Runtime exception below API 26 with unsupported Java nio API (with no lint error) [381126163]

Fixed

Bug

Status Update

No update yet.

Description

an...@steadfastinnovation.com

created issue #1

Nov 27, 2024 02:17AM

java.nio APIs can be used below API 26 with coreLibraryDesugaring "com.android.tools:desugar_jdk_libs_nio:2.1.3". However, as described in the java.nio customizations documentation:

The following is a list of features which aren't supported when the runtime device is strictly lower than API level 26. Calls to such APIs either return null or throw an instance of java.lang.UnsupportedOperationException.

java.nio.channels.AsynchronousFileChannel

Posix file features (group, owner, permissions), including reading or writing the attributes or attribute view or FileSystem#getUserPrincipalLookupService

Watch service, including FileSystem#newWatchService or Path#register

For example, running the following on API 21 produces a java.lang.UnsupportedOperationException:

Path path = new File("").toPath();

try(AsynchronousFileChannel open = AsynchronousFileChannel.open(path)) {
    open.read(ByteBuffer.allocate(1024), 1024);
} catch (IOException e) {
    throw new RuntimeException(e);
}

This is expected per the documentation, but is not discoverable except at runtime.

However, when using coreLibraryDesugaring "com.android.tools:desugar_jdk_libs:2.1.3" (the non-nio artifact), usages of this API (and all other java.nio APIs) produce lint errors unless wrapped in checks for API 26+.

Is it possible to show lint errors just for the APIs that will fail at runtime when they're not wrapped in API checks for API 26+ when using desugar_jdk_libs_nio? That way the build will fail rather than discovering this at runtime.

Comments

rk...@google.com <rk...@google.com> Nov 27, 2024 05:04PM

Assigned to an...@google.com.

tn...@google.com <tn...@google.com> #2Nov 27, 2024 05:26PM

Reassigned to sg...@google.com.

I believe you've been looking into this

        at com.android.tools.idea.gradle.project.sync.idea.SdkSyncUtil.findMatchingSdkForAddon(SdkSyncUtil.kt:175)
        at com.android.tools.idea.gradle.project.sync.idea.SdkSyncUtil.computeSdkReloadingAsNeeded(SdkSyncUtil.kt:127)

an...@steadfastinnovation.com <an...@steadfastinnovation.com> #3Nov 27, 2024 05:50PM

hm, in fact let's discuss how we handle SDKs/addons etc. and also bootlclasspath. We have an open issue with not supporting useLibrary which we need to fix.

sg...@google.com <sg...@google.com> #4Nov 28, 2024 09:58AM

Reassigned to cl...@google.com.

The issue seems to be in

// Find the path to the android.jar, so we can match this to the sdks and find which one is in use.
  val androidJarPath = bootClasspath.map { path ->
    File(path)
  }.firstOrNull { file ->
    file.name == FN_FRAMEWORK_LIBRARY
  } ?: return null

  // There is no android.jar file in the bootClasspath, we can't find the SDK
  // TODO: Maybe log here, this condition should never happen AFAIK.

  return allAndroidSdks.first { sdk ->
    sdk.rootProvider.getFiles(CLASSES).any { sdkFile ->
      filesEqual(virtualToIoFile(sdkFile), androidJarPath)
    }
  }

i.e. it seems that android.jar from the bootclasspath (as reported by AGP) is not found in any of Android SDKs registered with the IDE.

Al, do you modify bootclasspath for you project in some way? Also, can you please share a small project that reproduces the issue?

Bradley, you made some changes in this area in the past, does this ring a bell?

tn...@google.com <tn...@google.com> #5Nov 28, 2024 05:49PM

We have a custom SDK which we pull from our own servers. It's a modified API Level 32 that includes framework classes so that folk can work on a custom Launcher without needing to get into AOSP experience.

Unfortunately I can't share that publicly, but would that trigger the issue? Is there some kind of filter on allAndroidSdks which only includes Google sourced SDKs? The reason I'm asking is we've seen issues trying to run apps from AS where our custom SDK is selected, and compiles the code without an issue, but AS pops up a "Please select an Android SDK" error.

tn...@google.com <tn...@google.com> #6Dec 6, 2024 12:17AM

Marked as fixed, reassigned to tn...@google.com.

This is probably caused by https://issuetracker.google.com/238235638. Are you adding a custom SDK? If so, allAndroidSdks will be empty, and even though there is file with name android.jar in bootclasspath, the code above will fail?

an...@google.com <an...@google.com> #7Dec 12, 2024 03:57PM

That's very plausible. In which case could the exception be caught and the error be more meaningful (e.g. "Please install a Google-provided Android SDK"). Currently, in my opinion, the error doesn't give the user a lot of indication of the cause of the error and what they can do to resolve it.