util: rework strappenda(), and rename it strjoina()

After all it is now much more like strjoin() than strappend(). At the
same time, add support for NULL sentinels, even if they are normally not
necessary.

src/test/test-conf-files.c

@@ -59,12 +59,12 @@ static void test_conf_files_list(bool use_root) {
                 search_2 = "/dir2";
         } else {
                 root_dir = NULL;
-                search_1 = strappenda(tmp_dir, "/dir1");
-                search_2 = strappenda(tmp_dir, "/dir2");
+                search_1 = strjoina(tmp_dir, "/dir1");
+                search_2 = strjoina(tmp_dir, "/dir2");
         }
 
-        expect_a = strappenda(tmp_dir, "/dir1/a.conf");
-        expect_b = strappenda(tmp_dir, "/dir2/b.conf");
+        expect_a = strjoina(tmp_dir, "/dir1/a.conf");
+        expect_b = strjoina(tmp_dir, "/dir2/b.conf");
 
         assert_se(conf_files_list(&found_files, ".conf", root_dir, search_1, search_2, NULL) == 0);
         strv_print(found_files);

src/test/test-copy.c

@@ -90,15 +90,15 @@ static void test_copy_tree(void) {
         rm_rf_dangerous(original_dir, false, true, false);
 
         STRV_FOREACH(p, files) {
-                char *f = strappenda(original_dir, *p);
+                char *f = strjoina(original_dir, *p);
 
                 assert_se(mkdir_parents(f, 0755) >= 0);
                 assert_se(write_string_file(f, "file") == 0);
         }
 
         STRV_FOREACH_PAIR(link, p, links) {
-                char *f = strappenda(original_dir, *p);
-                char *l = strappenda(original_dir, *link);
+                char *f = strjoina(original_dir, *p);
+                char *l = strjoina(original_dir, *link);
 
                 assert_se(mkdir_parents(l, 0755) >= 0);
                 assert_se(symlink(f, l) == 0);
@@ -109,7 +109,7 @@ static void test_copy_tree(void) {
         STRV_FOREACH(p, files) {
                 _cleanup_free_ char *buf = NULL;
                 size_t sz = 0;
-                char *f = strappenda(copy_dir, *p);
+                char *f = strjoina(copy_dir, *p);
 
                 assert_se(access(f, F_OK) == 0);
                 assert_se(read_full_file(f, &buf, &sz) == 0);
@@ -118,8 +118,8 @@ static void test_copy_tree(void) {
 
         STRV_FOREACH_PAIR(link, p, links) {
                 _cleanup_free_ char *target = NULL;
-                char *f = strappenda(original_dir, *p);
-                char *l = strappenda(copy_dir, *link);
+                char *f = strjoina(original_dir, *p);
+                char *l = strjoina(copy_dir, *link);
 
                 assert_se(readlink_and_canonicalize(l, &target) == 0);
                 assert_se(path_equal(f, target));

src/test/test-namespace.c

@@ -42,8 +42,8 @@ static void test_tmpdir(const char *id, const char *A, const char *B) {
         assert_se((x.st_mode & 01777) == 0700);
         assert_se((y.st_mode & 01777) == 0700);
 
-        c = strappenda(a, "/tmp");
-        d = strappenda(b, "/tmp");
+        c = strjoina(a, "/tmp");
+        d = strjoina(b, "/tmp");
 
         assert_se(stat(c, &x) >= 0);
         assert_se(stat(d, &y) >= 0);

src/test/test-path-lookup.c

@@ -33,9 +33,9 @@ static void test_paths(SystemdRunningAs running_as, bool personal) {
         char *exists, *not;
 
         assert_se(mkdtemp(template));
-        exists = strappenda(template, "/exists");
+        exists = strjoina(template, "/exists");
         assert_se(mkdir(exists, 0755) == 0);
-        not = strappenda(template, "/not");
+        not = strjoina(template, "/not");
 
         assert_se(lookup_paths_init(&lp, running_as, personal, NULL, exists, not, not) == 0);
 

src/test/test-path.c

@@ -47,7 +47,7 @@ static int setup_test(Manager **m) {
         assert_se(manager_startup(tmp, NULL, NULL) >= 0);
 
         STRV_FOREACH(test_path, tests_path) {
-               rm_rf_dangerous(strappenda("/tmp/test-path_", *test_path), false, true, false);
+               rm_rf_dangerous(strjoina("/tmp/test-path_", *test_path), false, true, false);
         }
 
         *m = tmp;
@@ -201,7 +201,7 @@ static void test_path_directorynotempty(Manager *m) {
         assert_se(access(test_path, F_OK) < 0);
 
         assert_se(mkdir_p(test_path, 0755) >= 0);
-        assert_se(touch(strappenda(test_path, "test_file")) >= 0);
+        assert_se(touch(strjoina(test_path, "test_file")) >= 0);
 
         check_stop_unlink(m, unit, test_path, NULL);
 }

src/test/test-tmpfiles.c

@@ -30,7 +30,7 @@
 
 int main(int argc, char** argv) {
         const char *p = argv[1] ?: "/tmp";
-        char *pattern = strappenda(p, "/systemd-test-XXXXXX");
+        char *pattern = strjoina(p, "/systemd-test-XXXXXX");
         _cleanup_close_ int fd, fd2;
         _cleanup_free_ char *cmd, *cmd2;
 

src/test/test-util.c

@@ -1072,17 +1072,29 @@ static void test_strshorten(void) {
         assert_se(strlen(strshorten(s, 0)) == 0);
 }
 
-static void test_strappenda(void) {
+static void test_strjoina(void) {
         char *actual;
 
-        actual = strappenda("", "foo", "bar");
+        actual = strjoina("", "foo", "bar");
         assert_se(streq(actual, "foobar"));
 
-        actual = strappenda("foo", "bar", "baz");
+        actual = strjoina("foo", "bar", "baz");
         assert_se(streq(actual, "foobarbaz"));
 
-        actual = strappenda("foo", "", "bar", "baz");
+        actual = strjoina("foo", "", "bar", "baz");
         assert_se(streq(actual, "foobarbaz"));
+
+        actual = strjoina("foo");
+        assert_se(streq(actual, "foo"));
+
+        actual = strjoina(NULL);
+        assert_se(streq(actual, ""));
+
+        actual = strjoina(NULL, "foo");
+        assert_se(streq(actual, ""));
+
+        actual = strjoina("foo", NULL, "bar");
+        assert_se(streq(actual, "foo"));
 }
 
 static void test_is_symlink(void) {
@@ -1231,13 +1243,13 @@ static void test_execute_directory(void) {
         assert_se(mkdtemp(template_lo));
         assert_se(mkdtemp(template_hi));
 
-        name = strappenda(template_lo, "/script");
-        name2 = strappenda(template_hi, "/script2");
-        name3 = strappenda(template_lo, "/useless");
-        overridden = strappenda(template_lo, "/overridden");
-        override = strappenda(template_hi, "/overridden");
-        masked = strappenda(template_lo, "/masked");
-        mask = strappenda(template_hi, "/masked");
+        name = strjoina(template_lo, "/script");
+        name2 = strjoina(template_hi, "/script2");
+        name3 = strjoina(template_lo, "/useless");
+        overridden = strjoina(template_lo, "/overridden");
+        override = strjoina(template_hi, "/overridden");
+        masked = strjoina(template_lo, "/masked");
+        mask = strjoina(template_hi, "/masked");
 
         assert_se(write_string_file(name, "#!/bin/sh\necho 'Executing '$0\ntouch $(dirname $0)/it_works") == 0);
         assert_se(write_string_file(name2, "#!/bin/sh\necho 'Executing '$0\ntouch $(dirname $0)/it_works2") == 0);
@@ -1562,7 +1574,7 @@ int main(int argc, char *argv[]) {
         test_read_one_char();
         test_ignore_signals();
         test_strshorten();
-        test_strappenda();
+        test_strjoina();
         test_is_symlink();
         test_pid_is_unwaited();
         test_pid_is_alive();