From a0f5064ed0f3ee42a0b303e111bd89641a926676 Mon Sep 17 00:00:00 2001
From: "Luke T. Shumaker" <lukeshu@lukeshu.com>
Date: Mon, 10 Feb 2025 10:16:52 -0700
Subject: lib9p: Add comments clarifying why I split the `subctx`s the way I
 did

---
 lib9p/9p.c | 32 +++++++++++++++++++++++---------
 1 file changed, 23 insertions(+), 9 deletions(-)

(limited to 'lib9p/9p.c')

diff --git a/lib9p/9p.c b/lib9p/9p.c
index 51ff2eb..c54dae7 100644
--- a/lib9p/9p.c
+++ b/lib9p/9p.c
@@ -124,10 +124,12 @@ ssize_t _lib9p_validate(uint8_t                          xxx_low_typ_bit,
                         struct lib9p_ctx *ctx, uint8_t *net_bytes) {
 	/* Inspect the first 5 bytes ourselves.  */
 	struct _validate_ctx subctx = {
+		/* input */
 		.ctx        = ctx,
 		.net_size   = uint32le_decode(net_bytes),
 		.net_bytes  = net_bytes,
 
+		/* output */
 		.net_offset = 0,
 		.host_extra = 0,
 	};
@@ -171,17 +173,19 @@ 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) {
+	enum lib9p_msg_type typ = net_bytes[4];
+	*ret_typ = typ;
+	struct _lib9p_recv_tentry tentry = xxx_table[ctx->version][typ/2];
+
 	struct _unmarshal_ctx subctx = {
+		/* input */
 		.ctx        = ctx,
 		.net_bytes  = net_bytes,
 
+		/* output */
 		.net_offset = 0,
+		.extra      = ret_body + tentry.basesize,
 	};
-
-	enum lib9p_msg_type typ = net_bytes[4];
-	*ret_typ = typ;
-	struct _lib9p_recv_tentry tentry = xxx_table[ctx->version][typ/2];
-	subctx.extra = ret_body + tentry.basesize;
 	tentry.unmarshal(&subctx, ret_body);
 }
 
@@ -202,7 +206,10 @@ bool _lib9p_marshal(const struct _lib9p_send_tentry xxx_table[LIB9P_VER_NUM][0x8
                     struct lib9p_ctx *ctx, enum lib9p_msg_type typ, void *body,
                     uint8_t *ret_bytes) {
 	struct _marshal_ctx subctx = {
+		/* input */
 		.ctx        = ctx,
+
+		/* ouptut */
 		.net_bytes  = ret_bytes,
 		.net_offset = 0,
 	};
@@ -228,10 +235,12 @@ bool lib9p_Rmsg_marshal(struct lib9p_ctx *ctx, enum lib9p_msg_type typ, void *bo
 bool lib9p_stat_validate(struct lib9p_ctx *ctx, uint32_t net_size, uint8_t *net_bytes,
                          uint32_t *ret_net_size, ssize_t *ret_host_size) {
 	struct _validate_ctx subctx = {
+		/* input */
 		.ctx        = ctx,
 		.net_size   = net_size,
 		.net_bytes  = net_bytes,
 
+		/* output */
 		.net_offset = 0,
 		.host_extra = 0,
 	};
@@ -248,11 +257,13 @@ bool lib9p_stat_validate(struct lib9p_ctx *ctx, uint32_t net_size, uint8_t *net_
 uint32_t lib9p_stat_unmarshal(struct lib9p_ctx *ctx, uint8_t *net_bytes,
                               struct lib9p_stat *ret_obj, void *ret_extra) {
 	struct _unmarshal_ctx subctx = {
-		.ctx = ctx,
-		.net_bytes = net_bytes,
-		.net_offset = 0,
+		/* input */
+		.ctx        = ctx,
+		.net_bytes  = net_bytes,
 
-		.extra = ret_extra,
+		/* output */
+		.net_offset = 0,
+		.extra      = ret_extra,
 	};
 	_lib9p_stat_unmarshal(&subctx, ret_obj);
 	return subctx.net_offset;
@@ -263,7 +274,10 @@ uint32_t lib9p_stat_marshal(struct lib9p_ctx *ctx, uint32_t max_net_size, struct
 	struct lib9p_ctx _ctx = *ctx;
 	_ctx.max_msg_size = max_net_size;
 	struct _marshal_ctx subctx = {
+		/* input */
 		.ctx        = &_ctx,
+
+		/* output */
 		.net_bytes  = ret_bytes,
 		.net_offset = 0,
 	};
-- 
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