From 04a7d2a3ba85c01f1c9f28a0626318e6bbf7c3b0 Mon Sep 17 00:00:00 2001
From: Philippe Teuwen <yobibe@gmail.com>
Date: Fri, 18 Jan 2013 22:51:16 +0100
Subject: [PATCH] Allow device.optional=true to tolerate missing device

---
 libnfc/conf.c         | 10 ++++++++++
 libnfc/nfc-internal.c |  1 +
 libnfc/nfc-internal.h |  1 +
 libnfc/nfc.c          | 41 ++++++++++++++++++++++++++++++++++++-----
 4 files changed, 48 insertions(+), 5 deletions(-)

diff --git a/libnfc/conf.c b/libnfc/conf.c
index 635c75e..ab4ab0a 100644
--- a/libnfc/conf.c
+++ b/libnfc/conf.c
@@ -118,6 +118,16 @@ conf_keyvalue_context(void *data, const char *key, const char *value)
       context->user_defined_device_count++;
     }
     strcpy(context->user_defined_devices[context->user_defined_device_count - 1].connstring, value);
+  } else if (strcmp(key, "device.optional") == 0) {
+    if ((context->user_defined_device_count == 0) || context->user_defined_devices[context->user_defined_device_count - 1].optional) {
+      if (context->user_defined_device_count >= MAX_USER_DEFINED_DEVICES) {
+        log_put(LOG_GROUP, LOG_CATEGORY, NFC_LOG_PRIORITY_ERROR, "%s", "Configuration exceeded maximum user-defined devices.");
+        return;
+      }
+      context->user_defined_device_count++;
+    }
+    if ((strcmp(value, "true") == 0) || (strcmp(value, "True") == 0) || (strcmp(value, "1") == 0)) //optional
+      context->user_defined_devices[context->user_defined_device_count - 1].optional = true;
   } else {
     log_put(LOG_GROUP, LOG_CATEGORY, NFC_LOG_PRIORITY_INFO, "Unknown key in config line: %s = %s", key, value);
   }
diff --git a/libnfc/nfc-internal.c b/libnfc/nfc-internal.c
index 04b7c38..96d71a8 100644
--- a/libnfc/nfc-internal.c
+++ b/libnfc/nfc-internal.c
@@ -77,6 +77,7 @@ nfc_context_new(void)
   for (int i = 0; i < MAX_USER_DEFINED_DEVICES; i++) {
     strcpy(res->user_defined_devices[i].name, "");
     strcpy(res->user_defined_devices[i].connstring, "");
+    res->user_defined_devices[i].optional = false;
   }
   res->user_defined_device_count = 0;
 
diff --git a/libnfc/nfc-internal.h b/libnfc/nfc-internal.h
index 250e2b9..5d1ff03 100644
--- a/libnfc/nfc-internal.h
+++ b/libnfc/nfc-internal.h
@@ -157,6 +157,7 @@ struct nfc_driver {
 struct nfc_user_defined_device {
   char name[DEVICE_NAME_LENGTH];
   nfc_connstring connstring;
+  bool optional;
 };
 
 /**
diff --git a/libnfc/nfc.c b/libnfc/nfc.c
index da84208..595dda5 100644
--- a/libnfc/nfc.c
+++ b/libnfc/nfc.c
@@ -185,7 +185,7 @@ nfc_open(nfc_context *context, const nfc_connstring connstring)
         continue;
       }
       log_put(LOG_GROUP, LOG_CATEGORY, NFC_LOG_PRIORITY_DEBUG, "Unable to open \"%s\".", ncs);
-      return pnd;
+      return NULL;
     }
     for (uint32_t i = 0; i > context->user_defined_device_count; i++) {
       if (strcmp(ncs, context->user_defined_devices[i].connstring) == 0) {
@@ -244,10 +244,41 @@ nfc_list_devices(nfc_context *context, nfc_connstring connstrings[], const size_
   // Load manually configured devices (from config file and env variables)
   // TODO From env var...
   for (uint32_t i = 0; i < context->user_defined_device_count; i++) {
-    strcpy((char *)(connstrings + device_found), context->user_defined_devices[i].connstring);
-    device_found++;
-    if (device_found >= connstrings_len)
-      return device_found;
+    if (context->user_defined_devices[i].optional) {
+      // let's make sure the device exists
+      nfc_device *pnd = NULL;
+      char *env_log_level = getenv("LIBNFC_LOG_LEVEL");
+      char *old_env_log_level = NULL;
+      // do it silently
+      if (env_log_level) {
+        old_env_log_level = malloc(strlen(env_log_level)+1);
+        if ((old_env_log_level = malloc(strlen(env_log_level)+1)) == NULL)
+          exit(EXIT_FAILURE);
+        strcpy(old_env_log_level, env_log_level);
+      }
+      setenv("LIBNFC_LOG_LEVEL", "0", 1);
+      pnd = nfc_open(context, context->user_defined_devices[i].connstring);
+      if (old_env_log_level) {
+        setenv("LIBNFC_LOG_LEVEL", old_env_log_level, 1);
+        free(old_env_log_level);
+      } else {
+        unsetenv("LIBNFC_LOG_LEVEL");
+      }
+      if (pnd) {
+        nfc_close(pnd);
+        log_put(LOG_GROUP, LOG_CATEGORY, NFC_LOG_PRIORITY_DEBUG, "User device %s found", context->user_defined_devices[i].name);
+        strcpy((char *)(connstrings + device_found), context->user_defined_devices[i].connstring);
+        device_found ++;
+        if (device_found == connstrings_len)
+          break;
+      }
+    } else {
+      // manual choice is not marked as optional so let's take it blindly
+      strcpy((char *)(connstrings + device_found), context->user_defined_devices[i].connstring);
+      device_found++;
+      if (device_found >= connstrings_len)
+        return device_found;
+    }
   }
 
   // Device auto-detection