[gnome-initial-setup/gbsneto/accounts-crash-bug: 3/3] accounts: Also check against NAME_REGEX if provided

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit 2aee81e9aaf257dd223fa4d7001ac91f12b20821
Author: Georges Basile Stavracas Neto <georges stavracas gmail com>
Date:   Wed Jul 27 14:58:00 2022 -0300

    accounts: Also check against NAME_REGEX if provided
    
    In addition to checking if each character of the proposed username
    conforms to UNIX concentions, if /etc/adduser.conf is present and
    it provides NAME_REGEX, try and match the username against this
    regex too.
    
    This should fix cases where Initial Setup thinks the password is
    okay, but accountsservice rejects the proposed username.

 gnome-initial-setup/pages/account/um-utils.c | 51 ++++++++++++++++++++++++++++
 1 file changed, 51 insertions(+)
---
diff --git a/gnome-initial-setup/pages/account/um-utils.c b/gnome-initial-setup/pages/account/um-utils.c
index 39887498..9f9b2a29 100644
--- a/gnome-initial-setup/pages/account/um-utils.c
+++ b/gnome-initial-setup/pages/account/um-utils.c
@@ -106,6 +106,46 @@ is_valid_name (const gchar *name)
         return !is_empty;
 }
 
+static GRegex*
+get_adduser_regex (void)
+{
+        static gboolean initialized = FALSE;
+        static GRegex *adduser_regex = NULL;
+
+        if (!initialized) {
+                g_autofree gchar *contents = NULL;
+
+                if (g_file_get_contents ("/etc/adduser.conf", &contents, NULL, NULL)) {
+                        g_auto(GStrv) lines = g_strsplit (contents, "\n", -1);
+                        gsize i;
+
+                        for (i = 0; lines && lines[i] != NULL; i++) {
+                                g_autofree gchar *unquoted = NULL;
+                                gchar *line = g_strstrip (lines[i]);
+
+                                if (*line == '#' || !g_str_has_prefix (line, "NAME_REGEX="))
+                                        continue;
+
+                                line += strlen ("NAME_REGEX=");
+                                unquoted = g_shell_unquote (line, NULL);
+
+                                if (!unquoted)
+                                        continue;
+
+                                adduser_regex = g_regex_new (unquoted,
+                                                             G_REGEX_OPTIMIZE,
+                                                             0,
+                                                             NULL);
+                                break;
+                        }
+                }
+
+                initialized = TRUE;
+        }
+
+        return adduser_regex;
+}
+
 gboolean
 is_valid_username (const gchar *username, gboolean parental_controls_enabled, gchar **tip)
 {
@@ -139,6 +179,17 @@ is_valid_username (const gchar *username, gboolean parental_controls_enabled, gc
                                (*c == '-' && c != username)))
                            valid = FALSE;
                 }
+
+                /* Second, if useradd.conf provides a regex for username
+                 * validation, use it.
+                 */
+                if (valid) {
+                        GRegex *adduser_regex = get_adduser_regex ();
+
+                        if (adduser_regex)
+                                valid = g_regex_match (adduser_regex, username, 0, NULL);
+                }
+
         }
 
         parental_controls_conflict = (parental_controls_enabled && g_strcmp0 (username, "administrator") == 
0);