1 /*
2  * Copyright (C) 2018 The Android Open Source Project
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  *  * Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  *  * Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in
12  *    the documentation and/or other materials provided with the
13  *    distribution.
14  *
15  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
16  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
17  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
18  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
19  * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
20  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
21  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
22  * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
23  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
24  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
25  * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26  * SUCH DAMAGE.
27  */
28 
29 #pragma once
30 
31 // Android's 32-bit ABI shipped with a sigset_t too small to include any
32 // of the realtime signals, so we have both sigset_t and sigset64_t. Many
33 // new system calls only accept a sigset64_t, so this helps paper over
34 // the difference at zero cost to LP64 in most cases after the optimizer
35 // removes the unnecessary temporary `ptr`.
36 struct SigSetConverter {
37  public:
SigSetConverterSigSetConverter38   SigSetConverter(const sigset_t* s) : SigSetConverter(const_cast<sigset_t*>(s)) {}
39 
SigSetConverterSigSetConverter40   SigSetConverter(sigset_t* s) {
41 #if defined(__LP64__)
42     // sigset_t == sigset64_t on LP64.
43     ptr = s;
44 #else
45     sigset64 = {};
46     if (s != nullptr) {
47       original_ptr = s;
48       sigset = *s;
49       ptr = &sigset64;
50     } else {
51       ptr = nullptr;
52     }
53 #endif
54   }
55 
copy_outSigSetConverter56   void copy_out() {
57 #if defined(__LP64__)
58     // We used the original pointer directly, so no copy needed.
59 #else
60     *original_ptr = sigset;
61 #endif
62   }
63 
64   sigset64_t* ptr;
65 
66  private:
67   [[maybe_unused]] sigset_t* original_ptr;
68   union {
69     sigset_t sigset;
70     sigset64_t sigset64;
71   };
72 };
73