Hi Willy,
On 2025-02-22 10:38:51+0100, Willy Tarreau wrote:
On Mon, Feb 17, 2025 at 10:24:11PM +0100, Thomas Weißschuh wrote:
On 2025-02-16 10:39:40+0100, Willy Tarreau wrote:
On Wed, Feb 12, 2025 at 07:01:01PM +0100, Thomas Weißschuh wrote:
The nolibc testsuite can be run against other libcs to test for interoperability. Some aspects of the constructor execution are not standardized and musl does not provide all tested feature, for one it does not provide arguments to the constructors, anymore?
Skip the constructor tests on non-nolibc configurations.
I'm not much surprised, I've always avoided arguments in my use of constructors due to a lack of portability. However the patch disables all constructors tests, while I'm seeing that the linkage_test version does not make use of arguments, though there is an implied expectation that they're executed in declaration order, which is not granted.
The tests are written specifically to test for execution order. While we can not rely on the order for other libcs, the idea was to expect a given order for the nolibc implementation.
OK.
I'm wondering if we shouldn't make the tests more robust:
- explicitly set linkage_test_constructor_test_value to zero in the declaration, because here it's not set so we have no guarantee (we're not in the kernel)
Ack.
- only add values to check for cumulated values (e.g. |1 in const1, |2 in const2) and verify that the result is properly 3
This would stop validating the order.
That was my purpose but OK I got it. Then there's another option which preserves the order and even gives history:
__attribute__((constructor)) static void constructor1(void) { constructor_test_value = constructor_test_value * 0x10 + 1; }
__attribute__((constructor)) static void constructor2(void) { constructor_test_value = constructor_test_value * 0x10 + 2; } Then if executed in the right order, you'll find 0x12. If both are executed in any order, it will always be >= 0x10. If only one is executed, it will be < 0x10, and if none is executed, it's 0.
Sounds good! Do you want to write a patch? It should also add the missing zero-initializion of constructor_test_value.
Thomas