do not use misdesigned strbuf_split*()

The patch series by Junio Hamano with link below,
https://public-inbox.org/git/[email protected]/,
notices that the array of strbufs that calls to strbuf_split*() provides are merely used to store the strings gotten from the split and no edit are done on these resulting strings making the strbuf_split*() unideal for this usecase.

Commit d6fd08bd (sub-process: do not use strbuf_split*(), 2025-07-31) for example, in the series, observes that the subprocess_read_status() reads one packet line and tries to find "status=<foo>" by splitting the line into two strbufs which is an overkill to extract <foo>.

This series continues on this cleanup, by replacing instances of strbuf_split_max() with strchr() to get the required token around the delimiter where the token from the split is merely returned as char * and not strbufs and no edits are done on them.
This makes the code cleaner, faster and more efficient.

Tests have also been performed on the commits on Github CI. The link is shown below

https://github.com/git/git/pull/2080

Changes in v6
=============
- Modify commit messages to have proper structure
- Changed logic in get_default_ssh_signing_key() to use xmemdupz() if key has '\n' and xstrdup() if not.

Olamide Caleb Bello (2):
gpg-interface: do not use misdesigned strbuf_split*()
gpg-interface: do not use misdesigned strbuf_split*()

 gpg-interface.c | 34 +++++++++++++++++++++-------------
 1 file changed, 21 insertions(+), 13 deletions(-)

Range diff versus v5
====================

1: df8fbbd3a5 ! 1: 92fc78c203 gpg-interface: do not use misdesigned strbuf_split*()
@@ Commit message
gpg-interface: do not use misdesigned strbuf_split*()

In get_ssh_finger_print(), the output of the ssh-keygen command is
- put into fingerprint_stdout strbuf.
- The string in fingerprint_stdout is then split into up to 3 strbufs
- using strbuf_split_max(). However they are not modified after the split
- thereby not making use of the strbuf API as the fingerprint token is
- merely returned as a char * and not a strbuf. Hence they do not need to be
- strbufs.
+ put into fingerprint_stdout strbuf. The string in fingerprint_stdout
+ is then split into up to 3 strbufs using strbuf_split_max(). However they
+ are not modified after the split thereby not making use of the strbuf API
+ as the fingerprint token is merely returned as a char * and not a strbuf.
+ Hence they do not need to be strbufs.

Simplify the process of retrieving and returning the desired token by using strchr() to isolate the token and xmemdupz() to return a copy of the
2: 5df667227b ! 2: e52855242c gpg-interface: do not use misdesigned strbuf_split*()

    @@ Commit message

         Simplify the process of retrieving and returning the desired line by
         using strchr() to isolate the line and xmemdupz() to return a copy of the
    -    line.
    -    This removes the roundabout way of splitting the string into strbufs, just
    -    to return the line.
    +    line. This removes the roundabout way of splitting the string into
    +    strbufs, just to return the line.

         Reported-by: Junio Hamano <[email protected]>
         Helped-by: Christian Couder <[email protected]>
    @@ gpg-interface.c: static char *get_default_ssh_signing_key(void)
      	int n;
      	char *default_key = NULL;
      	const char *literal_key = NULL;
    -+	char *begin, *new_line, *first_line, *end;
    ++	char *begin, *new_line, *first_line;

      	if (!ssh_default_key_command)
      		die(_("either user.signingkey or gpg.ssh.defaultKeyCommand needs to be configured"));
    @@ gpg-interface.c: static char *get_default_ssh_signing_key(void)
     -		if (keys[0] && is_literal_ssh_key(keys[0]->buf, &literal_key)) {
     +		begin = key_stdout.buf;
     +		new_line = strchr(begin, '\n');
    -+		end = new_line ? new_line : strchr(begin, '\0');
    -+		first_line = xmemdupz(begin, end - begin);
    ++		if (new_line)
    ++			first_line = xmemdupz(begin, new_line - begin);
    ++		else
    ++			first_line = xstrdup(begin);
     +		if (is_literal_ssh_key(first_line, &literal_key)) {
      			/*
      			 * We only use `is_literal_ssh_key` here to check validity

--
2.51.0.463.g79cf913ea9