JAMES-4172 Fix truncated downloads for non-SingleBody EmailBodyPart b…

[omerfarukicen]

https://issues.apache.org/jira/browse/JAMES-4172

In EmailBodyPartBlob, the size and content methods used different calculation paths for non-SingleBody parts (e.g. message/rfc822):

• size relied on SizeUtils.sizeOf(entity) which returns the decoded size via SingleBody.size()
• content used DefaultMessageWriter.writeBody() which re-encodes the content (e.g. base64), producing more bytes than the decoded size

This mismatch caused Content-Length to be set smaller than the actual response body, resulting in truncated .eml downloads with missing attachments and MIME boundaries.

Fix by caching the written body bytes in a lazy val so that both size and content use the same data, ensuring Content-Length matches the actual stream length.

[quantranhong1999]

https://ci-builds.apache.org/job/james/job/ApacheJames/job/PR-2940/1/testReport/org.apache.james.jmap.rfc8621.memory/MemoryEmailParseMethodTest/parseShouldSuccessWhenAttachment_GuiceJamesServer_/

Related?

[chibenwa]

No strong objections

Let's fix the build and merge this.

[omerfarukicen]

The test parseShouldSuccessWhenAttachment fails because the size value changed from 797 to 807.

This is expected: the old code used SizeUtils.sizeOf(entity) which computes size via SingleBody.size() (decoded size), while the new code uses the actual byte count from DefaultMessageWriter.writeBody() (the real serialized size). The 10-byte difference comes from this discrepancy.

Since 807 reflects the true size of the written blob content (consistent with Content-Length and the actual download stream), I believe the test expectation should be updated to 807.

Shall I update the test to expect 807 instead of 797?

[chibenwa]

Shall I update the test to expect 807 instead of 797?

Likely yes!

[omerfarukicen]

Can you check pipeline process?

[chibenwa]

Hello
I retriggered a build but the test failure seems related
org.apache.james.jmap.rfc8621.memory.MemoryEmailParseMethodTest.parseShouldSuccessWhenAttachment(GuiceJamesServer)

[chibenwa]

JSON documents are different:
Different keys found in node "methodResponses[0][1].parsed.1_3", extra: "methodResponses[0][1].parsed.1_3.size",

"size":807 is expected...

expected: <{"attachments":[{"blobId":"1_3_3","charset":"UTF-8","disposition":"attachment","name":"whatever.txt","partId":"3","size":16,"type":"text/plain"}],"blobId":"1_3","bodyValues":{"2":{"isEncodingProblem":false,"isTruncated":false,"value":"test body
"}},"from":[{"email":"me@linagora.com","name":"Me ME"}],"hasAttachment":true,"headers":[{"name":"Return-Path","value":" me@linagora.com"}, {"name":"Delivered-To","value":" me@linagora.com"}, {"name":"Content-Type","value":" multipart/mixed; boundary="------------F6Ykx4Sf21a3Ovh9U5C4q1Qb""}, {"name":"Message-ID","value":" ed24d4ad-53c0-48c7-2fc9-39f762e4d98d@linagora.com"}, {"name":"Date","value":" Wed, 3 May 2023 07:36:49 +0700"}, {"name":"MIME-Version","value":" 1.0"}, {"name":"To","value":" Me ME me@linagora.com"}, {"name":"From","value":" Me ME me@linagora.com"}, {"name":"Subject","value":" test subject"}],"inReplyTo":null,"messageId":[ed24d4ad-53c0-48c7-2fc9-39f762e4d98d@linagora.com],"preview":"test body","references":null,"sentAt":"2023-05-03T00:36:49Z","subject":"test subject","to":[{"email":"me@linagora.com","name":"Me ME"}]}> but was: <{"attachments":[{"blobId":"1_3_3","charset":"UTF-8","disposition":"attachment","name":"whatever.txt","partId":"3","size":16,"type":"text/plain"}],"blobId":"1_3","bodyValues":{"2":{"isEncodingProblem":false,"isTruncated":false,"value":"test body
"}},"from":[{"email":"me@linagora.com","name":"Me ME"}],"hasAttachment":true,"headers":[{"name":"Return-Path","value":" me@linagora.com"}, {"name":"Delivered-To","value":" me@linagora.com"}, {"name":"Content-Type","value":" multipart/mixed; boundary="------------F6Ykx4Sf21a3Ovh9U5C4q1Qb""}, {"name":"Message-ID","value":" ed24d4ad-53c0-48c7-2fc9-39f762e4d98d@linagora.com"}, {"name":"Date","value":" Wed, 3 May 2023 07:36:49 +0700"}, {"name":"MIME-Version","value":" 1.0"}, {"name":"To","value":" Me ME me@linagora.com"}, {"name":"From","value":" Me ME me@linagora.com"}, {"name":"Subject","value":" test subject"}],"inReplyTo":null,"messageId":[ed24d4ad-53c0-48c7-2fc9-39f762e4d98d@linagora.com],"preview":"test body","references":null,"sentAt":"2023-05-03T00:36:49Z","size":807,"subject":"test subject","to":[{"email":"me@linagora.com","name":"Me ME"}]}>