Could not create link: A required privilege is not held by the client

[sethreidnz]

When I ran the command to link a project I got an error that appears to be related to permissions on my machine. I ran again as admin and it worked. Not sure of a solution but perhaps it should be documented that this may occur? Or a more helpful error message like "You may need to link the project as administrator"

Ran command:

nulink link -p -l C:\dev\mg-invocation\Kotahi.MG.Invocation\Kotahi.MG.Invocation.csproj -p Kotahi.MG.Invocation

Failed to create symlink, reverting changes to package folders.

Fatal error: Attempted symbolic link action: create
- from path: [C:\Users\sethr\.nuget\packages\kotahi.mg.invocation\1.0.16\lib]
-   to path: [C:\dev\mg-invocation\Kotahi.MG.Invocation\bin\Debug]
Exception: NuLink.Cli.SymbolicLinkException: Attempted symbolic link action: create
- from path: [C:\Users\sethr\.nuget\packages\kotahi.mg.invocation\1.0.16\lib]
-   to path: [C:\dev\mg-invocation\Kotahi.MG.Invocation\bin\Debug] ---> System.IO.IOException: Could not create link: A required privilege is not held by the client
   at Murphy.SymbolicLink.SymbolicLink.create(String target, String path)
   at NuLink.Cli.SymbolicLinkWithDiagnostics.Create(String fromPath, String toPath) in /home/appveyor/projects/nulink-dr8wu/source/NuLink.Cli/SymbolicLinkWithDiagnostics.cs:line 13
   --- End of inner exception stack trace ---
   at NuLink.Cli.SymbolicLinkWithDiagnostics.Create(String fromPath, String toPath) in /home/appveyor/projects/nulink-dr8wu/source/NuLink.Cli/SymbolicLinkWithDiagnostics.cs:line 17
   at NuLink.Cli.LinkCommand.<>c__DisplayClass2_0.<Execute>g__PerformOperation|5() in /home/appveyor/projects/nulink-dr8wu/source/NuLink.Cli/LinkCommand.cs:line 74
   at NuLink.Cli.LinkCommand.Execute(NuLinkCommandOptions options) in /home/appveyor/projects/nulink-dr8wu/source/NuLink.Cli/LinkCommand.cs:line 30
   at NuLink.Cli.Program.ExecuteCommand(String commandName, NuLinkCommandOptions options, Boolean isValid) in /home/appveyor/projects/nulink-dr8wu/source/NuLink.Cli/Program.cs:line 111

[felix-b]

Hi @sethreidnz, thanks for using NuLink!
You raise a good point.
Agree, it should be verified on all systems (also Linux and macOS) and documented.
Regarding the error message, I'd like to find a reliable way of determining that insufficient permissions were the root cause of the error (not by comparing exception message, which seems kind of unreliable to me).

[sethreidnz]

Sounds good. I really like this tool, and think that it should be part of nuget. Currently I've got a hectic schedule but if I find some time to think about this I'd be happy to try to improve this tool with you!

[quetzalcoatl]

Probably it tries to create a hardlink, not a junction - a difference between mklink /d and mklink /j

However, NuLink itself doesn't rely on mklink at all - it uses Murphy.SymbolicLink nuget, code of which seems to be gone, but from decompilation it seems it uses:

• Win32.CreateSymbolicLink(str,str,0)
• Win32.CreateSymbolicLink(str,str,1)
• Win32.DeviceIoControl(......)
• Win32.CreateFile(.....)
• Win32.GetFinalPathNameByHandle(....)

I suppose the first 2 ones are this winapi function which frankly seems to always require elevation (so it creates a hardlink "/d", not a junction "/j") unless 'developer mode' is on. Which actually we could rely on, since it's rather common thing for NuLink users to be developers. But still I don't like it. I think a Junction should be enough here.

also FYI:

• https://stackoverflow.com/questions/58038683/allow-mklink-for-a-non-admin-user
• https://stackoverflow.com/questions/64991523/why-are-administrator-privileges-required-to-create-a-symlink-on-windows

[quetzalcoatl]

Re creating junctions

• https://stackoverflow.com/questions/12904681/createsymboliclink-equivalent-to-mklink-j
• https://www.codeproject.com/Articles/194/Windows-2000-Junction-Points#The_Solution

and even some good soul already wrote that in C#, but I can't find any nuget for that atm

• https://gist.github.com/LGM-AdrianHum/260bc9ab3c4cd49bc8617a2abe84ca74