Reintegrate tools from trunk

1 files changed, 243 insertions, 0 deletions

diff --git a/tools/plink/timing.c b/tools/plink/timing.c
new file mode 100644
index 000000000..2b7b70cb9
--- /dev/null
+++ b/tools/plink/timing.c
@@ -0,0 +1,243 @@
+/*

+ * timing.c

+ * 

+ * This module tracks any timers set up by schedule_timer(). It

+ * keeps all the currently active timers in a list; it informs the

+ * front end of when the next timer is due to go off if that

+ * changes; and, very importantly, it tracks the context pointers

+ * passed to schedule_timer(), so that if a context is freed all

+ * the timers associated with it can be immediately annulled.

+ */

+

+#include <assert.h>

+#include <stdio.h>

+

+#include "putty.h"

+#include "tree234.h"

+

+struct timer {

+    timer_fn_t fn;

+    void *ctx;

+    long now;

+};

+

+static tree234 *timers = NULL;

+static tree234 *timer_contexts = NULL;

+static long now = 0L;

+

+static int compare_timers(void *av, void *bv)

+{

+    struct timer *a = (struct timer *)av;

+    struct timer *b = (struct timer *)bv;

+    long at = a->now - now;

+    long bt = b->now - now;

+

+    if (at < bt)

+	return -1;

+    else if (at > bt)

+	return +1;

+

+    /*

+     * Failing that, compare on the other two fields, just so that

+     * we don't get unwanted equality.

+     */

+#ifdef __LCC__

+    /* lcc won't let us compare function pointers. Legal, but annoying. */

+    {

+	int c = memcmp(&a->fn, &b->fn, sizeof(a->fn));

+	if (c < 0)

+	    return -1;

+	else if (c > 0)

+	    return +1;

+    }

+#else    

+    if (a->fn < b->fn)

+	return -1;

+    else if (a->fn > b->fn)

+	return +1;

+#endif

+

+    if (a->ctx < b->ctx)

+	return -1;

+    else if (a->ctx > b->ctx)

+	return +1;

+

+    /*

+     * Failing _that_, the two entries genuinely are equal, and we

+     * never have a need to store them separately in the tree.

+     */

+    return 0;

+}

+

+static int compare_timer_contexts(void *av, void *bv)

+{

+    char *a = (char *)av;

+    char *b = (char *)bv;

+    if (a < b)

+	return -1;

+    else if (a > b)

+	return +1;

+    return 0;

+}

+

+static void init_timers(void)

+{

+    if (!timers) {

+	timers = newtree234(compare_timers);

+	timer_contexts = newtree234(compare_timer_contexts);

+	now = GETTICKCOUNT();

+    }

+}

+

+long schedule_timer(int ticks, timer_fn_t fn, void *ctx)

+{

+    long when;

+    struct timer *t, *first;

+

+    init_timers();

+

+    when = ticks + GETTICKCOUNT();

+

+    /*

+     * Just in case our various defences against timing skew fail

+     * us: if we try to schedule a timer that's already in the

+     * past, we instead schedule it for the immediate future.

+     */

+    if (when - now <= 0)

+	when = now + 1;

+

+    t = snew(struct timer);

+    t->fn = fn;

+    t->ctx = ctx;

+    t->now = when;

+

+    if (t != add234(timers, t)) {

+	sfree(t);		       /* identical timer already exists */

+    } else {

+	add234(timer_contexts, t->ctx);/* don't care if this fails */

+    }

+

+    first = (struct timer *)index234(timers, 0);

+    if (first == t) {

+	/*

+	 * This timer is the very first on the list, so we must

+	 * notify the front end.

+	 */

+	timer_change_notify(first->now);

+    }

+

+    return when;

+}

+

+/*

+ * Call to run any timers whose time has reached the present.

+ * Returns the time (in ticks) expected until the next timer after

+ * that triggers.

+ */

+int run_timers(long anow, long *next)

+{

+    struct timer *first;

+

+    init_timers();

+

+#ifdef TIMING_SYNC

+    /*

+     * In this ifdef I put some code which deals with the

+     * possibility that `anow' disagrees with GETTICKCOUNT by a

+     * significant margin. Our strategy for dealing with it differs

+     * depending on platform, because on some platforms

+     * GETTICKCOUNT is more likely to be right whereas on others

+     * `anow' is a better gold standard.

+     */

+    {

+	long tnow = GETTICKCOUNT();

+

+	if (tnow + TICKSPERSEC/50 - anow < 0 ||

+	    anow + TICKSPERSEC/50 - tnow < 0

+	    ) {

+#if defined TIMING_SYNC_ANOW

+	    /*

+	     * If anow is accurate and the tick count is wrong,

+	     * this is likely to be because the tick count is

+	     * derived from the system clock which has changed (as

+	     * can occur on Unix). Therefore, we resolve this by

+	     * inventing an offset which is used to adjust all

+	     * future output from GETTICKCOUNT.

+	     * 

+	     * A platform which defines TIMING_SYNC_ANOW is

+	     * expected to have also defined this offset variable

+	     * in (its platform-specific adjunct to) putty.h.

+	     * Therefore we can simply reference it here and assume

+	     * that it will exist.

+	     */

+	    tickcount_offset += anow - tnow;

+#elif defined TIMING_SYNC_TICKCOUNT

+	    /*

+	     * If the tick count is more likely to be accurate, we

+	     * simply use that as our time value, which may mean we

+	     * run no timers in this call (because we got called

+	     * early), or alternatively it may mean we run lots of

+	     * timers in a hurry because we were called late.

+	     */

+	    anow = tnow;

+#else

+/*

+ * Any platform which defines TIMING_SYNC must also define one of the two

+ * auxiliary symbols TIMING_SYNC_ANOW and TIMING_SYNC_TICKCOUNT, to

+ * indicate which measurement to trust when the two disagree.

+ */

+#error TIMING_SYNC definition incomplete

+#endif

+	}

+    }

+#endif

+

+    now = anow;

+

+    while (1) {

+	first = (struct timer *)index234(timers, 0);

+

+	if (!first)

+	    return FALSE;	       /* no timers remaining */

+

+	if (find234(timer_contexts, first->ctx, NULL) == NULL) {

+	    /*

+	     * This timer belongs to a context that has been

+	     * expired. Delete it without running.

+	     */

+	    delpos234(timers, 0);

+	    sfree(first);

+	} else if (first->now - now <= 0) {

+	    /*

+	     * This timer is active and has reached its running

+	     * time. Run it.

+	     */

+	    delpos234(timers, 0);

+	    first->fn(first->ctx, first->now);

+	    sfree(first);

+	} else {

+	    /*

+	     * This is the first still-active timer that is in the

+	     * future. Return how long it has yet to go.

+	     */

+	    *next = first->now;

+	    return TRUE;

+	}

+    }

+}

+

+/*

+ * Call to expire all timers associated with a given context.

+ */

+void expire_timer_context(void *ctx)

+{

+    init_timers();

+

+    /*

+     * We don't bother to check the return value; if the context

+     * already wasn't in the tree (presumably because no timers

+     * ever actually got scheduled for it) then that's fine and we

+     * simply don't need to do anything.

+     */

+    del234(timer_contexts, ctx);

+}