav_generic_save_lock_record(dav_lockdb *lockdb,
+                                                apr_datum_t key,
+                                                dav_lock_discovery *direct,
+                                                dav_lock_indirect *indirect)
+{
+    dav_error *err;
+    apr_status_t status;
+    apr_datum_t val = { 0 };
+    char *ptr;
+    dav_lock_discovery *dp = direct;
+    dav_lock_indirect *ip = indirect;
+
+#if DAV_DEBUG
+    if (lockdb->ro) {
+        return dav_new_error(lockdb->info->pool,
+                             HTTP_INTERNAL_SERVER_ERROR, 0, 0,
+                             "INTERNAL DESIGN ERROR: the lockdb was opened "
+                             "readonly, but an attempt to save locks was "
+                             "performed.");
+    }
+#endif
+
+    if ((err = dav_generic_really_open_lockdb(lockdb)) != NULL) {
+        /* ### add a higher-level error? */
+        return err;
+    }
+
+    /* If nothing to save, delete key */
+    if (dp == NULL && ip == NULL) {
+        /* don't fail if the key is not present */
+        /* ### but what about other errors? */
+        apr_dbm_delete(lockdb->info->db, key);
+        return NULL;
+    }
+
+    while (dp) {
+        val.dsize += dav_size_direct(dp);
+        dp = dp->next;
+    }
+    while (ip) {
+        val.dsize += dav_size_indirect(ip);
+        ip = ip->next;
+    }
+
+    /* ### can this be apr_palloc() ? */
+    /* ### hmmm.... investigate the use of a buffer here */
+    ptr = val.dptr = apr_pcalloc(lockdb->info->pool, val.dsize);
+    dp  = direct;
+    ip  = indirect;
+
+    while (dp) {
+        /* Direct lock - lock_discovery struct follows */
+        *ptr++ = DAV_LOCK_DIRECT;
+        memcpy(ptr, dp, sizeof(dp->f));        /* Fixed portion of struct */
+        ptr += sizeof(dp->f);
+        memcpy(ptr, dp->locktoken, sizeof(*dp->locktoken));
+        ptr += sizeof(*dp->locktoken);
+        if (dp->owner == NULL) {
+            *ptr++ = '\0';
+        }
+        else {
+            memcpy(ptr, dp->owner, strlen(dp->owner) + 1);
+            ptr += strlen(dp->owner) + 1;
+        }
+        if (dp->auth_user == NULL) {
+            *ptr++ = '\0';
+        }
+        else {
+            memcpy(ptr, dp->auth_user, strlen(dp->auth_user) + 1);
+            ptr += strlen(dp->auth_user) + 1;
+        }
+
+        dp = dp->next;
+    }
+
+    while (ip) {
+        /* Indirect lock prefix */
+        *ptr++ = DAV_LOCK_INDIRECT;
+
+        memcpy(ptr, ip->locktoken, sizeof(*ip->locktoken));
+        ptr += sizeof(*ip->locktoken);
+
+        memcpy(ptr, &ip->timeout, sizeof(ip->timeout));
+        ptr += sizeof(ip->timeout);
+
+        memcpy(ptr, &ip->key.dsize, sizeof(ip->key.dsize));
+        ptr += sizeof(ip->key.dsize);
+
+        memcpy(ptr, ip->key.dptr, ip->key.dsize);
+        ptr += ip->key.dsize;
+
+        ip = ip->next;
+    }
+
+    if ((status = apr_dbm_store(lockdb->info->db, key, val)) != APR_SUCCESS) {
+        /* ### more details? add an error_id? */
+        err = dav_generic_dbm_new_error(lockdb->info->db, lockdb->info->pool,
+                                        status);
+        return dav_push_error(lockdb->info->pool,
+                              HTTP_INTERNAL_SERVER_ERROR,
+                              DAV_ERR_LOCK_SAVE_LOCK,
+                              "Could not save lock information.",
+                              err);
+    }
+
+    return NULL;
+}
+
+/*
+ * dav_load_lock_record:  Reads lock information about key from lock db;
+ *    creates linked lists of the direct and indirect locks.
+ *
+ *    If add_method = DAV_APPEND_LIST, the result will be appended to the
+ *    head of the direct and indirect lists supplied.
+ *
+ *    Passive lock removal:  If lock has timed out, it will not be returned.
+ *    ### How much "logging" does RFC 2518 require?
+ */
+static dav_error * dav_generic_load_lock_record(dav_lockdb *lockdb,
+                                                apr_datum_t key,
+                                                int add_method,
+                                                dav_lock_discovery **direct,
+                                                dav_lock_indirect **indirect)
+{
+    apr_pool_t *p = lockdb->info->pool;
+    dav_error *err;
+    apr_status_t status;
+    apr_size_t offset = 0;
+    int need_save = DAV_FALSE;
+    apr_datum_t val = { 0 };
+    dav_lock_discovery *dp;
+    dav_lock_indirect *ip;
+
+    if (add_method != DAV_APPEND_LIST) {
+        *direct = NULL;
+        *indirect = NULL;
+    }
+
+    if ((err = dav_generic_really_open_lockdb(lockdb)) != NULL) {
+        /* ### add a higher-level error? */
+        return err;
+    }
+
+    /*
+     * If we opened readonly and the db wasn't there, then there are no
+     * locks for this resource. Just exit.
+     */
+    if (lockdb->info->db == NULL) {
+        return NULL;
+    }
+
+    if ((status = apr_dbm_fetch(lockdb->info->db, key, &val)) != APR_SUCCESS) {
+        return dav_generic_dbm_new_error(lockdb->info->db, p, status);
+    }
+
+    if (!val.dsize) {
+        return NULL;
+    }
+
+    while (offset < val.dsize) {
+        switch (*(val.dptr + offset++)) {
+        case DAV_LOCK_DIRECT:
+            /* Create and fill a dav_lock_discovery structure */
+
+            dp = apr_pcalloc(p, sizeof(*dp));
+
+            /* Copy the dav_lock_discovery_fixed portion */
+            memcpy(dp, val.dptr + offset, sizeof(dp->f));
+            offset += sizeof(dp->f);
+
+            /* Copy the lock token. */
+            dp->locktoken = apr_pmemdup(p, val.dptr + offset, sizeof(*dp->locktoken));
+            offset += sizeof(*dp->locktoken);
+
+            /* Do we have an owner field? */
+            if (*(val.dptr + offset) == '\0') {
+                ++offset;
+            }
+            else {
+                apr_size_t len = strlen(val.dptr + offset);
+                dp->owner = apr_pstrmemdup(p, val.dptr + offset, len);
+                offset += len + 1;
+            }
+
+            if (*(val.dptr + offset) == '\0') {
+                ++offset;
+            }
+            else {
+                apr_size_t len = strlen(val.dptr + offset);
+                dp->auth_user = apr_pstrmemdup(p, val.dptr + offset, len);
+                offset += len + 1;
+            }
+
+            if (!dav_generic_lock_expired(dp->f.timeout)) {
+                dp->next = *direct;
+                *direct = dp;
+            }
+            else {
+                need_save = DAV_TRUE;
+            }
+            break;
+
+        case DAV_LOCK_INDIRECT:
+            /* Create and fill a dav_lock_indirect structure */
+
+            ip = apr_pcalloc(p, sizeof(*ip));
+            ip->locktoken = apr_pmemdup(p, val.dptr + offset, sizeof(*ip->locktoken));
+            offset += sizeof(*ip->locktoken);
+            memcpy(&ip->timeout, val.dptr + offset, sizeof(ip->timeout));
+            offset += sizeof(ip->timeout);
+            /* length of datum */
+            ip->key.dsize = *((int *) (val.dptr + offset));
+            offset += sizeof(ip->key.dsize);
+            ip->key.dptr = apr_pmemdup(p, val.dptr + offset, ip->key.dsize);
+            offset += ip->key.dsize;
+
+            if (!dav_generic_lock_expired(ip->timeout)) {
+                ip->next = *indirect;
+                *indirect = ip;
+            }
+            else {
+                need_save = DAV_TRUE;
+            }
+
+            break;
+
+        default:
+            apr_dbm_freedatum(lockdb->info->db, val);
+
+            /* ### should use a computed_desc and insert corrupt token data */
+            --offset;
+            return dav_new_error(p,
+                                 HTTP_INTERNAL_SERVER_ERROR,
+                                 DAV_ERR_LOCK_CORRUPT_DB, 0,
+                                 apr_psprintf(p,
+                                             "The lock database was found to "
+                                             "be corrupt. offset %"
+                                             APR_SIZE_T_FMT ", c=%02x",
+                                             offset, val.dptr[offset]));
+        }
+    }
+
+    apr_dbm_freedatum(lockdb->info->db, val);
+
+    /* Clean up this record if we found expired locks */
+    /*
+     * ### shouldn't do this if we've been opened READONLY. elide the
+     * ### timed-out locks from the response, but don't save that info back
+     */
+    if (need_save == DAV_TRUE) {
+        return dav_generic_save_lock_record(lockdb, key, *direct, *indirect);
+    }
+
+    return NULL;
+}
+
+/* resolve <indirect>, returning <*direct> */
+static dav_error * dav_generic_resolve(dav_lockdb *lockdb,
+                                       dav_lock_indirect *indirect,
+                                       dav_lock_discovery **direct,
+                                       dav_lock_discovery **ref_dp,
+                                       dav_lock_indirect **ref_ip)
+{
+    dav_error *err;
+    dav_lock_discovery *dir;
+    dav_lock_indirect *ind;
+
+    if ((err = dav_generic_load_lock_record(lockdb, indirect->key,
+                                       DAV_CREATE_LIST,
+                                       &dir, &ind)) != NULL) {
+        /* ### insert a higher-level description? */
+        return err;
+    }
+    if (ref_dp != NULL) {
+        *ref_dp = dir;
+        *ref_ip = ind;
+    }
+
+    for (; dir != NULL; dir = dir->next) {
+        if (!dav_compare_locktoken(indirect->locktoken, dir->locktoken)) {
+            *direct = dir;
+            return NULL;
+        }
+    }
+
+    /* No match found (but we should have found one!) */
+
+    /* ### use a different description and/or error ID? */
+    return dav_new_error(lockdb->info->pool,
+                         HTTP_INTERNAL_SERVER_ERROR,
+                         DAV_ERR_LOCK_CORRUPT_DB, 0,
+                         "The lock database was found to be corrupt. "
+                         "An indirect lock's direct lock could not "
+                         "be found.");
+}
+
+/* ---------------------------------------------------------------
+ *
+ * Property-related lock functions
+ *
+ */
+
+/*
+ * dav_generic_get_supportedlock:  Returns a static string for all
+ *    supportedlock properties. I think we save more returning a static string
+ *    than constructing it every time, though it might look cleaner.
+ */
+static const char *dav_generic_get_supportedlock(const dav_resource *resource)
+{
+    static const char supported[] = DEBUG_CR
+        "<D:lockentry>" DEBUG_CR
+        "<D:lockscope><D:exclusive/></D:lockscope>" DEBUG_CR
+        "<D:locktype><D:write/></D:locktype>" DEBUG_CR
+        "</D:lockentry>" DEBUG_CR
+        "<D:lockentry>" DEBUG_CR
+        "<D:lockscope><D:shared/></D:lockscope>" DEBUG_CR
+        "<D:locktype><D:write/></D:locktype>" DEBUG_CR
+        "</D:lockentry>" DEBUG_CR;
+
+    return supported;
+}
+
+/* ---------------------------------------------------------------
+ *
+ * General lock functions
+ *
+ */
+
+static dav_error * dav_generic_remove_locknull_state(dav_lockdb *lockdb,
+                                                 const dav_resource *resource)
+{
+    /* We don't need to do anything. */
+    return NULL;
+}
+
+static dav_error * dav_generic_create_lock(dav_lockdb *lockdb,
+                                      const dav_resource *resource,
+                                      dav_lock **lock)
+{
+    apr_datum_t key;
+
+    key = dav_generic_build_key(lockdb->info->pool, resource);
+
+    *lock = dav_generic_alloc_lock(lockdb, key, NULL);
+
+    (*lock)->is_locknull = !resource->exists;
+
+    return NULL;
+}
+
+static dav_error * dav_generic_get_locks(dav_lockdb *lockdb,
+                                         const dav_resource *resource,
+                                         int calltype,
+                                         dav_lock **locks)
+{
+    apr_pool_t *p = lockdb->info->pool;
+    apr_datum_t key;
+    dav_error *err;
+    dav_lock *lock = NULL;
+    dav_lock *newlock;
+    dav_lock_discovery *dp;
+    dav_lock_indirect *ip;
+
+#if DAV_DEBUG
+    if (calltype == DAV_GETLOCKS_COMPLETE) {
+        return dav_new_error(lockdb->info->pool,
+                             HTTP_INTERNAL_SERVER_ERROR, 0, 0,
+                             "INTERNAL DESIGN ERROR: DAV_GETLOCKS_COMPLETE "
+                             "is not yet supported");
+    }
+#endif
+
+    key = dav_generic_build_key(p, resource);
+    if ((err = dav_generic_load_lock_record(lockdb, key, DAV_CREATE_LIST,
+                                            &dp, &ip)) != NULL) {
+        /* ### push a higher-level desc? */
+        return err;
+    }
+
+    /* copy all direct locks to the result list */
+    for (; dp != NULL; dp = dp->next) {
+        newlock = dav_generic_alloc_lock(lockdb, key, dp->locktoken);
+        newlock->is_locknull = !resource->exists;
+        newlock->scope = dp->f.scope;
+        newlock->type = dp->f.type;
+        newlock->depth = dp->f.depth;
+        newlock->timeout = dp->f.timeout;
+        newlock->owner = dp->owner;
+        newlock->auth_user = dp->auth_user;
+
+        /* hook into the result list */
+        newlock->next = lock;
+        lock = newlock;
+    }
+
+    /* copy all the indirect locks to the result list. resolve as needed. */
+    for (; ip != NULL; ip = ip->next) {
+        newlock = dav_generic_alloc_lock(lockdb, ip->key, ip->locktoken);
+        newlock->is_locknull = !resource->exists;
+
+        if (calltype == DAV_GETLOCKS_RESOLVED) {
+            err = dav_generic_resolve(lockdb, ip, &dp, NULL, NULL);
+            if (err != NULL) {
+                /* ### push a higher-level desc? */
+                return err;
+            }
+
+            newlock->scope = dp->f.scope;
+            newlock->type = dp->f.type;
+            newlock->depth = dp->f.depth;
+            newlock->timeout = dp->f.timeout;
+            newlock->owner = dp->owner;
+            newlock->auth_user = dp->auth_user;
+        }
+        else {
+            /* DAV_GETLOCKS_PARTIAL */
+            newlock->rectype = DAV_LOCKREC_INDIRECT_PARTIAL;
+        }
+
+        /* hook into the result list */
+        newlock->next = lock;
+        lock = newlock;
+    }
+
+    *locks = lock;
+    return NULL;
+}
+
+static dav_error * dav_generic_find_lock(dav_lockdb *lockdb,
+                                         const dav_resource *resource,
+                                         const dav_locktoken *locktoken,
+                                         int partial_ok,
+                                         dav_lock **lock)
+{
+    dav_error *err;
+    apr_datum_t key;
+    dav_lock_discovery *dp;
+    dav_lock_indirect *ip;
+
+    *lock = NULL;
+
+    key = dav_generic_build_key(lockdb->info->pool, resource);
+    if ((err = dav_generic_load_lock_record(lockdb, key, DAV_CREATE_LIST,
+                                       &dp, &ip)) != NULL) {
+        /* ### push a higher-level desc? */
+        return err;
+    }
+
+    for (; dp != NULL; dp = dp->next) {
+        if (!dav_compare_locktoken(locktoken, dp->locktoken)) {
+            *lock = dav_generic_alloc_lock(lockdb, key, locktoken);
+            (*lock)->is_locknull = !resource->exists;
+            (*lock)->scope = dp->f.scope;
+            (*lock)->type = dp->f.type;
+            (*lock)->depth = dp->f.depth;
+            (*lock)->timeout = dp->f.timeout;
+            (*lock)->owner = dp->owner;
+            (*lock)->auth_user = dp->auth_user;
+            return NULL;
+        }
+    }
+
+    for (; ip != NULL; ip = ip->next) {
+        if (!dav_compare_locktoken(locktoken, ip->locktoken)) {
+            *lock = dav_generic_alloc_lock(lockdb, ip->key, locktoken);
+            (*lock)->is_locknull = !resource->exists;
+
+            /* ### nobody uses the resolving right now! */
+            if (partial_ok) {
+                (*lock)->rectype = DAV_LOCKREC_INDIRECT_PARTIAL;
+            }
+            else {
+                (*lock)->rectype = DAV_LOCKREC_INDIRECT;
+                if ((err = dav_generic_resolve(lockdb, ip, &dp,
+                                          NULL, NULL)) != NULL) {
+                    /* ### push a higher-level desc? */
+                    return err;
+                }
+                (*lock)->scope = dp->f.scope;
+                (*lock)->type = dp->f.type;
+                (*lock)->depth = dp->f.depth;
+                (*lock)->timeout = dp->f.timeout;
+                (*lock)->owner = dp->owner;
+                (*lock)->auth_user = dp->auth_user;
+            }
+            return NULL;
+        }
+    }
+
+    return NULL;
+}
+
+static dav_error * dav_generic_has_locks(dav_lockdb *lockdb,
+                                         const dav_resource *resource,
+                                         int *locks_present)
+{
+    dav_error *err;
+    apr_datum_t key;
+
+    *locks_present = 0;
+
+    if ((err = dav_generic_really_open_lockdb(lockdb)) != NULL) {
+        /* ### insert a higher-level error description */
+        return err;
+    }
+
+    /*
+     * If we opened readonly and the db wasn't there, then there are no
+     * locks for this resource. Just exit.
+     */
+    if (lockdb->info->db == NULL)
+        return NULL;
+
+    key = dav_generic_build_key(lockdb->info->pool, resource);
+
+    *locks_present = apr_dbm_exists(lockdb->info->db, key);
+
+    return NULL;
+}
+
+static dav_error * dav_generic_append_locks(dav_lockdb *lockdb,
+                                            const dav_resource *resource,
+                                            int make_indirect,
+                                            const dav_lock *lock)
+{
+    apr_pool_t *p = lockdb->info->pool;
+    dav_error *err;
+    dav_lock_indirect *ip;
+    dav_lock_discovery *dp;
+    apr_datum_t key;
+
+    key = dav_generic_build_key(lockdb->info->pool, resource);
+
+    err = dav_generic_load_lock_record(lockdb, key, 0, &dp, &ip);
+    if (err != NULL) {
+        /* ### maybe add in a higher-level description */
+        return err;
+    }
+
+    /*
+     * ### when we store the lock more directly, we need to update
+     * ### lock->rectype and lock->is_locknull
+     */
+
+    if (make_indirect) {
+        for (; lock != NULL; lock = lock->next) {
+
+            /* ### this works for any <lock> rectype */
+            dav_lock_indirect *newi = apr_pcalloc(p, sizeof(*newi));
+
+            /* ### shut off the const warning for now */
+            newi->locktoken = (dav_locktoken *)lock->locktoken;
+            newi->timeout   = lock->timeout;
+            newi->key       = lock->info->key;
+            newi->next      = ip;
+            ip              = newi;
+        }
+    }
+    else {
+        for (; lock != NULL; lock = lock->next) {
+            /* create and link in the right kind of lock */
+
+            if (lock->rectype == DAV_LOCKREC_DIRECT) {
+                dav_lock_discovery *newd = apr_pcalloc(p, sizeof(*newd));
+
+                newd->f.scope = lock->scope;
+                newd->f.type = lock->type;
+                newd->f.depth = lock->depth;
+                newd->f.timeout = lock->timeout;
+                /* ### shut off the const warning for now */
+                newd->locktoken = (dav_locktoken *)lock->locktoken;
+                newd->owner = lock->owner;
+                newd->auth_user = lock->auth_user;
+                newd->next = dp;
+                dp = newd;
+            }
+            else {
+                /* DAV_LOCKREC_INDIRECT(_PARTIAL) */
+
+                dav_lock_indirect *newi = apr_pcalloc(p, sizeof(*newi));
+
+                /* ### shut off the const warning for now */
+                newi->locktoken = (dav_locktoken *)lock->locktoken;
+                newi->key       = lock->info->key;
+                newi->next      = ip;
+                ip              = newi;
+            }
+        }
+    }
+
+    if ((err = dav_generic_save_lock_record(lockdb, key, dp, ip)) != NULL) {
+        /* ### maybe add a higher-level description */
+        return err;
+    }
+
+    return NULL;
+}
+
+static dav_error * dav_generic_remove_lock(dav_lockdb *lockdb,
+                                           const dav_resource *resource,
+                                           const dav_locktoken *locktoken)
+{
+    dav_error *err;
+    dav_lock_discovery *dh = NULL;
+    dav_lock_indirect *ih = NULL;
+    apr_datum_t key;
+
+    key = dav_generic_build_key(lockdb->info->pool, resource);
+
+    if (locktoken != NULL) {
+        dav_lock_discovery *dp;
+        dav_lock_discovery *dprev = NULL;
+        dav_lock_indirect *ip;
+        dav_lock_indirect *iprev = NULL;
+
+        if ((err = dav_generic_load_lock_record(lockdb, key, DAV_CREATE_LIST,
+                                           &dh, &ih)) != NULL) {
+            /* ### maybe add a higher-level description */
+            return err;
+        }
+
+        for (dp = dh; dp != NULL; dp = dp->next) {
+            if (dav_compare_locktoken(locktoken, dp->locktoken) == 0) {
+                if (dprev)
+                    dprev->next = dp->next;
+                else
+                    dh = dh->next;
+            }
+            dprev = dp;
+        }
+
+        for (ip = ih; ip != NULL; ip = ip->next) {
+            if (dav_compare_locktoken(locktoken, ip->locktoken) == 0) {
+                if (iprev)
+                    iprev->next = ip->next;
+                else
+                    ih = ih->next;
+            }
+            iprev = ip;
+        }
+
+    }
+
+    /* save the modified locks, or remove all locks (dh=ih=NULL). */
+    if ((err = dav_generic_save_lock_record(lockdb, key, dh, ih)) != NULL) {
+        /* ### maybe add a higher-level description */
+        return err;
+    }
+
+    return NULL;
+}
+
+static int dav_generic_do_refresh(dav_lock_discovery *dp,
+                                  const dav_locktoken_list *ltl,
+                                  time_t new_time)
+{
+    int dirty = 0;
+
+    for (; ltl != NULL; ltl = ltl->next) {
+        if (dav_compare_locktoken(dp->locktoken, ltl->locktoken) == 0)
+        {
+            dp->f.timeout = new_time;
+            dirty = 1;
+            break;
+        }
+    }
+
+    return dirty;
+}
+
+static dav_error * dav_generic_refresh_locks(dav_lockdb *lockdb,
+                                             const dav_resource *resource,
+                                             const dav_locktoken_list *ltl,
+                                             time_t new_time,
+                                             dav_lock **locks)
+{
+    dav_error *err;
+    apr_datum_t key;
+    dav_lock_discovery *dp;
+    dav_lock_discovery *dp_scan;
+    dav_lock_indirect *ip;
+    int dirty = 0;
+    dav_lock *newlock;
+
+    *locks = NULL;
+
+    key = dav_generic_build_key(lockdb->info->pool, resource);
+    if ((err = dav_generic_load_lock_record(lockdb, key, DAV_CREATE_LIST,
+                                            &dp, &ip)) != NULL) {
+        /* ### maybe add in a higher-level description */
+        return err;
+    }
+
+    /* ### we should be refreshing direct AND (resolved) indirect locks! */
+
+    /* refresh all of the direct locks on this resource */
+    for (dp_scan = dp; dp_scan != NULL; dp_scan = dp_scan->next) {
+        if (dav_generic_do_refresh(dp_scan, ltl, new_time)) {
+            /* the lock was refreshed. return the lock. */
+            newlock = dav_generic_alloc_lock(lockdb, key, dp_scan->locktoken);
+            newlock->is_locknull = !resource->exists;
+            newlock->scope = dp_scan->f.scope;
+            newlock->type = dp_scan->f.type;
+            newlock->depth = dp_scan->f.depth;
+            newlock->timeout = dp_scan->f.timeout;
+            newlock->owner = dp_scan->owner;
+            newlock->auth_user = dp_scan->auth_user;
+
+            newlock->next = *locks;
+            *locks = newlock;
+
+            dirty = 1;
+        }
+    }
+
+    /* if we refreshed any locks, then save them back. */
+    if (dirty
+        && (err = dav_generic_save_lock_record(lockdb, key, dp, ip)) != NULL) {
+        /* ### maybe add in a higher-level description */
+        return err;
+    }
+
+    /* for each indirect lock, find its direct lock and refresh it. */
+    for (; ip != NULL; ip = ip->next) {
+        dav_lock_discovery *ref_dp;
+        dav_lock_indirect *ref_ip;
+
+        if ((err = dav_generic_resolve(lockdb, ip, &dp_scan,
+                                       &ref_dp, &ref_ip)) != NULL) {
+            /* ### push a higher-level desc? */
+            return err;
+        }
+        if (dav_generic_do_refresh(dp_scan, ltl, new_time)) {
+            /* the lock was refreshed. return the lock. */
+            newlock = dav_generic_alloc_lock(lockdb, ip->key, dp->locktoken);
+            newlock->is_locknull = !resource->exists;
+            newlock->scope = dp->f.scope;
+            newlock->type = dp->f.type;
+            newlock->depth = dp->f.depth;
+            newlock->timeout = dp->f.timeout;
+            newlock->owner = dp->owner;
+            newlock->auth_user = dp_scan->auth_user;
+
+            newlock->next = *locks;
+            *locks = newlock;
+
+            /* save the (resolved) direct lock back */
+            if ((err = dav_generic_save_lock_record(lockdb, ip->key, ref_dp,
+                                                    ref_ip)) != NULL) {
+                /* ### push a higher-level desc? */
+                return err;
+            }
+        }
+    }
+
+    return NULL;
+}
+
+
+const dav_hooks_locks dav_hooks_locks_generic =
+{
+    dav_generic_get_supportedlock,
+    dav_generic_parse_locktoken,
+    dav_generic_format_locktoken,
+    dav_generic_compare_locktoken,
+    dav_generic_open_lockdb,
+    dav_generic_close_lockdb,
+    dav_generic_remove_locknull_state,
+    dav_generic_create_lock,
+    dav_generic_get_locks,
+    dav_generic_find_lock,
+    dav_generic_has_locks,
+    dav_generic_append_locks,
+    dav_generic_remove_lock,
+    dav_generic_refresh_locks,
+    NULL, /* lookup_resource */
+
+    NULL /* ctx */
+};