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package org.sufficientlysecure.keychain.operations;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.charset.Charset;
import java.nio.charset.CharsetDecoder;
import java.nio.charset.CoderResult;
import java.nio.charset.CodingErrorAction;
import android.content.ClipDescription;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
public class CharsetVerifier {
private final ByteBuffer bufWrap;
private final CharBuffer dummyOutput;
private final CharsetDecoder charsetDecoder;
private boolean isFinished;
private boolean isFaulty;
private boolean isGuessed;
private boolean isPossibleTextMimeType;
private boolean isTextMimeType;
private String charset;
public CharsetVerifier(@NonNull byte[] buf, String mimeType, @Nullable String charset) {
isPossibleTextMimeType = ClipDescription.compareMimeTypes(mimeType, "application/octet-stream")
|| ClipDescription.compareMimeTypes(mimeType, "application/x-download")
|| ClipDescription.compareMimeTypes(mimeType, "text/*");
if (!isPossibleTextMimeType) {
charsetDecoder = null;
bufWrap = null;
dummyOutput = null;
return;
}
isTextMimeType = ClipDescription.compareMimeTypes(mimeType, "text/*");
bufWrap = ByteBuffer.wrap(buf);
dummyOutput = CharBuffer.allocate(buf.length);
// the charset defaults to us-ascii, but we want to default to utf-8
if (charset == null || "us-ascii".equals(charset)) {
charset = "utf-8";
isGuessed = true;
} else {
isGuessed = false;
}
this.charset = charset;
charsetDecoder = Charset.forName(charset).newDecoder();
charsetDecoder.onMalformedInput(CodingErrorAction.REPORT);
charsetDecoder.onUnmappableCharacter(CodingErrorAction.REPORT);
charsetDecoder.reset();
}
public void write(int pos, int len) {
if (isFinished) {
throw new IllegalStateException("cannot write again after reading charset status!");
}
if (isFaulty || bufWrap == null) {
return;
}
bufWrap.rewind();
bufWrap.position(pos);
bufWrap.limit(len);
dummyOutput.rewind();
CoderResult result = charsetDecoder.decode(bufWrap, dummyOutput, false);
if (result.isError()) {
isFaulty = true;
}
}
private void finishIfNecessary() {
if (isFinished || isFaulty || bufWrap == null) {
return;
}
isFinished = true;
bufWrap.rewind();
bufWrap.limit(0);
dummyOutput.rewind();
CoderResult result = charsetDecoder.decode(bufWrap, dummyOutput, true);
if (result.isError()) {
isFaulty = true;
}
}
public boolean isCharsetFaulty() {
finishIfNecessary();
return isFaulty;
}
public boolean isCharsetGuessed() {
finishIfNecessary();
return isGuessed;
}
public String getCharset() {
finishIfNecessary();
if (!isPossibleTextMimeType || (isGuessed && isFaulty)) {
return null;
}
return charset;
}
public String getMaybeFaultyCharset() {
return charset;
}
public boolean isDefinitelyBinary() {
finishIfNecessary();
return !isTextMimeType && (!isPossibleTextMimeType || (isGuessed && isFaulty));
}
public boolean isProbablyText() {
return isTextMimeType || isPossibleTextMimeType && (!isGuessed || !isFaulty);
}
}
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