Load validator list from file:

* Adds local file:// URL support to the [validator_list_sites] stanza.
  The file:// URL must not contain a hostname. Allows a rippled node
  operator to "sideload" a new list if their node is unable to reach
  a validator list's web site before an old list expires. Lists
  loaded from a file will be validated in the same way a downloaded
  list is validated.
* Generalize file/dir "guards" from Config test so they can be reused
  in other tests.
* Check for error when reading validators.txt. Saves some parsing and
  checking of an empty string, and will give a more meaningful error.
* Completes RIPD-1674.

src/test/basics/FileUtilities_test.cpp

@@ -0,0 +1,76 @@
+//------------------------------------------------------------------------------
+/*
+    This file is part of rippled: https://github.com/ripple/rippled
+    Copyright (c) 2018 Ripple Labs Inc.
+
+    Permission to use, copy, modify, and/or distribute this software for any
+    purpose  with  or without fee is hereby granted, provided that the above
+    copyright notice and this permission notice appear in all copies.
+
+    THE  SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+    WITH  REGARD  TO  THIS  SOFTWARE  INCLUDING  ALL  IMPLIED  WARRANTIES  OF
+    MERCHANTABILITY  AND  FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+    ANY  SPECIAL ,  DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+    WHATSOEVER  RESULTING  FROM  LOSS  OF USE, DATA OR PROFITS, WHETHER IN AN
+    ACTION  OF  CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+    OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+*/
+//==============================================================================
+
+#include <ripple/basics/ByteUtilities.h>
+#include <ripple/basics/FileUtilities.h>
+#include <ripple/beast/unit_test.h>
+#include <test/unit_test/FileDirGuard.h>
+
+namespace ripple {
+
+class FileUtilities_test : public beast::unit_test::suite
+{
+public:
+    void testGetFileContents()
+    {
+        using namespace ripple::test::detail;
+        using namespace boost::system;
+
+        constexpr const char* expectedContents =
+            "This file is very short. That's all we need.";
+
+        FileDirGuard file(*this, "test_file", "test.txt",
+            expectedContents);
+
+        error_code ec;
+        auto const path = file.file();
+
+        {
+            // Test with no max
+            auto const good = getFileContents(ec, path);
+            BEAST_EXPECT(!ec);
+            BEAST_EXPECT(good == expectedContents);
+        }
+
+        {
+            // Test with large max
+            auto const good = getFileContents(ec, path, kilobytes(1));
+            BEAST_EXPECT(!ec);
+            BEAST_EXPECT(good == expectedContents);
+        }
+
+        {
+            // Test with small max
+            auto const bad = getFileContents(ec, path, 16);
+            BEAST_EXPECT(ec && ec.value() ==
+                boost::system::errc::file_too_large);
+            BEAST_EXPECT(bad.empty());
+        }
+
+    }
+
+    void run () override
+    {
+        testGetFileContents();
+    }
+};
+
+BEAST_DEFINE_TESTSUITE(FileUtilities, ripple_basics, ripple);
+
+} // ripple

src/test/basics/StringUtilities_test.cpp

@@ -80,6 +80,10 @@ public:
         BEAST_EXPECT(parseUrl (pUrl, "scheme://[::1]:123/path"));
         BEAST_EXPECT(*pUrl.port == 123);
         BEAST_EXPECT(pUrl.domain == "::1");
+        BEAST_EXPECT(parseUrl(pUrl, "nodomain:///path/path/path"));
+        BEAST_EXPECT(pUrl.scheme == "nodomain");
+        BEAST_EXPECT(pUrl.domain.empty());
+        BEAST_EXPECT(pUrl.path == "/path/path/path");
     }
 
     void testToString ()