1 | /* $Id: semwait.h 98103 2023-01-17 14:15:46Z vboxsync $ */
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2 | /** @file
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3 | * IPRT - Common semaphore wait code.
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4 | */
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5 |
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6 | /*
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7 | * Copyright (C) 2021-2023 Oracle and/or its affiliates.
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8 | *
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9 | * This file is part of VirtualBox base platform packages, as
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10 | * available from https://www.virtualbox.org.
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11 | *
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12 | * This program is free software; you can redistribute it and/or
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13 | * modify it under the terms of the GNU General Public License
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14 | * as published by the Free Software Foundation, in version 3 of the
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15 | * License.
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16 | *
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17 | * This program is distributed in the hope that it will be useful, but
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18 | * WITHOUT ANY WARRANTY; without even the implied warranty of
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19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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20 | * General Public License for more details.
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21 | *
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22 | * You should have received a copy of the GNU General Public License
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23 | * along with this program; if not, see <https://www.gnu.org/licenses>.
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24 | *
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25 | * The contents of this file may alternatively be used under the terms
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26 | * of the Common Development and Distribution License Version 1.0
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27 | * (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
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28 | * in the VirtualBox distribution, in which case the provisions of the
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29 | * CDDL are applicable instead of those of the GPL.
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30 | *
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31 | * You may elect to license modified versions of this file under the
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32 | * terms and conditions of either the GPL or the CDDL or both.
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33 | *
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34 | * SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
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35 | */
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36 |
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37 | #ifndef IPRT_INCLUDED_SRC_r3_posix_semwait_h
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38 | #define IPRT_INCLUDED_SRC_r3_posix_semwait_h
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39 | #ifndef RT_WITHOUT_PRAGMA_ONCE
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40 | # pragma once
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41 | #endif
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42 |
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43 |
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44 | /** @def IPRT_HAVE_PTHREAD_CONDATTR_SETCLOCK
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45 | * Set if the platform implements pthread_condattr_setclock().
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46 | * Enables the use of the monotonic clock for waiting on condition variables. */
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47 | #ifndef IPRT_HAVE_PTHREAD_CONDATTR_SETCLOCK
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48 | /* Linux detection */
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49 | # if defined(RT_OS_LINUX) && defined(__USE_XOPEN2K)
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50 | # include <features.h>
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51 | # if __GLIBC_PREREQ(2,6) /** @todo figure the exact version where this was added */
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52 | # define IPRT_HAVE_PTHREAD_CONDATTR_SETCLOCK
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53 | # endif
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54 | # endif
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55 | /** @todo check other platforms */
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56 | #endif
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57 |
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58 |
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59 | /**
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60 | * Converts a extended wait timeout specification to an absolute timespec and a
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61 | * relative nanosecond count.
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62 | *
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63 | * @note This does not check for RTSEMWAIT_FLAGS_INDEFINITE, caller should've
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64 | * done that already.
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65 | *
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66 | * @returns The relative wait in nanoseconds. 0 for a poll call, UINT64_MAX for
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67 | * an effectively indefinite wait.
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68 | * @param fFlags RTSEMWAIT_FLAGS_XXX.
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69 | * @param fMonotonicClock Whether the timeout is in monotonic (true) or real
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70 | * (false) time.
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71 | * @param uTimeout The timeout.
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72 | * @param pAbsDeadline Where to return the absolute deadline.
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73 | */
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74 | DECLINLINE(uint64_t) rtSemPosixCalcDeadline(uint32_t fFlags, uint64_t uTimeout, bool fMonotonicClock,
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75 | struct timespec *pAbsDeadline)
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76 | {
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77 | Assert(!(fFlags & RTSEMWAIT_FLAGS_INDEFINITE));
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78 |
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79 | /*
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80 | * Convert uTimeout to a relative value in nanoseconds.
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81 | */
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82 | if (fFlags & RTSEMWAIT_FLAGS_MILLISECS)
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83 | {
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84 | if (uTimeout < UINT64_MAX / RT_NS_1MS)
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85 | uTimeout = uTimeout * RT_NS_1MS;
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86 | else
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87 | return UINT64_MAX;
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88 | }
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89 | else if (uTimeout == UINT64_MAX) /* unofficial way of indicating an indefinite wait */
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90 | return UINT64_MAX;
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91 |
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92 | /*
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93 | * Make uTimeout relative and check for polling (zero timeout) calls.
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94 | */
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95 | uint64_t uAbsTimeout = uTimeout;
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96 | if (fFlags & RTSEMWAIT_FLAGS_ABSOLUTE)
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97 | {
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98 | uint64_t const u64Now = RTTimeSystemNanoTS();
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99 | if (uTimeout > u64Now)
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100 | uTimeout -= u64Now;
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101 | else
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102 | return 0;
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103 | }
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104 | else if (uTimeout == 0)
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105 | return 0;
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106 |
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107 | /*
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108 | * Calculate the deadline according to the clock we're using.
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109 | */
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110 | if (!fMonotonicClock)
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111 | {
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112 | #if defined(RT_OS_DARWIN) || defined(RT_OS_HAIKU)
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113 | struct timeval tv = {0,0};
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114 | gettimeofday(&tv, NULL);
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115 | pAbsDeadline->tv_sec = tv.tv_sec;
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116 | pAbsDeadline->tv_nsec = tv.tv_usec * 1000;
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117 | #else
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118 | clock_gettime(CLOCK_REALTIME, pAbsDeadline);
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119 | #endif
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120 | struct timespec TsAdd;
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121 | TsAdd.tv_nsec = uTimeout % RT_NS_1SEC;
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122 | TsAdd.tv_sec = uTimeout / RT_NS_1SEC;
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123 |
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124 | /* Check for 32-bit tv_sec overflows: */
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125 | if ( sizeof(pAbsDeadline->tv_sec) < sizeof(uint64_t)
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126 | && ( uTimeout >= (uint64_t)RT_NS_1SEC * UINT32_MAX
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127 | || (uint64_t)pAbsDeadline->tv_sec + pAbsDeadline->tv_sec >= UINT32_MAX) )
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128 | return UINT64_MAX;
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129 |
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130 | pAbsDeadline->tv_sec += TsAdd.tv_sec;
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131 | pAbsDeadline->tv_nsec += TsAdd.tv_nsec;
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132 | if ((uint32_t)pAbsDeadline->tv_nsec >= RT_NS_1SEC)
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133 | {
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134 | pAbsDeadline->tv_nsec -= RT_NS_1SEC;
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135 | pAbsDeadline->tv_sec++;
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136 | }
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137 | }
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138 | else
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139 | {
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140 | /* ASSUMES RTTimeSystemNanoTS() == RTTimeNanoTS() == clock_gettime(CLOCK_MONOTONIC). */
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141 | if (fFlags & RTSEMWAIT_FLAGS_RELATIVE)
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142 | {
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143 | uint64_t const nsNow = RTTimeSystemNanoTS();
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144 | uAbsTimeout += nsNow;
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145 | if (uAbsTimeout < nsNow)
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146 | return UINT64_MAX;
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147 | }
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148 |
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149 | /* Check for 32-bit tv_sec overflows: */
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150 | if ( sizeof(pAbsDeadline->tv_sec) < sizeof(uint64_t)
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151 | && uAbsTimeout >= (uint64_t)RT_NS_1SEC * UINT32_MAX)
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152 | return UINT64_MAX;
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153 |
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154 | pAbsDeadline->tv_nsec = uAbsTimeout % RT_NS_1SEC;
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155 | pAbsDeadline->tv_sec = uAbsTimeout / RT_NS_1SEC;
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156 | }
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157 |
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158 | return uTimeout;
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159 | }
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160 |
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161 | #endif /* !IPRT_INCLUDED_SRC_r3_posix_semwait_h */
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162 |
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