From 9610de881cfcd9bd15e064230714ae15cf621885 Mon Sep 17 00:00:00 2001
From: Sebastian Harl <sh@tokkee.org>
Date: Sun, 14 Dec 2014 16:30:20 +0100
Subject: [PATCH] utils/proto: Replaced sdb_proto_send_msg with
 sdb_proto_marshal.

The new function won't actually send the message but write it into a provided
buffer in the wire format. This allows for more flexible use of the function.
---
 src/client/sock.c         |  6 +++++-
 src/frontend/connection.c |  5 ++++-
 src/include/utils/proto.h | 13 ++++++++++++-
 src/utils/proto.c         | 20 +++++++++++---------
 4 files changed, 32 insertions(+), 12 deletions(-)

diff --git a/src/client/sock.c b/src/client/sock.c
index 533e9e3..eaa10ff 100644
--- a/src/client/sock.c
+++ b/src/client/sock.c
@@ -248,10 +248,14 @@ ssize_t
 sdb_client_send(sdb_client_t *client,
 		uint32_t cmd, uint32_t msg_len, const char *msg)
 {
+	char buf[2 * sizeof(uint32_t) + msg_len];
+
 	if ((! client) || (! client->fd))
 		return -1;
+	if (sdb_proto_marshal(buf, sizeof(buf), cmd, msg_len, msg) < 0)
+		return -1;
 
-	return sdb_proto_send_msg(client->fd, cmd, msg_len, msg);
+	return sdb_proto_send(client->fd, sizeof(buf), buf);
 } /* sdb_client_send */
 
 ssize_t
diff --git a/src/frontend/connection.c b/src/frontend/connection.c
index b27b3dd..66ccfd4 100644
--- a/src/frontend/connection.c
+++ b/src/frontend/connection.c
@@ -504,12 +504,15 @@ ssize_t
 sdb_connection_send(sdb_conn_t *conn, uint32_t code,
 		uint32_t msg_len, const char *msg)
 {
+	char buf[2 * sizeof(uint32_t) + msg_len];
 	ssize_t status;
 
 	if ((! conn) || (conn->fd < 0))
 		return -1;
+	if (sdb_proto_marshal(buf, sizeof(buf), code, msg_len, msg) < 0)
+		return -1;
 
-	status = sdb_proto_send_msg(conn->fd, code, msg_len, msg);
+	status = sdb_proto_send(conn->fd, sizeof(buf), buf);
 	if (status < 0) {
 		char errbuf[1024];
 
diff --git a/src/include/utils/proto.h b/src/include/utils/proto.h
index f3f1a87..9d4748a 100644
--- a/src/include/utils/proto.h
+++ b/src/include/utils/proto.h
@@ -59,8 +59,19 @@ sdb_proto_select(int fd, int type);
 ssize_t
 sdb_proto_send(int fd, size_t msg_len, const char *msg);
 
+/*
+ * sdb_proto_marshal:
+ * Encode the message into the wire format by adding an appropriate header.
+ * The encoded message is written to buf which has to be large enough to store
+ * the header (64 bits) and the entire message.
+ *
+ * Returns:
+ *  - the number of bytes of the full encoded message on success (even if less
+ *    than that fit into and was written to the buffer)
+ *  - a negative value on error
+ */
 ssize_t
-sdb_proto_send_msg(int fd, uint32_t code,
+sdb_proto_marshal(char *buf, size_t buf_len, uint32_t code,
 		uint32_t msg_len, const char *msg);
 
 uint32_t
diff --git a/src/utils/proto.c b/src/utils/proto.c
index 26c4826..3315e0c 100644
--- a/src/utils/proto.c
+++ b/src/utils/proto.c
@@ -125,24 +125,26 @@ sdb_proto_send(int fd, size_t msg_len, const char *msg)
 } /* sdb_proto_send */
 
 ssize_t
-sdb_proto_send_msg(int fd, uint32_t code,
+sdb_proto_marshal(char *buf, size_t buf_len, uint32_t code,
 		uint32_t msg_len, const char *msg)
 {
 	size_t len = 2 * sizeof(uint32_t) + msg_len;
-	char buffer[len];
-
 	uint32_t tmp;
 
+	if (buf_len < 2 * sizeof(uint32_t))
+		return -1;
+	if (buf_len < len) /* crop message */
+		msg_len -= (uint32_t)(len - buf_len);
+
 	tmp = htonl(code);
-	memcpy(buffer, &tmp, sizeof(tmp));
+	memcpy(buf, &tmp, sizeof(tmp));
 	tmp = htonl(msg_len);
-	memcpy(buffer + sizeof(tmp), &tmp, sizeof(tmp));
+	memcpy(buf + sizeof(tmp), &tmp, sizeof(tmp));
 
 	if (msg_len)
-		memcpy(buffer + 2 * sizeof(tmp), msg, msg_len);
-
-	return sdb_proto_send(fd, len, buffer);
-} /* sdb_proto_send_msg */
+		memcpy(buf + 2 * sizeof(tmp), msg, msg_len);
+	return len;
+} /* sdb_proto_marshal */
 
 uint32_t
 sdb_proto_get_int(sdb_strbuf_t *buf, size_t offset)
-- 
2.30.2