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make helper functions for nbt_proctag have similar IO as itself.

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fix: `procarr` was counting `nmem`, whilst we should be counting the
bytes.
fix: `procarr` wasn't actually writing to `struct nbt_array`'s `len`
member.
This commit is contained in:
Quinn
2025-08-25 12:40:17 +02:00
parent 44d2271972
commit 5644d377de
1 changed files with 23 additions and 21 deletions
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44
src/dat/nbt.c
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@@ -98,34 +98,38 @@ const u8 *nbt_nexttag(const u8 *restrict buf) {
return tag;
}
/* processes an array at `buf`, of `nmem` items with a size of `size`
* returns a malloc'd pointer (which may be `NULL`) to the data.
* the data is converted from big endian to little endian on little endian systems. */
MALLOC static void *nbt_procarr(const u8 *restrict buf, i32 nmem, uint size) {
struct nbt_array *ptr = malloc(sizeof(struct nbt_array) + nmem * size);
if (!ptr) return NULL;
memcpy(ptr->dat, buf, nmem * size);
/* Processes the incoming array data in `buf`. Which contains `nmem` items of `size`.
* The data shall be converted to little-endian on little-endian systems
* Outputs the allocated data to `out`, returns where the next pointer would be. */
static const u8 *procarr(const u8 *restrict buf, i32 nmem, uint size, struct nbt_array *restrict *restrict out) {
size_t len = nmem * size;
*out = malloc(sizeof(struct nbt_array) + len);
if (!*out) return buf + len;
memcpy((*out)->dat, buf, len);
(*out)->len = nmem;
buf += len;
/* Only include this code for little-endian systems. Since only they require this logic.
* Producing optimised code for other platforms. */
#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
if (size == 1) return ptr;
ssize_t i = 0;
while (i < nmem) {
if (size == 1) return buf;
size_t i = 0;
while (i < len) {
switch (size) {
case 2: *(u16 *)(ptr->dat + i) = be16toh(*(u16 *)(ptr->dat + i)); break;
case 4: *(u32 *)(ptr->dat + i) = be32toh(*(u32 *)(ptr->dat + i)); break;
case 8: *(u64 *)(ptr->dat + i) = be64toh(*(u64 *)(ptr->dat + i)); break;
case 2: *(u16 *)((*out)->dat + i) = be16toh(*(u16 *)((*out)->dat + i)); break;
case 4: *(u32 *)((*out)->dat + i) = be32toh(*(u32 *)((*out)->dat + i)); break;
case 8: *(u64 *)((*out)->dat + i) = be64toh(*(u64 *)((*out)->dat + i)); break;
default: __builtin_unreachable(); // this should be impossible
}
i += size;
}
#endif
return ptr;
return buf;
}
/* processes a `NBT_LIST` tag, and returns a pointer to malloc'd data, or `NULL`, depending on its success */
MALLOC static void *nbt_proclist(const u8 *restrict buf, const u8 *restrict *restrict out) {
/* calls `procarr` for the simple types available. */
static const u8 *proclist(const u8 *restrict buf, struct nbt_array *restrict *restrict out) {
uint size;
*out = NULL;
@@ -143,8 +147,7 @@ MALLOC static void *nbt_proclist(const u8 *restrict buf, const u8 *restrict *res
buf++;
i32 len = (i32)be32toh(*(u32 *)buf);
buf += 4;
*out = buf + (len * size);
return nbt_procarr(buf, len, size);
return procarr(buf, len, size, out);
}
const u8 *nbt_proctag(const u8 *restrict buf, u16 slen, void *restrict out) {
@@ -168,14 +171,13 @@ const u8 *nbt_proctag(const u8 *restrict buf, u16 slen, void *restrict out) {
case NBT_ARR_I64: nmem = be32toh(*(u32 *)ptr), size = 8, ptr += 4; break;
case NBT_LIST:
*(void **)out = nbt_proclist(ptr, &tmp);
return proclist(ptr, (struct nbt_array **)out);
return tmp;
default: return NULL;
}
*(void **)out = nbt_procarr(ptr, nmem, size);
return ptr + (size * nmem);
return procarr(ptr, nmem, size, (struct nbt_array **)out);
}
struct nbt_procdat nbt_initproc(struct nbt_path const *restrict pats, uint npats) {