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.

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
token. This removes the roundabout way of splitting the string into
strbufs just to return the token.

Reported-by: Junio Hamano <gitster@pobox.com>
Helped-by: Christian Couder <christian.couder@gmail.com>
Helped-by: Kristoffer Haugsbakk <kristofferhaugsbakk@fastmail.com>
Signed-off-by: Olamide Caleb Bello <belkid98@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Author: cloobTech

gpg-interface.c

@@ -821,8 +821,7 @@ static char *get_ssh_key_fingerprint(const char *signing_key)
 	struct child_process ssh_keygen = CHILD_PROCESS_INIT;
 	int ret = -1;
 	struct strbuf fingerprint_stdout = STRBUF_INIT;
-	struct strbuf **fingerprint;
-	char *fingerprint_ret;
+	char *fingerprint_ret, *begin, *delim;
 	const char *literal_key = NULL;
 
 	/*
@@ -845,13 +844,17 @@ static char *get_ssh_key_fingerprint(const char *signing_key)
 		die_errno(_("failed to get the ssh fingerprint for key '%s'"),
 			  signing_key);
 
-	fingerprint = strbuf_split_max(&fingerprint_stdout, ' ', 3);
-	if (!fingerprint[1])
-		die_errno(_("failed to get the ssh fingerprint for key '%s'"),
+	begin = fingerprint_stdout.buf;
+	delim = strchr(begin, ' ');
+	if (!delim)
+		die(_("failed to get the ssh fingerprint for key %s"),
 			  signing_key);
-
-	fingerprint_ret = strbuf_detach(fingerprint[1], NULL);
-	strbuf_list_free(fingerprint);
+	begin = delim + 1;
+	delim = strchr(begin, ' ');
+	if (!delim)
+	    die(_("failed to get the ssh fingerprint for key %s"),
+			  signing_key);
+	fingerprint_ret = xmemdupz(begin, delim - begin);
 	strbuf_release(&fingerprint_stdout);
 	return fingerprint_ret;
 }