Tencent/tinker · error · IllegalArgumentException

Comment too long: {} bytes

Error message

Comment too long: {} bytes

What it means

The zip end-of-central-directory record stores the archive comment length in 16 bits, so a comment whose UTF-8 encoding is 65,536 bytes or more cannot be written. setComment encodes immediately and throws IllegalArgumentException when newCommentBytes.length > 0xffff, failing fast rather than producing a truncated comment field.

Source

Thrown at third-party/tinker-ziputils/src/main/java/com/tencent/tinker/ziputils/ziputil/AlignedZipOutputStream.java:397

        if (currentEntry.getExtra() != null) {
            out.write(currentEntry.getExtra());
        }
        makePaddingToStream(out, padding);
    }

    /**
     * Sets the comment associated with the file being written.
     * @throws IllegalArgumentException if the comment is >= 64 Ki UTF-8 bytes.
     */
    public void setComment(String comment) {
        if (comment == null) {
            this.commentBytes = null;
            return;
        }

        byte[] newCommentBytes = comment.getBytes(Charset.forName("UTF-8"));
        if (newCommentBytes.length > 0xffff) {
            throw new IllegalArgumentException("Comment too long: " + newCommentBytes.length + " bytes");
        }
        this.commentBytes = newCommentBytes;
    }

    /**
     * Sets the <a href="Deflater.html#compression_level">compression level</a> to be used
     * for writing entry data.
     */
    public void setLevel(int level) {
        if (level < Deflater.DEFAULT_COMPRESSION || level > Deflater.BEST_COMPRESSION) {
            throw new IllegalArgumentException("Bad level: " + level);
        }
        compressionLevel = level;
    }

    /**
     * Sets the default compression method to be used when a {@code ZipEntry} doesn't
     * explicitly specify a method. See {@link ZipEntry#setMethod} for more details.

View on GitHub (pinned to 1b7ea02c23)

Solutions

1. Keep the comment under 65,535 UTF-8 bytes; enforce the limit where the comment string is assembled.
2. Move large metadata out of the comment into a dedicated zip entry (e.g. META-INF/metadata.json) with no size restrictions.
3. If the comment carries a signature/key block, shorten by hashing (store a digest plus a URL instead of full content).

Example fix

// before: stuffing arbitrary-length metadata into the comment
zos.setComment(buildMetadataJson()); // grows past 64Ki over time

// after: cap the comment and move bulk metadata to an entry
byte[] meta = buildMetadataJson();
if (meta.length > 0xffff) {
    zos.putNextEntry(new ZipEntry("META-INF/metadata.json"));
    zos.write(meta);
    zos.closeEntry();
    zos.setComment("see META-INF/metadata.json");
} else {
    zos.setComment(new String(meta, StandardCharsets.UTF_8));
}

// Validate comment size before calling setComment
static String fitComment(String comment) {
    if (comment == null) return null;
    byte[] b = comment.getBytes(java.nio.charset.StandardCharsets.UTF_8);
    if (b.length > 0xffff) throw new IllegalArgumentException("comment too long: " + b.length + " bytes");
    return comment;
}

try {
    zos.setComment(comment);
} catch (IllegalArgumentException e) {
    if (e.getMessage() != null && e.getMessage().startsWith("Comment too long")) {
        zos.setComment(comment.substring(0, comment.length() / 2)); // or move to an entry
    } else {
        throw e;
    }
}

When it happens

Trigger: Calling setComment with a very long string — e.g. embedding a JSON metadata blob, build manifest, or log excerpt as the zip comment.

Common situations: Build pipelines that stuff patch metadata (file lists, hashes, signatures) into the APK/zip comment and grow past 64Ki over time; multi-byte content (CJK) halving the effective character budget; copying a comment from another tool that allowed larger comments via Zip64 extensible records.

Related errors

• Name too long: {} UTF-8 bytes
• Expected ${DEX_IN_JAR_NAME} in ${file}
• CRC mismatch
• Size mismatch
• Entry already exists: {}

AI-assisted analysis of Tencent/tinker@1b7ea02c23 (2026-08-14). Data as JSON: /api/errors/c0c704cc93aa7165. Report an issue: GitHub.