lib/dbwrap: allow dbwrap_merge_dbufs() to update an existing buffer

This will be useful in future...

BUG: https://bugzilla.samba.org/show_bug.cgi?id=15125

Signed-off-by: Stefan Metzmacher <metze@samba.org>
Reviewed-by: Jeremy Allison <jra@samba.org>

3 files changed, 21 insertions, 12 deletions

diff --git a/lib/dbwrap/dbwrap.c b/lib/dbwrap/dbwrap.c
index 7555efaa3ab..9bdbd67dce1 100644
--- a/lib/dbwrap/dbwrap.c
+++ b/lib/dbwrap/dbwrap.c
@@ -680,22 +680,28 @@ static ssize_t tdb_data_buf(const TDB_DATA *dbufs, int num_dbufs,
 }
 
 
-TDB_DATA dbwrap_merge_dbufs(TALLOC_CTX *mem_ctx,
+NTSTATUS dbwrap_merge_dbufs(TDB_DATA *buf, TALLOC_CTX *mem_ctx,
 			    const TDB_DATA *dbufs, int num_dbufs)
 {
 	ssize_t len = tdb_data_buf(dbufs, num_dbufs, NULL, 0);
-	uint8_t *buf;
 
 	if (len == -1) {
-		return (TDB_DATA) {0};
+		return NT_STATUS_INVALID_PARAMETER;
 	}
 
-	buf = talloc_array(mem_ctx, uint8_t, len);
-	if (buf == NULL) {
-		return (TDB_DATA) {0};
+	if (buf->dsize != len) {
+		uint8_t *tmp;
+
+		tmp = talloc_realloc(mem_ctx, buf->dptr, uint8_t, len);
+		if (tmp == NULL && len != 0) {
+			return NT_STATUS_NO_MEMORY;
+		}
+
+		buf->dptr = tmp;
+		buf->dsize = len;
 	}
 
-	tdb_data_buf(dbufs, num_dbufs, buf, len);
+	tdb_data_buf(dbufs, num_dbufs, buf->dptr, buf->dsize);
 
-	return (TDB_DATA) { .dptr = buf, .dsize = len };
+	return NT_STATUS_OK;
 }
diff --git a/lib/dbwrap/dbwrap.h b/lib/dbwrap/dbwrap.h
index 9b8bf811ca6..cfae403b178 100644
--- a/lib/dbwrap/dbwrap.h
+++ b/lib/dbwrap/dbwrap.h
@@ -222,7 +222,7 @@ NTSTATUS dbwrap_parse_marshall_buf(const uint8_t *buf, size_t buflen,
 NTSTATUS dbwrap_unmarshall(struct db_context *db, const uint8_t *buf,
 			   size_t buflen);
 
-TDB_DATA dbwrap_merge_dbufs(TALLOC_CTX *mem_ctx,
+NTSTATUS dbwrap_merge_dbufs(TDB_DATA *buf, TALLOC_CTX *mem_ctx,
 			    const TDB_DATA *dbufs, int num_dbufs);
 
 
diff --git a/lib/dbwrap/dbwrap_rbt.c b/lib/dbwrap/dbwrap_rbt.c
index db456dfffba..691acef688d 100644
--- a/lib/dbwrap/dbwrap_rbt.c
+++ b/lib/dbwrap/dbwrap_rbt.c
@@ -149,9 +149,12 @@ static NTSTATUS db_rbt_storev(struct db_record *rec,
 	if (num_dbufs == 1) {
 		data = dbufs[0];
 	} else {
-		data = dbwrap_merge_dbufs(rec, dbufs, num_dbufs);
-		if (data.dptr == NULL) {
-			return NT_STATUS_NO_MEMORY;
+		NTSTATUS status;
+
+		data = (TDB_DATA) {0};
+		status = dbwrap_merge_dbufs(&data, rec, dbufs, num_dbufs);
+		if (!NT_STATUS_IS_OK(status)) {
+			return status;
 		}
 		to_free = data.dptr;
 	}