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-rw-r--r--source3/lib/g_lock.c594
1 files changed, 594 insertions, 0 deletions
diff --git a/source3/lib/g_lock.c b/source3/lib/g_lock.c
new file mode 100644
index 0000000000..6508b3995b
--- /dev/null
+++ b/source3/lib/g_lock.c
@@ -0,0 +1,594 @@
+/*
+ Unix SMB/CIFS implementation.
+ global locks based on dbwrap and messaging
+ Copyright (C) 2009 by Volker Lendecke
+
+ 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 3 of the License, 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, see <http://www.gnu.org/licenses/>.
+*/
+
+#include "includes.h"
+#include "g_lock.h"
+
+static NTSTATUS g_lock_force_unlock(struct g_lock_ctx *ctx, const char *name,
+ struct server_id pid);
+
+struct g_lock_ctx {
+ struct db_context *db;
+ struct messaging_context *msg;
+};
+
+/*
+ * The "g_lock.tdb" file contains records, indexed by the 0-terminated
+ * lockname. The record contains an array of "struct g_lock_rec"
+ * structures. Waiters have the lock_type with G_LOCK_PENDING or'ed.
+ */
+
+struct g_lock_rec {
+ enum g_lock_type lock_type;
+ struct server_id pid;
+};
+
+struct g_lock_ctx *g_lock_ctx_init(TALLOC_CTX *mem_ctx,
+ struct messaging_context *msg)
+{
+ struct g_lock_ctx *result;
+
+ result = talloc(mem_ctx, struct g_lock_ctx);
+ if (result == NULL) {
+ return NULL;
+ }
+ result->msg = msg;
+
+ result->db = db_open(result, lock_path("g_lock.tdb"), 0,
+ TDB_CLEAR_IF_FIRST, O_RDWR|O_CREAT, 0700);
+ if (result->db == NULL) {
+ DEBUG(1, ("g_lock_init: Could not open g_lock.tdb"));
+ TALLOC_FREE(result);
+ return NULL;
+ }
+ return result;
+}
+
+static bool g_lock_conflicts(enum g_lock_type lock_type,
+ const struct g_lock_rec *rec)
+{
+ enum g_lock_type rec_lock = rec->lock_type;
+
+ if ((rec_lock & G_LOCK_PENDING) != 0) {
+ return false;
+ }
+
+ /*
+ * Only tested write locks so far. Very likely this routine
+ * needs to be fixed for read locks....
+ */
+ if ((lock_type == G_LOCK_READ) && (rec_lock == G_LOCK_READ)) {
+ return false;
+ }
+ return true;
+}
+
+static bool g_lock_parse(TALLOC_CTX *mem_ctx, TDB_DATA data,
+ int *pnum_locks, struct g_lock_rec **plocks)
+{
+ int i, num_locks;
+ struct g_lock_rec *locks;
+
+ if ((data.dsize % sizeof(struct g_lock_rec)) != 0) {
+ DEBUG(1, ("invalid lock record length %d\n", (int)data.dsize));
+ return false;
+ }
+
+ num_locks = data.dsize / sizeof(struct g_lock_rec);
+ locks = talloc_array(mem_ctx, struct g_lock_rec, num_locks);
+ if (locks == NULL) {
+ DEBUG(1, ("talloc failed\n"));
+ return false;
+ }
+
+ memcpy(locks, data.dptr, data.dsize);
+
+ DEBUG(10, ("locks:\n"));
+ for (i=0; i<num_locks; i++) {
+ DEBUGADD(10, ("%s: %s %s\n",
+ procid_str(talloc_tos(), &locks[i].pid),
+ ((locks[i].lock_type & 1) == G_LOCK_READ) ?
+ "read" : "write",
+ (locks[i].lock_type & G_LOCK_PENDING) ?
+ "(pending)" : "(owner)"));
+
+ if (process_exists(locks[i].pid)) {
+ continue;
+ }
+ DEBUGADD(10, ("%s does not exist -- discarding\n",
+ procid_str(talloc_tos(), &locks[i].pid)));
+
+ if (i < (num_locks-1)) {
+ locks[i] = locks[num_locks-1];
+ }
+ num_locks -= 1;
+ }
+
+ *plocks = locks;
+ *pnum_locks = num_locks;
+ return true;
+}
+
+static struct g_lock_rec *g_lock_addrec(TALLOC_CTX *mem_ctx,
+ struct g_lock_rec *locks,
+ int num_locks,
+ const struct server_id pid,
+ enum g_lock_type lock_type)
+{
+ struct g_lock_rec *result;
+
+ result = talloc_realloc(mem_ctx, locks, struct g_lock_rec,
+ num_locks+1);
+ if (result == NULL) {
+ return NULL;
+ }
+
+ result[num_locks].pid = pid;
+ result[num_locks].lock_type = lock_type;
+ return result;
+}
+
+static void g_lock_got_retry(struct messaging_context *msg,
+ void *private_data,
+ uint32_t msg_type,
+ struct server_id server_id,
+ DATA_BLOB *data);
+static void g_lock_timedout(struct tevent_context *ev,
+ struct tevent_timer *te,
+ struct timeval current_time,
+ void *private_data);
+
+static NTSTATUS g_lock_trylock(struct g_lock_ctx *ctx, const char *name,
+ enum g_lock_type lock_type)
+{
+ struct db_record *rec = NULL;
+ struct g_lock_rec *locks = NULL;
+ int i, num_locks;
+ struct server_id self;
+ int our_index;
+ TDB_DATA data;
+ NTSTATUS status = NT_STATUS_OK;
+ NTSTATUS store_status;
+
+again:
+ rec = ctx->db->fetch_locked(ctx->db, talloc_tos(),
+ string_term_tdb_data(name));
+ if (rec == NULL) {
+ DEBUG(10, ("fetch_locked(\"%s\") failed\n", name));
+ status = NT_STATUS_LOCK_NOT_GRANTED;
+ goto done;
+ }
+
+ if (!g_lock_parse(talloc_tos(), rec->value, &num_locks, &locks)) {
+ DEBUG(10, ("g_lock_parse for %s failed\n", name));
+ status = NT_STATUS_INTERNAL_ERROR;
+ goto done;
+ }
+
+ self = procid_self();
+ our_index = -1;
+
+ for (i=0; i<num_locks; i++) {
+ if (procid_equal(&self, &locks[i].pid)) {
+ if (our_index != -1) {
+ DEBUG(1, ("g_lock_trylock: Added ourself "
+ "twice!\n"));
+ status = NT_STATUS_INTERNAL_ERROR;
+ goto done;
+ }
+ if ((locks[i].lock_type & G_LOCK_PENDING) == 0) {
+ DEBUG(1, ("g_lock_trylock: Found ourself not "
+ "pending!\n"));
+ status = NT_STATUS_INTERNAL_ERROR;
+ goto done;
+ }
+
+ our_index = i;
+
+ /* never conflict with ourself */
+ continue;
+ }
+ if (g_lock_conflicts(lock_type, &locks[i])) {
+ struct server_id pid = locks[i].pid;
+
+ if (!process_exists(pid)) {
+ TALLOC_FREE(locks);
+ TALLOC_FREE(rec);
+ status = g_lock_force_unlock(ctx, name, pid);
+ if (!NT_STATUS_IS_OK(status)) {
+ DEBUG(1, ("Could not unlock dead lock "
+ "holder!\n"));
+ goto done;
+ }
+ goto again;
+ }
+ lock_type |= G_LOCK_PENDING;
+ }
+ }
+
+ if (our_index == -1) {
+ /* First round, add ourself */
+
+ locks = g_lock_addrec(talloc_tos(), locks, num_locks,
+ self, lock_type);
+ if (locks == NULL) {
+ DEBUG(10, ("g_lock_addrec failed\n"));
+ status = NT_STATUS_NO_MEMORY;
+ goto done;
+ }
+ } else {
+ /*
+ * Retry. We were pending last time. Overwrite the
+ * stored lock_type with what we calculated, we might
+ * have acquired the lock this time.
+ */
+ locks[our_index].lock_type = lock_type;
+ }
+
+ data = make_tdb_data((uint8_t *)locks, talloc_get_size(locks));
+ store_status = rec->store(rec, data, 0);
+ if (!NT_STATUS_IS_OK(store_status)) {
+ DEBUG(1, ("rec->store failed: %s\n",
+ nt_errstr(store_status)));
+ status = store_status;
+ }
+
+done:
+ TALLOC_FREE(locks);
+ TALLOC_FREE(rec);
+
+ if (NT_STATUS_IS_OK(status) && (lock_type & G_LOCK_PENDING) != 0) {
+ return STATUS_PENDING;
+ }
+
+ return NT_STATUS_OK;
+}
+
+NTSTATUS g_lock_lock(struct g_lock_ctx *ctx, const char *name,
+ enum g_lock_type lock_type, struct timeval timeout)
+{
+ struct tevent_timer *te = NULL;
+ NTSTATUS status;
+ bool retry = false;
+ bool timedout = false;
+
+ DEBUG(10, ("Trying to acquire lock %d for %s\n", (int)lock_type,
+ name));
+
+ if (lock_type & ~1) {
+ DEBUG(1, ("Got invalid lock type %d for %s\n",
+ (int)lock_type, name));
+ return NT_STATUS_INVALID_PARAMETER;
+ }
+
+#ifdef CLUSTER_SUPPORT
+ if (lp_clustering()) {
+ status = ctdb_watch_us(messaging_ctdbd_connection());
+ if (!NT_STATUS_IS_OK(status)) {
+ DEBUG(10, ("could not register retry with ctdb: %s\n",
+ nt_errstr(status)));
+ goto done;
+ }
+ }
+#endif
+
+ status = messaging_register(ctx->msg, &retry, MSG_DBWRAP_G_LOCK_RETRY,
+ g_lock_got_retry);
+ if (!NT_STATUS_IS_OK(status)) {
+ DEBUG(10, ("messaging_register failed: %s\n",
+ nt_errstr(status)));
+ return status;
+ }
+again:
+ retry = false;
+
+ status = g_lock_trylock(ctx, name, lock_type);
+ if (NT_STATUS_IS_OK(status)) {
+ DEBUG(10, ("Got lock %s\n", name));
+ goto done;
+ }
+ if (!NT_STATUS_EQUAL(status, STATUS_PENDING)) {
+ DEBUG(10, ("g_lock_trylock failed: %s\n",
+ nt_errstr(status)));
+ goto done;
+ }
+
+ if (retry) {
+ goto again;
+ }
+
+ DEBUG(10, ("g_lock_trylock: Did not get lock, waiting...\n"));
+
+ if (te == NULL) {
+ te = tevent_add_timer(
+ ctx->msg->event_ctx, talloc_tos(),
+ timeval_current_ofs(timeout.tv_sec, timeout.tv_usec),
+ g_lock_timedout, &timedout);
+ if (te == NULL) {
+ DEBUG(10, ("tevent_add_timer failed\n"));
+ status = NT_STATUS_NO_MEMORY;
+ goto done;
+ }
+ }
+
+ while (true) {
+ if (tevent_loop_once(ctx->msg->event_ctx) == -1) {
+ DEBUG(1, ("tevent_loop_once failed\n"));
+ status = NT_STATUS_INTERNAL_ERROR;
+ goto done;
+ }
+ if (retry) {
+ goto again;
+ }
+ if (timedout) {
+ DEBUG(10, ("g_lock_lock timed out\n"));
+
+ te = NULL;
+
+ status = NT_STATUS_LOCK_NOT_GRANTED;
+ goto done;
+ }
+ }
+done:
+
+ if (!NT_STATUS_IS_OK(status)) {
+ NTSTATUS unlock_status;
+
+ unlock_status = g_lock_unlock(ctx, name);
+
+ if (!NT_STATUS_IS_OK(unlock_status)) {
+ DEBUG(1, ("Could not remove ourself from the locking "
+ "db: %s\n", nt_errstr(status)));
+ }
+ }
+
+ messaging_deregister(ctx->msg, MSG_DBWRAP_G_LOCK_RETRY, &retry);
+ TALLOC_FREE(te);
+
+ return status;
+}
+
+static void g_lock_got_retry(struct messaging_context *msg,
+ void *private_data,
+ uint32_t msg_type,
+ struct server_id server_id,
+ DATA_BLOB *data)
+{
+ bool *pretry = (bool *)private_data;
+
+ DEBUG(10, ("Got retry message from pid %s\n",
+ procid_str(talloc_tos(), &server_id)));
+
+ *pretry = true;
+}
+
+static void g_lock_timedout(struct tevent_context *ev,
+ struct tevent_timer *te,
+ struct timeval current_time,
+ void *private_data)
+{
+ bool *ptimedout = (bool *)private_data;
+ *ptimedout = true;
+ TALLOC_FREE(te);
+}
+
+static NTSTATUS g_lock_force_unlock(struct g_lock_ctx *ctx, const char *name,
+ struct server_id pid)
+{
+ struct db_record *rec = NULL;
+ struct g_lock_rec *locks = NULL;
+ int i, num_locks;
+ enum g_lock_type lock_type;
+ NTSTATUS status;
+
+ rec = ctx->db->fetch_locked(ctx->db, talloc_tos(),
+ string_term_tdb_data(name));
+ if (rec == NULL) {
+ DEBUG(10, ("fetch_locked(\"%s\") failed\n", name));
+ status = NT_STATUS_INTERNAL_ERROR;
+ goto done;
+ }
+
+ if (!g_lock_parse(talloc_tos(), rec->value, &num_locks, &locks)) {
+ DEBUG(10, ("g_lock_parse for %s failed\n", name));
+ status = NT_STATUS_INTERNAL_ERROR;
+ goto done;
+ }
+
+ for (i=0; i<num_locks; i++) {
+ if (procid_equal(&pid, &locks[i].pid)) {
+ break;
+ }
+ }
+
+ if (i == num_locks) {
+ DEBUG(10, ("g_lock_force_unlock: Lock not found\n"));
+ status = NT_STATUS_INTERNAL_ERROR;
+ goto done;
+ }
+
+ lock_type = locks[i].lock_type;
+
+ if (i < (num_locks-1)) {
+ locks[i] = locks[num_locks-1];
+ }
+ num_locks -= 1;
+
+ if (num_locks == 0) {
+ status = rec->delete_rec(rec);
+ } else {
+ TDB_DATA data;
+ data = make_tdb_data((uint8_t *)locks,
+ sizeof(struct g_lock_rec) * num_locks);
+ status = rec->store(rec, data, 0);
+ }
+
+ if (!NT_STATUS_IS_OK(status)) {
+ DEBUG(1, ("g_lock_force_unlock: Could not store record: %s\n",
+ nt_errstr(status)));
+ goto done;
+ }
+
+ if ((lock_type & G_LOCK_PENDING) == 0) {
+ /*
+ * We've been the lock holder. Tell all others to retry.
+ */
+ for (i=0; i<num_locks; i++) {
+ if ((locks[i].lock_type & G_LOCK_PENDING) == 0) {
+ continue;
+ }
+
+ /*
+ * Ping all waiters to retry
+ */
+ status = messaging_send(ctx->msg, locks[i].pid,
+ MSG_DBWRAP_G_LOCK_RETRY,
+ &data_blob_null);
+ if (!NT_STATUS_IS_OK(status)) {
+ DEBUG(1, ("sending retry to %s failed: %s\n",
+ procid_str(talloc_tos(),
+ &locks[i].pid),
+ nt_errstr(status)));
+ }
+ }
+ }
+done:
+
+ TALLOC_FREE(locks);
+ TALLOC_FREE(rec);
+ return status;
+}
+
+NTSTATUS g_lock_unlock(struct g_lock_ctx *ctx, const char *name)
+{
+ NTSTATUS status;
+
+ status = g_lock_force_unlock(ctx, name, procid_self());
+
+#ifdef CLUSTER_SUPPORT
+ if (lp_clustering()) {
+ ctdb_unwatch(messaging_ctdbd_connection());
+ }
+#endif
+ return status;
+}
+
+struct g_lock_locks_state {
+ int (*fn)(const char *name, void *private_data);
+ void *private_data;
+};
+
+static int g_lock_locks_fn(struct db_record *rec, void *priv)
+{
+ struct g_lock_locks_state *state = (struct g_lock_locks_state *)priv;
+
+ if ((rec->key.dsize == 0) || (rec->key.dptr[rec->key.dsize-1] != 0)) {
+ DEBUG(1, ("invalid key in g_lock.tdb, ignoring\n"));
+ return 0;
+ }
+ return state->fn((char *)rec->key.dptr, state->private_data);
+}
+
+int g_lock_locks(struct g_lock_ctx *ctx,
+ int (*fn)(const char *name, void *private_data),
+ void *private_data)
+{
+ struct g_lock_locks_state state;
+
+ state.fn = fn;
+ state.private_data = private_data;
+
+ return ctx->db->traverse_read(ctx->db, g_lock_locks_fn, &state);
+}
+
+NTSTATUS g_lock_dump(struct g_lock_ctx *ctx, const char *name,
+ int (*fn)(struct server_id pid,
+ enum g_lock_type lock_type,
+ void *private_data),
+ void *private_data)
+{
+ TDB_DATA data;
+ int i, num_locks;
+ struct g_lock_rec *locks = NULL;
+ bool ret;
+
+ if (ctx->db->fetch(ctx->db, talloc_tos(), string_term_tdb_data(name),
+ &data) != 0) {
+ return NT_STATUS_NOT_FOUND;
+ }
+
+ if ((data.dsize == 0) || (data.dptr == NULL)) {
+ return NT_STATUS_OK;
+ }
+
+ ret = g_lock_parse(talloc_tos(), data, &num_locks, &locks);
+
+ TALLOC_FREE(data.dptr);
+
+ if (!ret) {
+ DEBUG(10, ("g_lock_parse for %s failed\n", name));
+ return NT_STATUS_INTERNAL_ERROR;
+ }
+
+ for (i=0; i<num_locks; i++) {
+ if (fn(locks[i].pid, locks[i].lock_type, private_data) != 0) {
+ break;
+ }
+ }
+ TALLOC_FREE(locks);
+ return NT_STATUS_OK;
+}
+
+struct g_lock_get_state {
+ bool found;
+ struct server_id *pid;
+};
+
+static int g_lock_get_fn(struct server_id pid, enum g_lock_type lock_type,
+ void *priv)
+{
+ struct g_lock_get_state *state = (struct g_lock_get_state *)priv;
+
+ if ((lock_type & G_LOCK_PENDING) != 0) {
+ return 0;
+ }
+
+ state->found = true;
+ *state->pid = pid;
+ return 1;
+}
+
+NTSTATUS g_lock_get(struct g_lock_ctx *ctx, const char *name,
+ struct server_id *pid)
+{
+ struct g_lock_get_state state;
+ NTSTATUS status;
+
+ state.found = false;
+ state.pid = pid;
+
+ status = g_lock_dump(ctx, name, g_lock_get_fn, &state);
+ if (!NT_STATUS_IS_OK(status)) {
+ return status;
+ }
+ if (!state.found) {
+ return NT_STATUS_NOT_FOUND;
+ }
+ return NT_STATUS_OK;
+}
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