Add File hard link API and tests by SadPencil · Pull Request #120041 · dotnet/runtime

SadPencil · 2025-09-24T13:11:55Z

Introduce File.CreateHardLink and FileSystemInfo.CreateAsHardLink APIs to create hard links, with platform-specific implementations. Add comprehensive tests for hard link creation, behavior, and error cases for both File and FileInfo.

Implements and closes#69030

Introduce `File.CreateHardLink` and `FileSystemInfo.CreateAsHardLink` APIs to create hard links, with platform-specific implementations. Add comprehensive tests for hard link creation, behavior, and error cases for both File and FileInfo. Implements #69030

SadPencil · 2025-09-24T13:14:02Z

@dotnet-policy-service agree

This reverts commit e2dc032.

This reverts commit 8d8b8dd.

Copilot

Pull Request Overview

This pull request adds hard link creation APIs to .NET, implementing File.CreateHardLink and FileSystemInfo.CreateAsHardLink methods with platform-specific implementations for Windows and Unix systems.

Key changes:

Introduce public APIs for creating hard links in both File and FileSystemInfo classes
Add platform-specific implementations using Windows Kernel32 and Unix system calls
Implement comprehensive test coverage for hard link functionality

Reviewed Changes

Copilot reviewed 11 out of 11 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/libraries/System.Runtime/ref/System.Runtime.cs	Add public API signatures for CreateHardLink methods
src/libraries/System.Private.CoreLib/src/System/IO/File.cs	Implement File.CreateHardLink static method
src/libraries/System.Private.CoreLib/src/System/IO/FileSystemInfo.cs	Implement CreateAsHardLink instance method
src/libraries/System.Private.CoreLib/src/System/IO/FileSystem.Windows.cs	Windows-specific hard link implementation using Kernel32
src/libraries/System.Private.CoreLib/src/System/IO/FileSystem.Unix.cs	Unix-specific hard link implementation using link system call
src/libraries/System.Private.CoreLib/src/System.Private.CoreLib.Shared.projitems	Add Windows interop reference for CreateHardLink
src/libraries/Common/tests/System/IO/ReparsePointUtilities.cs	Add hard link test utilities and capability detection
src/libraries/System.Runtime/tests/System.IO.FileSystem.Tests/Base/HardLinks/BaseHardLinks.FileSystem.cs	Base test class with common hard link test scenarios
src/libraries/System.Runtime/tests/System.IO.FileSystem.Tests/File/HardLinks.cs	Tests for File.CreateHardLink API
src/libraries/System.Runtime/tests/System.IO.FileSystem.Tests/FileInfo/HardLinks.cs	Tests for FileInfo.CreateAsHardLink API
src/libraries/System.Runtime/tests/System.IO.FileSystem.Tests/System.IO.FileSystem.Tests.csproj	Add test files to project compilation

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

No functional changes.

Calling `File.WriteAllText` (creates the file if it does not exist) right after `CreateFile` might be redundant

SadPencil · 2025-10-10T08:40:31Z

Hi. May I ask the current review status of this PR?

SadPencil · 2025-10-20T16:17:40Z

@adamsitnik Thanks for your review! All review comments have been addressed. However this ConditionalClass comment requires your attention.

adamsitnik

It looks very good, PTAL at my comments regarding test cleanup.

…ks_FileSystem

…cLinks

jozkee

Thanks.

adamsitnik

LGTM, big thanks for your contribution @SadPencil !

… into feat-io-hardlink

github-actionsBot added the area-System.IO label Sep 24, 2025

dotnet-policy-serviceBot added the community-contribution Indicates that the PR has been added by a community member label Sep 24, 2025

SadPencil added 2 commits September 24, 2025 21:49

Update CompatibilitySuppressions.xml to suppress APICompat
8d8b8dd

Have to include unrelated suppressions as well
e2dc032

jkotas reviewed Sep 24, 2025
View reviewed changes

Comment threadsrc/coreclr/nativeaot/System.Private.CoreLib/src/CompatibilitySuppressions.xml Outdated

SadPencil added 4 commits September 25, 2025 00:23

Revert "Have to include unrelated suppressions as well"
eb72e2a
This reverts commit e2dc032.

Revert "Update CompatibilitySuppressions.xml to suppress APICompat"
a1d1196
This reverts commit 8d8b8dd.

Correct the expected exception in the hardlink test
944df06

Add CreateHardLink to ref
aa42eb4

build-analysisBot mentioned this pull request Sep 24, 2025
Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host. dotnet/dnceng#5922
Open
3 tasks

SadPencil mentioned this pull request Sep 24, 2025
Enhance documentation on updating reference source for new APIs #120062
Merged

SadPencil marked this pull request as ready for review September 24, 2025 17:17

CopilotAI review requested due to automatic review settings September 24, 2025 17:17

CopilotAI reviewed Sep 24, 2025
View reviewed changes

Comment threadsrc/libraries/System.Private.CoreLib/src/System/IO/FileSystemInfo.cs Outdated
Comment threadsrc/libraries/Common/tests/System/IO/ReparsePointUtilities.cs Outdated

Address incorrect comment
5536a86
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

SadPencil added 5 commits September 25, 2025 08:50

Reorder code blocks
941730d
No functional changes.

Merge branch 'main' into feat-io-hardlink
5029136

Slightly update the hard link test
ea28a89
Calling `File.WriteAllText` (creates the file if it does not exist) right after `CreateFile` might be redundant

Add mount helper assert to the base hard link test class
613d944

Merge branch 'main' into feat-io-hardlink
1ad09a8

build-analysisBot mentioned this pull request Sep 25, 2025
Unable to pull image from mcr.microsoft.com #117164
Closed

SadPencil requested a review from jkotas September 26, 2025 14:31

jkotas requested review from a team and removed request for jkotas September 26, 2025 14:43

Remove another unused include in System.Formats.Tar.Tests
eb968ac

adamsitnik reviewed Oct 20, 2025
View reviewed changes

SadPencil added 8 commits October 21, 2025 00:22

Remove the unwanted empty line in BaseHardLinks_FileSystem
ce6145f

Add clean up for test files in HardLinks tests
1eeb5f9

Add another clean up for test files in HardLinks tests
9c83786

Format BaseHardLinks.FileSystem.cs files
7b243d6

Remove the conditional attribute for the child classes of BaseHardLin…
9ab3bae
…ks_FileSystem

Remove the conditional attribute for the child classes of BaseSymboli…
e09869a
…cLinks

Apply the same style change for the symlink
baf0ba2

Merge branch 'main' into feat-io-hardlink
3736ecf

build-analysisBot mentioned this pull request Oct 20, 2025
"We stopped hearing from agent Azure Pipelines 32. Verify the agent machine is running and has a healthy network connection" dotnet/dnceng#1886
Open
3 tasks

Revert some attribute changes
48cff98

jozkee reviewed Oct 20, 2025
View reviewed changes

Comment thread...s/System.Runtime/tests/System.IO.FileSystem.Tests/Base/HardLinks/BaseHardLinks.FileSystem.cs Outdated
Comment threadsrc/libraries/System.Private.CoreLib/src/System/IO/File.cs

build-analysisBot mentioned this pull request Oct 20, 2025
Utf8JsonWriterTests.WriteValueWithExtremelyLongValue_ThrowsArgumentException test fails with OutOfMemoryException #120918
Closed

CopilotAI mentioned this pull request Oct 20, 2025
Mark memory-intensive Utf8JsonWriterTests for OuterLoop and 64-bit only #120925
Merged
7 tasks

SadPencil added 4 commits October 21, 2025 13:39

Revert the unnecessary file clean up for the hard link tests
c14ad79

Add FileNotFoundException to the XML document of hard link methods
fc49998

Merge branch 'main' into feat-io-hardlink
6703cdd

Merge branch 'main' into feat-io-hardlink
051dfd0

jozkee approved these changes Oct 21, 2025
View reviewed changes

jozkee reviewed Oct 21, 2025
View reviewed changes

Comment threadsrc/libraries/System.Private.CoreLib/src/System/IO/FileInfo.cs Outdated

adamsitnik approved these changes Oct 21, 2025
View reviewed changes

SadPencil added 3 commits October 22, 2025 00:14

Add test CreateHardLink_RelativePath()
56cfa93

Merge branch 'feat-io-hardlink' ofhttps://github.com/SadPencil/runtime…
80347bb
… into feat-io-hardlink

Remove incorrect XML doc for CreateAsHardLink
44c1e26

adamsitnik merged commit 7df435d into dotnet:mainOct 22, 2025
141 checks passed

SadPencil deleted the feat-io-hardlink branch October 22, 2025 12:04

dotnet-maestroBot mentioned this pull request Oct 23, 2025
[main] Source code updates from dotnet/runtime dotnet/dotnet#3024
Merged

github-actionsBot locked and limited conversation to collaborators Nov 22, 2025

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Add File hard link API and tests - #120041

Add File hard link API and tests#120041
adamsitnik merged 45 commits into
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Pull Request Overview

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SadPencil commented Sep 24, 2025•
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