From 3b993fabb69764cb97bccba4f4e1d75e2e0defdc Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marco=20Trevisan=20=28Trevi=C3=B1o=29?= <mail@3v1n0.net>
Date: Sun, 8 Nov 2020 02:12:05 +0100
Subject: [PATCH] verify/enroll: Save and use locally saved prints also for
 devices with storage

Some devices have storage but that's is limited enough not to be able
to store all the metadata, but just a fingerprint id.

In such case we also need to use the local storage to be able to verify.
Fprintd does this already, but we don't do it in the libfprint examples.

So, in in case we enroll, always save the print information to the disk,
while in case we verify we try to load the print from disk and we use
that in case its private data matches the one provided by the device.
---
 examples/enroll.c | 20 ++++++++++++--------
 examples/verify.c | 45 ++++++++++++++++++++++++++++++++++-----------
 2 files changed, 46 insertions(+), 19 deletions(-)

diff --git a/examples/enroll.c b/examples/enroll.c
index 8ef45697..e85fd60c 100644
--- a/examples/enroll.c
+++ b/examples/enroll.c
@@ -76,15 +76,19 @@ on_enroll_completed (FpDevice *dev, GAsyncResult *res, void *user_data)
     {
       enroll_data->ret_value = EXIT_SUCCESS;
 
-      if (!fp_device_has_storage (dev))
+      if (fp_device_has_storage (dev))
+        g_debug ("Device has storage, saving a print reference locally");
+      else
+        g_debug ("Device has not storage, saving print only locally");
+
+      /* Even if the device has storage, it may not be able to save all the
+       * metadata that the print contains, so we can always save a local copy
+       * containing the handle to the device print */
+      int r = print_data_save (print, enroll_data->finger);
+      if (r < 0)
         {
-          g_debug ("Device has not storage, saving locally");
-          int r = print_data_save (print, enroll_data->finger);
-          if (r < 0)
-            {
-              g_warning ("Data save failed, code %d", r);
-              enroll_data->ret_value = EXIT_FAILURE;
-            }
+          g_warning ("Data save failed, code %d", r);
+          enroll_data->ret_value = EXIT_FAILURE;
         }
     }
   else
diff --git a/examples/verify.c b/examples/verify.c
index 48ccd198..494d63e9 100644
--- a/examples/verify.c
+++ b/examples/verify.c
@@ -152,6 +152,26 @@ on_match_cb (FpDevice *dev, FpPrint *match, FpPrint *print,
     }
 }
 
+static FpPrint *
+get_stored_print (FpDevice *dev, VerifyData *verify_data)
+{
+  FpPrint *verify_print;
+
+  g_print ("Loading previously enrolled %s finger data...\n",
+           finger_to_string (verify_data->finger));
+
+  verify_print = print_data_load (dev, verify_data->finger);
+
+  if (!verify_print)
+    {
+      g_warning ("Failed to load fingerprint data");
+      g_warning ("Did you remember to enroll your %s finger first?",
+                 finger_to_string (verify_data->finger));
+    }
+
+  return verify_print;
+}
+
 static void
 on_list_completed (FpDevice *dev, GAsyncResult *res, gpointer user_data)
 {
@@ -165,15 +185,27 @@ on_list_completed (FpDevice *dev, GAsyncResult *res, gpointer user_data)
   if (!error)
     {
       FpPrint *verify_print = NULL;
+      g_autoptr(FpPrint) stored_print = NULL;
       guint i;
 
       if (!prints->len)
-        g_warning ("No prints saved on device");
+        {
+          g_warning ("No prints saved on device");
+          verify_quit (dev, verify_data);
+          return;
+        }
+
+      stored_print = get_stored_print (dev, verify_data);
 
       for (i = 0; i < prints->len; ++i)
         {
           FpPrint *print = prints->pdata[i];
 
+          if (stored_print && fp_print_equal (stored_print, print))
+            /* If the private print data matches, let's use the stored print
+             * as it contains more metadata to show */
+            print = stored_print;
+
           if (fp_print_get_finger (print) == verify_data->finger &&
               g_strcmp0 (fp_print_get_username (print), g_get_user_name ()) == 0)
             {
@@ -191,8 +223,6 @@ on_list_completed (FpDevice *dev, GAsyncResult *res, gpointer user_data)
 
       if (!verify_print)
         {
-          g_warning ("Did you remember to enroll your %s finger first?",
-                     finger_to_string (verify_data->finger));
           verify_quit (dev, verify_data);
           return;
         }
@@ -239,17 +269,10 @@ start_verification (FpDevice *dev, VerifyData *verify_data)
     }
   else
     {
-      g_print ("Loading previously enrolled %s finger data...\n",
-               finger_to_string (verify_data->finger));
-      g_autoptr(FpPrint) verify_print = NULL;
-
-      verify_print = print_data_load (dev, verify_data->finger);
+      g_autoptr(FpPrint) verify_print = get_stored_print (dev, verify_data);
 
       if (!verify_print)
         {
-          g_warning ("Failed to load fingerprint data");
-          g_warning ("Did you remember to enroll your %s finger first?",
-                     finger_to_string (verify_data->finger));
           verify_quit (dev, verify_data);
           return;
         }