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Add a check to reactor modules to ensure _initialize is only called once (#388)

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Calling _initialize multiple times is undefined behavior, since the
ctors are not guaranteed to be idempotent. We should have this safety
check which is similar to #329.
This commit is contained in:
Cheng Shao 2023-01-30 13:30:02 +01:00 committed by GitHub
parent b4814997f6
commit 9bec2d3aff
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1 changed files with 20 additions and 0 deletions
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20
libc-bottom-half/crt/crt1-reactor.c
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@ -1,7 +1,27 @@
#if defined(_REENTRANT)
#include <stdatomic.h>
extern void __wasi_init_tp(void);
#endif
extern void __wasm_call_ctors(void);
__attribute__((export_name("_initialize")))
void _initialize(void) {
#if defined(_REENTRANT)
static volatile atomic_int initialized = 0;
int expected = 0;
if (!atomic_compare_exchange_strong(&initialized, &expected, 1)) {
__builtin_trap();
}
__wasi_init_tp();
#else
static volatile int initialized = 0;
if (initialized != 0) {
__builtin_trap();
}
initialized = 1;
#endif
// The linker synthesizes this to call constructors.
__wasm_call_ctors();
}