From 1dd03fbc77a0280479f81aeccf24aac63c37cd08 Mon Sep 17 00:00:00 2001
From: Nick Mathewson <nickm@torproject.org>
Date: Fri, 1 Feb 2013 16:09:16 -0500
Subject: [PATCH] Fix a silly mistake in the tor_mathlog() documentation. Give
 it a unit test.

---
 src/common/util.c    |  2 +-
 src/test/test_util.c | 16 ++++++++++++++++
 2 files changed, 17 insertions(+), 1 deletion(-)

diff --git a/src/common/util.c b/src/common/util.c
index 071ba8f635..7d72a896f9 100644
--- a/src/common/util.c
+++ b/src/common/util.c
@@ -322,7 +322,7 @@ tor_log_mallinfo(int severity)
  * ===== */
 
 /**
- * Returns the natural logarithm of d base 2.  We defined this wrapper here so
+ * Returns the natural logarithm of d base e.  We defined this wrapper here so
  * to avoid conflicts with old versions of tor_log(), which were named log().
  */
 double
diff --git a/src/test/test_util.c b/src/test/test_util.c
index ad214b9e67..bed33fac25 100644
--- a/src/test/test_util.c
+++ b/src/test/test_util.c
@@ -17,6 +17,7 @@
 #ifdef _WIN32
 #include <tchar.h>
 #endif
+#include <math.h>
 
 /* XXXX this is a minimal wrapper to make the unit tests compile with the
  * changed tor_timegm interface. */
@@ -3240,6 +3241,20 @@ test_util_set_env_var_in_sl(void *ptr)
   smartlist_free(expected_resulting_env_vars);
 }
 
+static void
+test_util_mathlog(void *arg)
+{
+  double d;
+  (void) arg;
+
+  d = tor_mathlog(2.718281828);
+  tt_double_op(fabs(d - 1.0), <, .000001);
+  d = tor_mathlog(10);
+  tt_double_op(fabs(d - 2.30258509), <, .000001);
+ done:
+  ;
+}
+
 #define UTIL_LEGACY(name)                                               \
   { #name, legacy_test_helper, 0, &legacy_setup, test_util_ ## name }
 
@@ -3296,6 +3311,7 @@ struct testcase_t util_tests[] = {
   UTIL_TEST(read_file_eof_tiny_limit, 0),
   UTIL_TEST(read_file_eof_two_loops, 0),
   UTIL_TEST(read_file_eof_zero_bytes, 0),
+  UTIL_TEST(mathlog, 0),
   END_OF_TESTCASES
 };