X-Git-Url: https://git.octo.it/?p=rrdtool.git;a=blobdiff_plain;f=src%2Frrd_graph.c;h=390a66ec162ebe8ee80c48cf3932a62bf5eab7ed;hp=a93fbb1c52708ca3d047630eb587434c6ac29a00;hb=f467b805f7cbe821d1bfec27ad643067dd19ca10;hpb=f54455954eb3111c1b702d3ed7b9daff833690f3

diff --git a/src/rrd_graph.c b/src/rrd_graph.c
index a93fbb1..390a66e 100644
--- a/src/rrd_graph.c
+++ b/src/rrd_graph.c
@@ -29,6 +29,10 @@
 
 #include <locale.h>
 
+#ifdef HAVE_LANGINFO_H
+#include <langinfo.h>
+#endif
+
 #include "rrd_graph.h"
 #include "rrd_client.h"
 
@@ -1356,6 +1360,21 @@ int data_proc(
 }
 
 
+static int find_first_weekday(void){
+    static int first_weekday = -1;
+    if (first_weekday == -1){
+#if defined(HAVE_NL_LANGINFO)
+        /* according to http://sourceware.org/ml/libc-locales/2009-q1/msg00011.html */
+        long week_1stday_l = (long) nl_langinfo (_NL_TIME_WEEK_1STDAY);
+        if (week_1stday_l == 19971130) first_weekday = 0; /* Sun */
+        else if (week_1stday_l == 19971201) first_weekday = 1; /* Mon */
+        else first_weekday = 1; /* we go for a monday default */
+#else
+        first_weekday = 1;
+#endif
+    }
+    return first_weekday;
+}
 
 /* identify the point where the first gridline, label ... gets placed */
 
@@ -1397,10 +1416,10 @@ time_t find_first_time(
         tm.       tm_sec = 0;
         tm.       tm_min = 0;
         tm.       tm_hour = 0;
-        tm.       tm_mday -= tm.tm_wday - 1;    /* -1 because we want the monday */
+        tm.       tm_mday -= tm.tm_wday - find_first_weekday();
 
-        if (tm.tm_wday == 0)
-            tm.       tm_mday -= 7; /* we want the *previous* monday */
+        if (tm.tm_wday == 0 && find_first_weekday() > 0)
+            tm.       tm_mday -= 7; /* we want the *previous* week */
 
         break;
     case TMT_MONTH: