X-Git-Url: http://www.project-moonshot.org/gitweb/?p=trust_router.git;a=blobdiff_plain;f=common%2Ftr_util.c;fp=common%2Ftr_util.c;h=c3d03fba110be30b81aebfcb757fd1d792d80a0f;hp=2ce3c82d421c6241feaf689df50e886769f229fd;hb=6f65c9cce86719147d0b4dcc9823b25443c2d185;hpb=eaa1a8ceed54fbfadc2638cf383aaa12ab446a57

diff --git a/common/tr_util.c b/common/tr_util.c
index 2ce3c82..c3d03fb 100644
--- a/common/tr_util.c
+++ b/common/tr_util.c
@@ -36,8 +36,8 @@
 #include <stdio.h>
 #include <string.h>
 #include <time.h>
-#include <trust_router/tr_dh.h>
 #include <tr_util.h>
+#include <stdlib.h>
 
 void tr_bin_to_hex(const unsigned char * bin, size_t bin_len,
 		   char * hex_out, size_t hex_len)
@@ -51,9 +51,16 @@ void tr_bin_to_hex(const unsigned char * bin, size_t bin_len,
   }
 }
 
-/* Returns 0 if ts1==ts2, <0 if ts1<ts2, >= if ts1>ts2.
- * Assumes that tv_nsec <= 1e9. */
-int tr_cmp_timespec(struct timespec *ts1, struct timespec *ts2)
+/**
+ * Compare two timespecs
+ *
+ * Assumes tv_nsec <= 1e9
+ *
+ * @param ts1
+ * @param ts2
+ * @return 0 if ts1==ts2, -1 if ts1<ts2, 1 if ts1>ts2.
+ */
+int tr_cmp_timespec(const struct timespec *ts1, const struct timespec *ts2)
 {
   if (ts1->tv_sec > ts2->tv_sec)
     return 1;
@@ -71,3 +78,135 @@ int tr_cmp_timespec(struct timespec *ts1, struct timespec *ts2)
 
   return 0;
 }
+
+/**
+ * Compute ts1 + ts2
+ *
+ * @param ts1
+ * @param ts2
+ * @param sum ts1 + ts2
+ * @return 0 on success, nonzero on error
+ */
+int tr_add_timespec(const struct timespec *ts1, const struct timespec *ts2, struct timespec *sum)
+{
+  const time_t ONE_BILLION = 1000000000;
+
+  if (!ts1 || !ts2 || !sum)
+    return -1;
+
+  /* would be nice to do range checking, but I don't know a portable way to get the
+   * max value of a time_t. Figure that nsec <= 1e9 and seconds are unlikely to go off
+   * too close to infinity, so overflow is unlikely */
+  sum->tv_nsec = ts1->tv_nsec + ts2->tv_nsec;
+  sum->tv_sec = ts1->tv_sec + ts2->tv_sec;
+
+  /* make sure that we have no more than a second worth of nsec */
+  while (sum->tv_nsec >= ONE_BILLION) {
+    sum->tv_nsec -= ONE_BILLION;
+    sum->tv_sec += 1;
+  }
+
+  return 0;
+}
+
+/**
+ * Compute ts1 - ts2
+ *
+ * Allows negative results, which will be represented as a negative tv_sec.
+ * The returned tv_nsec is always positive and less than 1e9.
+ *
+ * (The value represented is tv_sec + tv_nsec/1e9 seconds - this is a little
+ * counterintuitive when tv_sec is negative. E.g., -1.5 seconds is represented
+ * as {-2, 500000000). Negative time_t values are not guaranteed to be supported
+ * anyway, so it's probably best to stay away from them.)
+ *
+ * @param ts1
+ * @param ts2
+ * @param diff ts1 - ts2
+ * @return 0 on success, nonzero on error
+ */
+int tr_sub_timespec(const struct timespec *ts1, const struct timespec *ts2, struct timespec *diff)
+{
+  const time_t ONE_BILLION = 1000000000;
+  struct timespec ts1_copy = {0};
+  struct timespec ts2_copy = {0};
+  
+  if (!ts1 || !ts2 || !diff)
+    return -1;
+
+  ts1_copy = *ts1;
+  ts2_copy = *ts2;
+  
+  while (ts2_copy.tv_nsec > ts1_copy.tv_nsec) {
+    /* Reduce ts2 by one second worth of nsec, balanced by removing a second
+     * from ts1. Repeat until ts2->tv_nsec <= ts1->tv_nsec. */
+    ts2_copy.tv_nsec -= ONE_BILLION;
+    ts1_copy.tv_sec -= 1;
+  }
+
+  diff->tv_nsec = ts1_copy.tv_nsec - ts2_copy.tv_nsec; /* >= 0 */
+  diff->tv_sec = ts1_copy.tv_sec - ts2_copy.tv_sec; /* sign indeterminate */
+
+  /* make sure we have no more than 1 sec worth of nsec */
+  while (diff->tv_nsec > ONE_BILLION) {
+    diff->tv_nsec -= ONE_BILLION;
+    diff->tv_sec += 1;
+  }
+
+  return 0;
+}
+
+/**
+ * Convert a struct timespec to a string representation
+ * @param ts
+ * @return
+ */
+char *timespec_to_str(const struct timespec *ts)
+{
+  struct tm tm;
+  char *s=NULL;
+
+  if (gmtime_r(&(ts->tv_sec), &tm)==NULL)
+    return NULL;
+
+  s=malloc(40); /* long enough to contain strftime result */
+  if (s==NULL)
+    return NULL;
+
+  if (strftime(s, 40, "%F %T UTC", &tm)==0) {
+    free(s);
+    return NULL;
+  }
+  return s;
+}
+
+/**
+ * Convert a time from one clock to another
+ *
+ * Because this involves reading each clock, it is not exact.
+ *
+ * @param from clock to convert from
+ * @param when time to convert, measured on the 'from' clock
+ * @param to clock to convert to
+ * @param dst destination, measured on the 'to' clock
+ * @return dst or null on error
+ */
+struct timespec *tr_clock_convert(clockid_t from, const struct timespec *when,
+                                  clockid_t to, struct timespec *dst)
+{
+  struct timespec now_from = {0};
+  struct timespec diff = {0}; /* difference between when and now_from */
+  struct timespec now_to = {0};
+
+  if ((clock_gettime(from, &now_from) != 0)
+      || (clock_gettime(to, &now_to) != 0)) {
+    return NULL;
+  }
+  if (tr_sub_timespec(when, &now_from, &diff) != 0) {
+    return NULL;
+  }
+  if (tr_add_timespec(&now_to, &diff, dst) != 0) {
+    return NULL;
+  }
+  return dst;
+}