X-Git-Url: https://git.distorted.org.uk/u/mdw/putty/blobdiff_plain/e41356ff1a423bcc7bbe3fbbc36407aa067c76e0..425b94fd77a3aa6158d08616f90a080f38a42625:/unix/uxmisc.c

diff --git a/unix/uxmisc.c b/unix/uxmisc.c
index 8441349b..300fc543 100644
--- a/unix/uxmisc.c
+++ b/unix/uxmisc.c
@@ -7,24 +7,36 @@
 #include <stdlib.h>
 #include <assert.h>
 #include <unistd.h>
+#include <time.h>
 #include <sys/time.h>
 #include <sys/types.h>
 #include <pwd.h>
 
 #include "putty.h"
 
-long tickcount_offset = 0;
-
 unsigned long getticks(void)
 {
-    struct timeval tv;
-    gettimeofday(&tv, NULL);
     /*
-     * We want to use milliseconds rather than microseconds,
-     * because we need a decent number of them to fit into a 32-bit
-     * word so it can be used for keepalives.
+     * We want to use milliseconds rather than the microseconds or
+     * nanoseconds given by the underlying clock functions, because we
+     * need a decent number of them to fit into a 32-bit word so it
+     * can be used for keepalives.
      */
-    return tv.tv_sec * 1000 + tv.tv_usec / 1000 + tickcount_offset;
+#if defined HAVE_CLOCK_GETTIME && defined HAVE_DECL_CLOCK_MONOTONIC
+    {
+        /* Use CLOCK_MONOTONIC if available, so as to be unconfused if
+         * the system clock changes. */
+        struct timespec ts;
+        if (clock_gettime(CLOCK_MONOTONIC, &ts) == 0)
+            return ts.tv_sec * TICKSPERSEC +
+                ts.tv_nsec / (1000000000 / TICKSPERSEC);
+    }
+#endif
+    {
+        struct timeval tv;
+        gettimeofday(&tv, NULL);
+        return tv.tv_sec * TICKSPERSEC + tv.tv_usec / (1000000 / TICKSPERSEC);
+    }
 }
 
 Filename *filename_from_str(const char *str)