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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);
}
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