win: Add open equivalent

util/file/file_writer_win.cc

+// Copyright 2014 The Crashpad Authors. All rights reserved.
+//
+// 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 "util/file/file_writer.h"
+
+#include <algorithm>
+
+#include <limits.h>
+
+#include "base/logging.h"
+#include "util/file/file_io.h"
+
+namespace crashpad {
+
+bool FileWriter::Open(const base::FilePath& path, int oflag, uint32_t mode) {
+  CHECK(!file_.is_valid());
+  DCHECK((oflag & O_WRONLY) || (oflag & O_RDWR));
+
+  DWORD file_access = 0;
+  switch (oflag & (O_RDONLY | O_WRONLY | O_RDWR)) {
+    case O_WRONLY:
+      file_access = GENERIC_WRITE;
+      break;
+    case O_RDWR:
+      file_access = GENERIC_READ | GENERIC_WRITE;
+      break;
+    default:
+      CHECK(false) << "Invalid open flag";
+  }
+
+  DWORD file_create = 0;
+  switch (oflag & (O_CREAT | O_EXCL | O_TRUNC)) {
+    case 0:
+    case O_EXCL:  // Ignore EXCL w/o CREAT.
+      file_create = OPEN_EXISTING;
+      break;
+    case O_CREAT:
+      file_create = OPEN_ALWAYS;
+      break;
+    case O_CREAT | O_EXCL:
+    case O_CREAT | O_TRUNC | O_EXCL:
+      file_create = CREATE_NEW;
+      break;
+    case O_TRUNC:
+    case O_TRUNC | O_EXCL:  // Ignore EXCL w/o CREAT.
+      file_create = TRUNCATE_EXISTING;
+      break;
+    case O_CREAT | O_TRUNC:
+      file_create = CREATE_ALWAYS;
+      break;
+    default:
+      CHECK(false) << "Invalid open flag";
+  }
+
+  DCHECK_EQ(oflag & ~(O_WRONLY | O_RDWR | O_CREAT | O_EXCL | O_TRUNC), 0)
+      << "Unhandled oflag value";
+
+  file_.reset(CreateFile(path.value().c_str(), file_access, 0, nullptr,
+                         file_create, FILE_ATTRIBUTE_NORMAL, nullptr));
+  if (!file_.is_valid()) {
+    PLOG(ERROR) << "CreateFile " << path.value().c_str();
+    return false;
+  }
+
+  return true;
+}
+
+FileOffset FileWriter::Seek(FileOffset offset, int whence) {
+  DCHECK(file_.is_valid());
+
+  DWORD method = 0;
+  switch (whence) {
+    case SEEK_SET:
+      method = FILE_BEGIN;
+      break;
+    case SEEK_CUR:
+      method = FILE_CURRENT;
+      break;
+    case SEEK_END:
+      method = FILE_END;
+      break;
+    default:
+      CHECK(false) << "Invalid whence";
+  }
+
+  LARGE_INTEGER li;
+  li.QuadPart = offset;
+  li.LowPart = SetFilePointer(file_.get(), li.LowPart, &li.HighPart, method);
+  if (li.LowPart == INVALID_SET_FILE_POINTER && GetLastError() != NO_ERROR) {
+    PLOG(ERROR) << "SetFilePointer";
+    return -1;
+  }
+
+  return li.QuadPart;
+}
+
+}  // namespace crashpad