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