Added tdb_change_int_atomic() to allow atomic updates of a tdb int value.

Jeremy.
(This used to be commit cf5015f15935605cf69078bc15251db61ddc48c7)

4 files changed, 44 insertions, 15 deletions

diff --git a/source3/include/proto.h b/source3/include/proto.h
index d6bc3c768c..5c9a739caa 100644
--- a/source3/include/proto.h
+++ b/source3/include/proto.h
@@ -126,7 +126,8 @@ int sys_fsusage(const char *path, SMB_BIG_UINT *dfree, SMB_BIG_UINT *dsize);
 
 /* The following definitions come from lib/genrand.c  */
 
-void generate_random_buffer( unsigned char *out, int len, BOOL re_seed);
+void set_rand_reseed_data(unsigned char *data, size_t len);
+void generate_random_buffer( unsigned char *out, int len, BOOL do_reseed_now);
 char *generate_random_str(size_t len);
 
 /* The following definitions come from lib/getsmbpass.c  */
@@ -4589,6 +4590,7 @@ int tdb_store_int_byblob(TDB_CONTEXT *tdb, char *keystr, size_t len, int v);
 int tdb_store_int(TDB_CONTEXT *tdb, char *keystr, int v);
 int tdb_store_by_string(TDB_CONTEXT *tdb, char *keystr, void *buffer, int len);
 TDB_DATA tdb_fetch_by_string(TDB_CONTEXT *tdb, char *keystr);
+int tdb_change_int_atomic(TDB_CONTEXT *tdb, char *keystr, int *oldval, int change_val);
 size_t tdb_pack(char *buf, int bufsize, char *fmt, ...);
 int tdb_unpack(char *buf, int bufsize, char *fmt, ...);
 
diff --git a/source3/smbd/process.c b/source3/smbd/process.c
index 74c0cbc96f..1f575e2a46 100644
--- a/source3/smbd/process.c
+++ b/source3/smbd/process.c
@@ -781,12 +781,12 @@ static BOOL smbd_process_limit(void)
 		/* Always add one to the smbd process count, as exit_server() always
 		 * subtracts one.
 		 */
-		tdb_lock_bystring(conn_tdb_ctx(), "INFO/total_smbds");
-		total_smbds = tdb_fetch_int(conn_tdb_ctx(), "INFO/total_smbds");
-		total_smbds = total_smbds < 0 ? 1 : total_smbds + 1;
-		tdb_store_int(conn_tdb_ctx(), "INFO/total_smbds", total_smbds);
-		tdb_unlock_bystring(conn_tdb_ctx(), "INFO/total_smbds");
-		
+
+		total_smbds = 1; /* In case we need to create the entry. */
+
+		if (tdb_change_int_atomic(conn_tdb_ctx(), "INFO/total_smbds", &total_smbds, 1) == -1)
+			return True;
+
 		return total_smbds > lp_max_smbd_processes();
 	}
 	else
diff --git a/source3/smbd/server.c b/source3/smbd/server.c
index 6f4f18562e..fcee30d667 100644
--- a/source3/smbd/server.c
+++ b/source3/smbd/server.c
@@ -421,16 +421,14 @@ static BOOL dump_core(void)
 /****************************************************************************
 update the current smbd process count
 ****************************************************************************/
+
 static void decrement_smbd_process_count(void)
 {
 	int total_smbds;
 
 	if (lp_max_smbd_processes()) {
-		tdb_lock_bystring(conn_tdb_ctx(), "INFO/total_smbds");
-		if ((total_smbds = tdb_fetch_int(conn_tdb_ctx(), "INFO/total_smbds")) > 0)
-			tdb_store_int(conn_tdb_ctx(), "INFO/total_smbds", total_smbds - 1);
-		
-		tdb_unlock_bystring(conn_tdb_ctx(), "INFO/total_smbds");
+		total_smbds = 0;
+		tdb_change_int_atomic(conn_tdb_ctx(), "INFO/total_smbds", &total_smbds, -1);
 	}
 }
 
diff --git a/source3/tdb/tdbutil.c b/source3/tdb/tdbutil.c
index a620f085a9..40f5a1246d 100644
--- a/source3/tdb/tdbutil.c
+++ b/source3/tdb/tdbutil.c
@@ -46,9 +46,6 @@ void tdb_unlock_bystring(TDB_CONTEXT *tdb, char *keyval)
 	tdb_chainunlock(tdb, key);
 }
 
-/* lock a chain by string key */
-
-
 /* fetch a value by a arbitrary blob key, return -1 if not found */
 int tdb_fetch_int_byblob(TDB_CONTEXT *tdb, char *keyval, size_t len)
 {
@@ -107,6 +104,7 @@ int tdb_store_by_string(TDB_CONTEXT *tdb, char *keystr, void *buffer, int len)
 
 /* Fetch a buffer using a null terminated string key.  Don't forget to call
    free() on the result dptr. */
+
 TDB_DATA tdb_fetch_by_string(TDB_CONTEXT *tdb, char *keystr)
 {
     TDB_DATA key;
@@ -117,6 +115,37 @@ TDB_DATA tdb_fetch_by_string(TDB_CONTEXT *tdb, char *keystr)
     return tdb_fetch(tdb, key);
 }
 
+/* Atomic integer change. Returns old value. To create, set initial value in *oldval. */
+
+int tdb_change_int_atomic(TDB_CONTEXT *tdb, char *keystr, int *oldval, int change_val)
+{
+	int val;
+	int ret = -1;
+
+	if (tdb_lock_bystring(tdb, keystr) == -1)
+		return -1;
+
+	if ((val = tdb_fetch_int(tdb, keystr)) == -1) {
+		if (tdb_error(tdb) != TDB_ERR_NOEXIST)
+			goto err_out;
+
+		val = *oldval;
+
+	} else {
+		*oldval = val;
+		val += change_val;
+	}
+		
+	if (tdb_store_int(tdb, keystr, val) == -1)
+		goto err_out;
+
+	ret = 0;
+
+  err_out:
+
+	tdb_unlock_bystring(tdb, keystr);
+	return ret;
+}
 
 /* useful pair of routines for packing/unpacking data consisting of
    integers and strings */