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[Java.Interop] Convert dot-separated class names before calling FindClass #1409

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jonathanpeppers merged 1 commit into from
Apr 20, 2026
Merged

[Java.Interop] Convert dot-separated class names before calling FindClass #1409

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76 changes: 51 additions & 25 deletions src/Java.Interop/Java.Interop/JniEnvironment.Types.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -51,7 +51,10 @@ static unsafe JniObjectReference TryFindClass (string classname, bool throwOnErr

var info = JniEnvironment.CurrentInfo;
#if FEATURE_JNIENVIRONMENT_JI_PINVOKES || FEATURE_JNIENVIRONMENT_JI_FUNCTION_POINTERS
if (TryRawFindClass (info.EnvironmentPointer, classname, out var c, out var thrown)) {
// Convert dot-separated names (e.g. "java.lang.Object") to JNI form ("java/lang/Object")
// before calling FindClass, because ART's CheckJNI aborts the process on dot-separated names.
var jniClassName = classname.Contains ('.') ? classname.Replace ('.', '/') : classname;
if (TryRawFindClass (info.EnvironmentPointer, jniClassName, out var c, out var thrown)) {
var r = new JniObjectReference (c, JniObjectReferenceType.Local);
JniEnvironment.LogCreateLocalRef (r);
return r;
Expand Down Expand Up @@ -382,32 +385,55 @@ static unsafe JniObjectReference TryFindClass (ReadOnlySpan<byte> classname, boo
throw new ArgumentException ("'classname' cannot be a zero-length string.", nameof (classname));

var info = JniEnvironment.CurrentInfo;
fixed (byte* _classname_ptr = classname) {
var c = JniNativeMethods.FindClass (info.EnvironmentPointer, (IntPtr) _classname_ptr);
var thrown = JniNativeMethods.ExceptionOccurred (info.EnvironmentPointer);
if (thrown == IntPtr.Zero) {
var r = new JniObjectReference (c, JniObjectReferenceType.Local);
JniEnvironment.LogCreateLocalRef (r);
return r;
}

RawExceptionClear (info.EnvironmentPointer);
var javaName = NewJavaNameFromUtf8 (info.EnvironmentPointer, classname);
try {
if (TryLoadClassWithFallback (info, thrown, javaName, throwOnError, out var result))
return result;
} finally {
JniObjectReference.Dispose (ref javaName);
}
if (!throwOnError)
return default;

var terminator = classname.IndexOf ((byte) 0);
var errorClassName = terminator >= 0
? Encoding.UTF8.GetString (classname.Slice (0, terminator))
: Encoding.UTF8.GetString (classname);
throw new InvalidOperationException ($"Could not find Java class '{errorClassName}'.");
var terminator = classname.IndexOf ((byte) 0);
var nameLength = terminator >= 0 ? terminator : classname.Length;

// Convert dot-separated names (e.g. "java.lang.Object"u8) to JNI form ("java/lang/Object")
// before calling FindClass, because ART's CheckJNI aborts the process on dot-separated names.
bool hasDots = classname.Slice (0, nameLength).IndexOf ((byte) '.') >= 0;
if (!hasDots) {
return TryFindClassFromPtr (info, classname, classname, terminator, throwOnError);
}

Span<byte> jniClassName = nameLength + 1 <= 256
? stackalloc byte [nameLength + 1]
: new byte [nameLength + 1];
for (int i = 0; i < nameLength; ++i)
jniClassName [i] = classname [i] == (byte) '.' ? (byte) '/' : classname [i];
jniClassName [nameLength] = 0;
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return TryFindClassFromPtr (info, classname, jniClassName, terminator, throwOnError);
}

static unsafe JniObjectReference TryFindClassFromPtr (JniEnvironmentInfo info, ReadOnlySpan<byte> classname, ReadOnlySpan<byte> findClassSpan, int terminator, bool throwOnError)
{
IntPtr c;
fixed (byte* _classname_ptr = findClassSpan) {
c = JniNativeMethods.FindClass (info.EnvironmentPointer, (IntPtr) _classname_ptr);
}
var thrown = JniNativeMethods.ExceptionOccurred (info.EnvironmentPointer);
if (thrown == IntPtr.Zero) {
var r = new JniObjectReference (c, JniObjectReferenceType.Local);
JniEnvironment.LogCreateLocalRef (r);
return r;
}

RawExceptionClear (info.EnvironmentPointer);
var javaName = NewJavaNameFromUtf8 (info.EnvironmentPointer, classname);
try {
if (TryLoadClassWithFallback (info, thrown, javaName, throwOnError, out var result))
return result;
} finally {
JniObjectReference.Dispose (ref javaName);
}
if (!throwOnError)
return default;

var errorClassName = terminator >= 0
? Encoding.UTF8.GetString (classname.Slice (0, terminator))
: Encoding.UTF8.GetString (classname);
throw new InvalidOperationException ($"Could not find Java class '{errorClassName}'.");
}
#endif // FEATURE_JNIENVIRONMENT_JI_FUNCTION_POINTERS
}
Expand Down