X-Git-Url: https://diplodocus.org/git/nmh/blobdiff_plain/1d03fb9aeca8ed1d59e41b938629e9d9ff8f49bf..86d4dcea853d7e37ff2615b793e3cb5dce7e3af0:/sbr/dtime.c

diff --git a/sbr/dtime.c b/sbr/dtime.c
index 56d874e0..0ed012b6 100644
--- a/sbr/dtime.c
+++ b/sbr/dtime.c
@@ -5,21 +5,32 @@
  * complete copyright information.
  */
 
-#include <h/mh.h>   /* for snprintf() */
-#include <h/nmh.h>
-#include <h/utils.h>
-#include <h/tws.h>
+#include "h/mh.h"
+#include "dtime.h"
+#include "h/nmh.h"
+#include "h/utils.h"
+#include "h/tws.h"
 #include <time.h>
 
 #if !defined(HAVE_STRUCT_TM_TM_GMTOFF)
 extern long timezone;
 #endif
 
+/* Size of largest possible int representing a time zone offset in minutes:
+   2,147,483,648 / 60 = 35,791,394 */
+#define DTZ_BUFFER_SIZE (sizeof "+3579139459")
+
+/*
+ * 1 if leap year, 0 otherwise.
+ */
+#define	isleapyear01(y)	\
+	(((y) % 4) ? 0 : (((y) % 100) ? 1 : (((y) % 400) ? 0 : 1)))
+
 /*
  * The number of days in the year, accounting for leap years
  */
 #define	dysize(y)	\
-	(((y) % 4) ? 365 : (((y) % 100) ? 366 : (((y) % 400) ? 365 : 366)))
+	(365 + isleapyear01(y))
 
 char *tw_moty[] = {
     "Jan", "Feb", "Mar", "Apr",
@@ -40,8 +51,13 @@ char *tw_ldotw[] = {
     "Saturday",  NULL
 };
 
-static int dmsize[] = {
-    31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
+static int dmsize[][12] = {
+    { /* Not a leap year */
+        31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
+    },
+    { /* Leap year: February = 29 */
+        31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
+    }
 };
 
 
@@ -118,7 +134,7 @@ dlocaltime (time_t *clock)
 
     tw.tw_clock = *clock;
 
-    return (&tw);
+    return &tw;
 }
 
 
@@ -165,7 +181,7 @@ dgmtime (time_t *clock)
 
     tw.tw_clock = *clock;
 
-    return (&tw);
+    return &tw;
 }
 
 
@@ -248,7 +264,8 @@ dtime (time_t *clock, int alpha_timezone)
 char *
 dasctime (struct tws *tw, int flags)
 {
-    char buffer[80];
+    char buffer[77];
+    char tzbuffer[DTZ_BUFFER_SIZE];
     static char result[80];
     int twf;
 
@@ -257,14 +274,14 @@ dasctime (struct tws *tw, int flags)
 
     /* Display timezone if known */
     if (tw->tw_flags & TW_SZEXP)
-	snprintf(result, sizeof(result), " %s", dtimezone(tw->tw_zone, tw->tw_flags | flags));
+	snprintf(tzbuffer, sizeof(tzbuffer), " %s", dtimezone(tw->tw_zone, tw->tw_flags | flags));
     else
-	result[0] = '\0';
+	tzbuffer[0] = '\0';
 
     snprintf(buffer, sizeof(buffer), "%02d %s %0*d %02d:%02d:%02d%s",
 	    tw->tw_mday, tw_moty[tw->tw_mon],
 	    tw->tw_year < 100 ? 2 : 4, tw->tw_year,
-	    tw->tw_hour, tw->tw_min, tw->tw_sec, result);
+	    tw->tw_hour, tw->tw_min, tw->tw_sec, tzbuffer);
 
     if ((twf = tw->tw_flags & TW_SDAY)) {
         if (twf == TW_SEXP)
@@ -285,9 +302,10 @@ dasctime (struct tws *tw, int flags)
  * return the string representation of the numeric offset.
  */
 
-char *dtimezone(int offset, int flags)
+char *
+dtimezone(int offset, int flags)
 {
-    static char buffer[sizeof "+3579139459"]; /* 2,147,483,648 / 60 = 35,791,394 */
+    static char buffer[DTZ_BUFFER_SIZE];
     bool pos;
     unsigned os, hours, mins;
 
@@ -306,6 +324,16 @@ char *dtimezone(int offset, int flags)
 }
 
 
+/*
+ * Last day of month (1-12) in given year.
+ */
+
+int
+dmlastday(int year, int mon)
+{
+    return dmsize[isleapyear01 (year)][mon - 1];
+}
+
 /*
  * Convert nmh time structure for local "broken-down"
  * time to calendar time (clock value).  This routine
@@ -316,7 +344,7 @@ char *dtimezone(int offset, int flags)
 time_t
 dmktime (struct tws *tw)
 {
-    int i, sec, min, hour, mday, mon, year;
+    int i, sec, min, hour, mday, mon, year, *msize;
     time_t result;
 
     if (tw->tw_clock != 0)
@@ -340,19 +368,21 @@ dmktime (struct tws *tw)
 
     for (i = 1970; i < year; i++)
 	result += dysize (i);
-    if (dysize (year) == 366 && mon >= 3)
-	result++;
+    msize = dmsize[isleapyear01 (year)];
     while (--mon)
-	result += dmsize[mon - 1];
+	result += msize[mon - 1];
     result += mday - 1;
-    result = 24 * result + hour;
-    result = 60 * result + min;
-    result = 60 * result + sec;
+    result *= 24; /* Days to hours. */
+    result += hour;
+    result *= 60; /* Hours to minutes. */
+    result += min;
+    result *= 60; /* Minutes to seconds. */
+    result += sec;
     result -= 60 * tw->tw_zone;
     if (tw->tw_flags & TW_DST)
-	result -= 60 * 60;
+	result -= 60 * 60; /* One hour. */
 
-    return (tw->tw_clock = result);
+    return tw->tw_clock = result;
 }
 
 
@@ -405,6 +435,6 @@ twsort (struct tws *tw1, struct tws *tw2)
     if (tw2->tw_clock == 0)
 	dmktime (tw2);
 
-    return ((c1 = tw1->tw_clock) > (c2 = tw2->tw_clock) ? 1
-	    : c1 == c2 ? 0 : -1);
+    return (c1 = tw1->tw_clock) > (c2 = tw2->tw_clock) ? 1
+	    : c1 == c2 ? 0 : -1;
 }