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## Reprodution if on Windows: ```Nim when defined(windows): var file: File let succ = file.open(<aFileHandle>) ``` then `succ` will be false. If tested, it can be found to fail with errno `22` and message: `Invalid argument` ## Problem After some investigations and tests, I found it's due to the `mode` argument for `fdopen`. Currently `NoInheritFlag`(`'N'` in Windows) is added to `mode` arg passed to `_fdopen`, but if referring to [Windows `_fdopen` doc](https://learn.microsoft.com/en-us/cpp/c-runtime-library/reference/fdopen-wfdopen?view=msvc-170), you'll find there is no `'N'` describled. That's `'N'` is not accepted by `_fdopen`. Therefore, the demo above will fail. ## In Addition To begin with, technologically speaking, when opening with a `fileHandle`(or called `fd`), there is no concept of fd-inheritable as `fd` is opened already. In POSIX, `NoInheritFlag` is defined as `e`. It's pointed out in [POSIX `open` man-doc](https://www.man7.org/linux/man-pages/man3/fopen.3.html) that `e` in mode is ignored for fdopen(), which means `e` for `fdopen()` is not wanted, just allowed. Therefore, better to also not pass `e` to `fdopen` --- In all, that's this PR.