/*
This file is part of GNUnet.
- Copyright (C) 2001-2013 GNUnet e.V.
+ Copyright (C) 2001-2013, 2018 GNUnet e.V.
GNUnet is free software: you can redistribute it and/or modify it
under the terms of the GNU Affero General Public License as published
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Affero General Public License for more details.
-
+
You should have received a copy of the GNU Affero General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+ SPDX-License-Identifier: AGPL3.0-or-later
*/
/**
* @brief functions for handling time and time arithmetic
*/
#include "platform.h"
-#include "gnunet_crypto_lib.h"
-#include "gnunet_time_lib.h"
+#include "gnunet_util_lib.h"
+#if __STDC_NO_ATOMICS__
+#define ATOMIC
+#else
+#ifdef HAVE_STDATOMIC_H
+#include <stdatomic.h>
+#define ATOMIC _Atomic
+#else
+#define __STDC_NO_ATOMICS__ 1
+#define ATOMIC
+#endif
+#endif
#define LOG(kind,...) GNUNET_log_from (kind, "util-time", __VA_ARGS__)
}
+/**
+ * Obtain the current time and make sure it is monotonically
+ * increasing. Guards against systems without an RTC or
+ * clocks running backwards and other nasty surprises. Does
+ * not guarantee that the returned time is near the current
+ * time returned by #GNUNET_TIME_absolute_get(). Two
+ * subsequent calls (within a short time period) may return the
+ * same value. Persists the last returned time on disk to
+ * ensure that time never goes backwards. As a result, the
+ * resulting value can be used to check if a message is the
+ * "most recent" value and replays of older messages (from
+ * the same origin) would be discarded.
+ *
+ * @param cfg configuration, used to determine where to
+ * store the time; user can also insist RTC is working
+ * nicely and disable the feature
+ * @return monotonically increasing time
+ */
+struct GNUNET_TIME_Absolute
+GNUNET_TIME_absolute_get_monotonic (const struct GNUNET_CONFIGURATION_Handle *cfg)
+{
+ static const struct GNUNET_CONFIGURATION_Handle *last_cfg;
+ static struct GNUNET_TIME_Absolute last_time;
+ static struct GNUNET_DISK_MapHandle *map_handle;
+ static ATOMIC volatile uint64_t *map;
+ struct GNUNET_TIME_Absolute now;
+
+ now = GNUNET_TIME_absolute_get ();
+ if (last_cfg != cfg)
+ {
+ char *filename;
+
+ if (NULL != map_handle)
+ {
+ GNUNET_DISK_file_unmap (map_handle);
+ map_handle = NULL;
+ }
+ map = NULL;
+
+ last_cfg = cfg;
+ if ( (NULL != cfg) &&
+ (GNUNET_OK ==
+ GNUNET_CONFIGURATION_get_value_filename (cfg,
+ "util",
+ "MONOTONIC_TIME_FILENAME",
+ &filename)) )
+ {
+ struct GNUNET_DISK_FileHandle *fh;
+
+ fh = GNUNET_DISK_file_open (filename,
+ GNUNET_DISK_OPEN_READWRITE | GNUNET_DISK_OPEN_CREATE,
+ GNUNET_DISK_PERM_USER_WRITE | GNUNET_DISK_PERM_GROUP_WRITE |
+ GNUNET_DISK_PERM_USER_READ | GNUNET_DISK_PERM_GROUP_READ);
+ if (NULL == fh)
+ {
+ GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
+ _("Failed to map `%s', cannot assure monotonic time!\n"),
+ filename);
+ }
+ else
+ {
+ off_t size;
+
+ size = 0;
+ GNUNET_break (GNUNET_OK ==
+ GNUNET_DISK_file_handle_size (fh,
+ &size));
+ if (size < sizeof (*map))
+ {
+ struct GNUNET_TIME_AbsoluteNBO o;
+
+ o = GNUNET_TIME_absolute_hton (now);
+ if (sizeof (o) !=
+ GNUNET_DISK_file_write (fh,
+ &o,
+ sizeof (o)))
+ size = 0;
+ else
+ size = sizeof (o);
+ }
+ if (size == sizeof (*map))
+ {
+ map = GNUNET_DISK_file_map (fh,
+ &map_handle,
+ GNUNET_DISK_MAP_TYPE_READWRITE,
+ sizeof (*map));
+ if (NULL == map)
+ GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
+ _("Failed to map `%s', cannot assure monotonic time!\n"),
+ filename);
+ }
+ else
+ {
+ GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
+ _("Failed to setup monotonic time file `%s', cannot assure monotonic time!\n"),
+ filename);
+ }
+ }
+ GNUNET_DISK_file_close (fh);
+ GNUNET_free (filename);
+ }
+ }
+ if (NULL != map)
+ {
+ struct GNUNET_TIME_AbsoluteNBO mt;
+
+#if __STDC_NO_ATOMICS__
+#if __GNUC__
+ mt.abs_value_us__ = __sync_fetch_and_or (map, 0);
+#else
+ mt.abs_value_us__ = *map; /* godspeed, pray this is atomic */
+#endif
+#else
+ mt.abs_value_us__ = atomic_load (map);
+#endif
+ last_time = GNUNET_TIME_absolute_max (GNUNET_TIME_absolute_ntoh (mt),
+ last_time);
+ }
+ if (now.abs_value_us <= last_time.abs_value_us)
+ now.abs_value_us = last_time.abs_value_us+1;
+ last_time = now;
+ if (NULL != map)
+ {
+ uint64_t val = GNUNET_TIME_absolute_hton (now).abs_value_us__;
+#if __STDC_NO_ATOMICS__
+#if __GNUC__
+ (void) __sync_lock_test_and_set (map, val);
+#else
+ *map = val; /* godspeed, pray this is atomic */
+#endif
+#else
+ atomic_store (map,
+ val);
+#endif
+ }
+ return now;
+}
+
+/**
+ * Destructor
+ */
+void __attribute__ ((destructor))
+GNUNET_util_time_fini ()
+{
+ (void) GNUNET_TIME_absolute_get_monotonic (NULL);
+}
/* end of time.c */
projects / oweals / gnunet.git / blobdiff