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add comments to point at where strict aliasing rule violations occur in data scripts

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this is definitely not all of them, a thorough rewrite must take place
to fix as many as we can.
This commit is contained in:
Quinn
2025-09-03 22:39:15 +02:00
parent 008604ff5e
commit 9cb0631df8
2 changed files with 13 additions and 9 deletions
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10
src/dat/nbt.c
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@@ -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;