[PATCH v3 1/2] gpg-interface: refactor the free-and-xmemdupz pattern

From: Hans Jerry Illikainen <hji@dyntopia.com>
Date: Nov 21, 2019, 23:43 UTC
Message-ID: <20191121234336.26300-2-hji@dyntopia.com>
In-Reply-To: <20191121234336.26300-1-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 | 23 ++++++++++++++++-------
 1 file changed, 16 insertions(+), 7 deletions(-)

diff --git a/gpg-interface.c b/gpg-interface.c
index d60115ca40..b4c4443287 100644
--- a/gpg-interface.c
+++ b/gpg-interface.c
@@ -105,6 +105,17 @@ static struct {
 	{ 0, "VALIDSIG ", GPG_STATUS_FINGERPRINT },
 };
 
+static void replace_cstring(const 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 +147,18 @@ 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 +170,8 @@ 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;

-- 
2.24.0.157.gba9f894af8