vmime::text::createFromString() drops spaces if an 8-bit word is followed by a 7-bit word

[RichardSteele]

Following example

vmime::mailbox mailbox(vmime::text("Test München West", vmime::charsets::WINDOWS_1252), "test@example.com");
vmime::utility::outputStreamAdapter adapter(std::cout);
mailbox.generate(adapter);

gives as output

=?us-ascii?Q?Test_?= =?windows-1252?Q?M=FCnchen?= =?us-ascii?Q?West?=
  <test@example.com>

The first space between Test and München is encoded as an underscore along with the first word: Test_. The second space between München and West is encoded with neither of the two words and thus lost. Decoding the text results in Test MünchenWest instead of Test München West.

This is caused by the way vmime::text::createFromString() handles transitions between 7-bit and 8-bit words:

vmime/src/vmime/text.cpp

Lines 310 to 346 in 1a35bb6

	if (is8bit) {
	if (count && prevIs8bit) {
	// No need to create a new encoded word, just append
	// the current word to the previous one.
	shared_ptr <word> w = getWordAt(getWordCount() - 1);
	w->getBuffer() += " " + chunk;
	} else {
	if (count) {
	shared_ptr <word> w = getWordAt(getWordCount() - 1);
	w->getBuffer() += ' ';
	}
	appendWord(make_shared <word>(chunk, ch));
	prevIs8bit = true;
	++count;
	}
	} else {
	if (count && !prevIs8bit) {
	shared_ptr <word> w = getWordAt(getWordCount() - 1);
	w->getBuffer() += " " + chunk;
	} else {
	appendWord(make_shared <word>(chunk, charset(charsets::US_ASCII)));
	prevIs8bit = false;
	++count;
	}
	}

If an 8-bit word follows a 7-bit word, a space is appended to the previous word (lines 321 - 324). The opposite case of a 7-bit word following an 8-bit word misses this behaviour (lines 339- 345). Pull request #284 fixes this.

[jengelh]

A trivial fix is to just generate a single vmime::word — which is what most MUA (e.g. Alpine, Thunderbird) do anyway.

+++ b/src/vmime/text.cpp
@@ -273,6 +273,7 @@ void text::createFromString(const string& in, const charset& ch) {
 
        removeAllWords();
 
+#if 0
        // Check whether there is a recommended encoding for this charset.
        // If so, the whole buffer will be encoded. Else, the number of
        // 7-bit (ASCII) bytes in the input will be used to determine if
@@ -288,7 +289,9 @@ void text::createFromString(const string& in, const charset& ch) {
        // If there are "too much" non-ASCII chars, encode everything
        if (alwaysEncode || asciiPercent < 60) {  // less than 60% ASCII chars
 
+#endif
                appendWord(make_shared <word>(in, ch));
+#if 0
 
        // Else, only encode words which need it
        } else {
@@ -363,6 +366,7 @@ void text::createFromString(const string& in, const charset& ch) {
                        }
                }
        }
+#endif
 }