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+/* vi: set sw=4 ts=4:
+ *
+ * cal.c - show calendar.
+ *
+ * Copyright 2011 Rob Landley <rob@landley.net>
+ *
+ * See http://opengroup.org/onlinepubs/9699919799/utilities/cal.html
+
+USE_CAL(NEWTOY(cal, ">2", TOYFLAG_USR|TOYFLAG_BIN))
+
+config CAL
+ bool "cal"
+ default y
+ help
+ usage: cal [[month] year]
+ Print a calendar.
+
+ With one argument, prints all months of the specified year.
+ With two arguments, prints calendar for month and year.
+*/
+
+#include "toys.h"
+
+// Write calendar into buffer: each line is 20 chars wide, end indicated
+// by empty string.
+
+static char *calstrings(char *buf, struct tm *tm)
+{
+ char temp[21];
+ int wday, mday, start, len, line;
+
+ // header
+ len = strftime(temp, 21, "%B %Y", tm);
+ len += (20-len)/2;
+ buf += sprintf(buf, "%*s%*s ", len, temp, 20-len, "");
+ buf++;
+ buf += sprintf(buf, "Su Mo Tu We Th Fr Sa ");
+ buf++;
+
+ // What day of the week does this month start on?
+ if (tm->tm_mday>1)
+ start = (36+tm->tm_wday-tm->tm_mday)%7;
+ else start = tm->tm_wday;
+
+ // What day does this month end on? Alas, libc doesn't tell us...
+ len = 31;
+ if (tm->tm_mon == 1) {
+ int year = tm->tm_year;
+ len = 28;
+ if (!(year & 3) && !((year&100) && !(year&400))) len++;
+ } else if ((tm->tm_mon+(tm->tm_mon>6 ? 1 : 0)) & 1) len = 30;
+
+ for (mday=line=0;line<6;line++) {
+ for (wday=0; wday<7; wday++) {
+ char *pat = " ";
+ if (!mday ? wday==start : mday<len) {
+ pat = "%2d ";
+ mday++;
+ }
+ buf += sprintf(buf, pat, mday);
+ }
+ buf++;
+ }
+
+ return buf;
+}
+
+void xcheckrange(long val, long low, long high)
+{
+ char *err = "%ld %s than %ld";
+
+ if (val < low) error_exit(err, val, "less", low);
+ if (val > high) error_exit(err, val, "greater", high);
+}
+
+// Worst case scenario toybuf usage: sizeof(struct tm) plus 21 bytes/line
+// plus 8 lines/month plus 12 months, comes to a bit over 2k of our 4k buffer.
+
+void cal_main(void)
+{
+ struct tm *tm;
+ char *buf = toybuf;
+
+ if (toys.optc) {
+ // Conveniently starts zeroed
+ tm = (struct tm *)toybuf;
+ buf += sizeof(struct tm);
+
+ // Last argument is year, one before that (if any) is month.
+ xcheckrange(tm->tm_year = atol(toys.optargs[--toys.optc]),1,9999);
+ tm->tm_year -= 1900;
+ tm->tm_mday = 1;
+ tm->tm_hour = 12; // noon to avoid timezone weirdness
+ if (toys.optc) {
+ xcheckrange(tm->tm_mon = atol(toys.optargs[--toys.optc]),1,12);
+ tm->tm_mon--;
+
+ // Print 12 months of the year
+
+ } else {
+ char *bufs[12];
+ int i, j, k;
+
+ for (i=0; i<12; i++) {
+ tm->tm_mon=i;
+ mktime(tm);
+ buf = calstrings(bufs[i]=buf, tm);
+ }
+
+ // 4 rows, 6 lines each, 3 columns
+ for (i=0; i<4; i++) {
+ for (j=0; j<8; j++) {
+ for(k=0; k<3; k++) {
+ char **b = bufs+(k+i*3);
+ *b += printf("%s ", *b);
+ }
+ puts("");
+ }
+ }
+ return;
+ }
+
+ // What day of the week does that start on?
+ mktime(tm);
+
+ } else {
+ time_t now;
+ time(&now);
+ tm = localtime(&now);
+ }
+
+ calstrings(buf, tm);
+ while (*buf) buf += printf("%s\n", buf);
+}