8346573: Can't use custom default file system provider with custom system class loader #22842

AlanBateman · 2024-12-20T09:47:32Z

If an application is deployed to use a custom default file system provider, and a custom system class loader, and initialisation of the custom system class loader uses the file system APIs, then it leads to a recursive initialisation issue. This issue has always existed but has only recently been reported. Using both configuration knobs at the same time is probably very rare but it does require attention in advance of any proposals that re-implement the java.io file classes on java.nio.file.

The proposed change here is to re-specify FileSystems.getDefault to use the default system class loader when locating the custom default file system provider. In spec terms, this is changing "system class loader" to "default system class loader" with a link to its meaning in ClassLoader.getSystemClassLoader. As part of the change I've expanded the wording to specify that the custom default file system provider must be public in a package exported to at least java.base, and that the one-arg constructor also be public. This additional clarification specifies long standing behavior and does not change any implementation.

The SetDefaultProvider.java test is expanded to add a new test the runs with both a custom default file system provider and custom system class loader, and where where the custom system class loader uses the file APIs in its initialisation.

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Change must not contain extraneous whitespace
Change requires CSR request JDK-8346709 to be approved
Commit message must refer to an issue

Issues

JDK-8346573: Can't use custom default file system provider with custom system class loader (Bug - P3)
JDK-8346709: Can't use custom default file system provider with custom system class loader (CSR)

Reviewers

Maxim Kartashev (@mkartashev - no project role)
Brian Burkhalter (@bplb - Reviewer)

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AlanBateman · 2024-12-20T09:47:45Z

/csr

bridgekeeper · 2024-12-20T09:48:15Z

👋 Welcome back alanb! 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 · 2024-12-20T09:48:21Z

@AlanBateman 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:

8346573: Can't use custom default file system provider with custom system class loader

Reviewed-by: mkartashev, bpb

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 48 new commits pushed to the master branch:

27646e5: 8344148: Add an explicit compiler phase for warning generation
8d388cc: 8346457: AOT cache creation crashes with "assert(pair_at(i).match() < pair_at(i+1).match()) failed: unsorted table entries"
d723597: 8345432: (ch, fs) Replace anonymous Thread with InnocuousThread
9c393a2: 8346953: Remove unnecessary @SuppressWarnings annotations (client, Make "can write" check work on Windows #2)
9a60f44: 8345668: ZoneOffset.ofTotalSeconds performance regression
12700cb: 8346264: "Total compile time" counter should include time spent in failing/bailout compiles
dd81f8d: 8344079: Minor fixes and cleanups to compiler lint-related code
ccf3d57: 8346985: Convert test/jdk/com/sun/jdi/ClassUnloadEventTest.java to Class-File API
594e519: 8346984: Remove ASM-based benchmarks from Class-File API benchmarks
c027f2e: 8346983: Remove ASM-based transforms from Class-File API tests
... and 38 more: https://git.openjdk.org/jdk/compare/54f34750edb284f4a49fb86c3939491211eb98fe...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.

➡️ To integrate this PR with the above commit message to the master branch, type /integrate in a new comment.

openjdk · 2024-12-20T09:48:43Z

@AlanBateman has indicated that a compatibility and specification (CSR) request is needed for this pull request.

@AlanBateman please create a CSR request for issue JDK-8346573 with the correct fix version. This pull request cannot be integrated until the CSR request is approved.

openjdk · 2024-12-20T09:49:08Z

@AlanBateman The following label will be automatically applied to this pull request:

nio

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

mlbridge · 2024-12-20T10:44:56Z

Webrevs

00: Full (7b331fef)

mkartashev

I'm not a reviewer, but this does solve the problem with the circular initialization that we had.

mkartashev · 2024-12-20T14:10:49Z

test/jdk/java/nio/file/spi/CustomSystemClassLoader.java

+
+        // use default file system
+        FileSystem fs = FileSystems.getDefault();
+        var path = fs.getPath("foo");


Maybe print the path out so that the whole thing does not get optimized away as vacuous in accordance with the language rules?

bplb

Looks fine to me.

ExE-Boss · 2024-12-21T02:34:17Z

src/java.base/share/classes/java/nio/file/FileSystems.java

-                        Constructor<?> ctor = c
-                            .getDeclaredConstructor(FileSystemProvider.class);
-                        provider = (FileSystemProvider)ctor.newInstance(provider);
+                        Class<?> c = Class.forName(cn, true, ClassLoaders.appClassLoader());


Note that this might break the case where a custom system ClassLoader doesn’t depend on a custom default FileSystemProvider but the latter depends on the custom system ClassLoader, so this should call ClassLoaders::appClassLoader() only when VM.isBooted() is false.

A custom default file system provider can't depend on a custom system ClassLoader. Think of access to the default file system as something that works at a much lower level that a class loader.

AlanBateman · 2025-01-07T10:33:44Z

/integrate

openjdk · 2025-01-07T10:34:20Z

Going to push as commit f119663.
Since your change was applied there have been 53 commits pushed to the master branch:

379ac34: 8346838: RISC-V: runtime/CommandLine/OptionsValidation/TestOptionsWithRanges.java crash with debug VMs
0285020: 8345676: [ubsan] ProcessImpl_md.c:561:40: runtime error: applying zero offset to null pointer on macOS aarch64
0a81676: 8346881: [ubsan] logSelection.cpp:154:24 / logSelectionList.cpp:72:94 : runtime error: applying non-zero offset 1 to null pointer
08debd3: 8346993: C2 SuperWord: refactor to make more vector nodes available in VectorNode::make
de02503: 8346832: runtime/CompressedOops/CompressedCPUSpecificClassSpaceReservation.java fails on RISC-V
27646e5: 8344148: Add an explicit compiler phase for warning generation
8d388cc: 8346457: AOT cache creation crashes with "assert(pair_at(i).match() < pair_at(i+1).match()) failed: unsorted table entries"
d723597: 8345432: (ch, fs) Replace anonymous Thread with InnocuousThread
9c393a2: 8346953: Remove unnecessary @SuppressWarnings annotations (client, Make "can write" check work on Windows #2)
9a60f44: 8345668: ZoneOffset.ofTotalSeconds performance regression
... and 43 more: https://git.openjdk.org/jdk/compare/54f34750edb284f4a49fb86c3939491211eb98fe...master

Your commit was automatically rebased without conflicts.

openjdk · 2025-01-07T10:34:33Z

@AlanBateman Pushed as commit f119663.

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

Initial commit

7b331fe

openjdk bot added the csr Pull request needs approved CSR before integration label Dec 20, 2024

openjdk bot added the nio [email protected] label Dec 20, 2024

AlanBateman marked this pull request as ready for review December 20, 2024 10:40

openjdk bot added the rfr Pull request is ready for review label Dec 20, 2024

mkartashev approved these changes Dec 20, 2024

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bplb approved these changes Dec 20, 2024

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ExE-Boss reviewed Dec 21, 2024

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openjdk bot added ready Pull request is ready to be integrated and removed csr Pull request needs approved CSR before integration labels Jan 6, 2025

openjdk bot added the integrated Pull request has been integrated label Jan 7, 2025

openjdk bot closed this Jan 7, 2025

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8346573: Can't use custom default file system provider with custom system class loader #22842

8346573: Can't use custom default file system provider with custom system class loader #22842

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8346573: Can't use custom default file system provider with custom system class loader #22842

8346573: Can't use custom default file system provider with custom system class loader #22842

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