Add Directory.CreateTempSubdirectory #73408

eerhardt · 2022-08-04T22:10:53Z

CreateTempSubdirectory will create a new uniquely named directory under the temp directory. This allows applications to write temporary files in a co-located directory.

Contributes to #72881

Note: I've decided not to implement the full approved API in #72881 because of the feedback on the File API. That will be added in a future PR.

CreateTempSubdirectory will create a new uniquely named directory under the temp directory. This allows applications to write temporary files in a co-located directory. Contributes to dotnet#72881

dotnet-issue-labeler · 2022-08-04T22:11:00Z

Note regarding the new-api-needs-documentation label:

This serves as a reminder for when your PR is modifying a ref *.cs file and adding/modifying public APIs, to please make sure the API implementation in the src *.cs file is documented with triple slash comments, so the PR reviewers can sign off that change.

ghost · 2022-08-04T22:11:21Z

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Issue Details

CreateTempSubdirectory will create a new uniquely named directory under the temp directory. This allows applications to write temporary files in a co-located directory.

Contributes to #72881

Note: I've decided not to implement the full approved API in #72881 because of the feedback on the File API. That will be added in a future PR.

Author:	eerhardt
Assignees:	-
Labels:	`area-System.IO`, `new-api-needs-documentation`
Milestone:	-

src/libraries/System.Private.CoreLib/src/System/IO/Directory.cs

src/libraries/System.Private.CoreLib/src/System/IO/Directory.Unix.cs

stephentoub · 2022-08-05T00:53:06Z

src/libraries/System.Private.CoreLib/src/System/IO/Directory.Windows.cs

+            while (attempts < MaxAttempts)
+            {
+                Interop.GetRandomBytes(pKey, RandomKeyLength);
+                Path.Populate83FileNameFromRandomBytes(pKey, RandomKeyLength, builder.RawChars.Slice(builder.Length, RandomFileNameLength));


Why is it important to use the 8.3 naming?

It isn't important. But it is what GetRandomFileName uses

runtime/src/libraries/System.Private.CoreLib/src/System/IO/Path.cs

Lines 281 to 289 in 916f1ad

public static unsafe string GetRandomFileName()

{

byte* pKey = stackalloc byte[KeyLength];

Interop.GetRandomBytes(pKey, KeyLength);

return string.Create(

12, (IntPtr)pKey, (span, key) => // 12 == 8 + 1 (for period) + 3

Populate83FileNameFromRandomBytes((byte*)key, KeyLength, span));

}

I'm just simulating a call to GetRandomFileName here, without allocating an intermediate string.

I can add a comment here, if that helps. Or did you have a different algorithm in mind for generating a folder name?

IMO having a period in the directory name seems a bit strange

IMO having a period in the directory name seems a bit strange

Does it really matter though? Code shouldn't depend on these names - they even have a different pattern between Windows and Unix. Besides, there are plenty of cases where directories have periods in their names - versions, namespace-like, etc.

e.g. C:\Program Files\dotnet\shared\Microsoft.NETCore.App\6.0.7.

jozkee

Other than existing comments and a few more I'm leaving, LGTM.

src/libraries/System.Private.CoreLib/src/System/IO/Directory.Windows.cs

src/libraries/System.Runtime.Loader/tests/ResourceAssemblyLoadContext.cs

src/libraries/System.IO.FileSystem/tests/Directory/CreateTempSubdirectory.cs

- Rewrite CreateTempSubdirectory and GetTempFileName on Unix to minimize allocations.

eerhardt · 2022-08-05T22:09:22Z

I have responded to all existing feedback and pushed new changes. PTAL.

src/libraries/System.Private.CoreLib/src/System/IO/Directory.cs

tmds · 2022-08-07T12:20:24Z

src/libraries/System.IO.FileSystem/tests/Directory/CreateTempSubdirectory.cs

+
+namespace System.IO.Tests
+{
+    public class Directory_CreateTempSubdirectory : FileSystemTest


Maybe verify that the filemode of the created directory is 700 on Unix. That is an important trait of this API.

Q: is it on Windows also guaranteed the resulting directory is only accessible to the current user?

Maybe verify that the filemode of the created directory is 700 on Unix.

Done.

Q: is it on Windows also guaranteed the resulting directory is only accessible to the current user?

No, on Windows there is no guarantee on the permissions of the directory. Just that it is empty, and it is in the TEMP directory.

src/libraries/System.Runtime/ref/System.Runtime.cs

adamsitnik

LGTM, thanks a lot @eerhardt !

src/libraries/Common/src/System/IO/TempFileCollection.cs

...sition/tests/System/ComponentModel/Composition/Hosting/DirectoryCatalogDebuggerProxyTests.cs

src/native/libs/System.Native/pal_io.h

src/libraries/System.Private.CoreLib/src/System/IO/Path.Unix.cs

src/libraries/System.Private.CoreLib/src/System/IO/Directory.Unix.cs

adamsitnik

…tests These tests had 3 methods that do the same thing. Consolidating down to one. Follow up to dotnet#73408

Add Directory.CreateTempSubdirectory

9f3ffa3

CreateTempSubdirectory will create a new uniquely named directory under the temp directory. This allows applications to write temporary files in a co-located directory. Contributes to dotnet#72881

eerhardt requested review from stephentoub, adamsitnik and jozkee August 4, 2022 22:10

dotnet-issue-labeler bot added area-System.IO new-api-needs-documentation labels Aug 4, 2022

ghost assigned eerhardt Aug 4, 2022

jkotas reviewed Aug 4, 2022

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This was referenced Aug 5, 2022

Infra improvements for Helix #68176

Closed

GC/API/GC/GetGCMemoryInfo/GetGCMemoryInfo.sh test failing intermittently on CoreCLR Linux ARM32 #73247

Closed

jozkee approved these changes Aug 5, 2022

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src/libraries/System.IO.FileSystem/tests/Directory/CreateTempSubdirectory.cs Outdated Show resolved Hide resolved

eerhardt added 2 commits August 5, 2022 16:47

PR feedback

5b86fd3

- Rewrite CreateTempSubdirectory and GetTempFileName on Unix to minimize allocations.

Fix tests on Windows.

d744ac9

Nirmal4G reviewed Aug 6, 2022

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src/libraries/System.Private.CoreLib/src/System/IO/Directory.cs Show resolved Hide resolved

tmds reviewed Aug 7, 2022

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src/libraries/System.Runtime/ref/System.Runtime.cs Show resolved Hide resolved

Assert UnixFileMode is 700 for created temp directory.

dc910fd

adamsitnik approved these changes Aug 9, 2022

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eerhardt added 2 commits August 9, 2022 15:01

PR feedback

5fd8d41

Rename ThrowExceptionForLastError to ThrowIOExceptionForLastError

e9f0a01

adamsitnik approved these changes Aug 10, 2022

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eerhardt merged commit 9fd407a into dotnet:main Aug 10, 2022

eerhardt deleted the AddCreateTempDirectory branch August 10, 2022 12:43

radical mentioned this pull request Aug 10, 2022

Path.GetTempFileName() sometimes fails on WASM due to insufficient randomness #73721

Closed

eerhardt added a commit to eerhardt/runtime that referenced this pull request Aug 12, 2022

Clean up temp directory methods in System.ComponentModel.Composition …

e247628

…tests These tests had 3 methods that do the same thing. Consolidating down to one. Follow up to dotnet#73408

eerhardt mentioned this pull request Aug 12, 2022

Clean up temp directory methods in System.ComponentModel.Composition tests #73857

Merged

danmoseley mentioned this pull request Aug 15, 2022

Unix: Move 'FileNotFound to DirectoryNotFound' handling to GetExceptionForIoErrno. #70661

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Add Directory.CreateTempSubdirectory #73408

Add Directory.CreateTempSubdirectory #73408

eerhardt commented Aug 4, 2022

dotnet-issue-labeler bot commented Aug 4, 2022

ghost commented Aug 4, 2022

stephentoub Aug 5, 2022 •

edited

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eerhardt Aug 5, 2022

eerhardt Aug 5, 2022

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eerhardt commented Aug 5, 2022

tmds Aug 7, 2022

tmds Aug 7, 2022

eerhardt Aug 8, 2022

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adamsitnik left a comment

	public static unsafe string GetRandomFileName()
	{
	byte* pKey = stackalloc byte[KeyLength];
	Interop.GetRandomBytes(pKey, KeyLength);

	return string.Create(
	12, (IntPtr)pKey, (span, key) => // 12 == 8 + 1 (for period) + 3
	Populate83FileNameFromRandomBytes((byte*)key, KeyLength, span));
	}

Add Directory.CreateTempSubdirectory #73408

Add Directory.CreateTempSubdirectory #73408

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eerhardt commented Aug 4, 2022

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stephentoub Aug 5, 2022 •

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