Add some sleeps to gnutls_try_handshake

* admin/merge-gnulib (GNULIB_MODULES): Add the nanosleep module.
* m4/gnulib-comp.m4 (gl_EARLY):
* lib/gnulib.mk.in: Automatic update.

* m4/nanosleep.m4:
* lib/nanosleep.c: New module.

* nt/mingw-cfg.site (gl_cv_func_free_preserves_errno):
* nt/gnulib-cfg.mk (OMIT_GNULIB_MODULE_nanosleep): Omit nanosleep,
since mingw has it.

* src/gnutls.c (gnutls_try_handshake): Add some sleeping to the
busy-wait loop so that we don't use 100% CPU here (bug#32452).

2 files changed, 208 insertions, 0 deletions

diff --git a/lib/gnulib.mk.in b/lib/gnulib.mk.in
index 3a9f5b9818e..3deeca98bef 100644
--- a/lib/gnulib.mk.in
+++ b/lib/gnulib.mk.in
@@ -129,6 +129,7 @@
 #  minmax \
 #  mkostemp \
 #  mktime \
+#  nanosleep \
 #  nproc \
 #  nstrftime \
 #  pathmax \
@@ -207,6 +208,7 @@ CPP = @CPP@
 CPPFLAGS = @CPPFLAGS@
 CRYPTOLIB = @CRYPTOLIB@
 CXX = @CXX@
+CXXCPP = @CXXCPP@
 CXXFLAGS = @CXXFLAGS@
 CYGWIN_OBJ = @CYGWIN_OBJ@
 C_SWITCH_MACHINE = @C_SWITCH_MACHINE@
@@ -283,6 +285,7 @@ GL_COND_OBJ_MEMPCPY_CONDITION = @GL_COND_OBJ_MEMPCPY_CONDITION@
 GL_COND_OBJ_MEMRCHR_CONDITION = @GL_COND_OBJ_MEMRCHR_CONDITION@
 GL_COND_OBJ_MINI_GMP_GNULIB_CONDITION = @GL_COND_OBJ_MINI_GMP_GNULIB_CONDITION@
 GL_COND_OBJ_MKOSTEMP_CONDITION = @GL_COND_OBJ_MKOSTEMP_CONDITION@
+GL_COND_OBJ_NANOSLEEP_CONDITION = @GL_COND_OBJ_NANOSLEEP_CONDITION@
 GL_COND_OBJ_OPEN_CONDITION = @GL_COND_OBJ_OPEN_CONDITION@
 GL_COND_OBJ_PSELECT_CONDITION = @GL_COND_OBJ_PSELECT_CONDITION@
 GL_COND_OBJ_PTHREAD_SIGMASK_CONDITION = @GL_COND_OBJ_PTHREAD_SIGMASK_CONDITION@
@@ -2497,6 +2500,16 @@ EXTRA_libgnu_a_SOURCES += mktime.c
 endif
 ## end   gnulib module mktime-internal
 
+## begin gnulib module nanosleep
+ifeq (,$(OMIT_GNULIB_MODULE_nanosleep))
+
+ifneq (,$(GL_COND_OBJ_NANOSLEEP_CONDITION))
+libgnu_a_SOURCES += nanosleep.c
+endif
+
+endif
+## end   gnulib module nanosleep
+
 ## begin gnulib module nproc
 ifeq (,$(OMIT_GNULIB_MODULE_nproc))
 
diff --git a/lib/nanosleep.c b/lib/nanosleep.c
new file mode 100644
index 00000000000..446794edc0b
--- /dev/null
+++ b/lib/nanosleep.c
@@ -0,0 +1,195 @@
+/* Provide a replacement for the POSIX nanosleep function.
+
+   Copyright (C) 1999-2000, 2002, 2004-2022 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 "verify.h"
+
+#include <stdbool.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.  */
+    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
+/* 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