1 | /* Provide a replacement for the POSIX nanosleep function.
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2 |
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3 | Copyright (C) 1999-2000, 2002, 2004-2021 Free Software Foundation, Inc.
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4 |
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5 | This file is free software: you can redistribute it and/or modify
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6 | it under the terms of the GNU Lesser General Public License as
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7 | published by the Free Software Foundation; either version 2.1 of the
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8 | License, or (at your option) any later version.
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9 |
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10 | This file is distributed in the hope that it will be useful,
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11 | but WITHOUT ANY WARRANTY; without even the implied warranty of
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12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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13 | GNU Lesser General Public License for more details.
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14 |
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15 | You should have received a copy of the GNU Lesser General Public License
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16 | along with this program. If not, see <https://www.gnu.org/licenses/>. */
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17 |
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18 | /* written by Jim Meyering
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19 | and Bruno Haible for the native Windows part */
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20 |
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21 | #include <config.h>
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22 |
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23 | #include <time.h>
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24 |
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25 | #include "intprops.h"
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26 | #include "sig-handler.h"
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27 | #include "verify.h"
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28 |
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29 | #include <stdbool.h>
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30 | #include <stdio.h>
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31 | #include <sys/types.h>
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32 | #include <sys/select.h>
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33 | #include <signal.h>
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34 |
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35 | #include <sys/time.h>
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36 | #include <errno.h>
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37 |
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38 | #include <unistd.h>
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39 |
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40 |
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41 | enum { BILLION = 1000 * 1000 * 1000 };
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42 |
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43 | #if HAVE_BUG_BIG_NANOSLEEP
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44 |
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45 | int
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46 | nanosleep (const struct timespec *requested_delay,
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47 | struct timespec *remaining_delay)
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48 | # undef nanosleep
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49 | {
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50 | /* nanosleep mishandles large sleeps due to internal overflow problems.
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51 | The worst known case of this is Linux 2.6.9 with glibc 2.3.4, which
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52 | can't sleep more than 24.85 days (2^31 milliseconds). Similarly,
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53 | cygwin 1.5.x, which can't sleep more than 49.7 days (2^32 milliseconds).
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54 | Solve this by breaking the sleep up into smaller chunks. */
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55 |
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56 | if (requested_delay->tv_nsec < 0 || BILLION <= requested_delay->tv_nsec)
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57 | {
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58 | errno = EINVAL;
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59 | return -1;
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60 | }
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61 |
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62 | {
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63 | /* Verify that time_t is large enough. */
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64 | verify (TYPE_MAXIMUM (time_t) / 24 / 24 / 60 / 60);
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65 | const time_t limit = 24 * 24 * 60 * 60;
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66 | time_t seconds = requested_delay->tv_sec;
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67 | struct timespec intermediate;
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68 | intermediate.tv_nsec = requested_delay->tv_nsec;
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69 |
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70 | while (limit < seconds)
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71 | {
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72 | int result;
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73 | intermediate.tv_sec = limit;
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74 | result = nanosleep (&intermediate, remaining_delay);
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75 | seconds -= limit;
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76 | if (result)
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77 | {
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78 | if (remaining_delay)
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79 | remaining_delay->tv_sec += seconds;
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80 | return result;
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81 | }
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82 | intermediate.tv_nsec = 0;
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83 | }
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84 | intermediate.tv_sec = seconds;
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85 | return nanosleep (&intermediate, remaining_delay);
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86 | }
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87 | }
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88 |
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89 | #elif defined _WIN32 && ! defined __CYGWIN__
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90 | /* Native Windows platforms. */
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91 |
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92 | # define WIN32_LEAN_AND_MEAN
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93 | # include <windows.h>
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94 |
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95 | /* The Windows API function Sleep() has a resolution of about 15 ms and takes
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96 | at least 5 ms to execute. We use this function for longer time periods.
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97 | Additionally, we use busy-looping over short time periods, to get a
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98 | resolution of about 0.01 ms. In order to measure such short timespans,
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99 | we use the QueryPerformanceCounter() function. */
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100 |
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101 | int
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102 | nanosleep (const struct timespec *requested_delay,
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103 | struct timespec *remaining_delay)
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104 | {
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105 | static bool initialized;
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106 | /* Number of performance counter increments per nanosecond,
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107 | or zero if it could not be determined. */
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108 | static double ticks_per_nanosecond;
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109 |
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110 | if (requested_delay->tv_nsec < 0 || BILLION <= requested_delay->tv_nsec)
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111 | {
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112 | errno = EINVAL;
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113 | return -1;
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114 | }
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115 |
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116 | /* For requested delays of one second or more, 15ms resolution is
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117 | sufficient. */
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118 | if (requested_delay->tv_sec == 0)
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119 | {
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120 | if (!initialized)
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121 | {
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122 | /* Initialize ticks_per_nanosecond. */
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123 | LARGE_INTEGER ticks_per_second;
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124 |
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125 | if (QueryPerformanceFrequency (&ticks_per_second))
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126 | ticks_per_nanosecond =
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127 | (double) ticks_per_second.QuadPart / 1000000000.0;
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128 |
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129 | initialized = true;
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130 | }
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131 | if (ticks_per_nanosecond)
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132 | {
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133 | /* QueryPerformanceFrequency worked. We can use
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134 | QueryPerformanceCounter. Use a combination of Sleep and
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135 | busy-looping. */
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136 | /* Number of milliseconds to pass to the Sleep function.
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137 | Since Sleep can take up to 8 ms less or 8 ms more than requested
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138 | (or maybe more if the system is loaded), we subtract 10 ms. */
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139 | int sleep_millis = (int) requested_delay->tv_nsec / 1000000 - 10;
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140 | /* Determine how many ticks to delay. */
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141 | LONGLONG wait_ticks = requested_delay->tv_nsec * ticks_per_nanosecond;
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142 | /* Start. */
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143 | LARGE_INTEGER counter_before;
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144 | if (QueryPerformanceCounter (&counter_before))
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145 | {
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146 | /* Wait until the performance counter has reached this value.
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147 | We don't need to worry about overflow, because the performance
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148 | counter is reset at reboot, and with a frequency of 3.6E6
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149 | ticks per second 63 bits suffice for over 80000 years. */
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150 | LONGLONG wait_until = counter_before.QuadPart + wait_ticks;
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151 | /* Use Sleep for the longest part. */
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152 | if (sleep_millis > 0)
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153 | Sleep (sleep_millis);
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154 | /* Busy-loop for the rest. */
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155 | for (;;)
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156 | {
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157 | LARGE_INTEGER counter_after;
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158 | if (!QueryPerformanceCounter (&counter_after))
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159 | /* QueryPerformanceCounter failed, but succeeded earlier.
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160 | Should not happen. */
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161 | break;
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162 | if (counter_after.QuadPart >= wait_until)
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163 | /* The requested time has elapsed. */
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164 | break;
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165 | }
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166 | goto done;
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167 | }
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168 | }
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169 | }
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170 | /* Implementation for long delays and as fallback. */
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171 | Sleep (requested_delay->tv_sec * 1000 + requested_delay->tv_nsec / 1000000);
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172 |
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173 | done:
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174 | /* Sleep is not interruptible. So there is no remaining delay. */
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175 | if (remaining_delay != NULL)
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176 | {
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177 | remaining_delay->tv_sec = 0;
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178 | remaining_delay->tv_nsec = 0;
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179 | }
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180 | return 0;
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181 | }
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182 |
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183 | #else
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184 | /* Unix platforms lacking nanosleep. */
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185 |
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186 | /* Some systems (MSDOS) don't have SIGCONT.
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187 | Using SIGTERM here turns the signal-handling code below
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188 | into a no-op on such systems. */
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189 | # ifndef SIGCONT
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190 | # define SIGCONT SIGTERM
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191 | # endif
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192 |
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193 | static sig_atomic_t volatile suspended;
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194 |
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195 | /* Handle SIGCONT. */
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196 |
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197 | static _GL_ASYNC_SAFE void
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198 | sighandler (int sig)
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199 | {
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200 | suspended = 1;
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201 | }
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202 |
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203 | /* Suspend execution for at least *TS_DELAY seconds. */
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204 |
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205 | static int
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206 | my_usleep (const struct timespec *ts_delay)
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207 | {
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208 | struct timeval tv_delay;
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209 | tv_delay.tv_sec = ts_delay->tv_sec;
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210 | tv_delay.tv_usec = (ts_delay->tv_nsec + 999) / 1000;
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211 | if (tv_delay.tv_usec == 1000000)
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212 | {
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213 | if (tv_delay.tv_sec == TYPE_MAXIMUM (time_t))
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214 | tv_delay.tv_usec = 1000000 - 1; /* close enough */
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215 | else
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216 | {
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217 | tv_delay.tv_sec++;
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218 | tv_delay.tv_usec = 0;
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219 | }
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220 | }
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221 | return select (0, NULL, NULL, NULL, &tv_delay);
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222 | }
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223 |
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224 | /* Suspend execution for at least *REQUESTED_DELAY seconds. The
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225 | *REMAINING_DELAY part isn't implemented yet. */
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226 |
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227 | int
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228 | nanosleep (const struct timespec *requested_delay,
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229 | struct timespec *remaining_delay)
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230 | {
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231 | static bool initialized;
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232 |
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233 | if (requested_delay->tv_nsec < 0 || BILLION <= requested_delay->tv_nsec)
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234 | {
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235 | errno = EINVAL;
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236 | return -1;
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237 | }
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238 |
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239 | /* set up sig handler */
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240 | if (! initialized)
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241 | {
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242 | struct sigaction oldact;
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243 |
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244 | sigaction (SIGCONT, NULL, &oldact);
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245 | if (get_handler (&oldact) != SIG_IGN)
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246 | {
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247 | struct sigaction newact;
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248 |
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249 | newact.sa_handler = sighandler;
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250 | sigemptyset (&newact.sa_mask);
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251 | newact.sa_flags = 0;
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252 | sigaction (SIGCONT, &newact, NULL);
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253 | }
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254 | initialized = true;
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255 | }
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256 |
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257 | suspended = 0;
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258 |
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259 | if (my_usleep (requested_delay) == -1)
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260 | {
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261 | if (suspended)
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262 | {
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263 | /* Calculate time remaining. */
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264 | /* FIXME: the code in sleep doesn't use this, so there's no
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265 | rush to implement it. */
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266 |
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267 | errno = EINTR;
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268 | }
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269 | return -1;
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270 | }
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271 |
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272 | /* FIXME: Restore sig handler? */
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273 |
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274 | return 0;
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275 | }
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276 | #endif
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