tdb: fix short write logic in tdb_new_database

Commit 207a213c/24fed55d purported to fix the problem of signals during
tdb_new_database (which could cause a spurious short write, hence a failure).
However, the code is wrong: newdb+written is not correct.

Fix this by introducing a general tdb_write_all() and using it here and in
the tracing code.

Cc: Stefan Metzmacher <metze@samba.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

3 files changed, 17 insertions, 17 deletions

diff --git a/lib/tdb/common/open.c b/lib/tdb/common/open.c
index dfe780d21b..3ff6b17c03 100644
--- a/lib/tdb/common/open.c
+++ b/lib/tdb/common/open.c
@@ -83,22 +83,8 @@ static int tdb_new_database(struct tdb_context *tdb, int hash_size)
 	/* Don't endian-convert the magic food! */
 	memcpy(newdb->magic_food, TDB_MAGIC_FOOD, strlen(TDB_MAGIC_FOOD)+1);
 	/* we still have "ret == -1" here */
-	written = write(tdb->fd, newdb, size);
-	if (written == size) {
+	if (tdb_write_all(tdb->fd, newdb, size))
 		ret = 0;
-	} else if (written != -1) {
-		/* call write once again, this usually should return -1 and
-		 * set errno appropriately */
-		size -= written;
-		written = write(tdb->fd, newdb+written, size);
-		if (written == size) {
-			ret = 0;
-		} else if (written >= 0) {
-			/* a second incomplete write - we give up.
-			 * guessing the errno... */
-			errno = ENOSPC;
-		}
-	}
 
   fail:
 	SAFE_FREE(newdb);
diff --git a/lib/tdb/common/tdb.c b/lib/tdb/common/tdb.c
index dac3f4e666..4d8c5fc59c 100644
--- a/lib/tdb/common/tdb.c
+++ b/lib/tdb/common/tdb.c
@@ -989,10 +989,24 @@ int tdb_repack(struct tdb_context *tdb)
 	return 0;
 }
 
+/* Even on files, we can get partial writes due to signals. */
+bool tdb_write_all(int fd, const void *buf, size_t count)
+{
+	while (count) {
+		size_t ret;
+		ret = write(fd, buf, count);
+		if (ret < 0)
+			return false;
+		buf = (const char *)buf + ret;
+		count -= ret;
+	}
+	return true;
+}
+
 #ifdef TDB_TRACE
 static void tdb_trace_write(struct tdb_context *tdb, const char *str)
 {
-	if (write(tdb->tracefd, str, strlen(str)) != strlen(str)) {
+	if (!tdb_write_alltdb->tracefd, str, strlen(str)) {
 		close(tdb->tracefd);
 		tdb->tracefd = -1;
 	}
diff --git a/lib/tdb/common/tdb_private.h b/lib/tdb/common/tdb_private.h
index e2167132b4..9d0f3bcd70 100644
--- a/lib/tdb/common/tdb_private.h
+++ b/lib/tdb/common/tdb_private.h
@@ -266,5 +266,5 @@ void tdb_io_init(struct tdb_context *tdb);
 int tdb_expand(struct tdb_context *tdb, tdb_off_t size);
 int tdb_rec_free_read(struct tdb_context *tdb, tdb_off_t off,
 		      struct tdb_record *rec);
-
+bool tdb_write_all(int fd, const void *buf, size_t count);
 int tdb_transaction_recover(struct tdb_context *tdb);