Invalid resource content when using new URL(URL context, String spec)

[voyachek]

I've used new URL(URL context, String spec) in the flowing scenario (native image):

URL url1 = ClassLoader.getSystemResource("r1.txt");
URL url2 = new URL(url1, "r2.txt");
System.out.println(new Scanner(url2.openStream(), "UTF-8").useDelimiter("\\A").next());

line 3 prints content of the resource pointed by url1, but must print the content of the resource pointed by url2 .

[olpaw]

@voyachek thanks for your bug report. I can confirm that this is not working as expected.

• Using -agentlib:native-image-agent=config-output-dir=./META-INF/native-image does not detect the resource usage of "r2.txt" (resource-config.json only contains {"resources":[{"pattern":"r1.txt"}]}
• A native-image built out of that code prints the contents of "r1.txt" instead of "r2.txt" (on JVM you get the contents from "r2.txt" as expected).

[olpaw]

@voyachek can you still reproduce the issue with the latest release?

[peter-hofer]

I don't see how we can pragmatically deal with this in the agent: getResource and getSystemResource return only a URL which does not carry the information that it refers to a classpath resource, and even if we knew, we would need to observe any transformation of such URLs and determine whether it still refers to a valid class path resource.

[peter-hofer]

Actually, the original issue (sans the agent part) seems like it could still be valid, reopening.

[jovanstevanovic]

Should be fixed with PR #3315.

[olpaw]

Note that this issue is not about the agent but if native image is able to compose resource URLs at image runtime.
It is fixed by PR #3315 and tested via CI. The test is in com.oracle.svm.test.NativeImageResourceTest#githubIssues:

graal/substratevm/src/com.oracle.svm.test/src/com/oracle/svm/test/NativeImageResourceTest.java

Line 57 in e34853d

public void githubIssues() {