text: /*	$NetBSD: calendar.c,v 1.52 2015/07/01 06:48:25 dholland Exp $	*/
  
  /*
   * Copyright (c) 1989, 1993, 1994
   *	The Regents of the University of California.  All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   * 3. Neither the name of the University nor the names of its contributors
   *    may be used to endorse or promote products derived from this software
   *    without specific prior written permission.
   *
   * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   * SUCH DAMAGE.
   */
  
  #include <sys/cdefs.h>
  #ifndef lint
  __COPYRIGHT("@(#) Copyright (c) 1989, 1993\
   The Regents of the University of California.  All rights reserved.");
  #endif /* not lint */
  
  #ifndef lint
  #if 0
  static char sccsid[] = "@(#)calendar.c	8.4 (Berkeley) 1/7/95";
  #endif
  __RCSID("$NetBSD: calendar.c,v 1.52 2015/07/01 06:48:25 dholland Exp $");
  #endif /* not lint */
  
  #include <sys/param.h>
  #include <sys/ioctl.h>
  #include <sys/time.h>
  #include <sys/stat.h>
  #include <sys/uio.h>
  #include <sys/wait.h>
  
  #include <assert.h>
  #include <ctype.h>
  #include <err.h>
  #include <errno.h>
  #include <fcntl.h>
  #include <pwd.h>
  #include <stdbool.h>
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  #include <time.h>
  #include <tzfile.h>
  #include <unistd.h>
  
  #include "pathnames.h"
  
  	/* flags used by calendar file parser */
  #define	F_ISMONTH	0x01
  #define	F_ISDAY		0x02
  #define	F_ISDOW		0x04
  #define	F_WILDMONTH	0x10
  #define	F_WILDDAY	0x20
  
  static unsigned short lookahead = 1;
  static unsigned short weekend = 2;
  static char *fname = NULL;
  static char *datestr = NULL;
  static const char *defaultnames[] = {"calendar", ".calendar", _PATH_SYSTEM_CALENDAR, NULL};
  static struct passwd *pw;
  static char path[MAXPATHLEN + 1];
  static bool doall = false;
  static bool cpp_restricted = false;
  
  /* 1-based month, 0-based days, cumulative */
  static const int daytab[][14] = {
  	{ 0, -1, 30, 58, 89, 119, 150, 180, 211, 242, 272, 303, 333, 364 },
  	{ 0, -1, 30, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365 },
  };
  static struct tm *tp;
  static const int *cumdays;
  static int offset, yrdays;
  static char dayname[10];
  
  static struct iovec header[] = {
  	{ __UNCONST("From: "), 6 },
  	{ NULL, 0 },
  	{ __UNCONST(" (Reminder Service)\nTo: "), 24 },
  	{ NULL, 0 },
  	{ __UNCONST("\nSubject: "), 10 },
  	{ NULL, 0 },
  	{ __UNCONST("'s Calendar\nPrecedence: bulk\n\n"),  30 },
  };
  
  static const char *days[] = {
  	"sun", "mon", "tue", "wed", "thu", "fri", "sat", NULL,
  };
  
  static const char *months[] = {
  	"jan", "feb", "mar", "apr", "may", "jun",
  	"jul", "aug", "sep", "oct", "nov", "dec", NULL,
  };
  
  static void	 atodays(int, char *, unsigned short *);
  static void	 cal(void);
  static void	 closecal(FILE *);
  static void	 changeuser(void);
  static int	 getday(char *);
  static int	 getfield(char *, char **, int *);
  static void	 getmmdd(struct tm *, char *);
  static int	 getmonth(char *);
  static bool	 isnow(char *);
  static FILE	*opencal(FILE **);
  static int	 tryopen(const char *, int);
  static void	 settime(void);
  static void	 usage(void) __dead;
  
  int
  main(int argc, char **argv)
  {
  	int ch;
  	const char *caldir;
  
  	(void)setprogname(argv[0]);	/* for portability */
  
  	while ((ch = getopt(argc, argv, "-ad:f:l:w:x")) != -1) {
  		switch (ch) {
  		case '-':		/* backward contemptible */
  		case 'a':
  			if (getuid()) {
  				errno = EPERM;
  				err(EXIT_FAILURE, NULL);
  			}
  			doall = true;
  			break;
  		case 'd':
  			datestr = optarg;
  			break;
  		case 'f':
  			fname = optarg;
  			break;
  		case 'l':
  			atodays(ch, optarg, &lookahead);
  			break;
  		case 'w':
  			atodays(ch, optarg, &weekend);
  			break;
  		case 'x':
  			cpp_restricted = true;
  			break;
  		case '?':
  		default:
  			usage();
  		}
  	}
  	argc -= optind;
  	argv += optind;
  
  	if (argc)
  		usage();
  
  	settime();
  	if (doall) {
  		/*
  		 * XXX - This ignores the user's CALENDAR_DIR variable.
  		 *       Run under user's login shell?
  		 */
  		if (setgroups(0, NULL) == -1) {
  			err(EXIT_FAILURE, "setgroups");
  		}
  		while ((pw = getpwent()) != NULL) {
  			if (setegid(pw->pw_gid) == -1) {
  				warn("%s: setegid", pw->pw_name);
  				continue;
  			}
  			if (seteuid(pw->pw_uid) == -1) {
  				warn("%s: seteuid", pw->pw_name);
  				continue;
  			}
  			if (chdir(pw->pw_dir) != -1) {
  				cal();
  			}
  			if (seteuid(0) == -1) {
  				warn("%s: seteuid back to 0", pw->pw_name);
  			}
  		}
  	} else if ((caldir = getenv("CALENDAR_DIR")) != NULL) {
  		if (chdir(caldir) != -1)
  			cal();
  	} else if ((pw = getpwuid(geteuid())) != NULL) {
  		if (chdir(pw->pw_dir) != -1)
  			cal();
  	}
  	return 0;
  }
  
  static void
  cal(void)
  {
  	bool printing;
  	FILE *fp, *in = NULL;
  	char *line;
  
  	if ((fp = opencal(&in)) == NULL || in == NULL)
  		return;
  	printing = false;
  	while ((line = fparseln(in,
  		    NULL, NULL, NULL, FPARSELN_UNESCCOMM)) != NULL) {
  		if (line[0] == '\0')
  			continue;
  		if (line[0] != '\t')
  			printing = isnow(line);
  		if (printing)
  			(void)fprintf(fp, "%s\n", line);
  		free(line);
  
  	}
  	closecal(fp);
  }
  
  static void
  settime(void)
  {
  	time_t now;
  
  	(void)time(&now);
  	tp = localtime(&now);
  	if (datestr)
  		getmmdd(tp, datestr);
  
  	if (isleap(tp->tm_year + TM_YEAR_BASE)) {
  		yrdays = DAYSPERLYEAR;
  		cumdays = daytab[1];
  	} else {
  		yrdays = DAYSPERNYEAR;
  		cumdays = daytab[0];
  	}
  	/* Friday displays Monday's events */
  	offset = tp->tm_wday == 5 ? lookahead + weekend : lookahead;
  	header[5].iov_base = dayname;
  	header[5].iov_len = strftime(dayname, sizeof(dayname), "%A", tp);
  }
  
  /*
   * Possible date formats include any combination of:
   *	3-charmonth			(January, Jan, Jan)
   *	3-charweekday			(Friday, Monday, mon.)
   *	numeric month or day		(1, 2, 04)
   *
   * Any character may separate them, or they may not be separated.  Any line,
   * following a line that is matched, that starts with "whitespace", is shown
   * along with the matched line.
   */
  static bool
  isnow(char *endp)
  {
  	int day;
  	int flags;
  	int month;
  	int v1;
  	int v2;
  
  	flags = 0;
  
  	/* didn't recognize anything, skip it */
  	if (!(v1 = getfield(endp, &endp, &flags)))
  		return false;
  
  	if ((flags & (F_ISDAY|F_ISDOW)) || v1 > 12) {
  		/* found a day */
  		day = v1;
  		/* if no recognizable month, assume wildcard ('*') month */
  		if ((month = getfield(endp, &endp, &flags)) == 0) {
  			flags |= F_ISMONTH | F_WILDMONTH;
  			month = tp->tm_mon + 1;
  		}
  	} else if (flags & F_ISMONTH) {
  		month = v1;
  		/* if no recognizable day, assume the first */
  		if ((day = getfield(endp, &endp, &flags)) == 0)
  			day = 1;
  	} else {
  		v2 = getfield(endp, &endp, &flags);
  		if (flags & F_ISMONTH) {
  			day = v1;
  			month = v2;
  		} else {
  			/* F_ISDAY set, v2 > 12, or no way to tell */
  			month = v1;
  			/* if no recognizable day, assume the first */
  			day = v2 ? v2 : 1;
  		}
  	}
  	/* if month is out of range, treat it as '*' */
  	if (month < 1 || month > 12) {
  		flags |= F_ISMONTH | F_WILDMONTH;
  		month = tp->tm_mon + 1;
  	}
  
  	if (flags & F_WILDMONTH && flags & F_WILDDAY)
  		return true;
  
  	if (flags & F_WILDMONTH && flags & F_ISDAY && day == tp->tm_mday)
  		return true;
  
  	if (flags & F_WILDMONTH && flags & F_ISDOW && day == tp->tm_wday + 1)
  		return true;
  
  	if (flags & F_ISMONTH && flags & F_WILDDAY && month == tp->tm_mon + 1)
  		return true;
  
  	if (flags & F_ISMONTH && flags & F_ISDOW && month == tp->tm_mon + 1 &&
  	    day == tp->tm_wday + 1)
  		return true;
  
  	if (flags & F_ISDOW)
  		day = tp->tm_mday + (((day - 1) - tp->tm_wday + 7) % 7);
  	day = cumdays[month] + day;
  
  	/* if today or today + offset days */
  	if (day >= tp->tm_yday && day <= tp->tm_yday + offset)
  		return true;
  
  	/* if number of days left in this year + days to event in next year */
  	if (yrdays - tp->tm_yday + day <= offset)
  		return true;
  
  	return false;
  }
  
  static int
  getfield(char *p, char **endp, int *flags)
  {
  	int val;
  	char *start;
  	char savech;
  
  /*
   * note this macro has an arg that isn't used ... it is retained
   * (it is believed) to make the macro call look more "natural"
   * and suggest at the call site what is happening.
   */
  #define FLDCHAR(a) (*p != '\0' && !isdigit((unsigned char)*p) && \
      !isalpha((unsigned char)*p) && *p != '*')
  
  	val = 0;
  	for (/*EMPTY*/; FLDCHAR(*p); ++p)
  		continue;
  	if (*p == '*') {			/* `*' is current month */
  		if (!(*flags & F_ISMONTH)) {
  			*flags |= F_ISMONTH | F_WILDMONTH;
  			*endp = p + 1;
  			return tp->tm_mon + 1;
  		} else {
  			*flags |= F_ISDAY | F_WILDDAY;
  			*endp = p + 1;
  			return 1;
  		}
  	}
  	if (isdigit((unsigned char)*p)) {
  		val = (int)strtol(p, &p, 10);	/* if 0, it's failure */
  		for (/*EMPTY*/; FLDCHAR(*p); ++p)
  			continue;
  		*endp = p;
  		return val;
  	}
  	for (start = p; *p != '\0' && isalpha((unsigned char)*p); p++)
  		continue;
  
  	savech = *p;
  	if (p != start) {
  		*p = '\0';
  		if ((val = getmonth(start)) != 0)
  			*flags |= F_ISMONTH;
  		else if ((val = getday(start)) != 0)
  			*flags |= F_ISDOW;
  		else {
  			*p = savech;
  			*endp = start;
  			return 0;
  		}
  	}
  	for (*p = savech; FLDCHAR(*p); ++p)
  		continue;
  	*endp = p;
  	return val;
  }
  
  static FILE *
  opencal(FILE **in)
  {
  	int fd = -1;
  	int pdes[2];
  
  	/* open up calendar file as stdin */
  	if (fname == NULL) {
  		for (const char **name = defaultnames; *name != NULL; name++) {
  			if ((fd = tryopen(*name, O_RDONLY)) == -1)
  				continue;
  			else
  				break;
  		}
  		if (fd == -1) {
  			if (doall)
  				return NULL;
  			err(EXIT_FAILURE, "Cannot open calendar file");
  		}
  	} else if ((fd = tryopen(fname, O_RDONLY)) == -1) {
  		if (doall)
  			return NULL;
  		err(EXIT_FAILURE, "Cannot open `%s'", fname);
  	}
  
  	if (pipe(pdes) == -1) {
  		warn("Cannot open pipe");
  		return NULL;
  	}
  
  	switch (fork()) {
  	case -1:
  		/* error */
  		(void)close(pdes[0]);
  		(void)close(pdes[1]);
  		return NULL;
  	case 0:
  		/* child */
  		/* set stdin to calendar file */
  		if (fd != STDIN_FILENO) {
  			(void)dup2(fd, STDIN_FILENO);
  			(void)close(fd);
  		}
  		/* set stdout to pipe input */
  		if (pdes[1] != STDOUT_FILENO) {
  			(void)dup2(pdes[1], STDOUT_FILENO);
  			(void)close(pdes[1]);
  		}
  		(void)close(pdes[0]);
  		if (doall) {
  			/* become the user properly */
  			changeuser();
  		}
  		/* tell CPP to only open regular files */
  		if(!cpp_restricted && setenv("CPP_RESTRICTED", "", 1) == -1)
  			err(EXIT_FAILURE, "Cannot restrict cpp");
  		cpp_restricted = true;
  
  		(void)execl(_PATH_CPP, "cpp", "-traditional", "-P", "-I.",
  		    "-I" _PATH_CALENDARS, NULL);
  		err(EXIT_FAILURE, "Cannot exec `%s'", _PATH_CPP);
  		/*NOTREACHED*/
  	default:
  		/* parent -- fdopen *in to pipe output */
  		*in = fdopen(pdes[0], "r");
  		(void)close(pdes[1]);
  
  		/* close calendar file */
  		close(fd);
  
  		/* not reading all calendar files, just set output to stdout */
  		if (!doall)
  			return stdout;
  
  		/*
  		 * Set output to a temporary file, so if no output
  		 * don't send mail.
  		 */
  		(void)snprintf(path, sizeof(path), "%s/_calXXXXXX", _PATH_TMP);
  		if ((fd = mkstemp(path)) == -1) {
  			warn("Cannot create temporary file");
  			return NULL;
  		}
  		return fdopen(fd, "w+");
  	}
  	/*NOTREACHED*/
  }
  
  static int
  tryopen(const char *pathname, int flags)
  {
  	int fd, serrno, zero;
  	struct stat st;
  
  	/*
  	 * XXX: cpp_restricted has inverted sense; it is false by default,
  	 * and -x sets it to true. CPP_RESTRICTED is set in the environment
  	 * if cpp_restricted is false... go figure. This should be fixed
  	 * later.
  	 */
  	if (doall && cpp_restricted == false) {
  		/*
  		 * We are running with the user's euid, so they can't
  		 * cause any mayhem (e.g. opening rewinding tape
  		 * devices) that they couldn't do easily enough on
  		 * their own. All we really need to worry about is opens
  		 * that hang, because that would DoS the calendar run.
  		 */
  		fd = open(pathname, flags | O_NONBLOCK);
  		if (fd == -1) {
  			return -1;
  		}
  		if (fstat(fd, &st) == -1) {
  			serrno = errno;
  			close(fd);
  			errno = serrno;
  			return -1;
  		}
  		if (S_ISCHR(st.st_mode) ||
  		    S_ISBLK(st.st_mode) ||
  		    S_ISFIFO(st.st_mode)) {
  			close(fd);
  
  			/* Call shenanigans in the daily output */
  			errno = EPERM;
  			warn("%s: %s", pw->pw_name, pathname);
  
  			errno = EPERM;
  			return -1;
  		}
  		if (S_ISDIR(st.st_mode)) {
  			/* Don't warn about this */
  			close(fd);
  			errno = EISDIR;
  			return -1;
  		}
  		if (!S_ISREG(st.st_mode)) {
  			/* There shouldn't be other cases to go here */
  			close(fd);
  			errno = EINVAL;
  			return -1;
  		}
  		zero = 0;
  		if (ioctl(fd, FIONBIO, &zero) == -1) {
  			serrno = errno;
  			warn("%s: %s: FIONBIO", pw->pw_name, pathname);
  			close(fd);
  			errno = serrno;
  			return -1;
  		}
  		return fd;
  	} else {
  		return open(pathname, flags);
  	}
  }
  
  static void
  closecal(FILE *fp)
  {
  	struct stat sbuf;
  	ssize_t nread;
  	int pdes[2];
  	int status;
  	char buf[1024];
  
  	if (!doall)
  		return;
  
  	(void)rewind(fp);
  	if (fstat(fileno(fp), &sbuf) == -1 || sbuf.st_size == 0)
  		goto done;
  	if (pipe(pdes) == -1)
  		goto done;
  
  	switch (fork()) {
  	case -1:
  		/* error */
  		(void)close(pdes[0]);
  		(void)close(pdes[1]);
  		break;
  	case 0:
  		/* child -- set stdin to pipe output */
  		if (pdes[0] != STDIN_FILENO) {
  			(void)dup2(pdes[0], STDIN_FILENO);
  			(void)close(pdes[0]);
  		}
  		(void)close(pdes[1]);
  		if (doall) {
  			/* become the user properly */
  			changeuser();
  		}
  		(void)execl(_PATH_SENDMAIL, "sendmail", "-i", "-t", "-F",
  		    "\"Reminder Service\"", "-f", "root", NULL);
  		err(EXIT_FAILURE, "Cannot exec `%s'", _PATH_SENDMAIL);
  		/*NOTREACHED*/
  	default:
  		/* parent -- write to pipe input */
  		(void)close(pdes[0]);
  
  		header[1].iov_base = header[3].iov_base = (void *)pw->pw_name;
  		header[1].iov_len = header[3].iov_len = strlen(pw->pw_name);
  		(void)writev(pdes[1], header, 7);
  		while ((nread = read(fileno(fp), buf, sizeof(buf))) > 0)
  			(void)write(pdes[1], buf, (size_t)nread);
  		(void)close(pdes[1]);
  		break;
  	}
  
  done:	(void)fclose(fp);
  	(void)unlink(path);
  	while (wait(&status) != -1)
  		continue;
  }
  
  static void
  changeuser(void)
  {
  	uid_t uid;
  	gid_t gid;
  
  	uid = geteuid();
  	gid = getegid();
  	assert(uid == pw->pw_uid);
  	assert(gid == pw->pw_gid);
  
  	if (seteuid(0) == -1) {
  		err(EXIT_FAILURE, "%s: changing user: cannot reassert uid 0",
  		    pw->pw_name);
  	}
  	if (setgid(gid) == -1) {
  		err(EXIT_FAILURE, "%s: cannot assume gid %d",
  		    pw->pw_name, (int)gid);
  	}
  	if (initgroups(pw->pw_name, gid) == -1) {
  		err(EXIT_FAILURE, "%s: cannot initgroups", pw->pw_name);
  	}
  	if (setuid(uid) == -1) {
  		err(EXIT_FAILURE, "%s: cannot assume uid %d",
  		    pw->pw_name, (int)uid);
  	}
  }
  
  static int
  getmonth(char *s)
  {
  	const char **p;
  
  	for (p = months; *p; ++p)
  		if (strncasecmp(s, *p, 3) == 0)
  			return (int)(p - months) + 1;
  	return 0;
  }
  
  static int
  getday(char *s)
  {
  	const char **p;
  
  	for (p = days; *p; ++p)
  		if (strncasecmp(s, *p, 3) == 0)
  			return (int)(p - days) + 1;
  	return 0;
  }
  
  static void
  atodays(int ch, char *arg, unsigned short *rvp)
  {
  	int u;
  
  	u = atoi(arg);
  	if (u < 0 || u > 366)
  		warnx("-%c %d out of range 0-366, ignored.", ch, u);
  	else
  		*rvp = u;
  }
  
  #define todigit(x) ((x) - '0')
  #define ATOI2(x) (todigit((x)[0]) * 10 + todigit((x)[1]))
  #define ISDIG2(x) (isdigit((unsigned char)(x)[0]) && isdigit((unsigned char)(x)[1]))
  
  static void
  getmmdd(struct tm *ptm, char *ds)
  {
  	bool ok = false;
  	struct tm ttm;
  
  	ttm = *ptm;
  	ttm.tm_isdst = -1;
  
  	if (ISDIG2(ds)) {
  		ttm.tm_mon = ATOI2(ds) - 1;
  		ds += 2;
  	}
  	if (ISDIG2(ds)) {
  		ttm.tm_mday = ATOI2(ds);
  		ds += 2;
  		ok = true;
  	}
  	if (ok) {
  		if (ISDIG2(ds) && ISDIG2(ds + 2)) {
  			ttm.tm_year = ATOI2(ds) * 100 - TM_YEAR_BASE;
  			ds += 2;
  			ttm.tm_year += ATOI2(ds);
  		} else if (ISDIG2(ds)) {
  			ttm.tm_year = ATOI2(ds);
  			if (ttm.tm_year < 69)
  				ttm.tm_year += 2000 - TM_YEAR_BASE;
  			else
  				ttm.tm_year += 1900 - TM_YEAR_BASE;
  		}
  	}
  	if (ok && mktime(&ttm) == -1)
  		ok = false;
  
  	if (ok)
  		*ptm = ttm;
  	else {
  		warnx("Can't convert `%s' to date, ignored.", ds);
  		usage();
  	}
  }
  
  __dead
  static void
  usage(void)
  {
  	(void)fprintf(stderr, "usage: %s [-ax] [-d MMDD[[YY]YY]"
  	    " [-f fname] [-l days] [-w days]\n", getprogname());
  	exit(1);
  }
  