thread: Use a flexible array member for "array" in SDL_TLSData.

Avoids UBSan warning (among other similar ones in SDL_thread.c):
src/thread/SDL_thread.c:109:13: runtime error: index 1 out of bounds for type 'struct (unnamed struct at src/thread/SDL_thread_c.h:70:5)[1]'
SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior src/thread/SDL_thread.c:109:13

(cherry picked from commit f9395a766f)
This commit is contained in:
William Horvath
2026-01-15 17:11:55 -08:00
committed by Sam Lantinga
parent 012443729d
commit 66a8454f2d
2 changed files with 9 additions and 2 deletions

View File

@@ -99,7 +99,7 @@ bool SDL_SetTLS(SDL_TLSID *id, const void *value, SDL_TLSDestructorCallback dest
oldlimit = storage ? storage->limit : 0;
newlimit = (storage_index + TLS_ALLOC_CHUNKSIZE);
new_storage = (SDL_TLSData *)SDL_realloc(storage, sizeof(*storage) + (newlimit - 1) * sizeof(storage->array[0]));
new_storage = (SDL_TLSData *)SDL_realloc(storage, sizeof(*storage) + newlimit * sizeof(storage->array[0]));
if (!new_storage) {
return false;
}

View File

@@ -67,11 +67,18 @@ extern void SDL_RunThread(SDL_Thread *thread);
typedef struct
{
int limit;
#ifdef _MSC_VER
#pragma warning(push)
#pragma warning(disable : 4200) // Flexible array members (C99)
#endif
struct
{
void *data;
void(SDLCALL *destructor)(void *);
} array[1];
} array[];
#ifdef _MSC_VER
#pragma warning(pop)
#endif
} SDL_TLSData;
// This is how many TLS entries we allocate at once