dns: rework write_to_netconfig()

The compiler warns when we ignore the return value from write().
And assigning it to an unused variable, causes another warning.
Make some use of it, at least to handle EINTR. All other errors
are still ignored.

While at it, rework the write code to first write to a buffer
in memory.

1 files changed, 38 insertions, 31 deletions

diff --git a/src/dns/nm-dns-manager.c b/src/dns/nm-dns-manager.c
index 6d4000b637..f7787ea52c 100644
--- a/src/dns/nm-dns-manager.c
+++ b/src/dns/nm-dns-manager.c
@@ -378,56 +378,59 @@ run_netconfig (NMDnsManager *self, GError **error, gint *stdin_fd)
 }
 
 static void
-write_to_netconfig (NMDnsManager *self, gint fd, const char *key, const char *value)
+netconfig_construct_str (NMDnsManager *self, GString *str, const char *key, const char *value)
 {
-	gs_free char *str = NULL;
+	if (value) {
+		_LOGD ("writing to netconfig: %s='%s'", key, value);
+		g_string_append_printf (str, "%s='%s'\n", key, value);
+	}
+}
+
+static void
+netconfig_construct_strv (NMDnsManager *self, GString *str, const char *key, const char *const*values)
+{
+	if (values) {
+		gs_free char *value = NULL;
 
-	str = g_strdup_printf ("%s='%s'\n", key, value);
-	_LOGD ("writing to netconfig: %s='%s'", key, value);
-	(void) write (fd, str, strlen (str));
+		value = g_strjoinv (" ", (char **) values);
+		netconfig_construct_str (self, str, key, value);
+	}
 }
 
 static SpawnResult
 dispatch_netconfig (NMDnsManager *self,
-                    char **searches,
-                    char **nameservers,
+                    const char *const*searches,
+                    const char *const*nameservers,
                     const char *nis_domain,
-                    char **nis_servers,
+                    const char *const*nis_servers,
                     GError **error)
 {
-	char *str;
 	GPid pid;
 	gint fd;
 	int status;
+	gssize l;
+	nm_auto_free_gstring GString *str = NULL;
 
 	pid = run_netconfig (self, error, &fd);
 	if (pid <= 0)
 		return SR_NOTFOUND;
 
+	str = g_string_new ("");
+
 	/* NM is writing already-merged DNS information to netconfig, so it
 	 * does not apply to a specific network interface.
 	 */
-	write_to_netconfig (self, fd, "INTERFACE", "NetworkManager");
+	netconfig_construct_str (self, str, "INTERFACE", "NetworkManager");
+	netconfig_construct_strv (self, str, "DNSSEARCH", searches);
+	netconfig_construct_strv (self, str, "DNSSERVERS", nameservers);
+	netconfig_construct_str (self, str, "NISDOMAIN", nis_domain);
+	netconfig_construct_strv (self, str, "NISSERVERS", nis_servers);
 
-	if (searches) {
-		str = g_strjoinv (" ", searches);
-		write_to_netconfig (self, fd, "DNSSEARCH", str);
-		g_free (str);
-	}
-
-	if (nameservers) {
-		str = g_strjoinv (" ", nameservers);
-		write_to_netconfig (self, fd, "DNSSERVERS", str);
-		g_free (str);
-	}
-
-	if (nis_domain)
-		write_to_netconfig (self, fd, "NISDOMAIN", nis_domain);
-
-	if (nis_servers) {
-		str = g_strjoinv (" ", nis_servers);
-		write_to_netconfig (self, fd, "NISSERVERS", str);
-		g_free (str);
+again:
+	l = write (fd, str->str, str->len);
+	if (l == -1)  {
+		if (errno == EINTR)
+			goto again;
 	}
 
 	nm_close (fd);
@@ -1112,8 +1115,12 @@ update_dns (NMDnsManager *self,
 			result = dispatch_resolvconf (self, searches, nameservers, options, error);
 			break;
 		case NM_DNS_MANAGER_RESOLV_CONF_MAN_NETCONFIG:
-			result = dispatch_netconfig (self, searches, nameservers, nis_domain,
-			                             nis_servers, error);
+			result = dispatch_netconfig (self,
+			                             (const char *const*) searches,
+			                             (const char *const*) nameservers,
+			                             nis_domain,
+			                             (const char *const*) nis_servers,
+			                             error);
 			break;
 		default:
 			g_assert_not_reached ();