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1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. | 1 // Copyright (c) 2012 The Chromium Authors. All rights reserved. |
2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
4 | 4 |
5 #include "base/rand_util.h" | 5 #include "base/rand_util.h" |
6 | 6 |
7 #include <errno.h> | 7 #include <errno.h> |
8 #include <fcntl.h> | 8 #include <fcntl.h> |
9 #include <unistd.h> | 9 #include <unistd.h> |
10 | 10 |
11 #include "base/file_util.h" | 11 #include "base/file_util.h" |
12 #include "base/lazy_instance.h" | 12 #include "base/lazy_instance.h" |
13 #include "base/logging.h" | 13 #include "base/logging.h" |
14 | 14 |
15 namespace { | 15 namespace { |
16 | 16 |
17 // We keep the file descriptor for /dev/urandom around so we don't need to | 17 // We keep the file descriptor for /dev/urandom around so we don't need to |
18 // reopen it (which is expensive), and since we may not even be able to reopen | 18 // reopen it (which is expensive), and since we may not even be able to reopen |
19 // it if we are later put in a sandbox. This class wraps the file descriptor so | 19 // it if we are later put in a sandbox. This class wraps the file descriptor so |
20 // we can use LazyInstance to handle opening it on the first access. | 20 // we can use LazyInstance to handle opening it on the first access. |
21 class URandomFd { | 21 class URandomFd { |
22 public: | 22 public: |
23 URandomFd() { | 23 URandomFd() : fd_(open("/dev/urandom", O_RDONLY)) { |
24 fd_ = open("/dev/urandom", O_RDONLY); | |
25 DCHECK_GE(fd_, 0) << "Cannot open /dev/urandom: " << errno; | 24 DCHECK_GE(fd_, 0) << "Cannot open /dev/urandom: " << errno; |
26 } | 25 } |
27 | 26 |
28 ~URandomFd() { | 27 ~URandomFd() { close(fd_); } |
29 close(fd_); | |
30 } | |
31 | 28 |
32 int fd() const { return fd_; } | 29 int fd() const { return fd_; } |
33 | 30 |
34 private: | 31 private: |
35 int fd_; | 32 const int fd_; |
36 }; | 33 }; |
37 | 34 |
38 base::LazyInstance<URandomFd>::Leaky g_urandom_fd = LAZY_INSTANCE_INITIALIZER; | 35 base::LazyInstance<URandomFd>::Leaky g_urandom_fd = LAZY_INSTANCE_INITIALIZER; |
39 | 36 |
40 } // namespace | 37 } // namespace |
41 | 38 |
42 namespace base { | 39 namespace base { |
43 | 40 |
44 // NOTE: This function must be cryptographically secure. http://crbug.com/140076 | 41 // NOTE: This function must be cryptographically secure. http://crbug.com/140076 |
wtc
2014/01/22 22:29:09
This comment should be in front of RandUint64(). I
DaleCurtis
2014/01/22 22:54:14
Done.
| |
42 void RandBytes(void* output, size_t output_length) { | |
wtc
2014/01/22 22:29:09
Define RandBytes after RandUint64, as the Style Gu
DaleCurtis
2014/01/22 22:54:14
Done.
| |
43 const int urandom_fd = g_urandom_fd.Pointer()->fd(); | |
44 const bool success = | |
45 ReadFromFD(urandom_fd, static_cast<char*>(output), output_length); | |
46 CHECK(success); | |
47 } | |
48 | |
45 uint64 RandUint64() { | 49 uint64 RandUint64() { |
46 uint64 number; | 50 uint64 number; |
47 | 51 RandBytes(&number, sizeof(number)); |
48 int urandom_fd = g_urandom_fd.Pointer()->fd(); | |
49 bool success = ReadFromFD(urandom_fd, reinterpret_cast<char*>(&number), | |
50 sizeof(number)); | |
51 CHECK(success); | |
52 | |
53 return number; | 52 return number; |
54 } | 53 } |
55 | 54 |
56 int GetUrandomFD(void) { | 55 int GetUrandomFD(void) { |
57 return g_urandom_fd.Pointer()->fd(); | 56 return g_urandom_fd.Pointer()->fd(); |
58 } | 57 } |
59 | 58 |
60 } // namespace base | 59 } // namespace base |
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