windows-mutex, windows-timedmutex: Follow pthread_mutex_trylock spec

[Bruno Haible]

pthread_mutex_trylock is required to fail with EBUSY if the mutex is a
non-recursive one and it is already locked by the current thread.
Similarly for mtx_trylock.

On native Windows, I observe that the Gnulib implementation does not
follow this spec, because
  - It uses the windows-mutex and windows-timedmutex modules.
  - This code uses the TryEnterCriticalSection function.
  - This function succeeds if the current thread already holds the lock,
    because a Windows CRITICAL_SECTION is semantically a recursive lock.

These patches fixes it, and add unit tests to verify the behaviour.


2024-08-06  Bruno Haible  <bruno@clisp.org>

        windows-timedrecmutex: Add tests.
        * tests/test-windows-timedrecmutex-type.c: New file.
        * modules/windows-timedrecmutex-tests: New file.

        windows-recmutex: Add tests.
        * tests/test-windows-recmutex-type.c: New file.
        * modules/windows-recmutex-tests: New file.

        windows-timedmutex: Add tests.
        * tests/test-windows-timedmutex-type.c: New file.
        * modules/windows-timedmutex-tests: New file.

        windows-mutex: Add tests.
        * tests/test-windows-mutex-type.c: New file.
        * modules/windows-mutex-tests: New file.

2024-08-06  Bruno Haible  <bruno@clisp.org>

        windows-mutex, windows-timedmutex: Follow pthread_mutex_trylock spec.
        * lib/windows-mutex.h (glwthread_mutex_t): Add 'owner' field.
        * lib/windows-mutex.c: Include <stdlib.h>.
        (glwthread_mutex_lock): Set the 'owner' field after entering the
        critical section.
        (glwthread_mutex_trylock): Detect whether the lock was previously locked
        by this thread. Set the 'owner' field after entering the critical
        section.
        (glwthread_mutex_unlock): Clear the 'owner' field before leaving the
        critical section.
        * lib/windows-timedmutex.h (glwthread_timedmutex_t): Add 'owner' field.
        * lib/windows-timedmutex.c: (glwthread_timedmutex_lock): Set the 'owner'
        field after entering the critical section.
        (glwthread_timedmutex_trylock): Detect whether the lock was previously
        locked by this thread. Set the 'owner' field after entering the critical
        section.
        (glwthread_timedmutex_unlock): Clear the 'owner' field before leaving
        the critical section.

0001-windows-mutex-windows-timedmutex-Follow-pthread_mute.patch
Description: Text Data

0002-windows-mutex-Add-tests.patch
Description: Text Data

0003-windows-timedmutex-Add-tests.patch
Description: Text Data

0004-windows-recmutex-Add-tests.patch
Description: Text Data

0005-windows-timedrecmutex-Add-tests.patch
Description: Text Data