lib9p: Split lib9p_{validate,unmarshal,marshal} into _Tmsg and _Rmsg variants

1 files changed, 60 insertions, 15 deletions

diff --git a/lib9p/9p.c b/lib9p/9p.c
index b464f63..8f3ae78 100644
--- a/lib9p/9p.c
+++ b/lib9p/9p.c
@@ -77,7 +77,11 @@ const char *lib9p_msg_type_str(struct lib9p_ctx *ctx, enum lib9p_msg_type typ) {
 
 /* main message functions *****************************************************/
 
-ssize_t lib9p_validate(struct lib9p_ctx *ctx, uint8_t *net_bytes) {
+static
+ssize_t _lib9p_validate(uint8_t                          xxx_low_typ_bit,
+                        const char                      *xxx_errmsg,
+                        const struct _lib9p_recv_tentry  xxx_table[LIB9P_VER_NUM][0x80],
+                        struct lib9p_ctx *ctx, uint8_t *net_bytes) {
 	/* Inspect the first 5 bytes ourselves.  */
 	struct _validate_ctx subctx = {
 		.ctx        = ctx,
@@ -90,13 +94,16 @@ ssize_t lib9p_validate(struct lib9p_ctx *ctx, uint8_t *net_bytes) {
 	if (subctx.net_size < 5)
 		return lib9p_error(ctx, LINUX_EBADMSG, "message is impossibly short");
 	uint8_t typ = net_bytes[4];
-	struct _lib9p_recv_tentry table = ((typ % 2 == 0) ? _lib9p_table_Tmsg_recv : _lib9p_table_Rmsg_recv)[ctx->version][typ/2];
-	if (!table.validate)
+	if (typ % 2 != xxx_low_typ_bit)
+		return lib9p_errorf(ctx, LINUX_EOPNOTSUPP, "%s: message_type=%s", xxx_errmsg,
+		                    lib9p_msg_type_str(ctx, typ));
+	struct _lib9p_recv_tentry tentry = xxx_table[ctx->version][typ/2];
+	if (!tentry.validate)
 		return lib9p_errorf(ctx, LINUX_EOPNOTSUPP, "unknown message type: %s (protocol_version=%s)",
 		                    lib9p_msg_type_str(ctx, typ), lib9p_version_str(ctx->version));
 
-	/* Now use the message-type-specific table to process the whole thing.  */
-	if (table.validate(&subctx))
+	/* Now use the message-type-specific tentry to process the whole thing.  */
+	if (tentry.validate(&subctx))
 		return -1;
 	assert(subctx.net_offset <= subctx.net_size);
 	if (subctx.net_offset < subctx.net_size)
@@ -105,13 +112,25 @@ ssize_t lib9p_validate(struct lib9p_ctx *ctx, uint8_t *net_bytes) {
 
 	/* Return.  */
 	ssize_t ret;
-	if (__builtin_add_overflow(table.basesize, subctx.host_extra, &ret))
+	if (__builtin_add_overflow(tentry.basesize, subctx.host_extra, &ret))
 		return lib9p_error(ctx, LINUX_EMSGSIZE, "unmarshalled payload overflows SSIZE_MAX");
 	return ret;
 }
 
-void lib9p_unmarshal(struct lib9p_ctx *ctx, uint8_t *net_bytes,
-                     enum lib9p_msg_type *ret_typ, void *ret_body) {
+ssize_t lib9p_Tmsg_validate(struct lib9p_ctx *ctx, uint8_t *net_bytes) {
+	return _lib9p_validate(0, "expected a T-message but got an R-message", _lib9p_table_Tmsg_recv,
+	                       ctx, net_bytes);
+}
+
+ssize_t lib9p_Rmsg_validate(struct lib9p_ctx *ctx, uint8_t *net_bytes) {
+	return _lib9p_validate(1, "expected an R-message but got a T-message", _lib9p_table_Rmsg_recv,
+	                       ctx, net_bytes);
+}
+
+static
+void _lib9p_unmarshal(const struct _lib9p_recv_tentry xxx_table[LIB9P_VER_NUM][0x80],
+                      struct lib9p_ctx *ctx, uint8_t *net_bytes,
+                      enum lib9p_msg_type *ret_typ, void *ret_body) {
 	struct _unmarshal_ctx subctx = {
 		.ctx        = ctx,
 		.net_bytes  = net_bytes,
@@ -121,21 +140,47 @@ void lib9p_unmarshal(struct lib9p_ctx *ctx, uint8_t *net_bytes,
 
 	enum lib9p_msg_type typ = net_bytes[4];
 	*ret_typ = typ;
-	struct _lib9p_recv_tentry table = ((typ % 2 == 0) ? _lib9p_table_Tmsg_recv : _lib9p_table_Rmsg_recv)[ctx->version][typ/2];
-	subctx.extra = ret_body + table.basesize;
-	table.unmarshal(&subctx, ret_body);
+	struct _lib9p_recv_tentry tentry = xxx_table[ctx->version][typ/2];
+	subctx.extra = ret_body + tentry.basesize;
+	tentry.unmarshal(&subctx, ret_body);
+}
+
+void lib9p_Tmsg_unmarshal(struct lib9p_ctx *ctx, uint8_t *net_bytes,
+                          enum lib9p_msg_type *ret_typ, void *ret_body) {
+	_lib9p_unmarshal(_lib9p_table_Tmsg_recv,
+	                 ctx, net_bytes, ret_typ, ret_body);
 }
 
-bool lib9p_marshal(struct lib9p_ctx *ctx, enum lib9p_msg_type typ, void *body,
-                   uint8_t *ret_bytes) {
+void lib9p_Rmsg_unmarshal(struct lib9p_ctx *ctx, uint8_t *net_bytes,
+                          enum lib9p_msg_type *ret_typ, void *ret_body) {
+	_lib9p_unmarshal(_lib9p_table_Rmsg_recv,
+	                 ctx, net_bytes, ret_typ, ret_body);
+}
+
+static
+bool _lib9p_marshal(const struct _lib9p_send_tentry xxx_table[LIB9P_VER_NUM][0x80],
+                    struct lib9p_ctx *ctx, enum lib9p_msg_type typ, void *body,
+                    uint8_t *ret_bytes) {
 	struct _marshal_ctx subctx = {
 		.ctx        = ctx,
 		.net_bytes  = ret_bytes,
 		.net_offset = 0,
 	};
 
-	struct _lib9p_send_tentry table = ((typ % 2 == 0) ? _lib9p_table_Tmsg_send : _lib9p_table_Rmsg_send)[ctx->version][typ/2];
-	return table.marshal(&subctx, body);
+	struct _lib9p_send_tentry tentry = xxx_table[ctx->version][typ/2];
+	return tentry.marshal(&subctx, body);
+}
+
+bool lib9p_Tmsg_marshal(struct lib9p_ctx *ctx, enum lib9p_msg_type typ, void *body,
+                        uint8_t *ret_bytes) {
+	assert(typ % 2 == 0);
+	return _lib9p_marshal(_lib9p_table_Tmsg_send, ctx, typ, body, ret_bytes);
+}
+
+bool lib9p_Rmsg_marshal(struct lib9p_ctx *ctx, enum lib9p_msg_type typ, void *body,
+                        uint8_t *ret_bytes) {
+	assert(typ % 2 == 1);
+	return _lib9p_marshal(_lib9p_table_Rmsg_send, ctx, typ, body, ret_bytes);
 }
 
 /* `struct lib9p_stat` helpers ************************************************/