8338851: Hoist os::Posix::realpath() to os::realpath() and implement on Windows #20683

stooke · 2024-08-22T18:36:39Z

This PR changes the status of realpath() from a Posix-specific API to a globally available API, i.e. adding it to the "Hotspot Porting API". Code would refer to os::realpath() instead of os::Posix::realpath().

This requires a Windows implementation of realpath(), using Windows _fullpath(), and renaming os::Posix::realpath() to os::realpath().

The main difference between POSIX and Windows behaviour is that POSIX actually requires an existing accessible file, while Windows will happily work with made-up filenames.

Please note that guidelines for doing this appear in src/hotspot/share/runtime/os.hpp

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Change must be properly reviewed (1 review required, with at least 1 Reviewer)
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Commit message must refer to an issue

Issue

JDK-8338851: Hoist os::Posix::realpath() to os::realpath() and implement on Windows (Enhancement - P4)

Reviewers

David Holmes (@dholmes-ora - Reviewer)
Thomas Stuefe (@tstuefe - Reviewer) Review applies to 33c4b402
Julian Waters (@TheShermanTanker - Committer) Review applies to 33c4b402

Reviewing

Using git

Checkout this PR locally:
$ git fetch https://git.openjdk.org/jdk.git pull/20683/head:pull/20683
$ git checkout pull/20683

Update a local copy of the PR:
$ git checkout pull/20683
$ git pull https://git.openjdk.org/jdk.git pull/20683/head

Using Skara CLI tools

Checkout this PR locally:
$ git pr checkout 20683

View PR using the GUI difftool:
$ git pr show -t 20683

Using diff file

Download this PR as a diff file:
https://git.openjdk.org/jdk/pull/20683.diff

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bridgekeeper · 2024-08-22T18:37:23Z

👋 Welcome back stooke! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

openjdk · 2024-08-22T18:38:41Z

@stooke This change now passes all automated pre-integration checks.

ℹ️ This project also has non-automated pre-integration requirements. Please see the file CONTRIBUTING.md for details.

After integration, the commit message for the final commit will be:

8338851: Hoist os::Posix::realpath() to os::realpath() and implement on Windows

Reviewed-by: dholmes, stuefe, jwaters

You can use pull request commands such as /summary, /contributor and /issue to adjust it as needed.

At the time when this comment was updated there had been 94 new commits pushed to the master branch:

e0dabfb: 8340279: Open source several AWT Dialog tests - Batch 2
f6fe5ea: 8341072: Open source several AWT Canvas and Rectangle related tests
22a1fee: 8341328: Refactor initial Assertion Predicate creation into separate classes
58d39c3: 8340313: Crash due to invalid oop in nmethod after C1 patching
3da6890: 8338751: ConfigureNotify behavior has changed in KWin 6.2
4e703b2: 8340140: Open some dialog awt tests 3
b4ab290: 8331959: Update PKCS#11 Cryptographic Token Interface to v3.1
2853852: 8342332: [JVMCI] Export CompilerToVM::Data::dtanh
ed68096: 8341862: PPC64: C1 unwind_handler fails to unlock synchronized methods with LM_MONITOR
d4f0ba7: 8342439: Build failure after 8338023
... and 84 more: https://git.openjdk.org/jdk/compare/780de009224b048fa51a119e1db6cc52daddaaf8...master

As there are no conflicts, your changes will automatically be rebased on top of these commits when integrating. If you prefer to avoid this automatic rebasing, please check the documentation for the /integrate command for further details.

As you do not have Committer status in this project an existing Committer must agree to sponsor your change. Possible candidates are the reviewers of this PR (@dholmes-ora, @tstuefe, @TheShermanTanker) but any other Committer may sponsor as well.

➡️ To flag this PR as ready for integration with the above commit message, type /integrate in a new comment. (Afterwards, your sponsor types /sponsor in a new comment to perform the integration).

openjdk · 2024-08-22T18:39:04Z

@stooke The following labels will be automatically applied to this pull request:

hotspot
serviceability

When this pull request is ready to be reviewed, an "RFR" email will be sent to the corresponding mailing lists. If you would like to change these labels, use the /label pull request command.

mlbridge · 2024-08-28T19:29:29Z

Webrevs

dholmes-ora

This is okay in principle but a few changes can be made.

Also it seems that none of the callers of realpath ever check errno so I think that can be removed.

Thanks

src/hotspot/os/posix/os_posix.cpp

src/hotspot/os/windows/os_windows.cpp

stooke · 2024-09-04T20:07:28Z

Hello, @dholmes-ora , and thank you for your review! I am in the process of attempting to address your concerns. Your review has resulted in simpler code for my implementation - so thanks for that too. Please let me know if you have more concerns or questions.

tstuefe

Looks good, thanks for the work. One question inline.

src/hotspot/os/windows/os_windows.cpp

TheShermanTanker

Looks good, just 1 comment

src/hotspot/os/posix/os_posix.cpp

dholmes-ora

Windows version looks better now, though still one issue that isn't really solvable - so I'd let it slide (especially as I think the errno settings should be removed anyway).

Thanks

src/hotspot/os/windows/os_windows.cpp

src/hotspot/share/runtime/os.hpp

src/hotspot/os/posix/os_posix.cpp

src/hotspot/os/windows/os_windows.cpp

dholmes-ora

Okay this seems fine to me now.

Thanks

test/hotspot/gtest/runtime/test_os.cpp

stooke · 2024-10-14T10:31:32Z

Hello, @dholmes-ora , could you please take another look? I've responded to your concerns about the macOS-specific tests, but I don't know if you feel my response is adequate.

dholmes-ora

Hi @stooke , I was away on vacation when you made the updates.

I'm afraid I still have some issues about expected behaviour on Windows with regard to the tests.

test/hotspot/gtest/runtime/test_os.cpp

dholmes-ora · 2024-10-15T23:59:10Z

test/hotspot/gtest/runtime/test_os.cpp

+  /* Returns ENOENT on Linux, ENAMETOOLONG on Windows */
+  EXPECT_TRUE(returnedBuffer == nullptr);
+#if defined(_WINDOWS)
+  EXPECT_TRUE(errno == ENAMETOOLONG);


Why is this the case? Our implementation does not set it and _fullpath makes no mention of it.

This is Windows behaviour - Windows 10 with VS 2022 at least. The existence of a file is not checked, but that non-existent filename better fit into the given buffer!

Okay. This behaviour is not specified but the test passed on our CI on Windows Server 2016 and 2019.

dholmes-ora · 2024-10-16T00:02:13Z

test/hotspot/gtest/runtime/test_os.cpp

+#endif
+
+TEST_VM(os, realpath) {
+  /* POSIX requires that the file exists, Windows doesn't */


I'm not sure what this comment means. I can't fully discern from

https://learn.microsoft.com/en-us/cpp/c-runtime-library/reference/fullpath-wfullpath?view=msvc-170

what Windows does if the path does not exist.

I can only report by example - on my local machine, Windows doesn't appear to care if the file exists or not, but according to the docs you point to, Windows does care if the drive letter is valid.
Adding an invalid drive letter test is beyond the current scope of this test.
I have expanded this comment to be more explanatory:

// POSIX requires that the file exists;
// Windows tests for a valid drive letter but may or may not test if the file exists.

stooke · 2024-10-16T12:51:51Z

@dholmes-ora thank you for your comments. I have updated the comments (and reformatted comments and #ifdef code to match the rest of the tests source.

dholmes-ora · 2024-10-17T00:45:47Z

test/hotspot/gtest/runtime/test_os.cpp

+  /* Returns ENOENT on Linux, ENAMETOOLONG on Windows */
+  EXPECT_TRUE(returnedBuffer == nullptr);
+#if defined(_WINDOWS)
+  EXPECT_TRUE(errno == ENAMETOOLONG);


Okay. This behaviour is not specified but the test passed on our CI on Windows Server 2016 and 2019.

stooke · 2024-10-17T07:12:34Z

/integrate

openjdk · 2024-10-17T07:13:53Z

@stooke
Your change (at version 1467917) is now ready to be sponsored by a Committer.

dholmes-ora · 2024-10-17T08:05:15Z

/sponsor

openjdk · 2024-10-17T08:06:38Z

Going to push as commit 7a64fbb.
Since your change was applied there have been 97 commits pushed to the master branch:

8862ca0: 8342338: Remove redundant IIOPURLTest.java
f9208fa: 8341715: PPC64: ObjectMonitor::_owner should be reset unconditionally in nmethod unlocking
fa39e84: 8342042: PPC64: compiler_fast_unlock_object flags failure instead of success
e0dabfb: 8340279: Open source several AWT Dialog tests - Batch 2
f6fe5ea: 8341072: Open source several AWT Canvas and Rectangle related tests
22a1fee: 8341328: Refactor initial Assertion Predicate creation into separate classes
58d39c3: 8340313: Crash due to invalid oop in nmethod after C1 patching
3da6890: 8338751: ConfigureNotify behavior has changed in KWin 6.2
4e703b2: 8340140: Open some dialog awt tests 3
b4ab290: 8331959: Update PKCS#11 Cryptographic Token Interface to v3.1
... and 87 more: https://git.openjdk.org/jdk/compare/780de009224b048fa51a119e1db6cc52daddaaf8...master

Your commit was automatically rebased without conflicts.

openjdk · 2024-10-17T08:06:54Z

@dholmes-ora @stooke Pushed as commit 7a64fbb.

💡 You may see a message that your pull request was closed with unmerged commits. This can be safely ignored.

hoist os::Posix::realpath() to os::realpath()

e59cad6

stooke mentioned this pull request Aug 22, 2024

8319873: Add windows implementation for jcmd System.map and System.dump_map #20597

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openjdk bot added serviceability hotspot labels Aug 22, 2024

stooke marked this pull request as ready for review August 28, 2024 19:25

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dholmes-ora suggested changes Aug 29, 2024

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stooke added 2 commits September 4, 2024 11:31

get rid of os::posix::realpath() and os::win32::realpath()

44609e8

simplify windwos realpath() implementation

b7f495b

tstuefe approved these changes Sep 5, 2024

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move os::realpath() to previous location

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openjdk bot removed the ready label Sep 11, 2024

move os::realpath() to previous location

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properly test for buffer too small for path

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dholmes-ora suggested changes Sep 12, 2024

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stooke added 3 commits September 12, 2024 09:47

fix missing return statement

4da45cb

fix indentation

1eeac69

remove empty line

33c4b40

dholmes-ora approved these changes Sep 13, 2024

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openjdk bot added the ready label Sep 13, 2024

stooke added 2 commits September 20, 2024 15:08

fix realpath test on macOS

a7a76e9

delete commented out code

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dholmes-ora suggested changes Sep 23, 2024

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stooke added 7 commits October 9, 2024 03:13

feedback from review

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account for Windows behviour changes

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remove accidently commited file

e8c29ff

Merge branch 'master' into pr_windows_realpath

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odd github behaviour

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spelling mistake

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clean up test code

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clean up comments per PR review

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clean up whitespace error

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8338851: Hoist os::Posix::realpath() to os::realpath() and implement on Windows #20683

8338851: Hoist os::Posix::realpath() to os::realpath() and implement on Windows #20683

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8338851: Hoist os::Posix::realpath() to os::realpath() and implement on Windows #20683

8338851: Hoist os::Posix::realpath() to os::realpath() and implement on Windows #20683

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