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authorMichael Lutz <michi@icosahedron.de>2020-12-14 00:11:39 +0100
committerMichael Lutz <michi@icosahedron.de>2021-02-13 20:08:53 +0100
commit9c9292949fa4d699c58d40abcac563a86df239dd (patch)
tree73dc0836d0e4de6c8beab14fa26982df495f070a /src/saveload/oldloader.cpp
parent0f621b4956b82313923ef28233cf52919f70eca3 (diff)
downloadopenttd-9c9292949fa4d699c58d40abcac563a86df239dd.tar.xz
Codechange: Don't use cpp_offsetof in the TTO/TTD savegame loader.
Many of the member variables that are used in the oldloader are inside types that are not standard layout types. Using pointer arithmetics to determine addresses of members inside types that are not standard layout is generally undefined behaviour. If we'd use C++17, it is conditionally supported, which means each compiler may or may not support it. And even then using it for individual array elements is syntactically not supported the the standard offsetof function.
Diffstat (limited to 'src/saveload/oldloader.cpp')
-rw-r--r--src/saveload/oldloader.cpp12
1 files changed, 5 insertions, 7 deletions
diff --git a/src/saveload/oldloader.cpp b/src/saveload/oldloader.cpp
index 42970c9a2..6bc07ad27 100644
--- a/src/saveload/oldloader.cpp
+++ b/src/saveload/oldloader.cpp
@@ -108,8 +108,6 @@ byte ReadByte(LoadgameState *ls)
*/
bool LoadChunk(LoadgameState *ls, void *base, const OldChunks *chunks)
{
- byte *base_ptr = (byte*)base;
-
for (const OldChunks *chunk = chunks; chunk->type != OC_END; chunk++) {
if (((chunk->type & OC_TTD) && _savegame_type == SGT_TTO) ||
((chunk->type & OC_TTO) && _savegame_type != SGT_TTO)) {
@@ -134,8 +132,8 @@ bool LoadChunk(LoadgameState *ls, void *base, const OldChunks *chunks)
break;
case OC_ASSERT:
- DEBUG(oldloader, 4, "Assert point: 0x%X / 0x%X", ls->total_read, chunk->offset + _bump_assert_value);
- if (ls->total_read != chunk->offset + _bump_assert_value) throw std::exception();
+ DEBUG(oldloader, 4, "Assert point: 0x%X / 0x%X", ls->total_read, (uint)(size_t)chunk->ptr + _bump_assert_value);
+ if (ls->total_read != (size_t)chunk->ptr + _bump_assert_value) throw std::exception();
default: break;
}
} else {
@@ -153,10 +151,10 @@ bool LoadChunk(LoadgameState *ls, void *base, const OldChunks *chunks)
}
/* When both pointers are nullptr, we are just skipping data */
- if (base_ptr == nullptr && chunk->ptr == nullptr) continue;
+ if (base == nullptr && chunk->ptr == nullptr) continue;
- /* Writing to the var: bits 8 to 15 have the VAR type */
- if (chunk->ptr == nullptr) ptr = base_ptr + chunk->offset;
+ /* Chunk refers to a struct member, get address in base. */
+ if (chunk->ptr == nullptr) ptr = (byte *)chunk->offset(base);
/* Write the data */
switch (GetOldChunkVarType(chunk->type)) {