Adding code. Closes #0.

include/internal/stack_line_reader.h

@@ -0,0 +1,49 @@
+// Copyright 2017 Google Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+// Reads a file line by line and stores the data on the stack. This allows
+// parsing files in one go without allocating.
+#ifndef THIRD_PARTY_CPU_FEATURES_INCLUDE_INTERNAL_STACK_LINE_READER_H_
+#define THIRD_PARTY_CPU_FEATURES_INCLUDE_INTERNAL_STACK_LINE_READER_H_
+
+#include <stdbool.h>
+
+#include "cpu_features_macros.h"
+#include "internal/string_view.h"
+
+START_CPP_NAMESPACE
+
+typedef struct {
+  char buffer[STACK_LINE_READER_BUFFER_SIZE];
+  StringView view;
+  int fd;
+  bool skip_mode;
+} StackLineReader;
+
+// Initializes a StackLineReader.
+void StackLineReader_Initialize(StackLineReader* reader, int fd);
+
+typedef struct {
+  StringView line;  // A view of the line.
+  bool eof;         // Nothing more to read, we reached EOF.
+  bool full_line;   // If false the line was truncated to
+                    // STACK_LINE_READER_BUFFER_SIZE.
+} LineResult;
+
+// Reads the file pointed to by fd and tries to read a full line.
+LineResult StackLineReader_NextLine(StackLineReader* reader);
+
+END_CPP_NAMESPACE
+
+#endif  // THIRD_PARTY_CPU_FEATURES_INCLUDE_INTERNAL_STACK_LINE_READER_H_