Add file reader (#1155)

* Add file reader
* Add a simple test example of parsing settings.
* Use new FileLineReader to parse Glass presets
* Trim CRLF from Glass preset name

firmware/test/application/mock_file.hpp

@@ -0,0 +1,89 @@
+/*
+ * Copyright (C) 2023 Kyle Reed
+ *
+ * This file is part of PortaPack.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2, or (at your option)
+ * any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; see the file COPYING.  If not, write to
+ * the Free Software Foundation, Inc., 51 Franklin Street,
+ * Boston, MA 02110-1301, USA.
+ */
+
+#pragma once
+
+#include "file.hpp"
+#include <cstring>
+#include <cstdio>
+#include <string>
+
+/* Mocks the File interface with a backing string. */
+class MockFile {
+   public:
+    using Error = File::Error;
+    using Offset = File::Offset;
+    using Size = File::Size;
+    template <typename T>
+    using Result = File::Result<T>;
+
+    MockFile(std::string data)
+        : data_{std::move(data)} {}
+
+    Size size() { return data_.size(); }
+
+    Result<Offset> seek(uint32_t offset) {
+        if ((int32_t)offset < 0)
+            return {static_cast<Error>(FR_BAD_SEEK)};
+
+        auto previous = offset_;
+
+        if (offset > size())
+            data_.resize(offset);
+
+        offset_ = offset;
+        return previous;
+    }
+
+    Result<Offset> truncate() {
+        data_.resize(offset_);
+        return offset_;
+    }
+
+    Result<Size> read(void* data, Size bytes_to_read) {
+        if (offset_ + bytes_to_read > size())
+            bytes_to_read = size() - offset_;
+
+        if (bytes_to_read == 0 || bytes_to_read > size())  // NB: underflow wrap
+            return 0;
+
+        memcpy(data, &data_[offset_], bytes_to_read);
+        offset_ += bytes_to_read;
+        return bytes_to_read;
+    }
+
+    Result<Size> write(const void* data, Size bytes_to_write) {
+        auto new_offset = offset_ + bytes_to_write;
+        if (new_offset >= size())
+            data_.resize(new_offset);
+
+        memcpy(&data_[offset_], data, bytes_to_write);
+        offset_ = new_offset;
+        return bytes_to_write;
+    }
+
+    Optional<Error> sync() {
+        return {};
+    }
+
+    std::string data_;
+    uint32_t offset_{0};
+};