Add a simple MappedFile to libbase and switch fastboot and libziparchive over.

This allows us to remove libziparchive's dependency on libutils.

Bug: http://b/79112958
Test: ran libbase and libziparchive tests, ran fastboot manually
Change-Id: I95c651976dad222863e5b8c37d4514b778f5dce7

1 files changed, 74 insertions, 0 deletions

diff --git a/base/include/android-base/mapped_file.h b/base/include/android-base/mapped_file.h
new file mode 100644
index 000000000..52d11eda9
--- /dev/null
+++ b/base/include/android-base/mapped_file.h
@@ -0,0 +1,74 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * 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.
+ */
+
+#pragma once
+
+#include "android-base/macros.h"
+
+#include <sys/types.h>
+
+#include <memory>
+
+#if defined(_WIN32)
+#include <windows.h>
+#define PROT_READ 1
+#define PROT_WRITE 2
+#else
+#include <sys/mman.h>
+#endif
+
+namespace android {
+namespace base {
+
+/**
+ * A region of a file mapped into memory.
+ */
+class MappedFile {
+ public:
+  /**
+   * Creates a new mapping of the file pointed to by `fd`. Unlike the underlying OS primitives,
+   * `offset` does not need to be page-aligned. If `PROT_WRITE` is set in `prot`, the mapping
+   * will be writable, otherwise it will be read-only. Mappings are always `MAP_SHARED`.
+   */
+  static std::unique_ptr<MappedFile> FromFd(int fd, off64_t offset, size_t length, int prot);
+
+  /**
+   * Removes the mapping.
+   */
+  ~MappedFile();
+
+  char* data() { return base_ + offset_; }
+  size_t size() { return size_; }
+
+ private:
+  DISALLOW_IMPLICIT_CONSTRUCTORS(MappedFile);
+
+  char* base_;
+  size_t size_;
+
+  size_t offset_;
+
+#if defined(_WIN32)
+  MappedFile(char* base, size_t size, size_t offset, HANDLE handle)
+      : base_(base), size_(size), offset_(offset), handle_(handle) {}
+  HANDLE handle_;
+#else
+  MappedFile(char* base, size_t size, size_t offset) : base_(base), size_(size), offset_(offset) {}
+#endif
+};
+
+}  // namespace base
+}  // namespace android