make sure we only use _NL_TIME_WEEK_1STDAY if we actually have it ... thanks kevin...

[rrdtool.git] / src / rrd_graph.c

diff --git a/src/rrd_graph.c b/src/rrd_graph.c
index a93fbb1..9e23a4a 100644 (file)
--- 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"
 
@@ -1355,7 +1359,21 @@ int data_proc(
     return 0;
 }
 
-
+static int find_first_weekday(void){
+    static int first_weekday = -1;
+    if (first_weekday == -1){
+#ifdef HAVE__NL_TIME_WEEK_1STDAY
+        /* 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 +1415,10 @@ 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: