format-patch: wrap long header lines

Subject and identity headers may be arbitrarily long. In the
past, we just assumed that single-line headers would be
reasonably short. For multi-line subjects that we squish
into a single line, we just "pre-folded" the data in
pp_title_line by adding a newline and indentation.

There were two problems. One is that, although rare,
single-line messages can actually be longer than the
recommended line-length limits. The second is that the
pre-folding interacted badly with rfc2047 encoding, leading
to malformed headers.

Instead, let's stop pre-folding the subject lines, and just
fold everything based on length in add_rfc2047, whether
it is encoded or not.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/pretty.c b/pretty.c
index 85499347514ec3e1d62d6caa9f53b886c556e345..0e167f463f864ca5516d2d5cf7df8595226090d7 100644 (file)
--- a/pretty.c
+++ b/pretty.c
@@ -216,7 +216,15 @@ static int is_rfc2047_special(char ch)
 static void add_rfc2047(struct strbuf *sb, const char *line, int len,
                       const char *encoding)
 {
-       int i, last;
+       static const int max_length = 78; /* per rfc2822 */
+       int i;
+       int line_len;
+
+       /* How many bytes are already used on the current line? */
+       for (i = sb->len - 1; i >= 0; i--)
+               if (sb->buf[i] == '\n')
+                       break;
+       line_len = sb->len - (i+1);
 
        for (i = 0; i < len; i++) {
                int ch = line[i];
@@ -225,14 +233,21 @@ static void add_rfc2047(struct strbuf *sb, const char *line, int len,
                if ((i + 1 < len) && (ch == '=' && line[i+1] == '?'))
                        goto needquote;
        }
-       strbuf_add(sb, line, len);
+       strbuf_add_wrapped_bytes(sb, line, len, 0, 1, max_length - line_len);
        return;
 
 needquote:
        strbuf_grow(sb, len * 3 + strlen(encoding) + 100);
        strbuf_addf(sb, "=?%s?q?", encoding);
-       for (i = last = 0; i < len; i++) {
+       line_len += strlen(encoding) + 5; /* 5 for =??q? */
+       for (i = 0; i < len; i++) {
                unsigned ch = line[i] & 0xFF;
+
+               if (line_len >= max_length - 2) {
+                       strbuf_addf(sb, "?=\n =?%s?q?", encoding);
+                       line_len = strlen(encoding) + 5 + 1; /* =??q? plus SP */
+               }
+
                /*
                 * We encode ' ' using '=20' even though rfc2047
                 * allows using '_' for readability.  Unfortunately,
@@ -240,12 +255,14 @@ needquote:
                 * leave the underscore in place.
                 */
                if (is_rfc2047_special(ch) || ch == ' ') {
-                       strbuf_add(sb, line + last, i - last);
                        strbuf_addf(sb, "=%02X", ch);
-                       last = i + 1;
+                       line_len += 3;
+               }
+               else {
+                       strbuf_addch(sb, ch);
+                       line_len++;
                }
        }
-       strbuf_add(sb, line + last, len - last);
        strbuf_addstr(sb, "?=");
 }
 
@@ -1106,11 +1123,10 @@ void pp_title_line(enum cmit_fmt fmt,
                   const char *encoding,
                   int need_8bit_cte)
 {
-       const char *line_separator = (fmt == CMIT_FMT_EMAIL) ? "\n " : " ";
        struct strbuf title;
 
        strbuf_init(&title, 80);
-       *msg_p = format_subject(&title, *msg_p, line_separator);
+       *msg_p = format_subject(&title, *msg_p, " ");
 
        strbuf_grow(sb, title.len + 1024);
        if (subject) {

diff --git a/t/t4014-format-patch.sh b/t/t4014-format-patch.sh
index 027c13d52cd701ba28e3c5e29c5431acfccdad73..9c663677df0887cc09ce2c8277ec300e8de4eaaa 100755 (executable)
--- a/t/t4014-format-patch.sh
+++ b/t/t4014-format-patch.sh
@@ -709,4 +709,88 @@ test_expect_success TTY 'format-patch --stdout paginates' '
        test_path_is_missing .git/pager_used
 '
 
+test_expect_success 'format-patch handles multi-line subjects' '
+       rm -rf patches/ &&
+       echo content >>file &&
+       for i in one two three; do echo $i; done >msg &&
+       git add file &&
+       git commit -F msg &&
+       git format-patch -o patches -1 &&
+       grep ^Subject: patches/0001-one.patch >actual &&
+       echo "Subject: [PATCH] one two three" >expect &&
+       test_cmp expect actual
+'
+
+test_expect_success 'format-patch handles multi-line encoded subjects' '
+       rm -rf patches/ &&
+       echo content >>file &&
+       for i in en två tre; do echo $i; done >msg &&
+       git add file &&
+       git commit -F msg &&
+       git format-patch -o patches -1 &&
+       grep ^Subject: patches/0001-en.patch >actual &&
+       echo "Subject: [PATCH] =?UTF-8?q?en=20tv=C3=A5=20tre?=" >expect &&
+       test_cmp expect actual
+'
+
+M8="foo bar "
+M64=$M8$M8$M8$M8$M8$M8$M8$M8
+M512=$M64$M64$M64$M64$M64$M64$M64$M64
+cat >expect <<'EOF'
+Subject: [PATCH] foo bar foo bar foo bar foo bar foo bar foo bar foo bar foo
+ bar foo bar foo bar foo bar foo bar foo bar foo bar foo bar
+ foo bar foo bar foo bar foo bar foo bar foo bar foo bar foo
+ bar foo bar foo bar foo bar foo bar foo bar foo bar foo bar
+ foo bar foo bar foo bar foo bar foo bar foo bar foo bar foo
+ bar foo bar foo bar foo bar foo bar foo bar foo bar foo bar
+ foo bar foo bar foo bar foo bar foo bar foo bar foo bar foo
+ bar foo bar foo bar foo bar foo bar foo bar foo bar foo bar
+ foo bar foo bar foo bar foo bar
+EOF
+test_expect_success 'format-patch wraps extremely long headers (ascii)' '
+       echo content >>file &&
+       git add file &&
+       git commit -m "$M512" &&
+       git format-patch --stdout -1 >patch &&
+       sed -n "/^Subject/p; /^ /p; /^$/q" <patch >subject &&
+       test_cmp expect subject
+'
+
+M8="föö bar "
+M64=$M8$M8$M8$M8$M8$M8$M8$M8
+M512=$M64$M64$M64$M64$M64$M64$M64$M64
+cat >expect <<'EOF'
+Subject: [PATCH] =?UTF-8?q?f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6?=
+ =?UTF-8?q?=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6?=
+ =?UTF-8?q?=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6?=
+ =?UTF-8?q?=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6?=
+ =?UTF-8?q?=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6?=
+ =?UTF-8?q?=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6?=
+ =?UTF-8?q?=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6?=
+ =?UTF-8?q?=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6?=
+ =?UTF-8?q?=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6?=
+ =?UTF-8?q?=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6?=
+ =?UTF-8?q?=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6?=
+ =?UTF-8?q?=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6?=
+ =?UTF-8?q?=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6?=
+ =?UTF-8?q?=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6?=
+ =?UTF-8?q?=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6?=
+ =?UTF-8?q?=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6?=
+ =?UTF-8?q?=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6?=
+ =?UTF-8?q?=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6?=
+ =?UTF-8?q?=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6?=
+ =?UTF-8?q?=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6?=
+ =?UTF-8?q?=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6?=
+ =?UTF-8?q?=C3=B6=20bar=20f=C3=B6=C3=B6=20bar?=
+EOF
+test_expect_success 'format-patch wraps extremely long headers (rfc2047)' '
+       rm -rf patches/ &&
+       echo content >>file &&
+       git add file &&
+       git commit -m "$M512" &&
+       git format-patch --stdout -1 >patch &&
+       sed -n "/^Subject/p; /^ /p; /^$/q" <patch >subject &&
+       test_cmp expect subject
+'
+
 test_done