mailinfo: correctly handle multiline 'Subject:' header

When native language (RU) is in use, subject header usually contains several
parts, e.g.

Subject: [Navy-patches] [PATCH]
	=?utf-8?b?0JjQt9C80LXQvdGR0L0g0YHQv9C40YHQvtC6INC/0LA=?=
	=?utf-8?b?0LrQtdGC0L7QsiDQvdC10L7QsdGF0L7QtNC40LzRi9GFINC00LvRjyA=?=
	=?utf-8?b?0YHQsdC+0YDQutC4?=

This exposes several bugs in builtin-mailinfo.c:

1. decode_b_segment: do not append explicit NUL -- explicit NUL was preventing
   correct header construction on parts concatenation via strbuf_addbuf in
   decode_header_bq.  Fixes:

-Subject: Изменён список пакетов необходимых для сборки
+Subject: Изменён список па

Then

2. Do not emit '\n' between "encoded-word" where RFC2046 says that linear
   white space between them are ignored when displaying.  Fixes:

-Subject: Изменён список пакетов необходимых для сборки
+Subject: Изменён список па кетов необходимых для сборки

Signed-off-by: Kirill Smelkov <kirr@mns.spb.ru>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

6 files changed, 114 insertions, 9 deletions

diff --git a/builtin-mailinfo.c b/builtin-mailinfo.c
index e890f7a6d1..fcb32c9818 100644
--- a/builtin-mailinfo.c
+++ b/builtin-mailinfo.c
@@ -430,13 +430,6 @@ static struct strbuf *decode_b_segment(const struct strbuf *b_seg)
 			c -= 'a' - 26;
 		else if ('0' <= c && c <= '9')
 			c -= '0' - 52;
-		else if (c == '=') {
-			/* padding is almost like (c == 0), except we do
-			 * not output NUL resulting only from it;
-			 * for now we just trust the data.
-			 */
-			c = 0;
-		}
 		else
 			continue; /* garbage */
 		switch (pos++) {
@@ -514,7 +507,25 @@ static int decode_header_bq(struct strbuf *it)
 		rfc2047 = 1;
 
 		if (in != ep) {
-			strbuf_add(&outbuf, in, ep - in);
+			/*
+			 * We are about to process an encoded-word
+			 * that begins at ep, but there is something
+			 * before the encoded word.
+			 */
+			char *scan;
+			for (scan = in; scan < ep; scan++)
+				if (!isspace(*scan))
+					break;
+
+			if (scan != ep || in == it->buf) {
+				/*
+				 * We should not lose that "something",
+				 * unless we have just processed an
+				 * encoded-word, and there is only LWS
+				 * before the one we are about to process.
+				 */
+				strbuf_add(&outbuf, in, ep - in);
+			}
 			in = ep;
 		}
 		/* E.g.
diff --git a/t/t5100-mailinfo.sh b/t/t5100-mailinfo.sh
index 198e3503d5..886d44910d 100755
--- a/t/t5100-mailinfo.sh
+++ b/t/t5100-mailinfo.sh
@@ -11,7 +11,7 @@ test_expect_success 'split sample box' \
 	'git mailsplit -o. ../t5100/sample.mbox >last &&
 	last=`cat last` &&
 	echo total is $last &&
-	test `cat last` = 11'
+	test `cat last` = 12'
 
 for mail in `echo 00*`
 do
diff --git a/t/t5100/info0012 b/t/t5100/info0012
new file mode 100644
index 0000000000..ac1216ff75
--- /dev/null
+++ b/t/t5100/info0012
@@ -0,0 +1,5 @@
+Author: Dmitriy Blinov
+Email: bda@mnsspb.ru
+Subject: Изменён список пакетов необходимых для сборки
+Date: Wed, 12 Nov 2008 17:54:41 +0300
+
diff --git a/t/t5100/msg0012 b/t/t5100/msg0012
new file mode 100644
index 0000000000..1dc2bf7f7f
--- /dev/null
+++ b/t/t5100/msg0012
@@ -0,0 +1,7 @@
+textlive-* исправлены на texlive-*
+docutils заменён на python-docutils
+
+Действительно, оказалось, что rest2web вытягивает за собой
+python-docutils. В то время как сам rest2web не нужен.
+
+Signed-off-by: Dmitriy Blinov <bda@mnsspb.ru>
diff --git a/t/t5100/patch0012 b/t/t5100/patch0012
new file mode 100644
index 0000000000..36a0b68161
--- /dev/null
+++ b/t/t5100/patch0012
@@ -0,0 +1,30 @@
+---
+ howto/build_navy.txt |    6 +++---
+ 1 files changed, 3 insertions(+), 3 deletions(-)
+
+diff --git a/howto/build_navy.txt b/howto/build_navy.txt
+index 3fd3afb..0ee807e 100644
+--- a/howto/build_navy.txt
++++ b/howto/build_navy.txt
+@@ -119,8 +119,8 @@
+    - libxv-dev
+    - libusplash-dev
+    - latex-make
+-   - textlive-lang-cyrillic
+-   - textlive-latex-extra
++   - texlive-lang-cyrillic
++   - texlive-latex-extra
+    - dia
+    - python-pyrex
+    - libtool
+@@ -128,7 +128,7 @@
+    - sox
+    - cython
+    - imagemagick
+-   - docutils
++   - python-docutils
+ 
+ #. на машине dinar: добавить свой открытый ssh-ключ в authorized_keys2 пользователя ddev
+ #. на своей машине: отредактировать /etc/sudoers (команда ``visudo``) примерно следующим образом::
+-- 
+1.5.6.5
diff --git a/t/t5100/sample.mbox b/t/t5100/sample.mbox
index 4bf7947b41..94da4daa1a 100644
--- a/t/t5100/sample.mbox
+++ b/t/t5100/sample.mbox
@@ -501,3 +501,55 @@ index 3e5fe51..aabfe5c 100644
 
 --=-=-=--
 
+From bda@mnsspb.ru Wed Nov 12 17:54:41 2008
+From: Dmitriy Blinov <bda@mnsspb.ru>
+To: navy-patches@dinar.mns.mnsspb.ru
+Date: Wed, 12 Nov 2008 17:54:41 +0300
+Message-Id: <1226501681-24923-1-git-send-email-bda@mnsspb.ru>
+X-Mailer: git-send-email 1.5.6.5
+MIME-Version: 1.0
+Content-Type: text/plain;
+  charset=utf-8
+Content-Transfer-Encoding: 8bit
+Subject: [Navy-patches] [PATCH]
+	=?utf-8?b?0JjQt9C80LXQvdGR0L0g0YHQv9C40YHQvtC6INC/0LA=?=
+	=?utf-8?b?0LrQtdGC0L7QsiDQvdC10L7QsdGF0L7QtNC40LzRi9GFINC00LvRjyA=?=
+	=?utf-8?b?0YHQsdC+0YDQutC4?=
+
+textlive-* исправлены на texlive-*
+docutils заменён на python-docutils
+
+Действительно, оказалось, что rest2web вытягивает за собой
+python-docutils. В то время как сам rest2web не нужен.
+
+Signed-off-by: Dmitriy Blinov <bda@mnsspb.ru>
+---
+ howto/build_navy.txt |    6 +++---
+ 1 files changed, 3 insertions(+), 3 deletions(-)
+
+diff --git a/howto/build_navy.txt b/howto/build_navy.txt
+index 3fd3afb..0ee807e 100644
+--- a/howto/build_navy.txt
++++ b/howto/build_navy.txt
+@@ -119,8 +119,8 @@
+    - libxv-dev
+    - libusplash-dev
+    - latex-make
+-   - textlive-lang-cyrillic
+-   - textlive-latex-extra
++   - texlive-lang-cyrillic
++   - texlive-latex-extra
+    - dia
+    - python-pyrex
+    - libtool
+@@ -128,7 +128,7 @@
+    - sox
+    - cython
+    - imagemagick
+-   - docutils
++   - python-docutils
+ 
+ #. на машине dinar: добавить свой открытый ssh-ключ в authorized_keys2 пользователя ddev
+ #. на своей машине: отредактировать /etc/sudoers (команда ``visudo``) примерно следующим образом::
+-- 
+1.5.6.5