Repo created

TMessagesProj/jni/voip/webrtc/base/rand_util_posix.cc

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+// Copyright (c) 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "base/rand_util.h"
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <unistd.h>
+
+#include "base/files/file_util.h"
+#include "base/logging.h"
+#include "base/no_destructor.h"
+#include "base/posix/eintr_wrapper.h"
+
+namespace {
+
+// We keep the file descriptor for /dev/urandom around so we don't need to
+// reopen it (which is expensive), and since we may not even be able to reopen
+// it if we are later put in a sandbox. This class wraps the file descriptor so
+// we can use a static-local variable to handle opening it on the first access.
+class URandomFd {
+ public:
+#if defined(OS_AIX)
+  // AIX has no 64-bit support for open falgs such as -
+  //  O_CLOEXEC, O_NOFOLLOW and O_TTY_INIT
+  URandomFd() : fd_(HANDLE_EINTR(open("/dev/urandom", O_RDONLY))) {
+    DPCHECK(fd_ >= 0) << "Cannot open /dev/urandom";
+  }
+#else
+  URandomFd() : fd_(HANDLE_EINTR(open("/dev/urandom", O_RDONLY | O_CLOEXEC))) {
+    DPCHECK(fd_ >= 0) << "Cannot open /dev/urandom";
+  }
+#endif
+
+  ~URandomFd() { close(fd_); }
+
+  int fd() const { return fd_; }
+
+ private:
+  const int fd_;
+};
+
+}  // namespace
+
+namespace base {
+
+void RandBytes(void* output, size_t output_length) {
+  const int urandom_fd = GetUrandomFD();
+  const bool success =
+      ReadFromFD(urandom_fd, static_cast<char*>(output), output_length);
+  CHECK(success);
+}
+
+int GetUrandomFD() {
+  static NoDestructor<URandomFd> urandom_fd;
+  return urandom_fd->fd();
+}
+
+}  // namespace base