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-rw-r--r--gl/lib/nanosleep.c276
1 files changed, 276 insertions, 0 deletions
diff --git a/gl/lib/nanosleep.c b/gl/lib/nanosleep.c
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+++ b/gl/lib/nanosleep.c
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+/* Provide a replacement for the POSIX nanosleep function.
+
+ Copyright (C) 1999-2000, 2002, 2004-2019 Free Software Foundation, Inc.
+
+ This program is free software: you can redistribute it and/or modify
+ it under the terms of the GNU General Public License as published by
+ the Free Software Foundation; either version 3 of the License, or
+ (at your option) any later version.
+
+ This program 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 General Public License for more details.
+
+ You should have received a copy of the GNU 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 "sig-handler.h"
+#include "verify.h"
+
+#include <stdbool.h>
+#include <stdio.h>
+#include <sys/types.h>
+#include <sys/select.h>
+#include <signal.h>
+
+#include <sys/time.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. */
+ verify (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
+/* Unix platforms lacking nanosleep. */
+
+/* Some systems (MSDOS) don't have SIGCONT.
+ Using SIGTERM here turns the signal-handling code below
+ into a no-op on such systems. */
+# ifndef SIGCONT
+# define SIGCONT SIGTERM
+# endif
+
+static sig_atomic_t volatile suspended;
+
+/* Handle SIGCONT. */
+
+static void
+sighandler (int sig)
+{
+ suspended = 1;
+}
+
+/* Suspend execution for at least *TS_DELAY seconds. */
+
+static int
+my_usleep (const struct timespec *ts_delay)
+{
+ struct timeval tv_delay;
+ tv_delay.tv_sec = ts_delay->tv_sec;
+ tv_delay.tv_usec = (ts_delay->tv_nsec + 999) / 1000;
+ if (tv_delay.tv_usec == 1000000)
+ {
+ if (tv_delay.tv_sec == TYPE_MAXIMUM (time_t))
+ tv_delay.tv_usec = 1000000 - 1; /* close enough */
+ else
+ {
+ tv_delay.tv_sec++;
+ tv_delay.tv_usec = 0;
+ }
+ }
+ return select (0, NULL, NULL, NULL, &tv_delay);
+}
+
+/* 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)
+{
+ static bool initialized;
+
+ if (requested_delay->tv_nsec < 0 || BILLION <= requested_delay->tv_nsec)
+ {
+ errno = EINVAL;
+ return -1;
+ }
+
+ /* set up sig handler */
+ if (! initialized)
+ {
+ struct sigaction oldact;
+
+ sigaction (SIGCONT, NULL, &oldact);
+ if (get_handler (&oldact) != SIG_IGN)
+ {
+ struct sigaction newact;
+
+ newact.sa_handler = sighandler;
+ sigemptyset (&newact.sa_mask);
+ newact.sa_flags = 0;
+ sigaction (SIGCONT, &newact, NULL);
+ }
+ initialized = true;
+ }
+
+ suspended = 0;
+
+ if (my_usleep (requested_delay) == -1)
+ {
+ if (suspended)
+ {
+ /* Calculate time remaining. */
+ /* FIXME: the code in sleep doesn't use this, so there's no
+ rush to implement it. */
+
+ errno = EINTR;
+ }
+ return -1;
+ }
+
+ /* FIXME: Restore sig handler? */
+
+ return 0;
+}
+#endif
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