Bug 1576828 - Remove pref mailnews.p7m_subparts_external and related code/tests. r=mkmelin DONTBUILD

mailnews/mailnews.js

@@ -163,7 +163,6 @@ pref("mail.label_ascii_only_mail_as_us_ascii", false);
 pref("mail.file_attach_binary",             false);
 pref("mail.show_headers",                   1); // some
 pref("mailnews.p7m_external", false);          // S/MIME parts are not external (but inline decrypted).
-pref("mailnews.p7m_subparts_external", true);  // S/MIME child parts are external. Protect against efail.
 pref("mail.pane_config.dynamic",            0);
 pref("mail.addr_book.mapit_url.format", "chrome://messenger-region/locale/region.properties");
 pref("mail.addr_book.mapit_url.1.name", "chrome://messenger-region/locale/region.properties");

mailnews/mime/src/mimei.cpp

@@ -666,8 +666,7 @@ MimeObjectClass *mime_find_class(const char *content_type, MimeHeaders *hdrs,
     else if (!PL_strcasecmp(content_type, APPLICATION_XPKCS7_MIME) ||
              !PL_strcasecmp(content_type, APPLICATION_PKCS7_MIME)) {
 
-      if (Preferences::GetBool("mailnews.p7m_subparts_external", true) &&
-          opts->is_child) {
+      if (opts->is_child) {
         // We do not allow encrypted parts except as top level.
         // Allowing them would leak the plain text in case the part is
         // cleverly hidden and the decrypted content gets included in

mailnews/mime/test/unit/test_alternate_p7m_handling.js

@@ -40,10 +40,6 @@ function* worker(params) {
   let msgHdr = synSet.getMsgHdr(0);
 
   Services.prefs.setBoolPref("mailnews.p7m_external", params.all_external);
-  Services.prefs.setBoolPref(
-    "mailnews.p7m_subparts_external",
-    params.subparts_external
-  );
 
   MsgHdrToMimeMessage(msgHdr, null, function(aMsgHdr, aMimeMsg) {
     try {
@@ -61,18 +57,10 @@ function* worker(params) {
 
 var tests = [
   parameterizeTest(worker, [
-    { messages, all_external: false, subparts_external: false, count: 0 },
-  ]),
-  // We are only testing with a p7m attachment, so whether all parts or just subparts are
-  // made external yields the same result: one attachment which is not inlined.
-  parameterizeTest(worker, [
-    { messages, all_external: true, subparts_external: false, count: 1 },
+    { messages, all_external: false, count: 1 },
   ]),
   parameterizeTest(worker, [
-    { messages, all_external: false, subparts_external: true, count: 1 },
-  ]),
-  parameterizeTest(worker, [
-    { messages, all_external: true, subparts_external: true, count: 1 },
+    { messages, all_external: true, count: 1 },
   ]),
 ];