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Fix MemoryMappedFileInputStream.read() returning values outside the unsigned byte range #875

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Merged
garydgregory merged 1 commit into from
Oct 25, 2026
+13 −1
Merged

Fix MemoryMappedFileInputStream.read() returning values outside the unsigned byte range #875

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2 changes: 1 addition & 1 deletion src/main/java/org/apache/commons/io/input/MemoryMappedFileInputStream.java
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Original file line number Diff line number Diff line change
Expand Up @@ -234,7 +234,7 @@ public int read() throws IOException {
return EOF;
}
}
return Short.toUnsignedInt(buffer.get());
return buffer.get() & 0xFF;
}

@Override
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12 changes: 12 additions & 0 deletions src/test/java/org/apache/commons/io/input/MemoryMappedFileInputStreamTest.java
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Original file line number Diff line number Diff line change
Expand Up @@ -211,6 +211,18 @@ void testReadAfterClose(final int len) throws Exception {
}
}

@Test
void testReadSingleByteIsUnsigned() throws IOException {
final byte[] expectedData = { 0x00, 0x01, 0x7F, (byte) 0x80, (byte) 0xAB, (byte) 0xFE, (byte) 0xFF };
final Path file = Files.write(Files.createTempFile(tempDir, null, null), expectedData);
try (InputStream inputStream = newInputStream(file, 4)) {
for (final byte expected : expectedData) {
assertEquals(expected & 0xFF, inputStream.read());
}
assertEquals(IOUtils.EOF, inputStream.read());
}
}

@Test
void testReadSingleByte() throws IOException {
// setup
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