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Fix data <-> function pointer casts in thread_win.c.

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The uses of |memcpy| to cast pointer-to-function to pointer-to-data and
back again did not have well-defined semantics. Use a union instead to
avoid the need for such a conversion get well-defined semantics.

Change-Id: I8ee54a83ba75440f7bc78c194eb55e2cf09b05d8
Reviewed-on: https://boringssl-review.googlesource.com/6972
Reviewed-by: David Benjamin <davidben@google.com>
This commit is contained in:
Brian Smith 2016-01-26 14:32:46 -10:00 committed by David Benjamin
parent f5f4be8fac
commit 9333d6df11
1 changed files with 16 additions and 12 deletions
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28
crypto/thread_win.c
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@ -31,7 +31,13 @@
OPENSSL_COMPILE_ASSERT(sizeof(CRYPTO_MUTEX) >= sizeof(CRITICAL_SECTION),
CRYPTO_MUTEX_too_small);
static void run_once(CRYPTO_once_t *once, void (*init)(void *), void *arg) {
union run_once_arg_t {
void (*func)(void);
void *data;
};
static void run_once(CRYPTO_once_t *once, void (*init)(union run_once_arg_t),
union run_once_arg_t arg) {
/* Values must be aligned. */
assert((((uintptr_t) once) & 3) == 0);
@ -72,17 +78,13 @@ static void run_once(CRYPTO_once_t *once, void (*init)(void *), void *arg) {
}
}
static void call_once_init(void *arg) {
void (*init_func)(void);
/* MSVC does not like casting between data and function pointers. */
memcpy(&init_func, &arg, sizeof(void *));
init_func();
static void call_once_init(union run_once_arg_t arg) {
arg.func();
}
void CRYPTO_once(CRYPTO_once_t *in_once, void (*init)(void)) {
void *arg;
/* MSVC does not like casting between data and function pointers. */
memcpy(&arg, &init, sizeof(void *));
union run_once_arg_t arg;
arg.func = init;
run_once(in_once, call_once_init, arg);
}
@ -109,16 +111,18 @@ void CRYPTO_MUTEX_cleanup(CRYPTO_MUTEX *lock) {
DeleteCriticalSection((CRITICAL_SECTION *) lock);
}
static void static_lock_init(void *arg) {
struct CRYPTO_STATIC_MUTEX *lock = arg;
static void static_lock_init(union run_once_arg_t arg) {
struct CRYPTO_STATIC_MUTEX *lock = arg.data;
if (!InitializeCriticalSectionAndSpinCount(&lock->lock, 0x400)) {
abort();
}
}
void CRYPTO_STATIC_MUTEX_lock_read(struct CRYPTO_STATIC_MUTEX *lock) {
union run_once_arg_t arg;
arg.data = lock;
/* Since we have to support Windows XP, read locks are actually exclusive. */
run_once(&lock->once, static_lock_init, lock);
run_once(&lock->once, static_lock_init, arg);
EnterCriticalSection(&lock->lock);
}