1 //===-- xray_utils.h --------------------------------------------*- C++ -*-===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file is a part of XRay, a dynamic runtime instrumentation system.
10 //
11 // Some shared utilities for the XRay runtime implementation.
12 //
13 //===----------------------------------------------------------------------===//
14 #ifndef XRAY_UTILS_H
15 #define XRAY_UTILS_H
16 
17 #include <cstddef>
18 #include <cstdint>
19 #include <sys/types.h>
20 #include <utility>
21 
22 #include "sanitizer_common/sanitizer_common.h"
23 #if SANITIZER_FUCHSIA
24 #include <zircon/types.h>
25 #endif
26 
27 namespace __xray {
28 
29 class LogWriter {
30 public:
31 #if SANITIZER_FUCHSIA
32  LogWriter(zx_handle_t Vmo) : Vmo(Vmo) {}
33 #else
34   explicit LogWriter(int Fd) : Fd(Fd) {}
35 #endif
36  ~LogWriter();
37 
38  // Write a character range into a log.
39  void WriteAll(const char *Begin, const char *End);
40 
41  void Flush();
42 
43  // Returns a new log instance initialized using the flag-provided values.
44  static LogWriter *Open();
45  // Closes and deallocates the log instance.
46  static void Close(LogWriter *LogWriter);
47 
48 private:
49 #if SANITIZER_FUCHSIA
50  zx_handle_t Vmo = ZX_HANDLE_INVALID;
51  uint64_t Offset = 0;
52 #else
53  int Fd = -1;
54 #endif
55 };
56 
57 constexpr size_t gcd(size_t a, size_t b) {
58   return (b == 0) ? a : gcd(b, a % b);
59 }
60 
61 constexpr size_t lcm(size_t a, size_t b) { return a * b / gcd(a, b); }
62 
63 constexpr size_t nearest_boundary(size_t number, size_t multiple) {
64   return multiple * ((number / multiple) + (number % multiple ? 1 : 0));
65 }
66 
67 constexpr size_t next_pow2_helper(size_t num, size_t acc) {
68   return (1u << acc) >= num ? (1u << acc) : next_pow2_helper(num, acc + 1);
69 }
70 
71 constexpr size_t next_pow2(size_t number) {
72   return next_pow2_helper(number, 1);
73 }
74 
75 template <class T> constexpr T &max(T &A, T &B) { return A > B ? A : B; }
76 
77 template <class T> constexpr T &min(T &A, T &B) { return A <= B ? A : B; }
78 
79 constexpr ptrdiff_t diff(uintptr_t A, uintptr_t B) {
80   return max(A, B) - min(A, B);
81 }
82 
83 } // namespace __xray
84 
85 #endif // XRAY_UTILS_H
86