Return FILE_EXISTS error when File::open fails due to include_excl=true

[saba-ja]

F´ Version
Affected Component

---

Feature Description

As described PR #666 the introduced change (defaulting include_excl=true) could silently break components using file OPEN_CREATE mode.
This happened in one of the custom ComLoggers with resetOnMax option. The open file was breaking with error OTHER_ERROR which was not clear.

To reduce the ambiguity of the file open returned error on file exist we should add error EEXIST 17 /* File exists */
to the following:

fprime/Os/Linux/File.cpp

Lines 87 to 105 in 0d717b0

	NATIVE_INT_TYPE fd = ::open(fileName,flags,userFlags);
	if (-1 == fd) {
	this->m_lastError = errno;
	switch (errno) {
	case ENOSPC:
	stat = NO_SPACE;
	break;
	case ENOENT:
	stat = DOESNT_EXIST;
	break;
	case EACCES:
	stat = NO_PERMISSION;
	break;
	default:
	stat = OTHER_ERROR;
	break;
	}
	}

...
case EEXIST:
    stat = FILE_EXISTS;
    break; 
...

Rationale

Returning general error OTHER_ERROR might be ambiguous when a file exist. Adding a more specific error type such as FILE_EXISTS might help reduce the ambiguity of the file open issue.