Re: [PATCH v5 6/7] replace: remove signature when using --graft

> Christian Couder <chriscool@tuxfamily.org> writes:
>
>> It could be misleading to keep a signature in a
>> replacement commit, so let's remove it.
>>
>> Note that there should probably be a way to sign
>> the replacement commit created when using --graft,
>> but this can be dealt with in another commit or
>> patch series.
>
> Both paragraphs read very sensibly.

>> --- a/builtin/replace.c
>> +++ b/builtin/replace.c
>> @@ -344,6 +344,11 @@ static int create_graft(int argc, const char **argv, int force)
>>
>>       replace_parents(&buf, argc, argv);
>>
>> +     if (remove_signature(&buf))
>> +             warning(_("the original commit '%s' has a gpg signature.\n"
>> +                       "It will be removed in the replacement commit!"),
>
> Hmmm...  does the second line of this message start with the usual
> "warning:" prefix?

>> diff --git a/commit.c b/commit.c
>> index fb7897c..54e157d 100644
>> --- a/commit.c
>> +++ b/commit.c
>> @@ -1177,6 +1177,40 @@ int parse_signed_commit(const struct commit *commit,
>>       return saw_signature;
>>  }
>>
>> +int remove_signature(struct strbuf *buf)
>> +{
>> +     const char *line = buf->buf;
>> +     const char *tail = buf->buf + buf->len;
>> +     int in_signature = 0;
>> +     const char *sig_start = NULL;
>> +     const char *sig_end = NULL;
>> +
>> +     while (line < tail) {
>> +             const char *next = memchr(line, '\n', tail - line);
>> +             next = next ? next + 1 : tail;
>
> This almost makes me wonder if we want something similar to
> strchrnul() we use for NUL-terminated strings, and I suspect that
> you would find more instances by running "git grep -A2 memchr".
>
> I don't know what such a helper function should be named, though.
> Certainly not "memchrnul()".

>> +             if (in_signature && line[0] == ' ')
>> +                     sig_end = next;
>> +             else if (starts_with(line, gpg_sig_header) &&
>> +                      line[gpg_sig_header_len] == ' ') {
>> +                     sig_start = line;
>> +                     sig_end = next;
>> +                     in_signature = 1;
>> +             } else {
>> +                     if (*line == '\n')
>> +                             /* dump the whole remainder of the buffer */
>> +                             next = tail;
>> +                     in_signature = 0;
>> +             }
>> +             line = next;
>> +     }
>> +
>> +     if (sig_start)
>> +             strbuf_remove(buf, sig_start - buf->buf, sig_end - sig_start);
>
> If there are two instances of gpg_sig, this will remove only the
> last one, but there is no chance both signatures of such a commit
> can validate OK, and we won't be losing something in between anyway,
> so it should be fine.