Import libsparse library from AOSP

base/cvd/android-base/mapped_file.cpp

@@ -0,0 +1,128 @@
+/*
+ * 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.
+ */
+
+#include "android-base/mapped_file.h"
+
+#include <utility>
+
+#include <errno.h>
+
+namespace android {
+namespace base {
+
+static constexpr char kEmptyBuffer[] = {'0'};
+
+static off64_t InitPageSize() {
+#if defined(_WIN32)
+  SYSTEM_INFO si;
+  GetSystemInfo(&si);
+  return si.dwAllocationGranularity;
+#else
+  return sysconf(_SC_PAGE_SIZE);
+#endif
+}
+
+std::unique_ptr<MappedFile> MappedFile::FromFd(borrowed_fd fd, off64_t offset, size_t length,
+                                               int prot) {
+#if defined(_WIN32)
+  return FromOsHandle(reinterpret_cast<HANDLE>(_get_osfhandle(fd.get())), offset, length, prot);
+#else
+  return FromOsHandle(fd.get(), offset, length, prot);
+#endif
+}
+
+std::unique_ptr<MappedFile> MappedFile::FromOsHandle(os_handle h, off64_t offset, size_t length,
+                                                     int prot) {
+  static const off64_t page_size = InitPageSize();
+  size_t slop = offset % page_size;
+  off64_t file_offset = offset - slop;
+  off64_t file_length = length + slop;
+
+#if defined(_WIN32)
+  HANDLE handle = CreateFileMappingW(
+      h, nullptr, (prot & PROT_WRITE) ? PAGE_READWRITE : PAGE_READONLY, 0, 0, nullptr);
+  if (handle == nullptr) {
+    // http://b/119818070 "app crashes when reading asset of zero length".
+    // Return a MappedFile that's only valid for reading the size.
+    if (length == 0 && ::GetLastError() == ERROR_FILE_INVALID) {
+      return std::unique_ptr<MappedFile>(
+          new MappedFile(const_cast<char*>(kEmptyBuffer), 0, 0, nullptr));
+    }
+    return nullptr;
+  }
+  void* base = MapViewOfFile(handle, (prot & PROT_WRITE) ? FILE_MAP_ALL_ACCESS : FILE_MAP_READ,
+                             (file_offset >> 32), file_offset, file_length);
+  if (base == nullptr) {
+    CloseHandle(handle);
+    return nullptr;
+  }
+  return std::unique_ptr<MappedFile>(
+      new MappedFile(static_cast<char*>(base), length, slop, handle));
+#else
+  void* base = mmap(nullptr, file_length, prot, MAP_SHARED, h, file_offset);
+  if (base == MAP_FAILED) {
+    // http://b/119818070 "app crashes when reading asset of zero length".
+    // mmap fails with EINVAL for a zero length region.
+    if (errno == EINVAL && length == 0) {
+      return std::unique_ptr<MappedFile>(new MappedFile(const_cast<char*>(kEmptyBuffer), 0, 0));
+    }
+    return nullptr;
+  }
+  return std::unique_ptr<MappedFile>(new MappedFile(static_cast<char*>(base), length, slop));
+#endif
+}
+
+MappedFile::MappedFile(MappedFile&& other)
+    : base_(std::exchange(other.base_, nullptr)),
+      size_(std::exchange(other.size_, 0)),
+      offset_(std::exchange(other.offset_, 0))
+#ifdef _WIN32
+      ,
+      handle_(std::exchange(other.handle_, nullptr))
+#endif
+{
+}
+
+MappedFile& MappedFile::operator=(MappedFile&& other) {
+  Close();
+  base_ = std::exchange(other.base_, nullptr);
+  size_ = std::exchange(other.size_, 0);
+  offset_ = std::exchange(other.offset_, 0);
+#ifdef _WIN32
+  handle_ = std::exchange(other.handle_, nullptr);
+#endif
+  return *this;
+}
+
+MappedFile::~MappedFile() {
+  Close();
+}
+
+void MappedFile::Close() {
+#if defined(_WIN32)
+  if (base_ != nullptr && size_ != 0) UnmapViewOfFile(base_);
+  if (handle_ != nullptr) CloseHandle(handle_);
+  handle_ = nullptr;
+#else
+  if (base_ != nullptr && size_ != 0) munmap(base_, size_ + offset_);
+#endif
+
+  base_ = nullptr;
+  offset_ = size_ = 0;
+}
+
+}  // namespace base
+}  // namespace android

base/cvd/android-base/mapped_file.h

@@ -0,0 +1,93 @@
+/*
+ * 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 <sys/types.h>
+
+#include <memory>
+
+#include "android-base/macros.h"
+#include "android-base/off64_t.h"
+#include "android-base/unique_fd.h"
+
+#if defined(_WIN32)
+#include <windows.h>
+#define PROT_READ 1
+#define PROT_WRITE 2
+using os_handle = HANDLE;
+#else
+#include <sys/mman.h>
+using os_handle = int;
+#endif
+
+namespace android {
+namespace base {
+
+/**
+ * A region of a file mapped into memory (for grepping: also known as MmapFile or file mapping).
+ */
+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(borrowed_fd fd, off64_t offset, size_t length,
+                                            int prot);
+
+  /**
+   * Same thing, but using the raw OS file handle instead of a CRT wrapper.
+   */
+  static std::unique_ptr<MappedFile> FromOsHandle(os_handle h, off64_t offset, size_t length,
+                                                  int prot);
+
+  /**
+   * Removes the mapping.
+   */
+  ~MappedFile();
+
+  /**
+   * Not copyable but movable.
+   */
+  MappedFile(MappedFile&& other);
+  MappedFile& operator=(MappedFile&& other);
+
+  char* data() const { return base_ + offset_; }
+  size_t size() const { return size_; }
+
+ private:
+  DISALLOW_IMPLICIT_CONSTRUCTORS(MappedFile);
+
+  void Close();
+
+  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