Calling java.nio.file.Path#toFile under Native Image will result in java.lang.UnsupportedOperationException

[linghengqian]

Describe the issue
A clear and concise description of the issue. We recommend using the latest snapshot builds to replicate the issue as bugs are constantly being fixed in the master branch

• Calling java.nio.file.Path#toFile under Native Image will result in java.lang.UnsupportedOperationException.

try (FileSystem fileSystem = FileSystems.newFileSystem(URI.create("resource:/"), Collections.emptyMap())) {
                Path result = fileSystem.getPath("h2.txt");
                assertDoesNotThrow(() -> {
                    InputStream inputStreamFirst = Files.newInputStream(result.toAbsolutePath());
                    inputStreamFirst.close();
                });
                assertDoesNotThrow(() -> {
                    File file = result.toFile();
                });
                assertDoesNotThrow(() -> {
                    InputStream inputStreamSecond = Files.newInputStream(result.toFile().toPath());
                    inputStreamSecond.close();
                });
            }

Steps to reproduce the issue
Please include both build steps as well as run steps

1. [e.g.: git clone --depth 1 https://git.myrepo.com/projectone ]
2. [e.g.: mvn clean package]

• I created relevant unit tests and reproduction steps at https://github.com/linghengqian/graalvm-v2302-path-tofile-test .

sudo apt install unzip zip curl sed -y
curl -s "https://get.sdkman.io" | bash
source "$HOME/.sdkman/bin/sdkman-init.sh"
sdk install java 17.0.9-graalce
sdk use java 17.0.9-graalce

git clone git@github.com:linghengqian/graalvm-v2302-path-tofile-test.git
cd ./graalvm-v2302-path-tofile-test/
./gradlew -Pagent clean test
./gradlew metadataCopy --task test
./gradlew clean nativeTest

Describe GraalVM and your environment:

• GraalVM version (latest snapshot builds can be found here), or commit id if built from source: [e.g. EE 19.3, CE 20.0, CE 20.1.0-dev-20200304_0848] CE 23.0.2
• JDK major version: [e.g.:8] 17
• OS: [e.g. macOS Catalina] Ubuntu 22.04.3
• Architecture: [e.g.: AMD64] AMD64

More details
Consider adding the --native-image-info and --verbose flags when building your native image and paste output below.

Add any other information about the problem here. Especially important are stack traces or log output. Feel free to link to gists or to screenshots if necessary.

Error Log

$ ./gradlew clean nativeTest

> Task :generateTestResourcesConfigFile
[native-image-plugin] Resources configuration written into /home/linghengqian/TwinklingLiftWorks/git/public/graalvm-v2302-path-tofile-test/build/native/generated/generateTestResourcesConfigFile/resource-config.json

> Task :nativeTestCompile
[native-image-plugin] GraalVM Toolchain detection is disabled
[native-image-plugin] GraalVM location read from environment variable: JAVA_HOME
[native-image-plugin] Native Image executable path: /home/linghengqian/.sdkman/candidates/java/17.0.9-graalce/lib/svm/bin/native-image
========================================================================================================================
GraalVM Native Image: Generating 'graalvm-v2302-path-tofile-test-tests' (executable)...
========================================================================================================================
For detailed information and explanations on the build output, visit:
https://github.com/oracle/graal/blob/master/docs/reference-manual/native-image/BuildOutput.md
------------------------------------------------------------------------------------------------------------------------
[1/8] Initializing...                                                                                    (8.5s @ 0.09GB)
 Java version: 17.0.9+9, vendor version: GraalVM CE 17.0.9+9.1
 Graal compiler: optimization level: 2, target machine: x86-64-v3
 C compiler: gcc (linux, x86_64, 11.4.0)
 Garbage collector: Serial GC (max heap size: 80% of RAM)
 1 user-specific feature(s)
 - org.graalvm.junit.platform.JUnitPlatformFeature
[junit-platform-native] Running in 'test listener' mode using files matching pattern [junit-platform-unique-ids*] found in folder [/home/linghengqian/TwinklingLiftWorks/git/public/graalvm-v2302-path-tofile-test/build/test-results/test/testlist] and its subfolders.
[2/8] Performing analysis...  [****]                                                                    (27.3s @ 0.70GB)
   6,007 (81.68%) of  7,354 types reachable
   9,265 (62.18%) of 14,900 fields reachable
  28,230 (53.55%) of 52,714 methods reachable
   1,802 types,     0 fields, and   710 methods registered for reflection
      59 types,    59 fields, and    52 methods registered for JNI access
       4 native libraries: dl, pthread, rt, z
[3/8] Building universe...                                                                               (3.5s @ 0.60GB)
[4/8] Parsing methods...      [**]                                                                       (2.2s @ 0.93GB)
[5/8] Inlining methods...     [***]                                                                      (1.4s @ 0.79GB)
[6/8] Compiling methods...    [*****]                                                                   (21.7s @ 0.84GB)
[7/8] Layouting methods...    [**]                                                                       (2.2s @ 1.21GB)
[8/8] Creating image...       [**]                                                                       (2.9s @ 0.58GB)
  12.02MB (44.07%) for code area:    17,383 compilation units
  14.12MB (51.80%) for image heap:  162,612 objects and 68 resources
   1.13MB ( 4.13%) for other data
  27.26MB in total
------------------------------------------------------------------------------------------------------------------------
Top 10 origins of code area:                                Top 10 object types in image heap:
   5.89MB java.base                                            2.66MB byte[] for code metadata
   3.78MB java.xml                                             1.57MB java.lang.String
 988.32kB svm.jar (Native Image)                               1.42MB java.lang.Class
 207.75kB junit-jupiter-engine-5.10.1.jar                      1.42MB byte[] for general heap data
 203.74kB jdk.zipfs                                            1.25MB byte[] for java.lang.String
 138.26kB junit-platform-launcher-1.10.1.jar                 752.07kB byte[] for embedded resources
 114.42kB java.logging                                       516.23kB com.oracle.svm.core.hub.DynamicHubCompanion
 111.19kB junit-platform-reporting-1.10.1.jar                513.00kB int[][]
 103.36kB junit-platform-engine-1.10.1.jar                   448.03kB java.util.HashMap$Node
  92.97kB junit-platform-commons-1.10.1.jar                  334.08kB java.lang.String[]
 326.92kB for 14 more packages                                 2.80MB for 1428 more object types
------------------------------------------------------------------------------------------------------------------------
Recommendations:
 HEAP: Set max heap for improved and more predictable memory usage.
 CPU:  Enable more CPU features with '-march=native' for improved performance.
------------------------------------------------------------------------------------------------------------------------
                        4.7s (6.5% of total time) in 102 GCs | Peak RSS: 2.29GB | CPU load: 4.84
------------------------------------------------------------------------------------------------------------------------
Produced artifacts:
 /home/linghengqian/TwinklingLiftWorks/git/public/graalvm-v2302-path-tofile-test/build/native/nativeTestCompile/graalvm-v2302-path-tofile-test-tests (executable)
========================================================================================================================
Finished generating 'graalvm-v2302-path-tofile-test-tests' in 1m 10s.
[native-image-plugin] Native Image written to: /home/linghengqian/TwinklingLiftWorks/git/public/graalvm-v2302-path-tofile-test/build/native/nativeTestCompile

> Task :nativeTest FAILED
JUnit Platform on Native Image - report
----------------------------------------

com.lingh.PathTest > test() FAILED


Failures (1):
  JUnit Jupiter:PathTest:test()
    MethodSource [className = 'com.lingh.PathTest', methodName = 'test', methodParameterTypes = '']
    => org.opentest4j.AssertionFailedError: Unexpected exception thrown: java.lang.UnsupportedOperationException
       org.junit.jupiter.api.AssertionFailureBuilder.build(AssertionFailureBuilder.java:152)
       org.junit.jupiter.api.AssertDoesNotThrow.createAssertionFailedError(AssertDoesNotThrow.java:84)
       org.junit.jupiter.api.AssertDoesNotThrow.assertDoesNotThrow(AssertDoesNotThrow.java:53)
       org.junit.jupiter.api.AssertDoesNotThrow.assertDoesNotThrow(AssertDoesNotThrow.java:36)
       org.junit.jupiter.api.Assertions.assertDoesNotThrow(Assertions.java:3168)
       [...]
     Caused by: java.lang.UnsupportedOperationException
       org.graalvm.nativeimage.builder/com.oracle.svm.core.jdk.resources.NativeImageResourcePath.toFile(NativeImageResourcePath.java:421)
       com.lingh.PathTest.lambda$test$2(PathTest.java:41)
       org.junit.jupiter.api.AssertDoesNotThrow.assertDoesNotThrow(AssertDoesNotThrow.java:49)
       [...]

Test run finished after 2 ms
[         2 containers found      ]
[         0 containers skipped    ]
[         2 containers started    ]
[         0 containers aborted    ]
[         2 containers successful ]
[         0 containers failed     ]
[         1 tests found           ]
[         0 tests skipped         ]
[         1 tests started         ]
[         0 tests aborted         ]
[         0 tests successful      ]
[         1 tests failed          ]


FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':nativeTest'.
> Process 'command '/home/linghengqian/TwinklingLiftWorks/git/public/graalvm-v2302-path-tofile-test/build/native/nativeTestCompile/graalvm-v2302-path-tofile-test-tests'' finished with non-zero exit value 1

* Try:
> Run with --stacktrace option to get the stack trace.
> Run with --info or --debug option to get more log output.
> Run with --scan to get full insights.
> Get more help at https://help.gradle.org.

BUILD FAILED in 1m 14s
8 actionable tasks: 8 executed

[jovanstevanovic]

Hi @linghengqian, I've examined the code snippet and the description you provided. I made the assumption that toFile throws UnsupportedOperationException, and I believe that assumption still holds.

• In cases where the code assumes an actual file to be available for a resource embedded in an image, the issue lies on the user side and not with us.
• The code example that you have provided would not work on Java as well if a resource is in a jar. (e.g. the example works with java -cp myclassesdir ResourceTest but not with java -cp myclasses.jar ResourceTest).

[linghengqian]

@jovanstevanovic Thanks for the clarification!