Re: [PATCH] generate a valid rfc2047 mail header for multi-line subject.

> xzer <xiaozhu@gmail.com> writes:
>
>> Subject: Re: [PATCH] generate a valid rfc2047 mail header for multi-line subject.
>
> We prefer to have "[PATCH] subsystem: description without final full-stop" here.
>
>> There is still a problem that git-am will lost the line break.
>
> What does "still" refer to?  It is unclear under what condition the
> command lose "the line break" (nor which line break you are refering to; I
> am guessing that you have a commit that begins with a multi-line paragraph
> and you are talking about line breaks between the lines in the first
> paragraph).
>

>> It's not easy to retain it, but as the first step, we can generate
>> a valid rfc2047 header now.
>
> Please describe what is broken (iow, "Given this sample input, we
> currently generate this output, which is not a valid rfc2047") and what
> the new output looks like ("Update pp_title_line() to generate this output
> instead.")
>

>> diff --git a/pretty.c b/pretty.c
>> index 8549934..f18a38d 100644
>> --- a/pretty.c
>> +++ b/pretty.c
>> @@ -249,6 +249,33 @@ needquote:
>>       strbuf_addstr(sb, "?=");
>>  }
>>
>> +static void add_rfc2047_multiline(struct strbuf *sb, const char *line, int len,
>> +                       const char *encoding)
>> +{
>> +     int first = 1;
>> +     char *mline = xmemdupz(line, len);
>> +     const char *cline = mline;
>> +     int offset = 0, linelen = 0;
>> +        for (;;) {
>
> You seem to have indent that uses SPs instead of HT around here...
>
>> +                linelen = get_one_line(cline);
>
> I can see you are trying to be careful not to let get_one_line() overstep
> past "len" the caller gave you by making a copy first, but is this
> overhead really necessary?  After all we know in this static function that
> the caller is feeding the contents from a strbuf, which always have a
> terminating NUL (and that is why it is Ok that get_one_line() is not a
> counted string interface).
>

>> +
>> +                cline += linelen;
>> +
>> +                if (!linelen)
>> +                        break;
>> +
>> +             if (!first)
>> +                     strbuf_addf(sb, "\n ");
>> +
>> +             offset = *(cline -1) == '\n';
>> +
>> +             add_rfc2047(sb, cline-linelen, linelen-offset, encoding);
>> +             first = 0;
>> +
>> +        }
>> +     free(mline);
>> +}
>
> So the general idea of this change (I am thinking aloud what should be in
> the updated commit log message as the problem description) is that:
>
>  - We currently give an entire multi-line paragraph string to the
>   add_rfc2047() function to be formatted as the title of the commit;
>
>  - The add_rfc2047() functionjust passes "\n" through, without making it a
>   folding whitespace followed by a newline, to help callers that want to
>   use this function to produce a header line that is rfc 2822 conformant;
>
>  - The patch introduces a new function add_rfc2047_multiline() that splits
>   its input and performs line folding for such a caller (namely, the
>   pp_title_line() function);
>
>  - Another caller of add_rfc2047(), pp_user_info, is not changed, and it
>   won't fold the name of the user that appear on the From: line.
>
> It is unclear if the last point is really the right thing to do, though.
> It is not a new problem that an author name that has a "\n" in it would
> break the output, but we probably would want to fix that case too here?
>