On Wednesday, 19 September 2018 at 09:58:30 UTC, Kagamin wrote:
On Wednesday, 19 September 2018 at 06:26:21 UTC, Vladimir
Panteleev wrote:
Someone mentioned in this thread that .NET runtime does do the
long-path workaround automatically.
AFAIK, CoreFX does, but .net doesn't. .net did its own path
normalization and length check, which can be turned off since
4.6.2.
Thanks. I had a quick look. It looks pretty involved. Here are
some of the relevant parts:
https://github.com/dotnet/corefx/blob/0566028e42a8f2fa86b8e0dd856d1f13d0fdce05/src/Common/src/CoreLib/System/IO/PathHelper.Windows.cs#L16-L43
https://github.com/dotnet/corefx/blob/0566028e42a8f2fa86b8e0dd856d1f13d0fdce05/src/Common/src/CoreLib/System/IO/PathHelper.Windows.cs#L68-L95
https://github.com/dotnet/corefx/blob/0566028e42a8f2fa86b8e0dd856d1f13d0fdce05/src/Common/src/CoreLib/System/IO/Path.Windows.cs#L37-L63
https://github.com/dotnet/corefx/blob/0566028e42a8f2fa86b8e0dd856d1f13d0fdce05/src/Common/src/CoreLib/System/IO/PathInternal.Windows.cs#L82-L99
https://github.com/dotnet/corefx/blob/0566028e42a8f2fa86b8e0dd856d1f13d0fdce05/src/Common/src/CoreLib/System/IO/PathInternal.Windows.cs#L118-L141
And for example directory deletion:
https://github.com/dotnet/corefx/blob/0566028e42a8f2fa86b8e0dd856d1f13d0fdce05/src/System.IO.FileSystem/src/System/IO/Directory.cs#L296-L300
https://github.com/dotnet/corefx/blob/0566028e42a8f2fa86b8e0dd856d1f13d0fdce05/src/Common/src/Interop/Windows/kernel32/Interop.RemoveDirectory.cs#L19-L23
Some things stood out to me:
- GetFullPathName is documented as also having the MAX_PATH
limit, but the framework seems to use it for normalization BEFORE
prepending the prefix.
https://docs.microsoft.com/en-us/windows/desktop/api/fileapi/nf-fileapi-getfullpathnamea
- GetFullPathName has a big warning on it about how you shouldn't
use it in multithreaded programs.
- The code seems to compare the length against 260 characters,
but in my tests, the limit is actually about 12 characters
shorter. The same file defines MaxShortDirectoryPath = 248, but
that constant isn't used anywhere in the code.
Maybe we shouldn't use this as a reference after all...
