1 files changed, 17 insertions, 0 deletions

diff --git a/acconfig.h b/acconfig.h
index a37c0823c..db7fd18b1 100644
--- a/acconfig.h
+++ b/acconfig.h
@@ -71,6 +71,10 @@
 # include <paths.h> /* For _PATH_XXX */
 #endif 
 
+#ifdef HAVE_SYS_TIME_H
+# include <sys/time.h> /* For timersub */
+#endif
+
 #ifndef SHUT_RDWR
 enum
 {
@@ -178,3 +182,16 @@ enum
 # define MAX(a,b) (((a)>(b))?(a):(b))
 # define MIN(a,b) (((a)<(b))?(a):(b))
 #endif
+
+#ifndef timersub
+#define timersub(a, b, result)                                                                            \
+   do {                                                                                                                                           \
+      (result)->tv_sec = (a)->tv_sec - (b)->tv_sec;           \
+      (result)->tv_usec = (a)->tv_usec - (b)->tv_usec;        \
+      if ((result)->tv_usec < 0) {                            \
+         --(result)->tv_sec;                                  \
+         (result)->tv_usec += 1000000;                        \
+      }                                                       \
+   } while (0)
+
+#endif