Set O_EXCL when opening file with include_excl

[Joshua-Anderson]

Originating Project/Creator
Affected Component	Os
Affected Architectures(s)
Related Issue(s)
Has Unit Tests (y/n)	y
Builds Without Errors (y/n)	y
Unit Tests Pass (y/n)	y
Documentation Included (y/n)

---

Change Description

When include_excl is set, set the O_EXCL flag. Previously this argument was unused (caught through gcc's unused parameter warning).

⚠️ Warning: This is a breaking change that silently changes default behavior.

Rationale

If we have an include_excl parameter, it should be respected. However, this does change the default behavior of File::open(const char* fileName, File::Mode mode), since it defaults include_excl to true. Because include_excl was ignored this effectively is equivalent to include_excl = false.

I think the default of not overwriting a file if it already exists is wise. Personally, I believe the value of enforcing this safer default is greater than the impact of breaking projects upgrading to F' 2.0 that implicitly depending on the overwrite on create behavior. However, this is a serious breaking change and it may make sense to keep the current unintentional default and update File::open(const char* fileName, File::Mode mode) to set the include_excl flag to false.

[LeStarch]

This should be discussed before we approve this change since it changes the behavior of an interface.

[LeStarch]

[LeStarch]

Since it only affects CREATE and that usage was corrected, I agree with the safer default. We'll add to upgrade notes to 2.0