Bug 1402550 - Enable saving an .eml file directly. r=mkmelin

- Fix `cmd_saveAsFile` for .eml files that have just been opened from the file system.
- Disable `cmd_saveAsTemplate` when such a message is displayed.
- When an attached .eml file is opened, try to preserve the filename in the URI (see bug 927640)

Based on https://github.com/Betterbird/thunderbird-patches/blob/main/128/bugs/927640-1402550-fix-saving-eml.patch, which is itself based on SeaMonkey code.

Differential Revision: https://phabricator.services.mozilla.com/D220719

--HG--
extra : amend_source : 5ffbc0fa2887431b173420fcbc7399ab72b76b55

mail/base/content/mailCommands.js

@@ -484,10 +484,33 @@ function SubscribeOKCallback(changeTable) {
   }
 }
 
+/**
+ * Save as file.
+ *
+ * @param {string[]} uris - URIs of files to save.
+ */
 function SaveAsFile(uris) {
   const filenames = [];
 
   for (const uri of uris) {
+    // Save an .eml files directly from its URL.
+    if (/type=application\/x-message-display$/.test(uri)) {
+      top.saveURL(
+        uri, // URL
+        null, // originalURL
+        "", // fileName (ignored)
+        null, // filePickerTitleKey
+        true, // shouldBypassCache
+        false, // skipPrompt
+        null, // referrerInfo
+        null, // cookieJarSettings
+        document, // sourceDocument
+        null, // isContentWindowPrivate,
+        Services.scriptSecurityManager.getSystemPrincipal() // principal
+      );
+      return;
+    }
+
     const msgHdr =
       MailServices.messageServiceFromURI(uri).messageURIToMsgHdr(uri);
     const nameBase = GenerateFilenameFromMsgHdr(msgHdr);

mail/base/content/mailCommon.js

@@ -537,8 +537,9 @@ var commandController = {
         }
         return false;
       case "cmd_viewPageSource":
-      case "cmd_saveAsTemplate":
         return numSelectedMessages == 1;
+      case "cmd_saveAsTemplate":
+        return numSelectedMessages == 1 && !isDummyMessage;
       case "cmd_reply":
       case "cmd_replySender":
       case "cmd_replyall":

mail/modules/AttachmentInfo.sys.mjs

@@ -242,7 +242,16 @@ export class AttachmentInfo {
         let tempFile = this.#temporaryFiles.get(url);
         if (!tempFile?.exists()) {
           tempFile = Services.dirsvc.get("TmpD", Ci.nsIFile);
-          tempFile.append("subPart.eml");
+          // Try to use the name of the attachment for the temporary file, so
+          // that the name is included in the URI of the message that is
+          // opened, and possibly saved as a file later by the user.
+          let sanitizedName = lazy.DownloadPaths.sanitize(this.name);
+          if (!sanitizedName) {
+            sanitizedName = "message.eml";
+          } else if (!/\.eml$/i.test(sanitizedName)) {
+            sanitizedName += ".eml";
+          }
+          tempFile.append(sanitizedName);
           tempFile.createUnique(0, 0o600);
           await saveToFile(tempFile.path, true);
 

mail/test/browser/composition/browser_emlActions.js

@@ -202,6 +202,57 @@ add_task(async function test_forward_eml_catchall() {
   await BrowserTestUtils.closeWindow(msgc); // close base .eml message
 });
 
+/**
+ * Test that saving an .eml opened from a file works.
+ */
+add_task(async function test_save_eml_as_file() {
+  const file = new FileUtils.File(getTestFilePath("data/testmsg.eml"));
+  const msgc = await open_message_from_file(file);
+  const pickerPromise = new Promise(resolve => {
+    SpecialPowers.MockFilePicker.init(window.browsingContext);
+    SpecialPowers.MockFilePicker.showCallback = picker => {
+      resolve(picker.defaultString);
+      return Ci.nsIFilePicker.returnOK;
+    };
+  });
+  EventUtils.synthesizeKey("s", { accelKey: true }, msgc);
+  Assert.equal(await pickerPromise, "testmsg.eml");
+  SpecialPowers.MockFilePicker.cleanup();
+  await BrowserTestUtils.closeWindow(msgc);
+});
+
+/**
+ * Test that an attached .eml that has been opened retains the correct filename
+ * when it is subsequently saved.
+ */
+add_task(async function test_save_eml_as_file() {
+  const file = new FileUtils.File(getTestFilePath("data/testmsg-nested.eml"));
+  const msgc = await open_message_from_file(file);
+  const aboutMessage = get_about_message(msgc);
+  const newWindowPromise = promise_new_window("mail:messageWindow");
+  await EventUtils.synthesizeMouseAtCenter(
+    aboutMessage.document.getElementById("attachmentName"),
+    {},
+    aboutMessage
+  );
+  const msgc2 = await newWindowPromise;
+  const pickerPromise = new Promise(resolve => {
+    SpecialPowers.MockFilePicker.init(window.browsingContext);
+    SpecialPowers.MockFilePicker.showCallback = picker => {
+      resolve(picker.defaultString);
+      return Ci.nsIFilePicker.returnOK;
+    };
+  });
+  EventUtils.synthesizeKey("s", { accelKey: true }, msgc2);
+  Assert.ok(
+    /that's why(-(\d)+)?\.eml/.test(await pickerPromise),
+    "Correct filename"
+  );
+  SpecialPowers.MockFilePicker.cleanup();
+  await BrowserTestUtils.closeWindow(msgc2);
+  await BrowserTestUtils.closeWindow(msgc);
+});
+
 /**
  * Test that clicking on a 'mailto:' link in an .eml opens a compose window.
  */

mail/test/browser/composition/data/testmsg-nested.eml

@@ -0,0 +1,40 @@
+Content-Type: multipart/mixed; boundary="------------86SaFvMNv7NcfmcG7KkR6fEI"
+Message-ID: <69bfee4a-e114-4e84-8c4b-6dc7a983a58a@example.com>
+Date: Tue, 3 Sep 2024 17:15:35 +0200
+MIME-Version: 1.0
+User-Agent: Mozilla Thunderbird
+From: Marge <marge@example.com>
+Subject: that's why
+To: Homer <homer@example.com>
+Content-Language: en-US
+
+This is a multi-part message in MIME format.
+--------------86SaFvMNv7NcfmcG7KkR6fEI
+Content-Type: text/plain; charset=UTF-8; format=flowed
+Content-Transfer-Encoding: 7bit
+
+
+--------------86SaFvMNv7NcfmcG7KkR6fEI
+Content-Type: message/rfc822; name=that's why.eml"
+Content-Disposition: attachment; filename="that's why.eml"
+Content-Transfer-Encoding: 7bit
+
+Return-Path: <homer@example.com>
+Received: from smtp.example.com (smtpu [10.0.0.52])
+	 by storage (Cyrus v2.3.7-Invoca-RPM-2.3.7-1.1) with LMTPA;
+	 Mon, 26 Dec 2011 20:49:16 +0200
+Message-ID: <4EF8C1A5.1060708@example.com>
+Date: Mon, 26 Dec 2011 20:49:09 +0200
+From: Homer <homer@example.com>
+MIME-Version: 1.0
+To: Marge <marge@example.com>
+Subject: why
+Content-Type: text/plain; charset=UTF-8; format=flowed
+Content-Transfer-Encoding: 7bit
+
+Because they're stupid, that's why. That's why everybody does everything!
+
+ -Homer
+
+
+--------------86SaFvMNv7NcfmcG7KkR6fEI--