ibus: fall back from unreadable machine id

ibus.c

@@ -55,24 +55,37 @@ unlinkaddr(void)
 	addrowned = 0;
 }
 
+static void
+machineidfiles(char *buf, int sz, char **path, int npath)
+{
+	int fd, i, n;
+
+	for(i = 0; i < npath; i++){
+		fd = open(path[i], 0);
+		if(fd < 0)
+			continue;
+		n = read(fd, buf, sz - 1);
+		close(fd);
+		if(n <= 0)
+			continue;
+		buf[n] = '\0';
+		while(n > 0 && (buf[n-1] == '\n' || buf[n-1] == '\r'))
+			buf[--n] = '\0';
+		if(n > 0)
+			return;
+	}
+	buf[0] = '\0';
+}
+
 static void
 machineid(char *buf, int sz)
 {
-	int fd, n;
+	char *path[] = {
+		"/etc/machine-id",
+		"/var/lib/dbus/machine-id",
+	};
 
-	fd = open("/etc/machine-id", 0);
+	machineidfiles(buf, sz, path, nelem(path));
-	if(fd < 0)
-		fd = open("/var/lib/dbus/machine-id", 0);
-	if(fd < 0){
-		buf[0] = '\0';
-		return;
-	}
-	n = read(fd, buf, sz - 1);
-	close(fd);
-	if(n < 0) n = 0;
-	buf[n] = '\0';
-	while(n > 0 && (buf[n-1] == '\n' || buf[n-1] == '\r'))
-		buf[--n] = '\0';
 }
 
 static void

tests/ibus_test.c

@@ -24,6 +24,49 @@ struct Ibusfix
 	int	pumpactive;
 };
 
+void
+ibus_machine_id_fallback(struct ct *t)
+{
+	char root[] = "/tmp/strans-machine-id.XXXXXX";
+	char primary[128], fallback[128], got[64];
+	char *path[2];
+	FILE *fp;
+	int madeprimary, madefallback;
+
+	madeprimary = 0;
+	madefallback = 0;
+	if(!CT_CHECK(t, mkdtemp(root) != nil))
+		return;
+	if(!CT_CHECK(t, snprintf(primary, sizeof primary, "%s/primary", root)
+	   < (int)sizeof primary) ||
+	   !CT_CHECK(t, snprintf(fallback, sizeof fallback, "%s/fallback", root)
+	   < (int)sizeof fallback))
+		goto cleanup;
+	if(!CT_CHECK(t, mkdir(primary, 0700) == 0))
+		goto cleanup;
+	madeprimary = 1;
+	fp = fopen(fallback, "w");
+	if(!CT_CHECK(t, fp != nil))
+		goto cleanup;
+	madefallback = 1;
+	if(!CT_CHECK(t, fputs("fallback-machine-id\n", fp) >= 0)){
+		fclose(fp);
+		goto cleanup;
+	}
+	if(!CT_CHECK(t, fclose(fp) == 0))
+		goto cleanup;
+	path[0] = primary;
+	path[1] = fallback;
+	machineidfiles(got, sizeof got, path, nelem(path));
+	CT_EQ_STR(t, "fallback-machine-id", got);
+cleanup:
+	if(madefallback)
+		CT_CHECK(t, unlink(fallback) == 0);
+	if(madeprimary)
+		CT_CHECK(t, rmdir(primary) == 0);
+	CT_CHECK(t, rmdir(root) == 0);
+}
+
 static void
 enginepump(void *arg)
 {

tests/test.h

@@ -71,5 +71,6 @@ void	ipc_response_max_and_drain(struct ct*);
 void	ipc_response_fragmented_and_truncated(struct ct*);
 void	ipc_broken_peer_send(struct ct*);
 void	server_connection_ownership(struct ct*);
+void	ibus_machine_id_fallback(struct ct*);
 void	ibus_context_lifecycle(struct ct*);
 void	ibus_active_release_lifecycle(struct ct*);

tests/unit_test.c

@@ -125,6 +125,7 @@ static const struct ct_test tests[] = {
 	{ "ipc/response-fragmented-truncated", ipc_response_fragmented_and_truncated },
 	{ "ipc/broken-peer-send", ipc_broken_peer_send },
 	{ "server/connection-ownership", server_connection_ownership },
+	{ "ibus/machine-id-fallback", ibus_machine_id_fallback },
 	{ "ibus/context-lifecycle", ibus_context_lifecycle },
 	{ "ibus/active-release-lifecycle", ibus_active_release_lifecycle },
 };