[PATCH 4/4] cli/show: show repaired form of "Mixed Up" mangled messages

[Daniel Kahn Gillmor <dkg@fifthhorseman.net>]

When showing a message that has been mangled in transit by an MTA in
the "Mixed up" way, "notmuch show" should instead show the repaired
form of the message.

Tracking the repaired GMimeObject for the lifetime of the mime_node so
that it is cleaned up properly is probably the trickiest part of this
patch, but the choices here are based on the idea that the
mime_node_context is the memory manager for the whole mime_node tree
in the first place, so new GMimeObject tree created on-the-fly during
message parsing should be disposed of in the same place.

Signed-off-by: Daniel Kahn Gillmor <dkg@fifthhorseman.net>
---
 mime-node.c                   | 22 ++++++++++++++++++++++
 test/T351-pgpmime-mangling.sh |  1 -
 2 files changed, 22 insertions(+), 1 deletion(-)

diff --git a/mime-node.c b/mime-node.c
index 3492bcd0..cafe1537 100644
--- a/mime-node.c
+++ b/mime-node.c
@@ -36,6 +36,9 @@ typedef struct mime_node_context {
     GMimeMessage *mime_message;
     _notmuch_message_crypto_t *msg_crypto;
 
+    /* repaired/unmangled parts that will need to be cleaned up */
+    GSList *repaired_parts;
+
     /* Context provided by the caller. */
     _notmuch_crypto_t *crypto;
 } mime_node_context_t;
@@ -52,9 +55,20 @@ _mime_node_context_free (mime_node_context_t *res)
     if (res->stream)
 	g_object_unref (res->stream);
 
+    if (res->repaired_parts)
+	g_slist_free_full (res->repaired_parts, g_object_unref);
+
     return 0;
 }
 
+/* keep track of objects that need to be destroyed when the mime node
+   context goes away. */
+static void
+_mime_node_context_track_repaired_part (mime_node_context_t *ctx, GMimeObject *part) {
+    if (part)
+	ctx->repaired_parts = g_slist_prepend (ctx->repaired_parts, part);
+}
+
 const _notmuch_message_crypto_t*
 mime_node_get_message_crypto_status (mime_node_t *node)
 {
@@ -286,6 +300,14 @@ _mime_node_create (mime_node_t *parent, GMimeObject *part, int numchild)
     if (GMIME_IS_PART (part)) {
 	node->nchildren = 0;
     } else if (GMIME_IS_MULTIPART (part)) {
+	GMimeObject *repaired_part = _notmuch_repair_mixed_up_mangled (part);
+	if (repaired_part) {
+	    /* This was likely "Mixed Up" in transit!  We replace it
+	     * with the more likely-to-be-correct variant. */
+	    _mime_node_context_track_repaired_part (node->ctx, repaired_part);
+	    part = repaired_part;
+	    node->part = part;
+	}
 	node->nchildren = g_mime_multipart_get_count (GMIME_MULTIPART (part));
     } else if (GMIME_IS_MESSAGE_PART (part)) {
 	/* Promote part to an envelope and open it */
diff --git a/test/T351-pgpmime-mangling.sh b/test/T351-pgpmime-mangling.sh
index a20066e4..a613fe3e 100755
--- a/test/T351-pgpmime-mangling.sh
+++ b/test/T351-pgpmime-mangling.sh
@@ -7,7 +7,6 @@ add_gnupg_home
 add_email_corpus mangling
 
 test_begin_subtest "handle 'Mixed-Up' mangled PGP/MIME message"
-test_subtest_known_broken
 output=$(notmuch show --format=json --decrypt=true id:mixed-up@mangling.notmuchmail.org)
 test_json_nodes <<<"$output" \
                 'body:[0][0][0]["body"][0]["content"][1]["content"]="The password is \"abcd1234!\", please do not tell anyone.\n"'
-- 
2.20.1