contrib/plugins: fix coverity warning in lockstep

Coverity complains that e don't check for a truncation when copying in
the path. Bail if we can't copy the whole path into sockaddr.

Fixes: CID 1519045
Fixes: CID 1519046
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20231009164104.369749-25-alex.bennee@linaro.org>

contrib/plugins/lockstep.c

@@ -245,6 +245,7 @@ static void vcpu_tb_trans(qemu_plugin_id_t id, struct qemu_plugin_tb *tb)
 static bool setup_socket(const char *path)
 {
     struct sockaddr_un sockaddr;
+    const gsize pathlen = sizeof(sockaddr.sun_path) - 1;
     int fd;
 
     fd = socket(AF_UNIX, SOCK_STREAM, 0);
@@ -254,7 +255,11 @@ static bool setup_socket(const char *path)
     }
 
     sockaddr.sun_family = AF_UNIX;
-    g_strlcpy(sockaddr.sun_path, path, sizeof(sockaddr.sun_path) - 1);
+    if (g_strlcpy(sockaddr.sun_path, path, pathlen) >= pathlen) {
+        perror("bad path");
+        return false;
+    }
+
     if (bind(fd, (struct sockaddr *)&sockaddr, sizeof(sockaddr)) < 0) {
         perror("bind socket");
         close(fd);
@@ -287,6 +292,7 @@ static bool connect_socket(const char *path)
 {
     int fd;
     struct sockaddr_un sockaddr;
+    const gsize pathlen = sizeof(sockaddr.sun_path) - 1;
 
     fd = socket(AF_UNIX, SOCK_STREAM, 0);
     if (fd < 0) {
@@ -295,7 +301,10 @@ static bool connect_socket(const char *path)
     }
 
     sockaddr.sun_family = AF_UNIX;
-    g_strlcpy(sockaddr.sun_path, path, sizeof(sockaddr.sun_path) - 1);
+    if (g_strlcpy(sockaddr.sun_path, path, pathlen) >= pathlen) {
+        perror("bad path");
+        return false;
+    }
 
     if (connect(fd, (struct sockaddr *)&sockaddr, sizeof(sockaddr)) < 0) {
         perror("failed to connect");