1 // Copyright 2017 The Abseil Authors.
2 //
3 // Licensed under the Apache License, Version 2.0 (the "License");
4 // you may not use this file except in compliance with the License.
5 // You may obtain a copy of the License at
6 //
7 //      https://www.apache.org/licenses/LICENSE-2.0
8 //
9 // Unless required by applicable law or agreed to in writing, software
10 // distributed under the License is distributed on an "AS IS" BASIS,
11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 // See the License for the specific language governing permissions and
13 // limitations under the License.
14 //
15 // -----------------------------------------------------------------------------
16 // File: seed_gen_exception.h
17 // -----------------------------------------------------------------------------
18 //
19 // This header defines an exception class which may be thrown if unpredictable
20 // events prevent the derivation of suitable seed-material for constructing a
21 // bit generator conforming to [rand.req.urng] (eg. entropy cannot be read from
22 // /dev/urandom on a Unix-based system).
23 //
24 // Note: if exceptions are disabled, `std::terminate()` is called instead.
25 
26 #ifndef ABSL_RANDOM_SEED_GEN_EXCEPTION_H_
27 #define ABSL_RANDOM_SEED_GEN_EXCEPTION_H_
28 
29 #include <exception>
30 
31 #include "absl/base/config.h"
32 
33 namespace absl {
34 ABSL_NAMESPACE_BEGIN
35 
36 //------------------------------------------------------------------------------
37 // SeedGenException
38 //------------------------------------------------------------------------------
39 class SeedGenException : public std::exception {
40  public:
41   SeedGenException() = default;
42   ~SeedGenException() override;
43   const char* what() const noexcept override;
44 };
45 
46 namespace random_internal {
47 
48 // throw delegator
49 [[noreturn]] void ThrowSeedGenException();
50 
51 }  // namespace random_internal
52 ABSL_NAMESPACE_END
53 }  // namespace absl
54 
55 #endif  // ABSL_RANDOM_SEED_GEN_EXCEPTION_H_
56