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Remove impossible UnsupportedEncodingException from Id3Decoder
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The list of charsets is already hard-coded, and using `Charset` types
ensures they will all be present at run-time, hence we will never
encounter an 'unsupported' charset.

PiperOrigin-RevId: 491324466
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@icbaker @rohitjoins
icbaker authored and rohitjoins committed Nov 29, 2022
1 parent 49c87f3 commit 5292e40
Showing 1 changed file with 46 additions and 58 deletions.
104 changes: 46 additions & 58 deletions libraries/extractor/src/main/java/androidx/media3/extractor/metadata/id3/Id3Decoder.java
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Original file line number Diff line number Diff line change
Expand Up @@ -26,9 +26,10 @@
import androidx.media3.extractor.metadata.MetadataInputBuffer;
import androidx.media3.extractor.metadata.SimpleMetadataDecoder;
import com.google.common.base.Ascii;
import com.google.common.base.Charsets;
import com.google.common.collect.ImmutableList;
import java.io.UnsupportedEncodingException;
import java.nio.ByteBuffer;
import java.nio.charset.Charset;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
Expand Down Expand Up @@ -436,30 +437,25 @@ private static Id3Frame decodeFrame(
+ frameSize);
}
return frame;
} catch (UnsupportedEncodingException e) {
Log.w(TAG, "Unsupported character encoding");
return null;
} finally {
id3Data.setPosition(nextFramePosition);
}
}

@Nullable
private static TextInformationFrame decodeTxxxFrame(ParsableByteArray id3Data, int frameSize)
throws UnsupportedEncodingException {
private static TextInformationFrame decodeTxxxFrame(ParsableByteArray id3Data, int frameSize) {
if (frameSize < 1) {
// Frame is malformed.
return null;
}

int encoding = id3Data.readUnsignedByte();
String charset = getCharsetName(encoding);

byte[] data = new byte[frameSize - 1];
id3Data.readBytes(data, 0, frameSize - 1);

int descriptionEndIndex = indexOfTerminator(data, 0, encoding);
String description = new String(data, 0, descriptionEndIndex, charset);
String description = new String(data, 0, descriptionEndIndex, getCharset(encoding));

ImmutableList<String> values =
decodeTextInformationFrameValues(
Expand All @@ -469,7 +465,7 @@ private static TextInformationFrame decodeTxxxFrame(ParsableByteArray id3Data, i

@Nullable
private static TextInformationFrame decodeTextInformationFrame(
ParsableByteArray id3Data, int frameSize, String id) throws UnsupportedEncodingException {
ParsableByteArray id3Data, int frameSize, String id) {
if (frameSize < 1) {
// Frame is malformed.
return null;
Expand All @@ -485,17 +481,17 @@ private static TextInformationFrame decodeTextInformationFrame(
}

private static ImmutableList<String> decodeTextInformationFrameValues(
byte[] data, final int encoding, final int index) throws UnsupportedEncodingException {
byte[] data, final int encoding, final int index) {
if (index >= data.length) {
return ImmutableList.of("");
}

ImmutableList.Builder<String> values = ImmutableList.builder();
String charset = getCharsetName(encoding);
int valueStartIndex = index;
int valueEndIndex = indexOfTerminator(data, valueStartIndex, encoding);
while (valueStartIndex < valueEndIndex) {
String value = new String(data, valueStartIndex, valueEndIndex - valueStartIndex, charset);
String value =
new String(data, valueStartIndex, valueEndIndex - valueStartIndex, getCharset(encoding));
values.add(value);

valueStartIndex = valueEndIndex + delimiterLength(encoding);
Expand All @@ -507,64 +503,60 @@ private static ImmutableList<String> decodeTextInformationFrameValues(
}

@Nullable
private static UrlLinkFrame decodeWxxxFrame(ParsableByteArray id3Data, int frameSize)
throws UnsupportedEncodingException {
private static UrlLinkFrame decodeWxxxFrame(ParsableByteArray id3Data, int frameSize) {
if (frameSize < 1) {
// Frame is malformed.
return null;
}

int encoding = id3Data.readUnsignedByte();
String charset = getCharsetName(encoding);

byte[] data = new byte[frameSize - 1];
id3Data.readBytes(data, 0, frameSize - 1);

int descriptionEndIndex = indexOfTerminator(data, 0, encoding);
String description = new String(data, 0, descriptionEndIndex, charset);
String description = new String(data, 0, descriptionEndIndex, getCharset(encoding));

int urlStartIndex = descriptionEndIndex + delimiterLength(encoding);
int urlEndIndex = indexOfZeroByte(data, urlStartIndex);
String url = decodeStringIfValid(data, urlStartIndex, urlEndIndex, "ISO-8859-1");
String url = decodeStringIfValid(data, urlStartIndex, urlEndIndex, Charsets.ISO_8859_1);

return new UrlLinkFrame("WXXX", description, url);
}

private static UrlLinkFrame decodeUrlLinkFrame(
ParsableByteArray id3Data, int frameSize, String id) throws UnsupportedEncodingException {
ParsableByteArray id3Data, int frameSize, String id) {
byte[] data = new byte[frameSize];
id3Data.readBytes(data, 0, frameSize);

int urlEndIndex = indexOfZeroByte(data, 0);
String url = new String(data, 0, urlEndIndex, "ISO-8859-1");
String url = new String(data, 0, urlEndIndex, Charsets.ISO_8859_1);

return new UrlLinkFrame(id, null, url);
}

private static PrivFrame decodePrivFrame(ParsableByteArray id3Data, int frameSize)
throws UnsupportedEncodingException {
private static PrivFrame decodePrivFrame(ParsableByteArray id3Data, int frameSize) {
byte[] data = new byte[frameSize];
id3Data.readBytes(data, 0, frameSize);

int ownerEndIndex = indexOfZeroByte(data, 0);
String owner = new String(data, 0, ownerEndIndex, "ISO-8859-1");
String owner = new String(data, 0, ownerEndIndex, Charsets.ISO_8859_1);

int privateDataStartIndex = ownerEndIndex + 1;
byte[] privateData = copyOfRangeIfValid(data, privateDataStartIndex, data.length);

return new PrivFrame(owner, privateData);
}

private static GeobFrame decodeGeobFrame(ParsableByteArray id3Data, int frameSize)
throws UnsupportedEncodingException {
private static GeobFrame decodeGeobFrame(ParsableByteArray id3Data, int frameSize) {
int encoding = id3Data.readUnsignedByte();
String charset = getCharsetName(encoding);
Charset charset = getCharset(encoding);

byte[] data = new byte[frameSize - 1];
id3Data.readBytes(data, 0, frameSize - 1);

int mimeTypeEndIndex = indexOfZeroByte(data, 0);
String mimeType = new String(data, 0, mimeTypeEndIndex, "ISO-8859-1");
String mimeType = new String(data, 0, mimeTypeEndIndex, Charsets.ISO_8859_1);

int filenameStartIndex = mimeTypeEndIndex + 1;
int filenameEndIndex = indexOfTerminator(data, filenameStartIndex, encoding);
Expand All @@ -582,10 +574,9 @@ private static GeobFrame decodeGeobFrame(ParsableByteArray id3Data, int frameSiz
}

private static ApicFrame decodeApicFrame(
ParsableByteArray id3Data, int frameSize, int majorVersion)
throws UnsupportedEncodingException {
ParsableByteArray id3Data, int frameSize, int majorVersion) {
int encoding = id3Data.readUnsignedByte();
String charset = getCharsetName(encoding);
Charset charset = getCharset(encoding);

byte[] data = new byte[frameSize - 1];
id3Data.readBytes(data, 0, frameSize - 1);
Expand All @@ -594,13 +585,13 @@ private static ApicFrame decodeApicFrame(
int mimeTypeEndIndex;
if (majorVersion == 2) {
mimeTypeEndIndex = 2;
mimeType = "image/" + Ascii.toLowerCase(new String(data, 0, 3, "ISO-8859-1"));
mimeType = "image/" + Ascii.toLowerCase(new String(data, 0, 3, Charsets.ISO_8859_1));
if ("image/jpg".equals(mimeType)) {
mimeType = "image/jpeg";
}
} else {
mimeTypeEndIndex = indexOfZeroByte(data, 0);
mimeType = Ascii.toLowerCase(new String(data, 0, mimeTypeEndIndex, "ISO-8859-1"));
mimeType = Ascii.toLowerCase(new String(data, 0, mimeTypeEndIndex, Charsets.ISO_8859_1));
if (mimeType.indexOf('/') == -1) {
mimeType = "image/" + mimeType;
}
Expand All @@ -621,15 +612,14 @@ private static ApicFrame decodeApicFrame(
}

@Nullable
private static CommentFrame decodeCommentFrame(ParsableByteArray id3Data, int frameSize)
throws UnsupportedEncodingException {
private static CommentFrame decodeCommentFrame(ParsableByteArray id3Data, int frameSize) {
if (frameSize < 4) {
// Frame is malformed.
return null;
}

int encoding = id3Data.readUnsignedByte();
String charset = getCharsetName(encoding);
Charset charset = getCharset(encoding);

byte[] data = new byte[3];
id3Data.readBytes(data, 0, 3);
Expand All @@ -654,13 +644,15 @@ private static ChapterFrame decodeChapterFrame(
int majorVersion,
boolean unsignedIntFrameSizeHack,
int frameHeaderSize,
@Nullable FramePredicate framePredicate)
throws UnsupportedEncodingException {
@Nullable FramePredicate framePredicate) {
int framePosition = id3Data.getPosition();
int chapterIdEndIndex = indexOfZeroByte(id3Data.getData(), framePosition);
String chapterId =
new String(
id3Data.getData(), framePosition, chapterIdEndIndex - framePosition, "ISO-8859-1");
id3Data.getData(),
framePosition,
chapterIdEndIndex - framePosition,
Charsets.ISO_8859_1);
id3Data.setPosition(chapterIdEndIndex + 1);

int startTime = id3Data.readInt();
Expand Down Expand Up @@ -695,13 +687,15 @@ private static ChapterTocFrame decodeChapterTOCFrame(
int majorVersion,
boolean unsignedIntFrameSizeHack,
int frameHeaderSize,
@Nullable FramePredicate framePredicate)
throws UnsupportedEncodingException {
@Nullable FramePredicate framePredicate) {
int framePosition = id3Data.getPosition();
int elementIdEndIndex = indexOfZeroByte(id3Data.getData(), framePosition);
String elementId =
new String(
id3Data.getData(), framePosition, elementIdEndIndex - framePosition, "ISO-8859-1");
id3Data.getData(),
framePosition,
elementIdEndIndex - framePosition,
Charsets.ISO_8859_1);
id3Data.setPosition(elementIdEndIndex + 1);

int ctocFlags = id3Data.readUnsignedByte();
Expand All @@ -713,7 +707,8 @@ private static ChapterTocFrame decodeChapterTOCFrame(
for (int i = 0; i < childCount; i++) {
int startIndex = id3Data.getPosition();
int endIndex = indexOfZeroByte(id3Data.getData(), startIndex);
children[i] = new String(id3Data.getData(), startIndex, endIndex - startIndex, "ISO-8859-1");
children[i] =
new String(id3Data.getData(), startIndex, endIndex - startIndex, Charsets.ISO_8859_1);
id3Data.setPosition(endIndex + 1);
}

Expand Down Expand Up @@ -792,23 +787,18 @@ private static int removeUnsynchronization(ParsableByteArray data, int length) {
return length;
}

/**
* Maps encoding byte from ID3v2 frame to a Charset.
*
* @param encodingByte The value of encoding byte from ID3v2 frame.
* @return Charset name.
*/
private static String getCharsetName(int encodingByte) {
/** Maps encoding byte from ID3v2 frame to a {@link Charset}. */
private static Charset getCharset(int encodingByte) {
switch (encodingByte) {
case ID3_TEXT_ENCODING_UTF_16:
return "UTF-16";
return Charsets.UTF_16;
case ID3_TEXT_ENCODING_UTF_16BE:
return "UTF-16BE";
return Charsets.UTF_16BE;
case ID3_TEXT_ENCODING_UTF_8:
return "UTF-8";
return Charsets.UTF_8;
case ID3_TEXT_ENCODING_ISO_8859_1:
default:
return "ISO-8859-1";
return Charsets.ISO_8859_1;
}
}

Expand Down Expand Up @@ -871,21 +861,19 @@ private static byte[] copyOfRangeIfValid(byte[] data, int from, int to) {

/**
* Returns a string obtained by decoding the specified range of {@code data} using the specified
* {@code charsetName}. An empty string is returned if the range is invalid.
* {@code charset}. An empty string is returned if the range is invalid.
*
* @param data The array from which to decode the string.
* @param from The start of the range.
* @param to The end of the range (exclusive).
* @param charsetName The name of the Charset to use.
* @param charset The {@link Charset} to use.
* @return The decoded string, or an empty string if the range is invalid.
* @throws UnsupportedEncodingException If the Charset is not supported.
*/
private static String decodeStringIfValid(byte[] data, int from, int to, String charsetName)
throws UnsupportedEncodingException {
private static String decodeStringIfValid(byte[] data, int from, int to, Charset charset) {
if (to <= from || to > data.length) {
return "";
}
return new String(data, from, to - from, charsetName);
return new String(data, from, to - from, charset);
}

private static final class Id3Header {
Expand Down

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