[PATCH v4 1/2] gpg-interface: refactor the free-and-xmemdupz pattern

[Hans Jerry Illikainen <hji@dyntopia.com>]

This commit introduces a static replace_cstring() function.  This
function simplifies the continuous pattern of free-and-xmemdupz() for
GPG status line parsing.

The benefit of having it in a single helper function is that it helps
avoid the need for duplicate code that does the same thing.  It also
helps avoid potential memleaks if parsing of new status lines are
introduced in the future.

Signed-off-by: Hans Jerry Illikainen <hji@dyntopia.com>
---
 gpg-interface.c | 22 +++++++++++++++-------
 1 file changed, 15 insertions(+), 7 deletions(-)

diff --git a/gpg-interface.c b/gpg-interface.c
index d60115ca40..37162c9a43 100644
--- a/gpg-interface.c
+++ b/gpg-interface.c
@@ -105,6 +105,16 @@ static struct {
 	{ 0, "VALIDSIG ", GPG_STATUS_FINGERPRINT },
 };
 
+static void replace_cstring(char **field, const char *line, const char *next)
+{
+	free(*field);
+
+	if (line && next)
+		*field = xmemdupz(line, next - line);
+	else
+		*field = NULL;
+}
+
 static void parse_gpg_output(struct signature_check *sigc)
 {
 	const char *buf = sigc->gpg_status;
@@ -136,21 +146,18 @@ static void parse_gpg_output(struct signature_check *sigc)
 				/* Do we have key information? */
 				if (sigcheck_gpg_status[i].flags & GPG_STATUS_KEYID) {
 					next = strchrnul(line, ' ');
-					free(sigc->key);
-					sigc->key = xmemdupz(line, next - line);
+					replace_cstring(&sigc->key, line, next);
 					/* Do we have signer information? */
 					if (*next && (sigcheck_gpg_status[i].flags & GPG_STATUS_UID)) {
 						line = next + 1;
 						next = strchrnul(line, '\n');
-						free(sigc->signer);
-						sigc->signer = xmemdupz(line, next - line);
+						replace_cstring(&sigc->signer, line, next);
 					}
 				}
 				/* Do we have fingerprint? */
 				if (sigcheck_gpg_status[i].flags & GPG_STATUS_FINGERPRINT) {
 					next = strchrnul(line, ' ');
-					free(sigc->fingerprint);
-					sigc->fingerprint = xmemdupz(line, next - line);
+					replace_cstring(&sigc->fingerprint, line, next);
 
 					/* Skip interim fields */
 					for (j = 9; j > 0; j--) {
@@ -162,7 +169,8 @@ static void parse_gpg_output(struct signature_check *sigc)
 
 					next = strchrnul(line, '\n');
 					free(sigc->primary_key_fingerprint);
-					sigc->primary_key_fingerprint = xmemdupz(line, next - line);
+					replace_cstring(&sigc->primary_key_fingerprint,
+							line, next);
 				}
 
 				break;
-- 
2.24.GIT