Re: [PATCH] format-patch: RFC 2047 says multi-octet character may not be split
From: Kirill Smelkov <hidden>
Date: 2016-06-15 22:56:20
Subsystem:
the rest · Maintainer:
Linus Torvalds
Possibly related (same subject, not in this thread)
- 2016-06-15 · Re: [PATCH] format-patch: RFC 2047 says multi-octet character may not be split · Kirill Smelkov <hidden>
- 2016-06-15 · Re: [PATCH] format-patch: RFC 2047 says multi-octet character may not be split · Kirill Smelkov <hidden>
- 2016-06-15 · [PATCH] format-patch: RFC 2047 says multi-octet character may not be split · Kirill Smelkov <hidden>
On Sat, Mar 09, 2013 at 07:27:23PM +0400, Kirill Smelkov wrote:
---- 8< ---- From: Kirill Smelkov <redacted> split
Sorry for the confusion...
---- 8< ----
From: Kirill Smelkov <redacted>
Even though an earlier attempt (bafc478..41dd00bad) cleaned
up RFC 2047 encoding, pretty.c::add_rfc2047() still decides
where to split the output line by going through the input
one byte at a time, and potentially splits a character in
the middle. A subject line may end up showing like this:
".... fö?? bar". (instead of ".... föö bar".)
if split incorrectly.
RFC 2047, section 5 (3) explicitly forbids such beaviour
Each 'encoded-word' MUST represent an integral number of
characters. A multi-octet character may not be split across
adjacent 'encoded- word's.
that means that e.g. for
Subject: .... föö bar
encoding
Subject: =?UTF-8?q?....=20f=C3=B6=C3=B6?=
=?UTF-8?q?=20bar?=
is correct, and
Subject: =?UTF-8?q?....=20f=C3=B6=C3?= <-- NOTE ö is broken here
=?UTF-8?q?=B6=20bar?=
is not, because "ö" character UTF-8 encoding C3 B6 is split here across
adjacent encoded words.
To fix the problem, make the loop grab one _character_ at a time and
determine its output length to see where to break the output line. Note
that this version only knows about UTF-8, but the logic to grab one
character is abstracted out in mbs_chrlen() function to make it possible
to extend it to other encodings with the help of iconv in the future.
(With help from Junio C Hamano [off-list ref])
Cc: Jan H. Schönherr <redacted>
Signed-off-by: Kirill Smelkov <redacted>
---
pretty.c | 34 ++++++++++++++++++++++------------
t/t4014-format-patch.sh | 27 ++++++++++++++-------------
utf8.c | 39 +++++++++++++++++++++++++++++++++++++++
utf8.h | 2 ++
4 files changed, 77 insertions(+), 25 deletions(-)
diff --git a/pretty.c b/pretty.c
index b57adef..41f04e6 100644
--- a/pretty.c
+++ b/pretty.c@@ -345,7 +345,7 @@ static int needs_rfc2047_encoding(const char *line, int len, return 0; } -static void add_rfc2047(struct strbuf *sb, const char *line, int len, +static void add_rfc2047(struct strbuf *sb, const char *line, size_t len, const char *encoding, enum rfc2047_type type) { static const int max_encoded_length = 76; /* per rfc2047 */
@@ -355,9 +355,22 @@ static void add_rfc2047(struct strbuf *sb, const char *line, int len, strbuf_grow(sb, len * 3 + strlen(encoding) + 100); strbuf_addf(sb, "=?%s?q?", encoding); line_len += strlen(encoding) + 5; /* 5 for =??q? */ - for (i = 0; i < len; i++) { - unsigned ch = line[i] & 0xFF; - int is_special = is_rfc2047_special(ch, type); + + while (len) { + /* + * RFC 2047, section 5 (3): + * + * Each 'encoded-word' MUST represent an integral number of + * characters. A multi-octet character may not be split across + * adjacent 'encoded- word's. + */ + const unsigned char *p = (const unsigned char *)line; + int chrlen = mbs_chrlen(&line, &len, encoding); + int is_special = (chrlen > 1) || is_rfc2047_special(*p, type); + + /* "=%02X" * chrlen, or the byte itself */ + const char *encoded_fmt = is_special ? "=%02X" : "%c"; + int encoded_len = is_special ? 3 * chrlen : 1; /* * According to RFC 2047, we could encode the special character
@@ -367,18 +380,15 @@ static void add_rfc2047(struct strbuf *sb, const char *line, int len, * causes ' ' to be encoded as '=20', avoiding this problem. */ - if (line_len + 2 + (is_special ? 3 : 1) > max_encoded_length) { + if (line_len + encoded_len + 2 > max_encoded_length) { + /* It won't fit with trailing "?=" --- break the line */ strbuf_addf(sb, "?=\n =?%s?q?", encoding); line_len = strlen(encoding) + 5 + 1; /* =??q? plus SP */ } - if (is_special) { - strbuf_addf(sb, "=%02X", ch); - line_len += 3; - } else { - strbuf_addch(sb, ch); - line_len++; - } + for (i = 0; i < chrlen; i++) + strbuf_addf(sb, encoded_fmt, p[i]); + line_len += encoded_len; } strbuf_addstr(sb, "?="); }
diff --git a/t/t4014-format-patch.sh b/t/t4014-format-patch.sh
index 78633cb..b993dae 100755
--- a/t/t4014-format-patch.sh
+++ b/t/t4014-format-patch.sh@@ -837,25 +837,26 @@ Subject: [PATCH] =?UTF-8?q?f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f?= =?UTF-8?q?=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar?= =?UTF-8?q?=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20?= =?UTF-8?q?bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6?= - =?UTF-8?q?=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3?= - =?UTF-8?q?=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?= - =?UTF-8?q?=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f?= + =?UTF-8?q?=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?= =?UTF-8?q?=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar?= =?UTF-8?q?=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20?= =?UTF-8?q?bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6?= - =?UTF-8?q?=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3?= - =?UTF-8?q?=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?= - =?UTF-8?q?=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f?= + =?UTF-8?q?=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?= =?UTF-8?q?=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar?= =?UTF-8?q?=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20?= =?UTF-8?q?bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6?= - =?UTF-8?q?=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3?= - =?UTF-8?q?=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?= - =?UTF-8?q?=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f?= - =?UTF-8?q?=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar?= + =?UTF-8?q?=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?= + =?UTF-8?q?=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar?= + =?UTF-8?q?=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20?= + =?UTF-8?q?bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6?= + =?UTF-8?q?=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?= + =?UTF-8?q?=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar?= + =?UTF-8?q?=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20bar=20f=C3=B6=C3=B6=20?= + =?UTF-8?q?bar?= EOF test_expect_success 'format-patch wraps extremely long subject (rfc2047)' ' rm -rf patches/ &&
diff --git a/utf8.c b/utf8.c
index 8f6e84b..7f64857 100644
--- a/utf8.c
+++ b/utf8.c@@ -531,3 +531,42 @@ char *reencode_string(const char *in, const char *out_encoding, const char *in_e return out; } #endif + +/* + * Returns first character length in bytes for multi-byte `text` according to + * `encoding`. + * + * - The `text` pointer is updated to point at the next character. + * - When `remainder_p` is not NULL, on entry `*remainder_p` is how much bytes + * we can consume from text, and on exit `*remainder_p` is reduced by returned + * character length. Otherwise `text` is treated as limited by NUL. + */ +int mbs_chrlen(const char **text, size_t *remainder_p, const char *encoding) +{ + int chrlen; + const char *p = *text; + size_t r = (remainder_p ? *remainder_p : SIZE_MAX); + + if (r < 1) + return 0; + + if (is_encoding_utf8(encoding)) { + pick_one_utf8_char(&p, &r); + + chrlen = p ? (p - *text) + : 1 /* not valid UTF-8 -> raw byte sequence */; + } + else { + /* + * TODO use iconv to decode one char and obtain its chrlen + * for now, let's treat encodings != UTF-8 as one-byte + */ + chrlen = 1; + } + + *text += chrlen; + if (remainder_p) + *remainder_p -= chrlen; + + return chrlen; +}
diff --git a/utf8.h b/utf8.h
index 501b2bd..1f8ecad 100644
--- a/utf8.h
+++ b/utf8.h@@ -22,4 +22,6 @@ char *reencode_string(const char *in, const char *out_encoding, const char *in_e #define reencode_string(a,b,c) NULL #endif +int mbs_chrlen(const char **text, size_t *remainder_p, const char *encoding); + #endif
--
1.8.2.rc2.366.g3bc8dda