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Diffstat (limited to 'lib/nanosleep.c')
| -rw-r--r-- | lib/nanosleep.c | 193 |
1 files changed, 193 insertions, 0 deletions
diff --git a/lib/nanosleep.c b/lib/nanosleep.c new file mode 100644 index 0000000..3f295f4 --- /dev/null +++ b/lib/nanosleep.c @@ -0,0 +1,193 @@ +/* Provide a replacement for the POSIX nanosleep function. + + Copyright (C) 1999-2000, 2002, 2004-2023 Free Software Foundation, Inc. + + This file is free software: you can redistribute it and/or modify + it under the terms of the GNU Lesser General Public License as + published by the Free Software Foundation; either version 2.1 of the + License, or (at your option) any later version. + + This file is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public License + along with this program. If not, see <https://www.gnu.org/licenses/>. */ + +/* written by Jim Meyering + and Bruno Haible for the native Windows part */ + +#include <config.h> + +#include <time.h> + +#include "intprops.h" + +#include <stdio.h> +#include <sys/types.h> +#include <sys/select.h> +#include <signal.h> + +#include <errno.h> + +#include <unistd.h> + + +enum { BILLION = 1000 * 1000 * 1000 }; + +#if HAVE_BUG_BIG_NANOSLEEP + +int +nanosleep (const struct timespec *requested_delay, + struct timespec *remaining_delay) +# undef nanosleep +{ + /* nanosleep mishandles large sleeps due to internal overflow problems. + The worst known case of this is Linux 2.6.9 with glibc 2.3.4, which + can't sleep more than 24.85 days (2^31 milliseconds). Similarly, + cygwin 1.5.x, which can't sleep more than 49.7 days (2^32 milliseconds). + Solve this by breaking the sleep up into smaller chunks. */ + + if (requested_delay->tv_nsec < 0 || BILLION <= requested_delay->tv_nsec) + { + errno = EINVAL; + return -1; + } + + { + /* Verify that time_t is large enough. */ + static_assert (TYPE_MAXIMUM (time_t) / 24 / 24 / 60 / 60); + const time_t limit = 24 * 24 * 60 * 60; + time_t seconds = requested_delay->tv_sec; + struct timespec intermediate; + intermediate.tv_nsec = requested_delay->tv_nsec; + + while (limit < seconds) + { + int result; + intermediate.tv_sec = limit; + result = nanosleep (&intermediate, remaining_delay); + seconds -= limit; + if (result) + { + if (remaining_delay) + remaining_delay->tv_sec += seconds; + return result; + } + intermediate.tv_nsec = 0; + } + intermediate.tv_sec = seconds; + return nanosleep (&intermediate, remaining_delay); + } +} + +#elif defined _WIN32 && ! defined __CYGWIN__ +/* Native Windows platforms. */ + +# define WIN32_LEAN_AND_MEAN +# include <windows.h> + +/* The Windows API function Sleep() has a resolution of about 15 ms and takes + at least 5 ms to execute. We use this function for longer time periods. + Additionally, we use busy-looping over short time periods, to get a + resolution of about 0.01 ms. In order to measure such short timespans, + we use the QueryPerformanceCounter() function. */ + +int +nanosleep (const struct timespec *requested_delay, + struct timespec *remaining_delay) +{ + static bool initialized; + /* Number of performance counter increments per nanosecond, + or zero if it could not be determined. */ + static double ticks_per_nanosecond; + + if (requested_delay->tv_nsec < 0 || BILLION <= requested_delay->tv_nsec) + { + errno = EINVAL; + return -1; + } + + /* For requested delays of one second or more, 15ms resolution is + sufficient. */ + if (requested_delay->tv_sec == 0) + { + if (!initialized) + { + /* Initialize ticks_per_nanosecond. */ + LARGE_INTEGER ticks_per_second; + + if (QueryPerformanceFrequency (&ticks_per_second)) + ticks_per_nanosecond = + (double) ticks_per_second.QuadPart / 1000000000.0; + + initialized = true; + } + if (ticks_per_nanosecond) + { + /* QueryPerformanceFrequency worked. We can use + QueryPerformanceCounter. Use a combination of Sleep and + busy-looping. */ + /* Number of milliseconds to pass to the Sleep function. + Since Sleep can take up to 8 ms less or 8 ms more than requested + (or maybe more if the system is loaded), we subtract 10 ms. */ + int sleep_millis = (int) requested_delay->tv_nsec / 1000000 - 10; + /* Determine how many ticks to delay. */ + LONGLONG wait_ticks = requested_delay->tv_nsec * ticks_per_nanosecond; + /* Start. */ + LARGE_INTEGER counter_before; + if (QueryPerformanceCounter (&counter_before)) + { + /* Wait until the performance counter has reached this value. + We don't need to worry about overflow, because the performance + counter is reset at reboot, and with a frequency of 3.6E6 + ticks per second 63 bits suffice for over 80000 years. */ + LONGLONG wait_until = counter_before.QuadPart + wait_ticks; + /* Use Sleep for the longest part. */ + if (sleep_millis > 0) + Sleep (sleep_millis); + /* Busy-loop for the rest. */ + for (;;) + { + LARGE_INTEGER counter_after; + if (!QueryPerformanceCounter (&counter_after)) + /* QueryPerformanceCounter failed, but succeeded earlier. + Should not happen. */ + break; + if (counter_after.QuadPart >= wait_until) + /* The requested time has elapsed. */ + break; + } + goto done; + } + } + } + /* Implementation for long delays and as fallback. */ + Sleep (requested_delay->tv_sec * 1000 + requested_delay->tv_nsec / 1000000); + + done: + /* Sleep is not interruptible. So there is no remaining delay. */ + if (remaining_delay != NULL) + { + remaining_delay->tv_sec = 0; + remaining_delay->tv_nsec = 0; + } + return 0; +} + +#else +/* Other platforms lacking nanosleep. + It's not clear whether these are still practical porting targets. + For now, just fall back on pselect. */ + +/* Suspend execution for at least *REQUESTED_DELAY seconds. The + *REMAINING_DELAY part isn't implemented yet. */ + +int +nanosleep (const struct timespec *requested_delay, + struct timespec *remaining_delay) +{ + return pselect (0, NULL, NULL, NULL, requested_delay, NULL); +} +#endif |