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Update syncio.nim, fixes "open by FileHandle" doesn't work on Windows (#23456)
## 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.
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@@ -648,6 +648,9 @@ const
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""
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else:
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""
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RawFormatOpen: array[FileMode, cstring] = [
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# used for open by FileHandle, which calls `fdopen`
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cstring("rb"), "wb", "w+b", "r+b", "ab"]
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FormatOpen: array[FileMode, cstring] = [
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cstring("rb" & NoInheritFlag), "wb" & NoInheritFlag, "w+b" & NoInheritFlag,
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"r+b" & NoInheritFlag, "ab" & NoInheritFlag
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@@ -749,7 +752,7 @@ proc open*(f: var File, filehandle: FileHandle,
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filehandle) else: filehandle
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if not setInheritable(oshandle, false):
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return false
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f = c_fdopen(filehandle, FormatOpen[mode])
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f = c_fdopen(filehandle, RawFormatOpen[mode])
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result = f != nil
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proc open*(filename: string,
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