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authorRoland McGrath <roland@gnu.org>1995-02-18 01:27:10 +0000
committerRoland McGrath <roland@gnu.org>1995-02-18 01:27:10 +0000
commit28f540f45bbacd939bfd07f213bcad2bf730b1bf (patch)
tree15f07c4c43d635959c6afee96bde71fb1b3614ee /sysdeps/mach/hurd/getitimer.c
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initial import
Diffstat (limited to 'sysdeps/mach/hurd/getitimer.c')
-rw-r--r--sysdeps/mach/hurd/getitimer.c104
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diff --git a/sysdeps/mach/hurd/getitimer.c b/sysdeps/mach/hurd/getitimer.c
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+/* Copyright (C) 1994, 1995 Free Software Foundation, Inc.
+This file is part of the GNU C Library.
+
+The GNU C Library is free software; you can redistribute it and/or
+modify it under the terms of the GNU Library General Public License as
+published by the Free Software Foundation; either version 2 of the
+License, or (at your option) any later version.
+
+The GNU C Library 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
+Library General Public License for more details.
+
+You should have received a copy of the GNU Library General Public
+License along with the GNU C Library; see the file COPYING.LIB.  If
+not, write to the Free Software Foundation, Inc., 675 Mass Ave,
+Cambridge, MA 02139, USA.  */
+
+#include <ansidecl.h>
+#include <stddef.h>
+#include <errno.h>
+#include <sys/time.h>
+#include <hurd.h>
+
+/* XXX Temporary cheezoid implementation; see __setitmr.c.  */
+
+/* These are defined in __setitmr.c.  */
+extern spin_lock_t _hurd_itimer_lock;
+extern struct itimerval _hurd_itimerval;
+extern struct timeval _hurd_itimer_started;
+
+static inline void
+subtract_timeval (struct timeval *from, const struct timeval *subtract)
+{
+  from->tv_usec -= subtract->tv_usec;
+  from->tv_sec -= subtract->tv_sec;
+  while (from->tv_usec < 0)
+    {
+      --from->tv_sec;
+      from->tv_usec += 1000000;
+    }
+}
+
+/* Set *VALUE to the current setting of timer WHICH.
+   Return 0 on success, -1 on errors.  */
+int
+DEFUN(__getitimer, (which, value),
+      enum __itimer_which which AND struct itimerval *value)
+{
+  struct itimerval val;
+  struct timeval elapsed;
+
+  switch (which)
+    {
+    default:
+      return __hurd_fail (EINVAL);
+
+    case ITIMER_VIRTUAL:
+    case ITIMER_PROF:
+      return __hurd_fail (ENOSYS);
+
+    case ITIMER_REAL:
+      break;
+    }
+
+  /* Get the time now.  */
+  if (__gettimeofday (&elapsed, NULL) < 0)
+    return -1;
+
+  /* Extract the current timer setting; and the time it was set, so we can
+     calculate the time elapsed so far.  */
+  HURD_CRITICAL_BEGIN;
+  __spin_lock (&_hurd_itimer_lock);
+  val = _hurd_itimerval;
+  subtract_timeval (&elapsed, &_hurd_itimer_started);
+  __spin_unlock (&_hurd_itimer_lock);
+  HURD_CRITICAL_END;
+
+  if ((val.it_value.tv_sec | val.it_value.tv_usec) != 0)
+    {
+      /* There is a pending alarm set.  VAL indicates the interval it was
+	 set for, relative to the time recorded in _hurd_itimer_started.
+	 Now compensate for the time elapsed since to get the user's
+	 conception of the current value of the timer (as if the value
+	 stored decreased every microsecond).  */
+      if (timercmp (&val.it_value, &elapsed, <))
+	{
+	  /* Hmm.  The timer should have just gone off, but has not been
+	     reset.  This is a possible timing glitch.  The alarm will signal
+	     soon, so fabricate a value for how soon.  */
+	  val.it_value.tv_sec = 0;
+	  val.it_value.tv_usec = 10; /* Random.  */
+	}
+      else
+	/* Subtract the time elapsed since the timer was set
+	   from the current timer value the user sees.  */
+	subtract_timeval (&val.it_value, &elapsed);
+    }
+
+  *value = val;
+  return 0;
+}
+
+weak_alias (__getitimer, getitimer)