From eb8ef94512478db71e26974ca86787b95fc01300 Mon Sep 17 00:00:00 2001
From: Daniel Schaefer <dhs@frame.work>
Date: Fri, 15 May 2026 13:36:18 +0800
Subject: [PATCH] fprintd-enroll: Prompt if finger already enrolled

Check if the requested finger is enrolled already, if yes, then ask for
confirmation to re-enroll it.
Previously, running without arguments would always erase the
right-index-finger without any confirmation from the user.
Now it says:

$ fprintd-enroll
Using device /net/reactivated/Fprint/Device/0
'right-index-finger' is already enrolled. Overwrite? [y/N]

Signed-off-by: Daniel Schaefer <dhs@frame.work>
---
 utils/enroll.c | 55 +++++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 54 insertions(+), 1 deletion(-)

diff --git a/utils/enroll.c b/utils/enroll.c
index 9b438d4..b254778 100644
--- a/utils/enroll.c
+++ b/utils/enroll.c
@@ -32,6 +32,7 @@ static FprintDBusManager *manager = NULL;
 static GDBusConnection *connection = NULL;
 static char *finger_name = NULL;
 static char **usernames = NULL;
+static gboolean force_overwrite = FALSE;
 
 typedef enum {
   ENROLL_INCOMPLETE,
@@ -101,6 +102,47 @@ open_device (const char *username)
   return g_steal_pointer (&dev);
 }
 
+static gboolean
+confirm_overwrite (FprintDBusDevice *dev, const char *username)
+{
+  g_autoptr(GError) error = NULL;
+  g_auto(GStrv) enrolled = NULL;
+  char buf[8];
+
+  if (!fprint_dbus_device_call_list_enrolled_fingers_sync (dev, username,
+                                                           G_DBUS_CALL_FLAGS_ALLOW_INTERACTIVE_AUTHORIZATION,
+                                                           -1, &enrolled, NULL,
+                                                           &error))
+    {
+      if (g_dbus_error_is_remote_error (error))
+        {
+          g_autofree char *dbus_error =
+            g_dbus_error_get_remote_error (error);
+          if (g_str_equal (dbus_error,
+                           "net.reactivated.Fprint.Error.NoEnrolledPrints"))
+            return TRUE;
+        }
+
+      g_print ("ListEnrolledFingers failed: %s\n", error->message);
+      exit (1);
+    }
+
+  if (enrolled == NULL ||
+      !g_strv_contains ((const char **) enrolled, finger_name))
+    return TRUE;
+
+  if (force_overwrite)
+    return TRUE;
+
+  g_print ("'%s' is already enrolled. Overwrite? [y/N] ", finger_name);
+  fflush (stdout);
+
+  if (!fgets (buf, sizeof (buf), stdin))
+    return FALSE;
+
+  return buf[0] == 'y' || buf[0] == 'Y';
+}
+
 static void
 enroll_result (GObject *object, const char *result, gboolean done, void *user_data)
 {
@@ -210,6 +252,7 @@ release_device (FprintDBusDevice *dev)
 
 static const GOptionEntry entries[] = {
   { "finger", 'f',  0, G_OPTION_ARG_STRING, &finger_name, "Finger selected to verify (default is automatic)", NULL },
+  { "force", 'y',  0, G_OPTION_ARG_NONE, &force_overwrite, "Overwrite an existing enrollment without prompting", NULL },
   { G_OPTION_REMAINING, '\0', 0, G_OPTION_ARG_STRING_ARRAY, &usernames, NULL, "[username]" },
   { NULL }
 };
@@ -220,6 +263,7 @@ main (int argc, char **argv)
   g_autoptr(FprintDBusDevice) dev = NULL;
   GOptionContext *context;
   FprintEnrollStatus status;
+  const char *username;
 
   g_autoptr(GError) err = NULL;
 
@@ -239,7 +283,16 @@ main (int argc, char **argv)
 
   create_manager ();
 
-  dev = open_device (usernames ? usernames[0] : "");
+  username = usernames ? usernames[0] : "";
+  dev = open_device (username);
+  if (!confirm_overwrite (dev, username))
+    {
+      g_print ("Not overwriting existing enrollment.\n");
+      release_device (dev);
+      g_free (finger_name);
+      g_strfreev (usernames);
+      return EXIT_FAILURE;
+    }
   status = do_enroll (dev);
   release_device (dev);
   g_free (finger_name);