Add a comment describing the sorted subkeys
[ira/wip.git] / source3 / registry / reg_backend_db.c
index 0d976be10d47adb4364e757c47546f561c1102e8..344bc4124d360797db07d06e4323c3e03fb0811e 100644 (file)
@@ -390,14 +390,14 @@ WERROR regdb_init(void)
                return WERR_OK;
        }
 
-       regdb = db_open_trans(NULL, state_path("registry.tdb"), 0,
+       regdb = db_open(NULL, state_path("registry.tdb"), 0,
                              REG_TDB_FLAGS, O_RDWR, 0600);
        if (!regdb) {
-               regdb = db_open_trans(NULL, state_path("registry.tdb"), 0,
+               regdb = db_open(NULL, state_path("registry.tdb"), 0,
                                      REG_TDB_FLAGS, O_RDWR|O_CREAT, 0600);
                if (!regdb) {
                        werr = ntstatus_to_werror(map_nt_error_from_unix(errno));
-                       DEBUG(0,("regdb_init: Failed to open registry %s (%s)\n",
+                       DEBUG(1,("regdb_init: Failed to open registry %s (%s)\n",
                                state_path("registry.tdb"), strerror(errno) ));
                        return werr;
                }
@@ -416,7 +416,7 @@ WERROR regdb_init(void)
                           vers_id, REGVER_V1));
                status = dbwrap_trans_store_int32(regdb, vstring, REGVER_V1);
                if (!NT_STATUS_IS_OK(status)) {
-                       DEBUG(0, ("regdb_init: error storing %s = %d: %s\n",
+                       DEBUG(1, ("regdb_init: error storing %s = %d: %s\n",
                                  vstring, REGVER_V1, nt_errstr(status)));
                        return ntstatus_to_werror(status);
                } else {
@@ -444,7 +444,7 @@ WERROR regdb_open( void )
        
        become_root();
 
-       regdb = db_open_trans(NULL, state_path("registry.tdb"), 0,
+       regdb = db_open(NULL, state_path("registry.tdb"), 0,
                              REG_TDB_FLAGS, O_RDWR, 0600);
        if ( !regdb ) {
                result = ntstatus_to_werror( map_nt_error_from_unix( errno ) );
@@ -536,21 +536,36 @@ static bool regdb_store_keys_internal(const char *key, REGSUBKEY_CTR *ctr)
        /* pack all the strings */
 
        for (i=0; i<num_subkeys; i++) {
-               len += tdb_pack(buffer+len, buflen-len, "f",
-                               regsubkey_ctr_specific_key(ctr, i));
-               if (len > buflen) {
-                       /* allocate some extra space */
-                       buffer = (uint8 *)SMB_REALLOC(buffer, len*2);
+               size_t thistime;
+
+               thistime = tdb_pack(buffer+len, buflen-len, "f",
+                                   regsubkey_ctr_specific_key(ctr, i));
+               if (len+thistime > buflen) {
+                       size_t thistime2;
+                       /*
+                        * tdb_pack hasn't done anything because of the short
+                        * buffer, allocate extra space.
+                        */
+                       buffer = SMB_REALLOC_ARRAY(buffer, uint8_t,
+                                                  (len+thistime)*2);
                        if(buffer == NULL) {
                                DEBUG(0, ("regdb_store_keys: Failed to realloc "
-                                         "memory of size [%d]\n", len*2));
+                                         "memory of size [%u]\n",
+                                         (unsigned int)(len+thistime)*2));
+                               ret = false;
+                               goto done;
+                       }
+                       buflen = (len+thistime)*2;
+                       thistime2 = tdb_pack(
+                               buffer+len, buflen-len, "f",
+                               regsubkey_ctr_specific_key(ctr, i));
+                       if (thistime2 != thistime) {
+                               DEBUG(0, ("tdb_pack failed\n"));
                                ret = false;
                                goto done;
                        }
-                       buflen = len*2;
-                       len = tdb_pack(buffer+len, buflen-len, "f",
-                                      regsubkey_ctr_specific_key(ctr, i));
                }
+               len += thistime;
        }
 
        /* finally write out the data */
@@ -563,6 +578,16 @@ static bool regdb_store_keys_internal(const char *key, REGSUBKEY_CTR *ctr)
                goto done;
        }
 
+       /*
+        * Delete a sorted subkey cache for regdb_key_exists, will be
+        * recreated automatically
+        */
+       keyname = talloc_asprintf(ctx, "%s/%s", REG_SORTED_SUBKEYS_PREFIX,
+                                 keyname);
+       if (keyname != NULL) {
+               dbwrap_delete_bystring(regdb, keyname);
+       }
+
 done:
        TALLOC_FREE(ctx);
        SAFE_FREE(buffer);
@@ -701,8 +726,15 @@ bool regdb_store_keys(const char *key, REGSUBKEY_CTR *ctr)
                if (!path) {
                        goto cancel;
                }
-               /* Ignore errors here, we might have no values around */
-               dbwrap_delete_bystring(regdb, path);
+               status = dbwrap_delete_bystring(regdb, path);
+               /* Don't fail if there are no values around. */
+               if (!NT_STATUS_IS_OK(status) &&
+                   !NT_STATUS_EQUAL(status, NT_STATUS_NOT_FOUND))
+               {
+                       DEBUG(1, ("Deleting %s failed: %s\n", path,
+                                 nt_errstr(status)));
+                       goto cancel;
+               }
                TALLOC_FREE(path);
 
                /* (c) Delete the list of subkeys of this key */
@@ -716,8 +748,12 @@ bool regdb_store_keys(const char *key, REGSUBKEY_CTR *ctr)
                        goto cancel;
                }
                status = dbwrap_delete_bystring(regdb, path);
-               if (!NT_STATUS_IS_OK(status)) {
-                       DEBUG(1, ("Deleting %s failed\n", path));
+               /* Don't fail if the subkey record was not found. */
+               if (!NT_STATUS_IS_OK(status) &&
+                   !NT_STATUS_EQUAL(status, NT_STATUS_NOT_FOUND))
+               {
+                       DEBUG(1, ("Deleting %s failed: %s\n", path,
+                                 nt_errstr(status)));
                        goto cancel;
                }
                TALLOC_FREE(path);
@@ -845,6 +881,192 @@ done:
        return ret;
 }
 
+/*
+ * regdb_key_exists() is a very frequent operation. It can be quite
+ * time-consuming to fully fetch the parent's subkey list, talloc_strdup all
+ * subkeys and then compare the keyname linearly to all the parent's subkeys.
+ *
+ * The following code tries to make this operation as efficient as possible:
+ * Per registry key we create a list of subkeys that is very efficient to
+ * search for existence of a subkey. Its format is:
+ *
+ * 4 bytes num_subkeys
+ * 4*num_subkey bytes offset into the string array
+ * then follows a sorted list of subkeys in uppercase
+ *
+ * This record is created by create_sorted_subkeys() on demand if it does not
+ * exist. scan_parent_subkeys() uses regdb->parse_record to search the sorted
+ * list, the parsing code and the binary search can be found in
+ * parent_subkey_scanner. The code uses parse_record() to avoid a memcpy of
+ * the potentially large subkey record.
+ *
+ * The sorted subkey record is deleted in regdb_store_keys_internal and
+ * recreated on demand.
+ */
+
+static int cmp_keynames(const void *p1, const void *p2)
+{
+       return StrCaseCmp(*((char **)p1), *((char **)p2));
+}
+
+static bool create_sorted_subkeys(const char *key, const char *sorted_keyname)
+{
+       char **sorted_subkeys;
+       REGSUBKEY_CTR *ctr;
+       bool result = false;
+       NTSTATUS status;
+       char *buf;
+       char *p;
+       int i, res;
+       size_t len;
+
+       ctr = talloc(talloc_tos(), REGSUBKEY_CTR);
+       if (ctr == NULL) {
+               return false;
+       }
+
+       res = regdb_fetch_keys(key, ctr);
+       if (res == -1) {
+               goto fail;
+       }
+
+       sorted_subkeys = talloc_array(ctr, char *, ctr->num_subkeys);
+       if (sorted_subkeys == NULL) {
+               goto fail;
+       }
+
+       len = 4 + 4*ctr->num_subkeys;
+
+       for (i = 0; i<ctr->num_subkeys; i++) {
+               sorted_subkeys[i] = talloc_strdup_upper(sorted_subkeys,
+                                                       ctr->subkeys[i]);
+               if (sorted_subkeys[i] == NULL) {
+                       goto fail;
+               }
+               len += strlen(sorted_subkeys[i])+1;
+       }
+
+       qsort(sorted_subkeys, ctr->num_subkeys, sizeof(char *), cmp_keynames);
+
+       buf = talloc_array(ctr, char, len);
+       if (buf == NULL) {
+               goto fail;
+       }
+       p = buf + 4 + 4*ctr->num_subkeys;
+
+       SIVAL(buf, 0, ctr->num_subkeys);
+
+       for (i=0; i<ctr->num_subkeys; i++) {
+               ptrdiff_t offset = p - buf;
+               SIVAL(buf, 4 + 4*i, offset);
+               strlcpy(p, sorted_subkeys[i], len-offset);
+               p += strlen(sorted_subkeys[i]) + 1;
+       }
+
+       status = dbwrap_trans_store_bystring(
+               regdb, sorted_keyname, make_tdb_data((uint8_t *)buf, len),
+               TDB_REPLACE);
+       if (!NT_STATUS_IS_OK(status)) {
+               goto fail;
+       }
+
+       result = true;
+ fail:
+       TALLOC_FREE(ctr);
+       return result;
+}
+
+struct scan_subkey_state {
+       char *name;
+       bool scanned;
+       bool found;
+};
+
+static int parent_subkey_scanner(TDB_DATA key, TDB_DATA data,
+                                void *private_data)
+{
+       struct scan_subkey_state *state =
+               (struct scan_subkey_state *)private_data;
+       uint32_t num_subkeys;
+       uint32_t l, u;
+
+       if (data.dsize < sizeof(uint32_t)) {
+               return -1;
+       }
+
+       state->scanned = true;
+       state->found = false;
+
+       tdb_unpack(data.dptr, data.dsize, "d", &num_subkeys);
+
+       l = 0;
+       u = num_subkeys;
+
+       while (l < u) {
+               uint32_t idx = (l+u)/2;
+               char *s = (char *)data.dptr + IVAL(data.dptr, 4 + 4*idx);
+               int comparison = strcmp(state->name, s);
+
+               if (comparison < 0) {
+                       u = idx;
+               } else if (comparison > 0) {
+                       l = idx + 1;
+               } else {
+                       state->found = true;
+                       return 0;
+               }
+       }
+       return 0;
+}
+
+static bool scan_parent_subkeys(const char *parent, const char *name)
+{
+       char *path = NULL;
+       char *key = NULL;
+       struct scan_subkey_state state = { 0, };
+       bool result = false;
+       int res;
+
+       state.name = NULL;
+
+       path = normalize_reg_path(talloc_tos(), parent);
+       if (path == NULL) {
+               goto fail;
+       }
+
+       key = talloc_asprintf(talloc_tos(), "%s/%s",
+                             REG_SORTED_SUBKEYS_PREFIX, path);
+       if (key == NULL) {
+               goto fail;
+       }
+
+       state.name = talloc_strdup_upper(talloc_tos(), name);
+       if (state.name == NULL) {
+               goto fail;
+       }
+       state.scanned = false;
+
+       res = regdb->parse_record(regdb, string_term_tdb_data(key),
+                                 parent_subkey_scanner, &state);
+
+       if (state.scanned) {
+               result = state.found;
+       } else {
+               if (!create_sorted_subkeys(path, key)) {
+                       goto fail;
+               }
+               res = regdb->parse_record(regdb, string_term_tdb_data(key),
+                                         parent_subkey_scanner, &state);
+               if ((res == 0) && (state.scanned)) {
+                       result = state.found;
+               }
+       }
+
+ fail:
+       TALLOC_FREE(path);
+       TALLOC_FREE(state.name);
+       return result;
+}
 
 /**
  * Check for the existence of a key.
@@ -881,26 +1103,8 @@ static bool regdb_key_exists(const char *key)
                value = regdb_fetch_key_internal(mem_ctx, path);
                ret = (value.dptr != NULL);
        } else {
-               /* get the list of subkeys of the parent key */
-               uint32 num_items, len, i;
-               fstring subkeyname;
-
                *p = '\0';
-               p++;
-               value = regdb_fetch_key_internal(mem_ctx, path);
-               if (value.dptr == NULL) {
-                       goto done;
-               }
-
-               len = tdb_unpack(value.dptr, value.dsize, "d", &num_items);
-               for (i = 0; i < num_items; i++) {
-                       len += tdb_unpack(value.dptr +len, value.dsize -len,
-                                         "f", &subkeyname);
-                       if (strequal(subkeyname, p)) {
-                               ret = true;
-                               goto done;
-                       }
-               }
+               ret = scan_parent_subkeys(path, p+1);
        }
 
 done:
@@ -916,7 +1120,6 @@ done:
 
 int regdb_fetch_keys(const char *key, REGSUBKEY_CTR *ctr)
 {
-       WERROR werr;
        uint32 num_items;
        uint8 *buf;
        uint32 buflen, len;
@@ -929,37 +1132,61 @@ int regdb_fetch_keys(const char *key, REGSUBKEY_CTR *ctr)
        DEBUG(11,("regdb_fetch_keys: Enter key => [%s]\n", key ? key : "NULL"));
 
        if (!regdb_key_exists(key)) {
-               goto fail;
+               goto done;
        }
 
        ctr->seqnum = regdb_get_seqnum();
 
        value = regdb_fetch_key_internal(frame, key);
 
+       if (value.dptr == NULL) {
+               DEBUG(10, ("regdb_fetch_keys: no subkeys found for key [%s]\n",
+                          key));
+               ret = 0;
+               goto done;
+       }
+
        buf = value.dptr;
        buflen = value.dsize;
+       len = tdb_unpack( buf, buflen, "d", &num_items);
 
-       if ( !buf ) {
-               DEBUG(5,("regdb_fetch_keys: tdb lookup failed to locate key [%s]\n", key));
-               goto fail;
-       }
+       /*
+        * The following code breaks the abstraction that reg_objects.c sets
+        * up with regsubkey_ctr_addkey(). But if we use that with the current
+        * data structure of ctr->subkeys being an unsorted array, we end up
+        * with an O(n^2) algorithm for retrieving keys from the tdb
+        * file. This is pretty pointless, as we have to trust the data
+        * structure on disk not to have duplicates anyway. The alternative to
+        * breaking this abstraction would be to set up a more sophisticated
+        * data structure in REGSUBKEY_CTR.
+        *
+        * This makes "net conf list" for a registry with >1000 shares
+        * actually usable :-)
+        */
 
-       len = tdb_unpack( buf, buflen, "d", &num_items);
+       ctr->subkeys = talloc_array(ctr, char *, num_items);
+       if (ctr->subkeys == NULL) {
+               DEBUG(5, ("regdb_fetch_keys: could not allocate subkeys\n"));
+               goto done;
+       }
+       ctr->num_subkeys = num_items;
 
        for (i=0; i<num_items; i++) {
                len += tdb_unpack(buf+len, buflen-len, "f", subkeyname);
-               werr = regsubkey_ctr_addkey(ctr, subkeyname);
-               if (!W_ERROR_IS_OK(werr)) {
-                       DEBUG(5, ("regdb_fetch_keys: regsubkey_ctr_addkey "
-                                 "failed: %s\n", dos_errstr(werr)));
-                       goto fail;
+               ctr->subkeys[i] = talloc_strdup(ctr->subkeys, subkeyname);
+               if (ctr->subkeys[i] == NULL) {
+                       DEBUG(5, ("regdb_fetch_keys: could not allocate "
+                                 "subkeyname\n"));
+                       TALLOC_FREE(ctr->subkeys);
+                       ctr->num_subkeys = 0;
+                       goto done;
                }
        }
 
        DEBUG(11,("regdb_fetch_keys: Exit [%d] items\n", num_items));
 
        ret = num_items;
- fail:
+done:
        TALLOC_FREE(frame);
        return ret;
 }
@@ -1132,8 +1359,7 @@ bool regdb_store_values( const char *key, REGVAL_CTR *values )
                goto done;
        }
 
-       status = dbwrap_trans_store(regdb, string_term_tdb_data(keystr), data,
-                                   TDB_REPLACE);
+       status = dbwrap_trans_store_bystring(regdb, keystr, data, TDB_REPLACE);
 
        result = NT_STATUS_IS_OK(status);
 
@@ -1207,8 +1433,7 @@ static WERROR regdb_set_secdesc(const char *key,
 
        if (secdesc == NULL) {
                /* assuming a delete */
-               status = dbwrap_trans_delete(regdb,
-                                            string_term_tdb_data(tdbkey));
+               status = dbwrap_trans_delete_bystring(regdb, tdbkey);
                if (NT_STATUS_IS_OK(status)) {
                        err = WERR_OK;
                } else {
@@ -1224,8 +1449,7 @@ static WERROR regdb_set_secdesc(const char *key,
                goto done;
        }
 
-       status = dbwrap_trans_store(regdb, string_term_tdb_data(tdbkey),
-                                   tdbdata, 0);
+       status = dbwrap_trans_store_bystring(regdb, tdbkey, tdbdata, 0);
        if (!NT_STATUS_IS_OK(status)) {
                err = ntstatus_to_werror(status);
                goto done;