Cross platform low level file IO wrappers

util/file/fd_io.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/fd_io.h"
-
-#include <unistd.h>
-
-#include "base/logging.h"
-#include "base/numerics/safe_conversions.h"
-#include "base/posix/eintr_wrapper.h"
-
-namespace {
-
-struct ReadTraits {
-  using VoidBufferType = void*;
-  using CharBufferType = char*;
-  static ssize_t Operate(int fd, CharBufferType buffer, size_t size) {
-    return read(fd, buffer, size);
-  }
-};
-
-struct WriteTraits {
-  using VoidBufferType = const void*;
-  using CharBufferType = const char*;
-  static ssize_t Operate(int fd, CharBufferType buffer, size_t size) {
-    return write(fd, buffer, size);
-  }
-};
-
-template <typename Traits>
-ssize_t ReadOrWrite(int fd,
-                    typename Traits::VoidBufferType buffer,
-                    size_t size) {
-  typename Traits::CharBufferType buffer_c =
-      reinterpret_cast<typename Traits::CharBufferType>(buffer);
-
-  ssize_t total_bytes = 0;
-  while (size > 0) {
-    ssize_t bytes = HANDLE_EINTR(Traits::Operate(fd, buffer_c, size));
-    if (bytes < 0) {
-      return bytes;
-    } else if (bytes == 0) {
-      break;
-    }
-
-    buffer_c += bytes;
-    size -= bytes;
-    total_bytes += bytes;
-  }
-
-  return total_bytes;
-}
-
-}  // namespace
-
-namespace crashpad {
-
-ssize_t ReadFD(int fd, void* buffer, size_t size) {
-  return ReadOrWrite<ReadTraits>(fd, buffer, size);
-}
-
-ssize_t WriteFD(int fd, const void* buffer, size_t size) {
-  return ReadOrWrite<WriteTraits>(fd, buffer, size);
-}
-
-bool LoggingReadFD(int fd, void* buffer, size_t size) {
-  ssize_t expect = base::checked_cast<ssize_t>(size);
-  ssize_t rv = ReadFD(fd, buffer, size);
-  if (rv < 0) {
-    PLOG(ERROR) << "read";
-    return false;
-  }
-  if (rv != expect) {
-    LOG(ERROR) << "read: expected " << expect << ", observed " << rv;
-    return false;
-  }
-
-  return true;
-}
-
-bool LoggingWriteFD(int fd, const void* buffer, size_t size) {
-  ssize_t expect = base::checked_cast<ssize_t>(size);
-  ssize_t rv = WriteFD(fd, buffer, size);
-  if (rv < 0) {
-    PLOG(ERROR) << "write";
-    return false;
-  }
-  if (rv != expect) {
-    LOG(ERROR) << "write: expected " << expect << ", observed " << rv;
-    return false;
-  }
-
-  return true;
-}
-
-void CheckedReadFD(int fd, void* buffer, size_t size) {
-  CHECK(LoggingReadFD(fd, buffer, size));
-}
-
-void CheckedWriteFD(int fd, const void* buffer, size_t size) {
-  CHECK(LoggingWriteFD(fd, buffer, size));
-}
-
-void CheckedReadFDAtEOF(int fd) {
-  char c;
-  ssize_t rv = ReadFD(fd, &c, 1);
-  if (rv < 0) {
-    PCHECK(rv == 0) << "read";
-  } else {
-    CHECK_EQ(rv, 0) << "read";
-  }
-}
-
-bool LoggingCloseFD(int fd) {
-  int rv = IGNORE_EINTR(close(fd));
-  PLOG_IF(ERROR, rv != 0) << "close";
-  return rv == 0;
-}
-
-void CheckedCloseFD(int fd) {
-  CHECK(LoggingCloseFD(fd));
-}
-
-}  // namespace crashpad