Initial version of new file wrapper

webrtc/base/file_posix.cc

+/*
+ *  Copyright (c) 2016 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "webrtc/base/file.h"
+
+#include <unistd.h>
+#include <errno.h>
+
+namespace rtc {
+
+#define HANDLE_EINTR(x)                                     \
+  ({                                                        \
+    decltype(x) eintr_wrapper_result;                       \
+    do {                                                    \
+      eintr_wrapper_result = (x);                           \
+    } while (eintr_wrapper_result == -1 && errno == EINTR); \
+    eintr_wrapper_result;                                   \
+  })

[sprang_webrtc, 2016/08/15 09:43:07]

I think I would actually preffer having explicit code rather than this macro,
despite that adding some boilderplate.

+
+size_t File::WriteNoBestEffort(const uint8_t* data, size_t length) {
+  ssize_t rv = HANDLE_EINTR(write(file_, data, length));
+  return rv < 0 ? 0 : size_t{rv};

[sprang_webrtc, 2016/08/15 09:43:07]

Prefer static_cast<size_t>() to size_t{}
Also don't think you need this cast here, unless ssize_t is actually larger than
size_t? In that case do a static assert.

[palmkvist, 2016/08/16 08:55:35]

Done.

+}
+
+size_t File::ReadNoBestEffort(uint8_t* buffer, size_t length) {
+  ssize_t rv = HANDLE_EINTR(read(file_, buffer, length));
+  return rv < 0 ? 0 : size_t{rv};
+}
+
+size_t File::WriteAtNoBestEffort(const uint8_t* data,
+                                 size_t length,
+                                 size_t offset) {
+  ssize_t rv = HANDLE_EINTR(pwrite(file_, data, length, offset));
+  return rv < 0 ? 0 : size_t{rv};
+}
+
+size_t File::ReadAtNoBestEffort(uint8_t* data, size_t length, size_t offset) {
+  ssize_t rv = HANDLE_EINTR(pread(file_, data, length, offset));
+  return rv < 0 ? 0 : size_t{rv};
+}
+
+bool File::Seek(size_t offset) {
+  static_assert(sizeof(size_t) <= sizeof(off_t), "size_t must fit in off_t");
+  return lseek(file_, off_t{offset}, SEEK_SET) != ((off_t)-1);
+}
+
+bool File::Close() {
+  if (file_ == rtc::kInvalidPlatformFileValue)
+    return false;
+  bool ret = close(file_) == 0;
+  file_ = rtc::kInvalidPlatformFileValue;
+  return ret;
+}
+
+}  // namespace rtc