ppkarwasz commented on code in PR #781:
URL: https://github.com/apache/commons-io/pull/781#discussion_r2328576906
##########
src/main/java/org/apache/commons/io/FileSystem.java:
##########
@@ -624,75 +631,102 @@ CharSequence trimExtension(final CharSequence cs) {
return index < 0 ? cs : cs.subSequence(0, index);
}
- private boolean isLegalFileLength(final CharSequence candidate, final
Charset charset) {
- if (candidate == null || candidate.length() == 0) {
- return false;
- }
- if (lengthUnit == LengthUnit.CHARS) {
- return candidate.length() <= getMaxFileNameLength();
- }
- final CharsetEncoder encoder = charset.newEncoder();
- try {
- final ByteBuffer buffer =
encoder.encode(CharBuffer.wrap(candidate));
- return buffer.remaining() <= getMaxFileNameLength();
- } catch (CharacterCodingException e) {
- // If we can't encode, it's not legal
- return false;
- }
- }
+ /**
+ * Strategy for measuring and truncating file or path names in different
units.
+ * Implementations measure length and can truncate to a specified limit.
+ */
+ enum NameLengthStrategy {
+ /** Length measured as encoded bytes. */
+ BYTES {
+ @Override
+ int getLength(final CharSequence value, final Charset charset) {
+ final CharsetEncoder enc = charset.newEncoder()
+ .onMalformedInput(CodingErrorAction.REPORT)
+ .onUnmappableCharacter(CodingErrorAction.REPORT);
+ try {
+ return enc.encode(CharBuffer.wrap(value)).remaining();
+ } catch (CharacterCodingException e) {
+ // Unencodable ⇒ does not fit any byte limit.
+ return Integer.MAX_VALUE;
+ }
+ }
- CharSequence truncateFileName(final CharSequence candidate, final Charset
charset) {
- final int maxFileNameLength = getMaxFileNameLength();
- // Character-based limit: simple substring if needed.
- if (lengthUnit == LengthUnit.CHARS) {
- return candidate.length() <= maxFileNameLength ? candidate :
candidate.subSequence(0, maxFileNameLength);
- }
+ @Override
+ CharSequence truncate(final CharSequence value, final int limit,
final Charset charset) {
+ final CharsetEncoder encoder = charset.newEncoder()
+ .onMalformedInput(CodingErrorAction.REPORT)
+ .onUnmappableCharacter(CodingErrorAction.REPORT);
- // Byte-based limit
- return truncateByBytes(candidate, charset, maxFileNameLength);
- }
+ if (!encoder.canEncode(value)) {
+ throw new IllegalArgumentException(
+ "The value " + value + " cannot be encoded using "
+ charset.name());
+ }
- static CharSequence truncateByBytes(final CharSequence candidate, final
Charset charset, final int maxBytes) {
- // Byte-based limit
- final CharsetEncoder encoder = charset.newEncoder()
- .onMalformedInput(CodingErrorAction.REPORT)
- .onUnmappableCharacter(CodingErrorAction.REPORT);
+ // Fast path: if even the worst-case expansion fits, we're
done.
+ if (value.length() <= Math.floor(limit /
encoder.maxBytesPerChar())) {
+ return value;
+ }
- if (!encoder.canEncode(candidate)) {
- throw new IllegalArgumentException(
- "File name contains characters that cannot be encoded with
charset " + charset.name());
- }
+ // Slow path: encode into a fixed-size byte buffer.
+ final ByteBuffer out = ByteBuffer.allocate(limit);
+ final CharBuffer in = CharBuffer.wrap(value);
- // Fast path: if even the worst-case expansion fits, we're done.
- if (candidate.length() <= Math.floor(maxBytes /
encoder.maxBytesPerChar())) {
- return candidate;
- }
+ // Encode until the first character that would exceed the byte
budget.
+ final CoderResult cr = encoder.encode(in, out, true);
+
+ if (cr.isUnderflow()) {
+ // Entire candidate fit within maxFileNameLength bytes.
+ return value;
+ }
- // Slow path: encode into a fixed-size byte buffer.
- final ByteBuffer out = ByteBuffer.allocate(maxBytes);
- final CharBuffer in = CharBuffer.wrap(candidate);
+ // We ran out of space mid-encode: truncate BEFORE the
offending character.
+ return value.subSequence(0, in.position());
+ }
+ },
- // Encode until the first character that would exceed the byte budget.
- final CoderResult cr = encoder.encode(in, out, true);
+ /** Length measured as UTF-16 code units (i.e., {@code
CharSequence.length()}). */
+ UTF16_CHARS {
+ @Override
+ int getLength(final CharSequence value, final Charset charset) {
+ return value.length();
+ }
- if (cr.isUnderflow()) {
- // Entire candidate fit within maxFileNameLength bytes.
- return candidate;
+ @Override
+ CharSequence truncate(final CharSequence value, final int limit,
final Charset charset) {
+ return value.length() <= limit ? value : value.subSequence(0,
limit);
+ }
+ };
+
+ /**
+ * Gets the measured length in this strategy’s unit.
+ *
+ * @param value The value to measure, not null.
+ * @param charset The charset to use when measuring in bytes.
+ * @return The length in this strategy’s unit.
+ */
+ abstract int getLength(CharSequence value, Charset charset);
+
+ /**
+ * Tests if the measured length is less or equal the {@code limit}.
+ *
+ * @param value The value to measure, not null.
+ * @param limit The limit to compare to.
+ * @param charset The charset to use when measuring in bytes.
+ * @return {@code true} if the measured length is less or equal the
{@code limit}, {@code false} otherwise.
+ */
+ final boolean isWithinLimit(final CharSequence value, final int limit,
final Charset charset) {
+ return getLength(value, charset) <= limit;
}
- // We ran out of space mid-encode: truncate BEFORE the offending
character.
- return candidate.subSequence(0, in.position());
+ /**
+ * Truncates to {@code limit} in this strategy’s unit (no-op if
already within limit).
+ *
+ * @param value The value to truncate, not null.
+ * @param limit The limit to truncate to.
+ * @param charset The charset to use when measuring in bytes.
+ * @return The truncated value, not null.
+ */
+ abstract CharSequence truncate(CharSequence value, int limit, Charset
charset);
Review Comment:
Good point, I will fix it.
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