test-nss-users: add new nss test that resolves users and groups

Inspired by https://bugzilla.redhat.com/show_bug.cgi?id=1929936.
This is similar to test-nss-hosts, but does users, groups, uid, gids.

Functions tested are:
_nss_*_getpwnam_r
_nss_*_getgrnam_r
_nss_*_getpwgid_r
_nss_*_getgrgid_r

Other entry points should be tested too, but it's not relevant to the bug
I was investigating, so I'm leaving that for later ;)

1 files changed, 42 insertions, 0 deletions

diff --git a/src/test/nss-test-util.c b/src/test/nss-test-util.c
new file mode 100644
index 0000000000..fc1d724a2f
--- /dev/null
+++ b/src/test/nss-test-util.c
@@ -0,0 +1,42 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <dlfcn.h>
+#include <stdio.h>
+#include <unistd.h>
+
+#include "nss-test-util.h"
+#include "string-util.h"
+
+const char* nss_status_to_string(enum nss_status status, char *buf, size_t buf_len) {
+        switch (status) {
+        case NSS_STATUS_TRYAGAIN:
+                return "NSS_STATUS_TRYAGAIN";
+        case NSS_STATUS_UNAVAIL:
+                return "NSS_STATUS_UNAVAIL";
+        case NSS_STATUS_NOTFOUND:
+                return "NSS_STATUS_NOTFOUND";
+        case NSS_STATUS_SUCCESS:
+                return "NSS_STATUS_SUCCESS";
+        case NSS_STATUS_RETURN:
+                return "NSS_STATUS_RETURN";
+        default:
+                snprintf(buf, buf_len, "%i", status);
+                return buf;
+        }
+};
+
+void* nss_open_handle(const char *dir, const char *module, int flags) {
+        const char *path = NULL;
+        void *handle;
+
+        if (dir)
+                path = strjoina(dir, "/libnss_", module, ".so.2");
+        if (!path || access(path, F_OK) < 0)
+                path = strjoina("libnss_", module, ".so.2");
+
+        log_debug("Using %s", path);
+        handle = dlopen(path, flags);
+        if (!handle)
+                log_error("Failed to load module %s: %s", module, dlerror());
+        return handle;
+}