From b72b8eaee1de5e58451e58021bc3e09ba9a63e46 Mon Sep 17 00:00:00 2001
From: Quinn <quinnthepigeon@proton.me>
Date: Wed, 3 Sep 2025 22:39:15 +0200
Subject: [PATCH] add comments to point at where strict aliasing rule
 violations occur in data scripts

this is definitely not all of them, a thorough rewrite must take place
to fix as many as we can.
---
 src/dat/mcx.c | 12 ++++++------
 src/dat/nbt.c | 10 +++++++---
 2 files changed, 13 insertions(+), 9 deletions(-)

diff --git a/src/dat/mcx.c b/src/dat/mcx.c
index dfd05f2..d2a8955 100644
--- a/src/dat/mcx.c
+++ b/src/dat/mcx.c
@@ -18,8 +18,8 @@
 /* Moves chunks `src_s` to `src_e` (inclusive) from `src`, back onto `dst`. */
 static void mvchunks(u8 *restrict buf, u8 *src, u8 *dst, int src_s, int src_e) {
 	assert(src > dst);
-	u32 *table = (u32 *)buf;
-	size_t len = src - dst; // acquire the amount of bytes that we shall move
+	u32 *table = (u32 *)buf; // BUG: strict aliasing
+	size_t len = src - dst;  // acquire the amount of bytes that we shall move
 	assert(!(len % SECTOR));
 
 	// count how many bytes we need to move, whilst updating location data
@@ -36,7 +36,7 @@ static void mvchunks(u8 *restrict buf, u8 *src, u8 *dst, int src_s, int src_e) {
  * Returns the bytes removed by this function. */
 static size_t delchunk(u8 *restrict buf, size_t rmb, int sidx, int eidx) {
 	// load the table data
-	u32 *table = (u32 *)buf;
+	u32 *table = (u32 *)buf; // BUG: strict aliasing
 	size_t slen, bidx, blen;
 	slen = be32toh(table[sidx]) & 0xFF;          // acquire the sector length of the chunk
 	bidx = (be32toh(table[sidx]) >> 8) * SECTOR; // acquire and compute the byte offset the chunk starts at
@@ -62,7 +62,7 @@ size_t mcx_delchunk(u8 *restrict buf, int chunk) {
 
 size_t mcx_delchunk_range(u8 *restrict buf, int start, int end) {
 	assert(start < end && end < CHUNKS);
-	u32 *table = (u32 *)buf;
+	u32 *table = (u32 *)buf; // BUG: strict aliasing
 	u8 *dst = buf + (be32toh(table[start]) >> 8) * SECTOR;
 	u8 *src = buf + (be32toh(table[end]) >> 8) * SECTOR;
 	src += (be32toh(table[end]) & 0xFF) * SECTOR;
@@ -70,8 +70,8 @@ size_t mcx_delchunk_range(u8 *restrict buf, int start, int end) {
 	// zeroes-out the chunk data within this range. (and set the timestamp)
 	u32 ts = htobe32(time(NULL));
 	for (int i = start; i <= end; i++) {
-		table[i] = 0;
-		table[i + CHUNKS] = ts;
+		table[i] = 0;           // BUG: strict aliasing
+		table[i + CHUNKS] = ts; // BUG: strict aliasing
 	}
 
 	// move the remaining chunks down
diff --git a/src/dat/nbt.c b/src/dat/nbt.c
index d8de46c..a2157eb 100644
--- a/src/dat/nbt.c
+++ b/src/dat/nbt.c
@@ -30,6 +30,7 @@ static const u8 *procarr(const u8 *restrict buf, i32 nmem, uint size, struct nbt
 	if (size == 1) return buf;
 	size_t i = 0;
 	while (i < len) {
+		// BUG: strict aliasing
 		switch (size) {
 		case 2:  *(u16 *)((*out)->dat + i) = be16toh(*(u16 *)((*out)->dat + i)); break;
 		case 4:  *(u32 *)((*out)->dat + i) = be32toh(*(u32 *)((*out)->dat + i)); break;
@@ -59,7 +60,7 @@ static const u8 *proclist(const u8 *restrict buf, struct nbt_array *restrict *re
 	}
 
 	buf++;
-	i32 len = (i32)be32toh(*(u32 *)buf);
+	i32 len = (i32)be32toh(*(u32 *)buf); // BUG: strict aliasing
 	buf += 4;
 	return procarr(buf, len, size, out);
 }
@@ -71,6 +72,7 @@ const u8 *nbt_proctag(const u8 *restrict buf, u16 slen, void *restrict out) {
 	i32 nmem;
 	uint size;
 
+	// BUG: strict aliasing
 	switch (*buf) {
 	case NBT_I8:  *(u8 *)out = *ptr; return ptr + 1;
 	case NBT_I16: *(u16 *)out = be16toh(*(u16 *)ptr); return ptr + 2;
@@ -102,6 +104,7 @@ const u8 *nbt_proctag(const u8 *restrict buf, u16 slen, void *restrict out) {
 static const u8 *nexttag_list(const u8 *restrict ptr, uint *restrict const dpt, i32 *restrict const lens, u8 *restrict const tags) {
 	const u8 *tag = ptr;
 	ptr++;
+	// BUG: strict aliasing
 	switch (*tag) {
 	case NBT_END: break;
 	case NBT_I8:  ptr += (i32)be32toh(*(u32 *)ptr) * 1; break;
@@ -114,7 +117,7 @@ static const u8 *nexttag_list(const u8 *restrict ptr, uint *restrict const dpt,
 		// TODO: handle out of bounds... Might not be required if we use flexible array member
 		(*dpt)++;
 		tags[*dpt] = *tag;
-		lens[*dpt] = (i32)be32toh(*(u32 *)ptr);
+		lens[*dpt] = (i32)be32toh(*(u32 *)ptr); // BUG: strict aliasing
 		break;
 	}
 	ptr += 4;
@@ -136,9 +139,10 @@ static const u8 *nexttag(const u8 *restrict tag, uint *restrict const dpt, i32 *
 		*dpt -= !lens[*dpt];
 	} else {
 		type = *tag;
-		ptr += be16toh(*(u16 *)(tag + 1)) + 3;
+		ptr += be16toh(*(u16 *)(tag + 1)) + 3; // BUG: strict aliasing
 	}
 
+	// BUG: strict aliasing
 	switch (type) {
 	case NBT_I8:  ptr += 1; break;
 	case NBT_I16: ptr += 2; break;