bug#32746: setitimer API is obsolescent

[Paul Eggert <eggert@cs.ucla.edu>]

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Eli Zaretskii wrote:

> However, I think it might be too early to remove support for
> setitimer, because some platforms have problems with it.  AFAIK, macOS
> and some *BSD version either don't have that family or have buggy
> implementations.

In that case never mind about removing use of setitimer. I'm attaching a patch 
against my previous proposal for fixup on the MS-Windows side, in the light of 
your other comments; good luck with it, and feel free to ignore the whole thing 
if it doesn't work. As before, it's untested and no doubt it has problems.

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From b52b0505bb53fa00943847eabc60b096bbbdfb80 Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Mon, 17 Sep 2018 09:04:06 -0700
Subject: [PATCH] =?UTF-8?q?Patch=20inspired=20by=20Eli=E2=80=99s=20review?=
 =?UTF-8?q?=20(Bug#32764#10)?=
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* nt/inc/sys/time.h (pthread_attr_t): Remove.
(struct sigevent): Remove sigev_notify_attributes.
(CLOCK_REALTIME, clockid_t):
Define only if CLOCK_REALTIME isn’t already defined.
(clockid_t): Just use int rather than getting fancy.
(CLOCK_REALTIME, CLOCK_THREAD_CPUTIME_ID):
Just use a macro rather than getting fancy.
(CLOCK_THREAD_CPUTIME_ID): Define to an unlikely int
instead of getting fancy.
* nt/mingw-cfg.site (ac_cv_func_timer_settime): Set to yes.
* src/w32proc.c (timer_gettime): Remove unused local and stray
use of it.
(timer_settime): Fix use of undeclared var.
Reverse sense of TIMER_ABSTIME.
---
 nt/inc/sys/time.h | 15 ++++++++++-----
 nt/mingw-cfg.site |  2 ++
 src/w32proc.c     | 10 ++++------
 3 files changed, 16 insertions(+), 11 deletions(-)

diff --git a/nt/inc/sys/time.h b/nt/inc/sys/time.h
index d03bc456ea..b238e36967 100644
--- a/nt/inc/sys/time.h
+++ b/nt/inc/sys/time.h
@@ -9,7 +9,6 @@ struct itimerspec
   struct  timespec it_value;	/* current value */
 };
 
-typedef struct pthread_attr_t *pthread_attr_t;
 union sigval
 {
   int sival_int;
@@ -21,14 +20,20 @@ struct sigevent
   int sigev_signo;
   union sigval sigev_value;
   void (*sigev_notify_function) (union sigval);
-  pthread_attr_t *sigev_notify_attributes;
+  /* Although POSIX requires 'pthread_attr_t *sigev_notify_attributes;',
+     that might clash with MinGW and Emacs *doesn’t need it.  */
 };
 #define SIGEV_SIGNAL 0
 
 #define TIMER_ABSTIME 1
-typedef enum { CLOCK_REALTIME, CLOCK_THREAD_CPUTIME_ID } clockid_t;
-#define CLOCK_REALTIME CLOCK_REALTIME
-#define CLOCK_THREAD_CPUTIME_ID CLOCK_THREAD_CPUTIME_ID
+
+#ifndef CLOCK_REALTIME
+typedef int clockid_t;
+# define CLOCK_REALTIME 0
+#endif
+#ifndef CLOCK_THREAD_CPUTIME_ID
+# define CLOCK_THREAD_CPUTIME_ID 106 /* unlikely to clash */
+#endif
 typedef struct
 {
   clockid_t clockid;
diff --git a/nt/mingw-cfg.site b/nt/mingw-cfg.site
index d9a824008c..25d5a40eb1 100644
--- a/nt/mingw-cfg.site
+++ b/nt/mingw-cfg.site
@@ -132,5 +132,7 @@ gl_cv_func_svid_putenv=yes
 ac_cv_func_sbrk=yes
 ac_cv_func_getrlimit=yes
 ac_cv_func_setrlimit=yes
+# Implemented in w32proc.c
+ac_cv_func_timer_settime=yes
 # GCC warnings that produce too much noise
 gl_cv_warn_c__Wredundant_decls=no
diff --git a/src/w32proc.c b/src/w32proc.c
index 23869768cf..20b7d6a220 100644
--- a/src/w32proc.c
+++ b/src/w32proc.c
@@ -651,7 +651,6 @@ timer_gettime (timer_t timerid, struct itimerspec *value)
   ULONGLONG expire, reload;
   CRITICAL_SECTION *crit;
   struct itimer_data *itimer;
-  HANDLE thread_hand;
   bool realtime = timerid.clockid == CLOCK_REALTIME;
 
   if (disable_itimers)
@@ -671,7 +670,6 @@ timer_gettime (timer_t timerid, struct itimerspec *value)
 
   itimer = realtime ? &real_itimer : &prof_itimer;
 
-  ticks_now = w32_get_timer_time (thread_hand);
   t_expire = &itimer->expire;
   t_reload = &itimer->reload;
   crit = realtime ? &crit_real : &crit_prof;
@@ -753,15 +751,15 @@ timer_settime (timer_t timerid, int flags,
   else
     reload += ns / (1000000000 / TIMER_TICKS_PER_SEC);
 
-  expire = ex.tv_sec * TIMER_TICKS_PER_SEC;
-  ns = ex.tv_nsec;
-  if (ex.tv_sec == 0
+  expire = value->it_value.tv_sec * TIMER_TICKS_PER_SEC;
+  ns = value->it_value.tv_nsec;
+  if (value->it_value.tv_sec == 0
       && 0 < ns && ns < clocks_min * (1000000000 / TIMER_TICKS_PER_SEC))
     expire = clocks_min;
   else
     reload += ns / (1000000000 / TIMER_TICKS_PER_SEC);
 
-  if (flags & TIMER_ABSTIME)
+  if (! (flags & TIMER_ABSTIME))
     expire += ticks_now;
 
   EnterCriticalSection (crit);
-- 
2.17.1