/* 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); }