Mercurial > hg > toybox
view toys/posix/cal.c @ 1531:3ff823086c99 draft
Teach ln -f to leave original target alone if link creation fails.
Suggested by Ashwini Sharma, I wound up implementing it by creating the new
link at a temporary name and renaming it over the old one instead of renaming
the old file out of the way and putting it back if it failed.
(Because "mkdir -p one/one/blah && ln -sf /bin/one one" would otherwise
rename one/one out of the way and only notice it can't delete it way at the
end when recovery's darn awkward, vs create new thing and if rename fails
(including EISDIR) that's the main error path. And yes the temporary name
is in the same directory as the destination so we never rename between mounts.)
link over the old one instead of renaming the old file and renaming it back.
author | Rob Landley <rob@landley.net> |
---|---|
date | Wed, 22 Oct 2014 17:11:06 -0500 |
parents | fc1bb49e58a9 |
children |
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/* 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); }