always try empty passphrase first

passphrase_cache.cc

@@ -14,6 +14,9 @@ namespace pEp {
         std::lock_guard<std::mutex> lock(_mtx);
         cleanup();
 
+        if (callee(""))
+            return true;
+
         for (auto entry=_cache.begin(); entry!=_cache.end(); ++entry) {
             if (callee(entry->passphrase)) {
                 refresh(entry);

passphrase_cache.hh

@@ -35,6 +35,7 @@ namespace pEp {
 
         // for each passphrase call the callee until it returns true for a
         // matching passphrase or no passphrases are left
+        // always tests empty passphrase first
         // returns true if a passphrase was matching, false otherwise
         using passphrase_callee = std::function<bool(std::string)>;
         bool for_each_passphrase(const passphrase_callee& callee);

test/test_passphrase_cache.cc

@@ -12,18 +12,18 @@ int main()
     cache.add("world");
 
     std::cout << "expected: two passphrases\n";
-    cache.for_each_passphrase([&](std::string passphrase){std::cout << passphrase << "\n"; return false;});
+    cache.for_each_passphrase([&](std::string passphrase){std::cout << "'" << passphrase << "'\n"; return false;});
 
     std::cout << "expected: one passphrase\n";
-    cache.for_each_passphrase([&](std::string passphrase){std::cout << passphrase << "\n"; return true;});
+    cache.for_each_passphrase([&](std::string passphrase){std::cout << "'" << passphrase << "'\n"; return passphrase != "";});
 
     std::cout << "expected: two passphrases but reverse order\n";
-    cache.for_each_passphrase([&](std::string passphrase){std::cout << passphrase << "\n"; return false;});
+    cache.for_each_passphrase([&](std::string passphrase){std::cout << "'" << passphrase << "'\n"; return false;});
 
     sleep(2);
 
     std::cout << "expected: no passphrase\n";
-    cache.for_each_passphrase([&](std::string passphrase){std::cout << passphrase << "\n"; return false;});
+    cache.for_each_passphrase([&](std::string passphrase){std::cout << "'" << passphrase << "'\n"; return false;});
 
     return 0;
 }