mojo filesystem: Simplify full file reading/writing.

components/filesystem/directory_impl.cc

Index: components/filesystem/directory_impl.cc
diff --git a/components/filesystem/directory_impl.cc b/components/filesystem/directory_impl.cc
index 8c86fc7043bb47dd7f9c2a4b6a260f79277d9e28..7fd7a4cc9c52bb57c02f3306bbff88428c90e0e3 100644
--- a/components/filesystem/directory_impl.cc
+++ b/components/filesystem/directory_impl.cc
@@ -15,6 +15,7 @@
 #include "build/build_config.h"
 #include "components/filesystem/file_impl.h"
 #include "components/filesystem/util.h"
+#include "mojo/common/common_type_converters.h"
 
 namespace filesystem {
 
@@ -64,7 +65,7 @@ void DirectoryImpl::OpenFile(const mojo::String& raw_path,
 
 #if defined(OS_WIN)
   // On Windows, FILE_FLAG_BACKUP_SEMANTICS is needed to open a directory.
-  if (DirectoryExists(path))
+  if (base::DirectoryExists(path))
     open_flags |= base::File::FLAG_BACKUP_SEMANTICS;
 #endif  // OS_WIN
 
@@ -215,4 +216,69 @@ void DirectoryImpl::Flush(const FlushCallback& callback) {
   callback.Run(FileError::OK);
 }
 
+void DirectoryImpl::ReadEntireFile(const mojo::String& raw_path,
+                                   const ReadEntireFileCallback& callback) {
+  base::FilePath path;
+  FileError error = ValidatePath(raw_path, directory_path_, &path);
+  if (error != FileError::OK) {
+    callback.Run(error, mojo::Array<uint8_t>(0));
+    return;
+  }
+
+  if (base::DirectoryExists(path)) {
+    callback.Run(FileError::NOT_A_FILE, mojo::Array<uint8_t>(0));
+    return;
+  }
+
+  base::File base_file(path, base::File::FLAG_OPEN | base::File::FLAG_READ);
+  if (!base_file.IsValid()) {
+    callback.Run(GetError(base_file), mojo::Array<uint8_t>(0));
+    return;
+  }
+
+  std::string contents;
+  const int kBufferSize = 1 << 16;
+  scoped_ptr<char[]> buf(new char[kBufferSize]);
+  int len;
+  while ((len = base_file.ReadAtCurrentPos(buf.get(), kBufferSize)) > 0)
+    contents.append(buf.get(), len);
+
+  callback.Run(FileError::OK, mojo::Array<uint8_t>::From(contents));
+}
+
+void DirectoryImpl::WriteFile(const mojo::String& raw_path,
+                              mojo::Array<uint8_t> data,
+                              const WriteFileCallback& callback) {
+  base::FilePath path;
+  FileError error = ValidatePath(raw_path, directory_path_, &path);
+  if (error != FileError::OK) {
+    callback.Run(error);
+    return;
+  }
+
+  if (base::DirectoryExists(path)) {
+    callback.Run(FileError::NOT_A_FILE);
+    return;
+  }
+
+  base::File base_file(path,
+                       base::File::FLAG_CREATE_ALWAYS | base::File::FLAG_WRITE);
+  if (!base_file.IsValid()) {
+    callback.Run(GetError(base_file));
+    return;
+  }
+
+  // If we're given empty data, we don't write and just truncate the file.
+  if (data.size()) {
+    const int data_size = static_cast<int>(data.size());
+    if (base_file.Write(0, reinterpret_cast<char*>(&data.front()),
+                        data_size) == -1) {
+      callback.Run(GetError(base_file));
+      return;
+    }
+  }
+
+  callback.Run(FileError::OK);
+}
+
 }  // namespace filesystem