From 2f7918deec140ef837070bb749a35ed19bfcd0ec Mon Sep 17 00:00:00 2001
From: Martijn Dekker <martijn@inlv.org>
Date: Fri, 15 Jan 2021 19:05:32 +0000
Subject: [PATCH] libast: backport tvsleep(3) from ksh 93v- (re: 2db9953a)

src/lib/libast/tm/tvsleep.c:
- Since the 'sleep' builtin was backported/fixed from ksh93v- and
  ksh2020, it makes sense to use the latest/last tvsleep(3), too.
  Looks like this added an interrupt check (errno == EINTR).
  Also, new fallback versions for systems without nanosleep(2).

Documentation: src/lib/libast/man/tv.3 (unchanged)
---
 src/lib/libast/tm/tvsleep.c | 183 +++++++++++++++++++++++++-----------
 1 file changed, 126 insertions(+), 57 deletions(-)

diff --git a/src/lib/libast/tm/tvsleep.c b/src/lib/libast/tm/tvsleep.c
index 78da80247..3a1b9aefe 100644
--- a/src/lib/libast/tm/tvsleep.c
+++ b/src/lib/libast/tm/tvsleep.c
@@ -1,7 +1,7 @@
 /***********************************************************************
 *                                                                      *
 *               This software is part of the ast package               *
-*          Copyright (c) 1985-2011 AT&T Intellectual Property          *
+*          Copyright (c) 1985-2013 AT&T Intellectual Property          *
 *                      and is licensed under the                       *
 *                 Eclipse Public License, Version 1.0                  *
 *                    by AT&T Intellectual Property                     *
@@ -14,34 +14,30 @@
 *                            AT&T Research                             *
 *                           Florham Park NJ                            *
 *                                                                      *
-*                 Glenn Fowler <gsf@research.att.com>                  *
-*                  David Korn <dgk@research.att.com>                   *
-*                   Phong Vo <kpv@research.att.com>                    *
+*               Glenn Fowler <glenn.s.fowler@gmail.com>                *
+*                    David Korn <dgkorn@gmail.com>                     *
+*                     Phong Vo <phongvo@gmail.com>                     *
 *                                                                      *
 ***********************************************************************/
 #pragma prototyped
 
 #include <tv.h>
 #include <tm.h>
+#include <error.h>
 
 #include "FEATURE/tvlib"
 
-#if !_lib_nanosleep
+#if !_lib_nanosleep && !_lib_usleep
 # if _lib_select
 #  if _sys_select
 #   include <sys/select.h>
 #  else
 #   include <sys/socket.h>
 #  endif
-# else
-#  if !_lib_usleep
-#   if _lib_poll_notimer
-#    undef _lib_poll
-#   endif
-#   if _lib_poll
-#    include <poll.h>
-#   endif
-#  endif
+# elif _lib_poll_notimer
+#  undef _lib_poll
+# elif _lib_poll
+#  include <poll.h>
 # endif
 #endif
 
@@ -49,6 +45,8 @@
  * sleep for tv
  * non-zero exit if sleep did not complete
  * with remaining time in rv
+ *
+ * NOTE: some systems hide nanosleep() outside of libc
  */
 
 int
@@ -63,7 +61,7 @@ tvsleep(register const Tv_t* tv, register Tv_t* rv)
 
 	stv.tv_sec = tv->tv_sec;
 	stv.tv_nsec = tv->tv_nsec;
-	if ((r = nanosleep(&stv, &srv)) && rv)
+	if ((r = nanosleep(&stv, &srv)) && errno == EINTR && rv)
 	{
 		rv->tv_sec = srv.tv_sec;
 		rv->tv_nsec = srv.tv_nsec;
@@ -72,72 +70,143 @@ tvsleep(register const Tv_t* tv, register Tv_t* rv)
 
 #else
 
+	Tv_t		bv;
+
+	tvgettime(&bv);
+	{
+
 #if _lib_select
 
 	struct timeval	stv;
 
 	stv.tv_sec = tv->tv_sec;
-	stv.tv_usec = tv->tv_nsec / 1000;
-	if (select(0, NiL, NiL, NiL, &stv) < 0)
-	{
-		if (rv)
-			*rv = *tv;
-		return -1;
-	}
-	if (rv)
-	{
-		rv->tv_sec = stv.tv_sec;
-		rv->tv_nsec = stv.tv_usec * 1000;
-	}
-	return 0;
+	if (!(stv.tv_usec = tv->tv_nsec / 1000))
+		stv.tv_usec = 1;
+	if (select(0, NiL, NiL, NiL, &stv) >= 0)
+		return 0;
 
 #else
 
-	unsigned int		s = tv->tv_sec;
-	uint32_t		n = tv->tv_nsec;
+	uint32_t	s = tv->tv_sec;
+	uint32_t	n = tv->tv_nsec;
+	unsigned int	t;
 
 #if _lib_usleep
 
-
-	unsigned long		t;
-
-	if (t = (n + 999L) / 1000L)
+	if (s < (0x7fffffff / 1000000))
 	{
-		usleep(t);
-		s -= t / 1000000L;
-		n = 0;
+		int	oerrno;
+
+		oerrno = errno;
+		errno = 0;
+		usleep(s * 1000000 + n / 1000);
+		if (!errno)
+		{
+			errno = oerrno;
+			return 0;
+		}
+	}
+	else
+	{
+
+#endif
+
+		if (s += (n + 999999999L) / 1000000000L)
+		{
+			while (s)
+			{
+				if (s > UINT_MAX)
+				{
+					t = UINT_MAX;
+					s -= UINT_MAX;
+				}
+				else
+				{
+					t = s;
+					s = 0;
+				}
+				if (t = sleep(t))
+				{
+					if (rv)
+					{
+						rv->tv_sec = s + t;
+						rv->tv_nsec = 0;
+					}
+					return -1;
+				}
+			}
+			return 0;
+		}
+
+#if _lib_usleep
+
+		if (t = (n + 999L) / 1000L)
+		{
+			int	oerrno;
+
+			oerrno = errno;
+			errno = 0;
+			usleep(t);
+			if (!errno)
+			{
+				errno = oerrno;
+				return 0;
+			}
+		}
 	}
 
-#else
-
-#if _lib_poll
+#elif _lib_poll
 
 	struct pollfd		pfd;
 	int			t;
 
-	if ((t = (n + 999999L) / 1000000L) > 0)
-	{
-		poll(&pfd, 0, t);
-		s -= t / 1000L;
-		n = 0;
+	if (!(t = (n + 999999L) / 1000000L))
+		t = 1;
+	if (poll(&pfd, 0, t) >= 0)
+		return 0;
+
+#endif
+
+#endif
+
 	}
-
-#endif
-
-#endif
-
-	if ((s += (n + 999999999L) / 1000000000L) && (s = sleep(s)))
+ bad:
+	if (errno == EINTR && rv)
 	{
-		if (rv)
+		tvgettime(rv);
+		if (rv->tv_nsec < bv.tv_nsec)
 		{
-			rv->tv_sec = s;
+			rv->tv_nsec += 1000000000L;
+			rv->tv_sec--;
+		}
+		rv->tv_nsec -= bv.tv_nsec;
+		rv->tv_sec -= bv.tv_sec;
+		if (rv->tv_sec > tv->tv_sec)
+		{
+			rv->tv_sec = 0;
 			rv->tv_nsec = 0;
 		}
-		return -1;
+		else
+		{
+			rv->tv_sec = tv->tv_sec - rv->tv_sec;
+			if (rv->tv_nsec > tv->tv_nsec)
+			{
+				if (!rv->tv_sec)
+				{
+					rv->tv_sec = 0;
+					rv->tv_nsec = 0;
+				}
+				else
+				{
+					rv->tv_sec--;
+					rv->tv_nsec = 1000000000L - rv->tv_nsec + tv->tv_nsec;
+				}
+			}
+			else
+				rv->tv_nsec = tv->tv_nsec - rv->tv_nsec;
+		}
 	}
-	return 0;
-
-#endif
+	return -1;
 
 #endif