root/usr.sbin/zic/zic.c
/*      $OpenBSD: zic.c,v 1.32 2025/06/23 13:53:11 millert Exp $        */
/*
** This file is in the public domain, so clarified as of
** 2006-07-17 by Arthur David Olson.
*/

#include <sys/types.h>
#include <sys/wait.h>
#include <sys/stat.h>
#include <ctype.h>
#include <err.h>
#include <errno.h>
#include <inttypes.h>
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>
#include <unistd.h>
#include <time.h>

#include "tzfile.h"

#define TRUE    1
#define FALSE   0

#define TYPE_SIGNED(type) (((type) -1) < 0)

#define YEARSPERREPEAT  400     /* years before a Gregorian repeat */

#define GRANDPARENTED   "Local time zone must be set--see zic manual page"

#include <stdarg.h>

#define ZIC_VERSION_PRE_2013 '2'
#define ZIC_VERSION     '3'

typedef int_fast64_t    zic_t;
#define ZIC_MIN INT_FAST64_MIN
#define ZIC_MAX INT_FAST64_MAX
#define SCNdZIC SCNdFAST64

#ifndef ZIC_MAX_ABBR_LEN_WO_WARN
#define ZIC_MAX_ABBR_LEN_WO_WARN        6
#endif /* !defined ZIC_MAX_ABBR_LEN_WO_WARN */

#define MKDIR_UMASK (S_IRUSR|S_IWUSR|S_IXUSR|S_IRGRP|S_IXGRP|S_IROTH|S_IXOTH)

#define end(cp, n)      (memchr((cp), '\0', (n)))

struct rule {
        const char      *r_filename;
        int             r_linenum;
        const char      *r_name;

        zic_t           r_loyear;       /* for example, 1986 */
        zic_t           r_hiyear;       /* for example, 1986 */
        int             r_lowasnum;
        int             r_hiwasnum;

        int             r_month;        /* 0..11 */

        int             r_dycode;       /* see below */
        int             r_dayofmonth;
        int             r_wday;

        zic_t           r_tod;          /* time from midnight */
        int             r_todisstd;     /* above is standard time if TRUE */
                                        /* or wall clock time if FALSE */
        int             r_todisgmt;     /* above is GMT if TRUE */
                                        /* or local time if FALSE */
        zic_t           r_stdoff;       /* offset from standard time */
        const char      *r_abbrvar;     /* variable part of abbreviation */

        int             r_todo;         /* a rule to do (used in outzone) */
        zic_t           r_temp;         /* used in outzone */
};

/*
**      r_dycode                r_dayofmonth    r_wday
*/

#define DC_DOM          0       /* 1..31 */     /* unused */
#define DC_DOWGEQ       1       /* 1..31 */     /* 0..6 (Sun..Sat) */
#define DC_DOWLEQ       2       /* 1..31 */     /* 0..6 (Sun..Sat) */

struct zone {
        const char      *z_filename;
        int             z_linenum;

        const char      *z_name;
        zic_t           z_gmtoff;
        const char      *z_rule;
        const char      *z_format;
        char            z_format_specifier;

        zic_t           z_stdoff;

        struct rule     *z_rules;
        int             z_nrules;

        struct rule     z_untilrule;
        zic_t           z_untiltime;
};

static void     addtt(zic_t starttime, int type);
static int      addtype(zic_t gmtoff, const char *abbr, int isdst,
            int ttisstd, int ttisgmt);
static void     leapadd(zic_t t, int positive, int rolling, int count);
static void     adjleap(void);
static void     associate(void);
static void     dolink(const char *fromfield, const char *tofield);
static char     **getfields(char *buf);
static zic_t    gethms(const char *string, const char *errstrng, int signable);
static void     infile(const char *filename);
static void     inleap(char **fields, int nfields);
static void     inlink(char **fields, int nfields);
static void     inrule(char **fields, int nfields);
static int      inzcont(char **fields, int nfields);
static int      inzone(char **fields, int nfields);
static int      inzsub(char **fields, int nfields, int iscont);
static int      itsdir(const char *name);
static int      mkdirs(char *filename);
static void     newabbr(const char *abbr);
static zic_t    oadd(zic_t t1, zic_t t2);
static void     outzone(const struct zone *zp, int ntzones);
static zic_t    rpytime(const struct rule *rp, zic_t wantedy);
static void     rulesub(struct rule *rp, const char *loyearp, const char *hiyearp,
            const char *typep, const char *monthp,
            const char *dayp, const char *timep);
static zic_t    tadd(zic_t t1, zic_t t2);

extern char     *__progname;

/* Bound on length of what %z can expand to.  */
enum { PERCENT_Z_LEN_BOUND = sizeof "+995959" - 1 };

static int              charcnt;
static int              errors;
static const char       *filename;
static int              leapcnt;
static int              leapseen;
static zic_t            leapminyear;
static zic_t            leapmaxyear;
static int              linenum;
static int              max_abbrvar_len = PERCENT_Z_LEN_BOUND;
static int              max_format_len;
static const zic_t      max_time = INT_FAST64_MAX;
static zic_t            max_year;
static const zic_t      min_time = INT_FAST64_MIN;
static zic_t            min_year;
static int              noise;
static const char       *rfilename;
static int              rlinenum;
static int              timecnt;
static int              typecnt;

/*
** Line codes.
*/

#define LC_RULE         0
#define LC_ZONE         1
#define LC_LINK         2
#define LC_LEAP         3

/*
** Which fields are which on a Zone line.
*/

#define ZF_NAME         1
#define ZF_GMTOFF       2
#define ZF_RULE         3
#define ZF_FORMAT       4
#define ZF_TILYEAR      5
#define ZF_TILMONTH     6
#define ZF_TILDAY       7
#define ZF_TILTIME      8
#define ZONE_MINFIELDS  5
#define ZONE_MAXFIELDS  9

/*
** Which fields are which on a Zone continuation line.
*/

#define ZFC_GMTOFF      0
#define ZFC_RULE        1
#define ZFC_FORMAT      2
#define ZFC_TILYEAR     3
#define ZFC_TILMONTH    4
#define ZFC_TILDAY      5
#define ZFC_TILTIME     6
#define ZONEC_MINFIELDS 3
#define ZONEC_MAXFIELDS 7

/*
** Which files are which on a Rule line.
*/

#define RF_NAME         1
#define RF_LOYEAR       2
#define RF_HIYEAR       3
#define RF_COMMAND      4
#define RF_MONTH        5
#define RF_DAY          6
#define RF_TOD          7
#define RF_STDOFF       8
#define RF_ABBRVAR      9
#define RULE_FIELDS     10

/*
** Which fields are which on a Link line.
*/

#define LF_FROM         1
#define LF_TO           2
#define LINK_FIELDS     3

/*
** Which fields are which on a Leap line.
*/

#define LP_YEAR         1
#define LP_MONTH        2
#define LP_DAY          3
#define LP_TIME         4
#define LP_CORR         5
#define LP_ROLL         6
#define LEAP_FIELDS     7

/*
** Year synonyms.
*/

#define YR_MINIMUM      0
#define YR_MAXIMUM      1
#define YR_ONLY         2

static struct rule      *rules;
static int              nrules; /* number of rules */

static struct zone      *zones;
static int              nzones; /* number of zones */

struct link {
        const char      *l_filename;
        int             l_linenum;
        const char      *l_from;
        const char      *l_to;
};

static struct link      *links;
static int              nlinks;

struct lookup {
        const char      *l_word;
        const int       l_value;
};

static struct lookup const      *byword(const char *string, const struct lookup *lp);

static struct lookup const      line_codes[] = {
        { "Rule",       LC_RULE },
        { "Zone",       LC_ZONE },
        { "Link",       LC_LINK },
        { "Leap",       LC_LEAP },
        { NULL,         0}
};

static struct lookup const      mon_names[] = {
        { "January",    TM_JANUARY },
        { "February",   TM_FEBRUARY },
        { "March",      TM_MARCH },
        { "April",      TM_APRIL },
        { "May",        TM_MAY },
        { "June",       TM_JUNE },
        { "July",       TM_JULY },
        { "August",     TM_AUGUST },
        { "September",  TM_SEPTEMBER },
        { "October",    TM_OCTOBER },
        { "November",   TM_NOVEMBER },
        { "December",   TM_DECEMBER },
        { NULL,         0 }
};

static struct lookup const      wday_names[] = {
        { "Sunday",     TM_SUNDAY },
        { "Monday",     TM_MONDAY },
        { "Tuesday",    TM_TUESDAY },
        { "Wednesday",  TM_WEDNESDAY },
        { "Thursday",   TM_THURSDAY },
        { "Friday",     TM_FRIDAY },
        { "Saturday",   TM_SATURDAY },
        { NULL,         0 }
};

static struct lookup const      lasts[] = {
        { "last-Sunday",        TM_SUNDAY },
        { "last-Monday",        TM_MONDAY },
        { "last-Tuesday",       TM_TUESDAY },
        { "last-Wednesday",     TM_WEDNESDAY },
        { "last-Thursday",      TM_THURSDAY },
        { "last-Friday",        TM_FRIDAY },
        { "last-Saturday",      TM_SATURDAY },
        { NULL,                 0 }
};

static struct lookup const      begin_years[] = {
        { "minimum",    YR_MINIMUM },
        { "maximum",    YR_MAXIMUM },
        { NULL,         0 }
};

static struct lookup const      end_years[] = {
        { "minimum",    YR_MINIMUM },
        { "maximum",    YR_MAXIMUM },
        { "only",       YR_ONLY },
        { NULL,         0 }
};

static struct lookup const      leap_types[] = {
        { "Rolling",    TRUE },
        { "Stationary", FALSE },
        { NULL,         0 }
};

static const int        len_months[2][MONSPERYEAR] = {
        { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 },
        { 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }
};

static const int        len_years[2] = {
        DAYSPERNYEAR, DAYSPERLYEAR
};

static struct attype {
        zic_t           at;
        unsigned char   type;
}                       attypes[TZ_MAX_TIMES];

static zic_t            gmtoffs[TZ_MAX_TYPES];
static char             isdsts[TZ_MAX_TYPES];
static unsigned char    abbrinds[TZ_MAX_TYPES];
static char             ttisstds[TZ_MAX_TYPES];
static char             ttisgmts[TZ_MAX_TYPES];
static char             chars[TZ_MAX_CHARS];
static zic_t            trans[TZ_MAX_LEAPS];
static zic_t            corr[TZ_MAX_LEAPS];
static char             roll[TZ_MAX_LEAPS];

/*
** Memory allocation.
*/

static __pure void *
memcheck(void *ptr)
{
        if (ptr == NULL)
                err(1, "Memory exhausted");
        return ptr;
}

static char *
ecatalloc(char *start, const char *tail)
{
        size_t len;
        char *str;

        len = strlen(start) + strlen(tail) + 1;
        str = memcheck(realloc(start, len));
        strlcat(str, tail, len);
        return str;
}

#define emalloc(size)           memcheck(malloc(size))
#define ereallocarray(ptr, nmemb, size)         memcheck(reallocarray(ptr, nmemb, size))
#define erealloc(ptr, size)     memcheck(realloc((ptr), (size)))
#define ecpyalloc(ptr)          memcheck(strdup(ptr))

/*
** Error handling.
*/

static void
eats(const char *name, int num, const char *rname, int rnum)
{
        filename = name;
        linenum = num;
        rfilename = rname;
        rlinenum = rnum;
}

static void
eat(const char *name, int num)
{
        eats(name, num, NULL, -1);
}

static void __attribute__((__format__ (printf, 1, 0)))
verror(const char *const string, va_list args)
{
        /*
        ** Match the format of "cc" to allow sh users to
        **      zic ... 2>&1 | error -t "*" -v
        ** on BSD systems.
        */
        fprintf(stderr, "\"%s\", line %d: ", filename, linenum);
        vfprintf(stderr, string, args);
        if (rfilename != NULL)
                fprintf(stderr, " (rule from \"%s\", line %d)",
                        rfilename, rlinenum);
        fprintf(stderr, "\n");
        ++errors;
}

static void __attribute__((__format__ (printf, 1, 2)))
error(const char *const string, ...)
{
        va_list args;
        va_start(args, string);
        verror(string, args);
        va_end(args);
}

static void __attribute__((__format__ (printf, 1, 2)))
warning(const char *const string, ...)
{
        va_list args;
        fprintf(stderr, "warning: ");
        va_start(args, string);
        verror(string, args);
        va_end(args);
        --errors;
}

static const char *
scheck(const char *string, const char *format)
{
        const char      *fp, *result;
        char            *fbuf, *tp, dummy;
        int             c;

        result = "";
        if (string == NULL || format == NULL)
                return result;
        fbuf = reallocarray(NULL, strlen(format) + 2, 2);
        if (fbuf == NULL)
                return result;
        fp = format;
        tp = fbuf;

        /*
        ** Copy directives, suppressing each conversion that is not
        ** already suppressed.  Scansets containing '%' are not
        ** supported; e.g., the conversion specification "%[%]" is not
        ** supported.  Also, multibyte characters containing a
        ** non-leading '%' byte are not supported.
        */
        while ((*tp++ = c = *fp++) != '\0') {
                if (c != '%')
                        continue;
                if (isdigit((unsigned char)*fp)) {
                        const char *f = fp;
                        char *t = tp;
                        do {
                                *t++ = c = *f++;
                        } while (isdigit((unsigned char)c));
                        if (c == '$') {
                                fp = f;
                                tp = t;
                        }
                }
                *tp++ = '*';
                if (*fp == '*')
                        ++fp;
                if ((*tp++ = *fp++) == '\0')
                        break;
        }

        *(tp - 1) = '%';
        *tp++ = 'c';
        *tp = '\0';
        if (sscanf(string, fbuf, &dummy) != 1)
                result = format;
        free(fbuf);
        return result;
}

static __dead void
usage(void)
{
        fprintf(stderr,
            "usage: %s [-v] [-d directory] [-L leapsecondfilename] [-l timezone]\n"
            "\t\t[-p timezone] [filename ...]\n",
                __progname);
        exit(EXIT_FAILURE);
}

static const char       *psxrules;
static const char       *lcltime;
static const char       *directory;
static const char       *leapsec;

int
main(int argc, char **argv)
{
        int     i, j, c;

        if (pledge("stdio rpath wpath cpath proc exec", NULL) == -1)
                err(1, "pledge");

        umask(umask(S_IWGRP | S_IWOTH) | (S_IWGRP | S_IWOTH));
        while ((c = getopt(argc, argv, "d:l:p:L:vy:")) != -1)
                switch (c) {
                        default:
                                usage();
                        case 'd':
                                if (directory == NULL)
                                        directory = optarg;
                                else
                                        errx(1, "More than one -d option specified");
                                break;
                        case 'l':
                                if (lcltime == NULL)
                                        lcltime = optarg;
                                else
                                        errx(1, "More than one -l option specified");
                                break;
                        case 'p':
                                if (psxrules == NULL)
                                        psxrules = optarg;
                                else
                                        errx(1, "More than one -p option specified");
                                break;
                        case 'y':
                                warning("ignoring obsolescent option -y");
                                break;
                        case 'L':
                                if (leapsec == NULL)
                                        leapsec = optarg;
                                else
                                        errx(1, "More than one -L option specified");
                                break;
                        case 'v':
                                noise = TRUE;
                                break;
                }
        if (optind == argc - 1 && strcmp(argv[optind], "=") == 0)
                usage();        /* usage message by request */
        if (directory == NULL)
                directory = TZDIR;

        if (optind < argc && leapsec != NULL) {
                infile(leapsec);
                adjleap();
        }

        for (i = optind; i < argc; ++i)
                infile(argv[i]);
        if (errors)
                exit(EXIT_FAILURE);
        associate();
        for (i = 0; i < nzones; i = j) {
                /*
                ** Find the next non-continuation zone entry.
                */
                for (j = i + 1; j < nzones && zones[j].z_name == NULL; ++j)
                        continue;
                outzone(&zones[i], j - i);
        }
        /*
        ** Make links.
        */
        for (i = 0; i < nlinks; ++i) {
                eat(links[i].l_filename, links[i].l_linenum);
                dolink(links[i].l_from, links[i].l_to);
                if (noise)
                        for (j = 0; j < nlinks; ++j)
                                if (strcmp(links[i].l_to,
                                        links[j].l_from) == 0)
                                                warning("link to link");
        }
        if (lcltime != NULL) {
                eat("command line", 1);
                dolink(lcltime, TZDEFAULT);
        }
        if (psxrules != NULL) {
                eat("command line", 1);
                dolink(psxrules, TZDEFRULES);
        }
        return (errors == 0) ? EXIT_SUCCESS : EXIT_FAILURE;
}

static void
dolink(const char *fromfield, const char *tofield)
{
        char    *fromname, *toname;

        if (fromfield[0] == '/')
                fromname = ecpyalloc(fromfield);
        else {
                fromname = ecpyalloc(directory);
                fromname = ecatalloc(fromname, "/");
                fromname = ecatalloc(fromname, fromfield);
        }
        if (tofield[0] == '/')
                toname = ecpyalloc(tofield);
        else {
                toname = ecpyalloc(directory);
                toname = ecatalloc(toname, "/");
                toname = ecatalloc(toname, tofield);
        }
        /*
        ** We get to be careful here since
        ** there's a fair chance of root running us.
        */
        if (!itsdir(toname))
                remove(toname);
        if (link(fromname, toname) != 0) {
                int     result;

                if (mkdirs(toname) != 0)
                        exit(EXIT_FAILURE);

                result = link(fromname, toname);
                if (result != 0 && errno == EXDEV)
                        result = symlink(fromname, toname);
                if (result != 0)
                        err(1, "Can't link from %s to %s", fromname, toname);
        }
        free(fromname);
        free(toname);
}

static int
itsdir(const char *name)
{
        char    *myname;
        int     accres;

        myname = ecpyalloc(name);
        myname = ecatalloc(myname, "/.");
        accres = access(myname, F_OK);
        free(myname);
        return accres == 0;
}

/*
** Associate sets of rules with zones.
*/

/*
** Sort by rule name.
*/

static int
rcomp(const void *cp1, const void *cp2)
{
        return strcmp(((const struct rule *) cp1)->r_name,
                ((const struct rule *) cp2)->r_name);
}

static void
associate(void)
{
        struct zone     *zp;
        struct rule     *rp;
        int             base, out, i, j;

        if (nrules != 0) {
                qsort(rules, nrules, sizeof *rules, rcomp);
                for (i = 0; i < nrules - 1; ++i) {
                        if (strcmp(rules[i].r_name,
                                rules[i + 1].r_name) != 0)
                                        continue;
                        if (strcmp(rules[i].r_filename,
                                rules[i + 1].r_filename) == 0)
                                        continue;
                        eat(rules[i].r_filename, rules[i].r_linenum);
                        warning("same rule name in multiple files");
                        eat(rules[i + 1].r_filename, rules[i + 1].r_linenum);
                        warning("same rule name in multiple files");
                        for (j = i + 2; j < nrules; ++j) {
                                if (strcmp(rules[i].r_name,
                                        rules[j].r_name) != 0)
                                                break;
                                if (strcmp(rules[i].r_filename,
                                        rules[j].r_filename) == 0)
                                                continue;
                                if (strcmp(rules[i + 1].r_filename,
                                        rules[j].r_filename) == 0)
                                                continue;
                                break;
                        }
                        i = j - 1;
                }
        }
        for (i = 0; i < nzones; ++i) {
                zp = &zones[i];
                zp->z_rules = NULL;
                zp->z_nrules = 0;
        }
        for (base = 0; base < nrules; base = out) {
                rp = &rules[base];
                for (out = base + 1; out < nrules; ++out)
                        if (strcmp(rp->r_name, rules[out].r_name) != 0)
                                break;
                for (i = 0; i < nzones; ++i) {
                        zp = &zones[i];
                        if (strcmp(zp->z_rule, rp->r_name) != 0)
                                continue;
                        zp->z_rules = rp;
                        zp->z_nrules = out - base;
                }
        }
        for (i = 0; i < nzones; ++i) {
                zp = &zones[i];
                if (zp->z_nrules == 0) {
                        /*
                        ** Maybe we have a local standard time offset.
                        */
                        eat(zp->z_filename, zp->z_linenum);
                        zp->z_stdoff = gethms(zp->z_rule, "unruly zone",
                                TRUE);
                        /*
                        ** Note, though, that if there's no rule,
                        ** a '%s' in the format is a bad thing.
                        */
                        if (zp->z_format_specifier == 's')
                                error("%s", "%s in ruleless zone");
                }
        }
        if (errors)
                exit(EXIT_FAILURE);
}

static void
infile(const char *name)
{
        FILE                    *fp;
        char                    **fields, *cp;
        const struct lookup     *lp;
        int                     nfields, wantcont, num;
        char                    buf[BUFSIZ];

        if (strcmp(name, "-") == 0) {
                name = "standard input";
                fp = stdin;
        } else if ((fp = fopen(name, "r")) == NULL)
                err(1, "Can't open %s", name);
        wantcont = FALSE;
        for (num = 1; ; ++num) {
                eat(name, num);
                if (fgets(buf, sizeof buf, fp) != buf)
                        break;
                cp = strchr(buf, '\n');
                if (cp == NULL) {
                        error("line too long");
                        exit(EXIT_FAILURE);
                }
                *cp = '\0';
                fields = getfields(buf);
                nfields = 0;
                while (fields[nfields] != NULL) {
                        static char     nada;

                        if (strcmp(fields[nfields], "-") == 0)
                                fields[nfields] = &nada;
                        ++nfields;
                }
                if (nfields == 0) {
                        /* nothing to do */
                } else if (wantcont) {
                        wantcont = inzcont(fields, nfields);
                } else {
                        lp = byword(fields[0], line_codes);
                        if (lp == NULL)
                                error("input line of unknown type");
                        else switch (lp->l_value) {
                                case LC_RULE:
                                        inrule(fields, nfields);
                                        wantcont = FALSE;
                                        break;
                                case LC_ZONE:
                                        wantcont = inzone(fields, nfields);
                                        break;
                                case LC_LINK:
                                        inlink(fields, nfields);
                                        wantcont = FALSE;
                                        break;
                                case LC_LEAP:
                                        if (name != leapsec)
                                                fprintf(stderr,
                                                    "%s: Leap line in non leap seconds file %s\n",
                                                        __progname, name);
                                                /* no exit? */
                                        else
                                                inleap(fields, nfields);
                                        wantcont = FALSE;
                                        break;
                                default:        /* "cannot happen" */
                                        errx(1, "panic: Invalid l_value %d", lp->l_value);
                        }
                }
                free(fields);
        }
        if (ferror(fp))
                errx(1, "Error reading %s", filename);
        if (fp != stdin && fclose(fp))
                err(1, "Error closing %s", filename);
        if (wantcont)
                error("expected continuation line not found");
}

/*
** Convert a string of one of the forms
**      h       -h      hh:mm   -hh:mm  hh:mm:ss        -hh:mm:ss
** into a number of seconds.
** A null string maps to zero.
** Call error with errstring and return zero on errors.
*/

static zic_t
gethms(const char *string, const char *errstring, int signable)
{
        zic_t   hh;
        int     mm, ss, sign;

        if (string == NULL || *string == '\0')
                return 0;
        if (!signable)
                sign = 1;
        else if (*string == '-') {
                sign = -1;
                ++string;
        } else
                sign = 1;
        if (sscanf(string, scheck(string, "%"SCNdZIC), &hh) == 1)
                mm = ss = 0;
        else if (sscanf(string, scheck(string, "%"SCNdZIC":%d"), &hh, &mm) == 2)
                ss = 0;
        else if (sscanf(string, scheck(string, "%"SCNdZIC":%d:%d"),
            &hh, &mm, &ss) != 3) {
                error("%s", errstring);
                return 0;
        }
        if (hh < 0 ||
            mm < 0 || mm >= MINSPERHOUR ||
            ss < 0 || ss > SECSPERMIN) {
                error("%s", errstring);
                return 0;
        }
        if (ZIC_MAX / SECSPERHOUR < hh) {
                error("time overflow");
                return 0;
        }
        return oadd(sign * hh * SECSPERHOUR, sign * (mm * SECSPERMIN + ss));
}

static void
inrule(char **fields, int nfields)
{
        static struct rule      r;

        if (nfields != RULE_FIELDS) {
                error("wrong number of fields on Rule line");
                return;
        }
        if (*fields[RF_NAME] == '\0') {
                error("nameless rule");
                return;
        }
        r.r_filename = filename;
        r.r_linenum = linenum;
        r.r_stdoff = gethms(fields[RF_STDOFF], "invalid saved time", TRUE);
        rulesub(&r, fields[RF_LOYEAR], fields[RF_HIYEAR], fields[RF_COMMAND],
                fields[RF_MONTH], fields[RF_DAY], fields[RF_TOD]);
        r.r_name = ecpyalloc(fields[RF_NAME]);
        r.r_abbrvar = ecpyalloc(fields[RF_ABBRVAR]);
        if (max_abbrvar_len < strlen(r.r_abbrvar))
                max_abbrvar_len = strlen(r.r_abbrvar);
        rules = ereallocarray(rules, nrules + 1, sizeof *rules);
        rules[nrules++] = r;
}

static int
inzone(char **fields, int nfields)
{
        int     i;

        if (nfields < ZONE_MINFIELDS || nfields > ZONE_MAXFIELDS) {
                error("wrong number of fields on Zone line");
                return FALSE;
        }
        if (strcmp(fields[ZF_NAME], TZDEFAULT) == 0 && lcltime != NULL) {
                error("\"Zone %s\" line and -l option are mutually exclusive",
                    TZDEFAULT);
                return FALSE;
        }
        if (strcmp(fields[ZF_NAME], TZDEFRULES) == 0 && psxrules != NULL) {
                error("\"Zone %s\" line and -p option are mutually exclusive",
                    TZDEFRULES);
                return FALSE;
        }
        for (i = 0; i < nzones; ++i)
                if (zones[i].z_name != NULL &&
                    strcmp(zones[i].z_name, fields[ZF_NAME]) == 0) {
                        error("duplicate zone name %s (file \"%s\", line %d)",
                            fields[ZF_NAME],
                            zones[i].z_filename,
                            zones[i].z_linenum);
                        return FALSE;
                }
        return inzsub(fields, nfields, FALSE);
}

static int
inzcont(char **fields, int nfields)
{
        if (nfields < ZONEC_MINFIELDS || nfields > ZONEC_MAXFIELDS) {
                error("wrong number of fields on Zone continuation line");
                return FALSE;
        }
        return inzsub(fields, nfields, TRUE);
}

static int
inzsub(char **fields, int nfields, int iscont)
{
        char            *cp;
        char            *cp1;
        static struct zone      z;
        int             i_gmtoff, i_rule, i_format;
        int             i_untilyear, i_untilmonth;
        int             i_untilday, i_untiltime;
        int             hasuntil;

        if (iscont) {
                i_gmtoff = ZFC_GMTOFF;
                i_rule = ZFC_RULE;
                i_format = ZFC_FORMAT;
                i_untilyear = ZFC_TILYEAR;
                i_untilmonth = ZFC_TILMONTH;
                i_untilday = ZFC_TILDAY;
                i_untiltime = ZFC_TILTIME;
                z.z_name = NULL;
        } else {
                i_gmtoff = ZF_GMTOFF;
                i_rule = ZF_RULE;
                i_format = ZF_FORMAT;
                i_untilyear = ZF_TILYEAR;
                i_untilmonth = ZF_TILMONTH;
                i_untilday = ZF_TILDAY;
                i_untiltime = ZF_TILTIME;
                z.z_name = ecpyalloc(fields[ZF_NAME]);
        }
        z.z_filename = filename;
        z.z_linenum = linenum;
        z.z_gmtoff = gethms(fields[i_gmtoff], "invalid UT offset", TRUE);
        if ((cp = strchr(fields[i_format], '%')) != 0) {
                if ((*++cp != 's' && *cp != 'z') || strchr(cp, '%')
                    || strchr(fields[i_format], '/')) {
                        error("invalid abbreviation format");
                        return FALSE;
                }
        }
        z.z_rule = ecpyalloc(fields[i_rule]);
        z.z_format = cp1 = ecpyalloc(fields[i_format]);
        z.z_format_specifier = cp ? *cp : '\0';
        if (z.z_format_specifier == 'z') {
                if (noise) {
                        warning("format '%%z' not handled by pre-2015 versions "
                            "of zic");
                }
                cp1[cp - fields[i_format]] = 's';
        }
        if (max_format_len < strlen(z.z_format))
                max_format_len = strlen(z.z_format);
        hasuntil = nfields > i_untilyear;
        if (hasuntil) {
                z.z_untilrule.r_filename = filename;
                z.z_untilrule.r_linenum = linenum;
                rulesub(&z.z_untilrule,
                        fields[i_untilyear],
                        "only",
                        "",
                        (nfields > i_untilmonth) ?
                        fields[i_untilmonth] : "Jan",
                        (nfields > i_untilday) ? fields[i_untilday] : "1",
                        (nfields > i_untiltime) ? fields[i_untiltime] : "0");
                z.z_untiltime = rpytime(&z.z_untilrule,
                        z.z_untilrule.r_loyear);
                if (iscont && nzones > 0 &&
                    z.z_untiltime > min_time &&
                    z.z_untiltime < max_time &&
                    zones[nzones - 1].z_untiltime > min_time &&
                    zones[nzones - 1].z_untiltime < max_time &&
                    zones[nzones - 1].z_untiltime >= z.z_untiltime) {
                        error("Zone continuation line end time is not after end time of previous line");
                        return FALSE;
                }
        }
        zones = ereallocarray(zones, nzones + 1, sizeof *zones);
        zones[nzones++] = z;
        /*
        ** If there was an UNTIL field on this line,
        ** there's more information about the zone on the next line.
        */
        return hasuntil;
}

static void
inleap(char **fields, int nfields)
{
        const char              *cp;
        const struct lookup     *lp;
        int                     i, j;
        zic_t                   year;
        int                     month, day;
        zic_t                   dayoff, tod;
        zic_t                   t;

        if (nfields != LEAP_FIELDS) {
                error("wrong number of fields on Leap line");
                return;
        }
        dayoff = 0;
        cp = fields[LP_YEAR];
        if (sscanf(cp, scheck(cp, "%"SCNdZIC), &year) != 1) {
                /*
                ** Leapin' Lizards!
                */
                error("invalid leaping year");
                return;
        }
        if (!leapseen || leapmaxyear < year)
                leapmaxyear = year;
        if (!leapseen || leapminyear > year)
                leapminyear = year;
        leapseen = TRUE;
        j = EPOCH_YEAR;
        while (j != year) {
                if (year > j) {
                        i = len_years[isleap(j)];
                        ++j;
                } else {
                        --j;
                        i = -len_years[isleap(j)];
                }
                dayoff = oadd(dayoff, i);
        }
        if ((lp = byword(fields[LP_MONTH], mon_names)) == NULL) {
                error("invalid month name");
                return;
        }
        month = lp->l_value;
        j = TM_JANUARY;
        while (j != month) {
                i = len_months[isleap(year)][j];
                dayoff = oadd(dayoff, i);
                ++j;
        }
        cp = fields[LP_DAY];
        if (sscanf(cp, scheck(cp, "%d"), &day) != 1 ||
            day <= 0 || day > len_months[isleap(year)][month]) {
                error("invalid day of month");
                return;
        }
        dayoff = oadd(dayoff, day - 1);
        if (dayoff < 0 && !TYPE_SIGNED(zic_t)) {
                error("time before zero");
                return;
        }
        if (dayoff < min_time / SECSPERDAY) {
                error("time too small");
                return;
        }
        if (dayoff > max_time / SECSPERDAY) {
                error("time too large");
                return;
        }
        t = (zic_t) dayoff * SECSPERDAY;
        tod = gethms(fields[LP_TIME], "invalid time of day", FALSE);
        cp = fields[LP_CORR];
        {
                int     positive;
                int             count;

                if (strcmp(cp, "") == 0) { /* infile() turns "-" into "" */
                        positive = FALSE;
                        count = 1;
                } else if (strcmp(cp, "--") == 0) {
                        positive = FALSE;
                        count = 2;
                } else if (strcmp(cp, "+") == 0) {
                        positive = TRUE;
                        count = 1;
                } else if (strcmp(cp, "++") == 0) {
                        positive = TRUE;
                        count = 2;
                } else {
                        error("illegal CORRECTION field on Leap line");
                        return;
                }
                if ((lp = byword(fields[LP_ROLL], leap_types)) == NULL) {
                        error("illegal Rolling/Stationary field on Leap line");
                        return;
                }
                leapadd(tadd(t, tod), positive, lp->l_value, count);
        }
}

static void
inlink(char **fields, int nfields)
{
        struct link     l;

        if (nfields != LINK_FIELDS) {
                error("wrong number of fields on Link line");
                return;
        }
        if (*fields[LF_FROM] == '\0') {
                error("blank FROM field on Link line");
                return;
        }
        if (*fields[LF_TO] == '\0') {
                error("blank TO field on Link line");
                return;
        }
        l.l_filename = filename;
        l.l_linenum = linenum;
        l.l_from = ecpyalloc(fields[LF_FROM]);
        l.l_to = ecpyalloc(fields[LF_TO]);
        links = ereallocarray(links, nlinks + 1, sizeof *links);
        links[nlinks++] = l;
}

static void
rulesub(struct rule * const rp, const char * const loyearp,
    const char * const hiyearp, const char * const typep,
    const char * const monthp, const char * const dayp,
    const char * const timep)
{
        const struct lookup     *lp;
        const char              *cp;
        char                    *dp, *ep;

        if ((lp = byword(monthp, mon_names)) == NULL) {
                error("invalid month name");
                return;
        }
        rp->r_month = lp->l_value;
        rp->r_todisstd = FALSE;
        rp->r_todisgmt = FALSE;
        dp = ecpyalloc(timep);
        if (*dp != '\0') {
                ep = dp + strlen(dp) - 1;
                switch (tolower((unsigned char)*ep)) {
                case 's':       /* Standard */
                        rp->r_todisstd = TRUE;
                        rp->r_todisgmt = FALSE;
                        *ep = '\0';
                        break;
                case 'w':       /* Wall */
                        rp->r_todisstd = FALSE;
                        rp->r_todisgmt = FALSE;
                        *ep = '\0';
                        break;
                case 'g':       /* Greenwich */
                case 'u':       /* Universal */
                case 'z':       /* Zulu */
                        rp->r_todisstd = TRUE;
                        rp->r_todisgmt = TRUE;
                        *ep = '\0';
                        break;
                }
        }
        rp->r_tod = gethms(dp, "invalid time of day", FALSE);
        free(dp);
        /*
        ** Year work.
        */
        cp = loyearp;
        lp = byword(cp, begin_years);
        rp->r_lowasnum = lp == NULL;
        if (!rp->r_lowasnum) switch ((int) lp->l_value) {
                case YR_MINIMUM:
                        rp->r_loyear = ZIC_MIN;
                        break;
                case YR_MAXIMUM:
                        rp->r_loyear = ZIC_MAX;
                        break;
                default:        /* "cannot happen" */
                        errx(1, "panic: Invalid l_value %d", lp->l_value);
        } else if (sscanf(cp, scheck(cp, "%"SCNdZIC), &rp->r_loyear) != 1) {
                error("invalid starting year");
                return;
        }
        cp = hiyearp;
        lp = byword(cp, end_years);
        rp->r_hiwasnum = lp == NULL;
        if (!rp->r_hiwasnum) switch ((int) lp->l_value) {
                case YR_MINIMUM:
                        rp->r_hiyear = ZIC_MIN;
                        break;
                case YR_MAXIMUM:
                        rp->r_hiyear = ZIC_MAX;
                        break;
                case YR_ONLY:
                        rp->r_hiyear = rp->r_loyear;
                        break;
                default:        /* "cannot happen" */
                        errx(1, "panic: Invalid l_value %d", lp->l_value);
        } else if (sscanf(cp, scheck(cp, "%"SCNdZIC), &rp->r_hiyear) != 1) {
                error("invalid ending year");
                return;
        }
        if (rp->r_loyear > rp->r_hiyear) {
                error("starting year greater than ending year");
                return;
        }
        if (*typep != '\0') {
                if (rp->r_loyear == rp->r_hiyear) {
                        error("typed single year");
                        return;
                }
                warning("year type is obsolete; use \"-\" instead");
        }
        /*
        ** Day work.
        ** Accept things such as:
        **      1
        **      last-Sunday
        **      Sun<=20
        **      Sun>=7
        */
        dp = ecpyalloc(dayp);
        if ((lp = byword(dp, lasts)) != NULL) {
                rp->r_dycode = DC_DOWLEQ;
                rp->r_wday = lp->l_value;
                rp->r_dayofmonth = len_months[1][rp->r_month];
        } else {
                if ((ep = strchr(dp, '<')) != 0)
                        rp->r_dycode = DC_DOWLEQ;
                else if ((ep = strchr(dp, '>')) != 0)
                        rp->r_dycode = DC_DOWGEQ;
                else {
                        ep = dp;
                        rp->r_dycode = DC_DOM;
                }
                if (rp->r_dycode != DC_DOM) {
                        *ep++ = 0;
                        if (*ep++ != '=') {
                                error("invalid day of month");
                                free(dp);
                                return;
                        }
                        if ((lp = byword(dp, wday_names)) == NULL) {
                                error("invalid weekday name");
                                free(dp);
                                return;
                        }
                        rp->r_wday = lp->l_value;
                }
                if (sscanf(ep, scheck(ep, "%d"), &rp->r_dayofmonth) != 1 ||
                    rp->r_dayofmonth <= 0 ||
                    (rp->r_dayofmonth > len_months[1][rp->r_month])) {
                        error("invalid day of month");
                        free(dp);
                        return;
                }
        }
        free(dp);
}

static void
convert(int_fast32_t val, unsigned char *buf)
{
        int     i;
        int     shift;

        for (i = 0, shift = 24; i < 4; ++i, shift -= 8)
                buf[i] = val >> shift;
}

static void
convert64(zic_t val, unsigned char *buf)
{
        int     i;
        int     shift;

        for (i = 0, shift = 56; i < 8; ++i, shift -= 8)
                buf[i] = val >> shift;
}

static void
puttzcode(int_fast32_t val, FILE *fp)
{
        char    buf[4];

        convert(val, buf);
        fwrite(buf, sizeof buf, 1, fp);
}

static void
puttzcode64(zic_t val, FILE *fp)
{
        char    buf[8];

        convert64(val, buf);
        fwrite(buf, sizeof buf, 1, fp);
}

static int
atcomp(const void *avp, const void *bvp)
{
        const zic_t     a = ((const struct attype *) avp)->at;
        const zic_t     b = ((const struct attype *) bvp)->at;

        return (a < b) ? -1 : (a > b);
}

static int
is32(zic_t x)
{
        return INT32_MIN <= x && x <= INT32_MAX;
}

static void
writezone(const char *const name, const char *const string, char version)
{
        FILE                    *fp;
        int                     i, j;
        int                     leapcnt32, leapi32;
        int                     timecnt32, timei32;
        int                     pass;
        static char             *fullname;
        static const struct tzhead      tzh0;
        static struct tzhead    tzh;
        zic_t                   ats[TZ_MAX_TIMES];
        unsigned char           types[TZ_MAX_TIMES];
        size_t                  len;

        /*
        ** Sort.
        */
        if (timecnt > 1)
                qsort(attypes, timecnt, sizeof *attypes, atcomp);
        /*
        ** Optimize.
        */
        {
                int     fromi;
                int     toi;

                toi = 0;
                fromi = 0;
                while (fromi < timecnt && attypes[fromi].at < min_time)
                        ++fromi;
                if (isdsts[0] == 0)
                        while (fromi < timecnt && attypes[fromi].type == 0)
                                ++fromi;        /* handled by default rule */
                for ( ; fromi < timecnt; ++fromi) {
                        if (toi != 0 && ((attypes[fromi].at +
                            gmtoffs[attypes[toi - 1].type]) <=
                            (attypes[toi - 1].at + gmtoffs[toi == 1 ? 0 :
                            attypes[toi - 2].type]))) {
                                attypes[toi - 1].type = attypes[fromi].type;
                                continue;
                        }
                        if (toi == 0 ||
                            attypes[toi - 1].type != attypes[fromi].type)
                                attypes[toi++] = attypes[fromi];
                }
                timecnt = toi;
        }
        /*
        ** Transfer.
        */
        for (i = 0; i < timecnt; ++i) {
                ats[i] = attypes[i].at;
                types[i] = attypes[i].type;
        }
        /*
        ** Correct for leap seconds.
        */
        for (i = 0; i < timecnt; ++i) {
                j = leapcnt;
                while (--j >= 0)
                        if (ats[i] > trans[j] - corr[j]) {
                                ats[i] = tadd(ats[i], corr[j]);
                                break;
                        }
        }
        /*
        ** Figure out 32-bit-limited starts and counts.
        */
        timecnt32 = timecnt;
        timei32 = 0;
        leapcnt32 = leapcnt;
        leapi32 = 0;
        while (timecnt32 > 0 && !is32(ats[timecnt32 - 1]))
                --timecnt32;
        while (timecnt32 > 0 && !is32(ats[timei32])) {
                --timecnt32;
                ++timei32;
        }
        while (leapcnt32 > 0 && !is32(trans[leapcnt32 - 1]))
                --leapcnt32;
        while (leapcnt32 > 0 && !is32(trans[leapi32])) {
                --leapcnt32;
                ++leapi32;
        }
        len = strlen(directory) + 1 + strlen(name) + 1;
        fullname = erealloc(fullname, len);
        snprintf(fullname, len, "%s/%s", directory, name);
        /*
        ** Remove old file, if any, to snap links.
        */
        if (!itsdir(fullname) && remove(fullname) != 0 && errno != ENOENT)
                err(1, "Can't remove %s", fullname);
        if ((fp = fopen(fullname, "wb")) == NULL) {
                if (mkdirs(fullname) != 0)
                        exit(EXIT_FAILURE);
                if ((fp = fopen(fullname, "wb")) == NULL)
                        err(1, "Can't create %s", fullname);
        }
        for (pass = 1; pass <= 2; ++pass) {
                int     thistimei, thistimecnt;
                int     thisleapi, thisleapcnt;
                int     thistimelim, thisleaplim;
                int     writetype[TZ_MAX_TIMES];
                int     typemap[TZ_MAX_TYPES];
                int     thistypecnt;
                char    thischars[TZ_MAX_CHARS];
                char    thischarcnt;
                int     indmap[TZ_MAX_CHARS];

                if (pass == 1) {
                        thistimei = timei32;
                        thistimecnt = timecnt32;
                        thisleapi = leapi32;
                        thisleapcnt = leapcnt32;
                } else {
                        thistimei = 0;
                        thistimecnt = timecnt;
                        thisleapi = 0;
                        thisleapcnt = leapcnt;
                }
                thistimelim = thistimei + thistimecnt;
                thisleaplim = thisleapi + thisleapcnt;
                for (i = 0; i < typecnt; ++i)
                        writetype[i] = thistimecnt == timecnt;
                if (thistimecnt == 0) {
                        /*
                        ** No transition times fall in the current
                        ** (32- or 64-bit) window.
                        */
                        if (typecnt != 0)
                                writetype[typecnt - 1] = TRUE;
                } else {
                        for (i = thistimei - 1; i < thistimelim; ++i)
                                if (i >= 0)
                                        writetype[types[i]] = TRUE;
                        /*
                        ** For America/Godthab and Antarctica/Palmer
                        */
                        if (thistimei == 0)
                                writetype[0] = TRUE;
                }
#ifndef LEAVE_SOME_PRE_2011_SYSTEMS_IN_THE_LURCH
                /*
                ** For some pre-2011 systems: if the last-to-be-written
                ** standard (or daylight) type has an offset different from the
                ** most recently used offset,
                ** append an (unused) copy of the most recently used type
                ** (to help get global "altzone" and "timezone" variables
                ** set correctly).
                */
                {
                        int     mrudst, mrustd, hidst, histd, type;

                        hidst = histd = mrudst = mrustd = -1;
                        for (i = thistimei; i < thistimelim; ++i)
                                if (isdsts[types[i]])
                                        mrudst = types[i];
                                else
                                        mrustd = types[i];
                        for (i = 0; i < typecnt; ++i)
                                if (writetype[i]) {
                                        if (isdsts[i])
                                                hidst = i;
                                        else
                                                histd = i;
                                }
                        if (hidst >= 0 && mrudst >= 0 && hidst != mrudst &&
                            gmtoffs[hidst] != gmtoffs[mrudst]) {
                                isdsts[mrudst] = -1;
                                type = addtype(gmtoffs[mrudst],
                                    &chars[abbrinds[mrudst]],
                                    TRUE, ttisstds[mrudst],
                                    ttisgmts[mrudst]);
                                isdsts[mrudst] = TRUE;
                                writetype[type] = TRUE;
                        }
                        if (histd >= 0 && mrustd >= 0 && histd != mrustd &&
                            gmtoffs[histd] != gmtoffs[mrustd]) {
                                isdsts[mrustd] = -1;
                                type = addtype(gmtoffs[mrustd],
                                    &chars[abbrinds[mrustd]],
                                    FALSE, ttisstds[mrustd],
                                    ttisgmts[mrustd]);
                                isdsts[mrustd] = FALSE;
                                writetype[type] = TRUE;
                        }
                }
#endif /* !defined LEAVE_SOME_PRE_2011_SYSTEMS_IN_THE_LURCH */
                thistypecnt = 0;
                for (i = 0; i < typecnt; ++i)
                        typemap[i] = writetype[i] ?  thistypecnt++ : -1;
                for (i = 0; i < sizeof indmap / sizeof indmap[0]; ++i)
                        indmap[i] = -1;
                thischarcnt = 0;
                for (i = 0; i < typecnt; ++i) {
                        char    *thisabbr;

                        if (!writetype[i])
                                continue;
                        if (indmap[abbrinds[i]] >= 0)
                                continue;
                        thisabbr = &chars[abbrinds[i]];
                        for (j = 0; j < thischarcnt; ++j)
                                if (strcmp(&thischars[j], thisabbr) == 0)
                                        break;
                        if (j == thischarcnt) {
                                strlcpy(&thischars[(int) thischarcnt],
                                    thisabbr, sizeof(thischars) - thischarcnt);
                                thischarcnt += strlen(thisabbr) + 1;
                        }
                        indmap[abbrinds[i]] = j;
                }
#define DO(field)       fwrite(tzh.field, sizeof tzh.field, 1, fp)
                tzh = tzh0;
                strncpy(tzh.tzh_magic, TZ_MAGIC, sizeof tzh.tzh_magic);
                tzh.tzh_version[0] = version;
                convert(thistypecnt, tzh.tzh_ttisgmtcnt);
                convert(thistypecnt, tzh.tzh_ttisstdcnt);
                convert(thisleapcnt, tzh.tzh_leapcnt);
                convert(thistimecnt, tzh.tzh_timecnt);
                convert(thistypecnt, tzh.tzh_typecnt);
                convert(thischarcnt, tzh.tzh_charcnt);
                DO(tzh_magic);
                DO(tzh_version);
                DO(tzh_reserved);
                DO(tzh_ttisgmtcnt);
                DO(tzh_ttisstdcnt);
                DO(tzh_leapcnt);
                DO(tzh_timecnt);
                DO(tzh_typecnt);
                DO(tzh_charcnt);
#undef DO
                for (i = thistimei; i < thistimelim; ++i)
                        if (pass == 1)
                                puttzcode(ats[i], fp);
                        else
                                puttzcode64(ats[i], fp);
                for (i = thistimei; i < thistimelim; ++i) {
                        unsigned char   uc;

                        uc = typemap[types[i]];
                        fwrite(&uc, sizeof uc, 1, fp);
                }
                for (i = 0; i < typecnt; ++i)
                        if (writetype[i]) {
                                puttzcode(gmtoffs[i], fp);
                                putc(isdsts[i], fp);
                                putc((unsigned char)indmap[abbrinds[i]], fp);
                        }
                if (thischarcnt != 0)
                        fwrite(thischars, sizeof thischars[0], thischarcnt, fp);
                for (i = thisleapi; i < thisleaplim; ++i) {
                        zic_t   todo;

                        if (roll[i]) {
                                if (timecnt == 0 || trans[i] < ats[0]) {
                                        j = 0;
                                        while (isdsts[j])
                                                if (++j >= typecnt) {
                                                        j = 0;
                                                        break;
                                                }
                                } else {
                                        j = 1;
                                        while (j < timecnt &&
                                            trans[i] >= ats[j])
                                                ++j;
                                        j = types[j - 1];
                                }
                                todo = tadd(trans[i], -gmtoffs[j]);
                        } else
                                todo = trans[i];
                        if (pass == 1)
                                puttzcode(todo, fp);
                        else
                                puttzcode64(todo, fp);
                        puttzcode(corr[i], fp);
                }
                for (i = 0; i < typecnt; ++i)
                        if (writetype[i])
                                putc(ttisstds[i], fp);
                for (i = 0; i < typecnt; ++i)
                        if (writetype[i])
                                putc(ttisgmts[i], fp);
        }
        fprintf(fp, "\n%s\n", string);
        if (ferror(fp) || fclose(fp))
                errx(1, "Error writing %s", fullname);
}

static char const *
abbroffset(char *buf, zic_t offset)
{
        char sign = '+';
        int seconds, minutes;

        if (offset < 0) {
                offset = -offset;
                sign = '-';
        }

        seconds = offset % SECSPERMIN;
        offset /= SECSPERMIN;
        minutes = offset % MINSPERHOUR;
        offset /= MINSPERHOUR;
        if (100 <= offset) {
                error("%%z UTC offset magnitude exceeds 99:59:59");
                return "%z";
        } else {
                char *p = buf;
                *p++ = sign;
                *p++ = '0' + offset / 10;
                *p++ = '0' + offset % 10;
                if (minutes | seconds) {
                        *p++ = '0' + minutes / 10;
                        *p++ = '0' + minutes % 10;
                        if (seconds) {
                                *p++ = '0' + seconds / 10;
                                *p++ = '0' + seconds % 10;
                        }
                }
                *p = '\0';
                return buf;
        }
}

static void
doabbr(char *abbr, size_t size, struct zone const *zp, const char *letters,
    zic_t stdoff, int doquotes)
{
        char    *cp, *slashp;
        size_t  len;
        char const *format = zp->z_format;

        slashp = strchr(format, '/');
        if (slashp == NULL) {
                char letterbuf[PERCENT_Z_LEN_BOUND + 1];
                if (zp->z_format_specifier == 'z')
                        letters = abbroffset(letterbuf, zp->z_gmtoff + stdoff);
                else if (letters == NULL)
                        letters = "%s";
                snprintf(abbr, size, format, letters);
        } else if (stdoff != 0) {
                strlcpy(abbr, slashp + 1, size);
        } else {
                if (slashp - format + 1 < size)
                        size = slashp - format + 1;
                strlcpy(abbr, format, size);
        }
        if (!doquotes)
                return;
        for (cp = abbr; *cp != '\0'; ++cp)
                if (strchr("ABCDEFGHIJKLMNOPQRSTUVWXYZ", *cp) == NULL &&
                        strchr("abcdefghijklmnopqrstuvwxyz", *cp) == NULL)
                                break;
        len = strlen(abbr);
        if (len > 0 && *cp == '\0')
                return;
        abbr[len + 2] = '\0';
        abbr[len + 1] = '>';
        for ( ; len > 0; --len)
                abbr[len] = abbr[len - 1];
        abbr[0] = '<';
}

static void
updateminmax(zic_t x)
{
        if (min_year > x)
                min_year = x;
        if (max_year < x)
                max_year = x;
}

static int
stringoffset(char *result, size_t size, zic_t offset)
{
        int     hours, minutes, seconds;
        char    *ep;

        result[0] = '\0';
        if (offset < 0) {
                strlcpy(result, "-", size);
                offset = -offset;
        }
        seconds = offset % SECSPERMIN;
        offset /= SECSPERMIN;
        minutes = offset % MINSPERHOUR;
        offset /= MINSPERHOUR;
        hours = offset;
        if (hours >= HOURSPERDAY * DAYSPERWEEK) {
                result[0] = '\0';
                return -1;
        }
        ep = end(result, size);
        snprintf(ep, size - (ep - result), "%d", hours);
        if (minutes != 0 || seconds != 0) {
                ep = end(result, size);
                snprintf(ep, size - (ep - result), ":%02d", minutes);
                if (seconds != 0) {
                        ep = end(result, size);
                        snprintf(ep, size - (ep - result), ":%02d", seconds);
                }
        }
        return 0;
}

static int
stringrule(char *result, size_t size, const struct rule *rp, zic_t dstoff,
    zic_t gmtoff)
{
        zic_t   tod = rp->r_tod;
        int     compat = 0;
        char    *ep;

        ep = end(result, size);
        size -= ep - result;
        result = ep;
        if (rp->r_dycode == DC_DOM) {
                int     month, total;

                if (rp->r_dayofmonth == 29 && rp->r_month == TM_FEBRUARY)
                        return -1;
                total = 0;
                for (month = 0; month < rp->r_month; ++month)
                        total += len_months[0][month];
                /* Omit the "J" in Jan and Feb, as that's shorter.  */
                if (rp->r_month <= 1) {
                        snprintf(result, size, "%d",
                            total + rp->r_dayofmonth - 1);
                } else {
                        snprintf(result, size, "J%d",
                            total + rp->r_dayofmonth);
                }
        } else {
                int     week, wdayoff, wday = rp->r_wday;

                if (rp->r_dycode == DC_DOWGEQ) {
                        wdayoff = (rp->r_dayofmonth - 1) % DAYSPERWEEK;
                        if (wdayoff)
                                compat = 2013;
                        wday -= wdayoff;
                        tod += wdayoff * SECSPERDAY;
                        week = 1 + (rp->r_dayofmonth - 1) / DAYSPERWEEK;
                } else if (rp->r_dycode == DC_DOWLEQ) {
                        if (rp->r_dayofmonth == len_months[1][rp->r_month])
                                week = 5;
                        else {
                                wdayoff = rp->r_dayofmonth % DAYSPERWEEK;
                                if (wdayoff)
                                        compat = 2013;
                                wday -= wdayoff;
                                tod += wdayoff * SECSPERDAY;
                                week = rp->r_dayofmonth / DAYSPERWEEK;
                        }
                } else
                        return -1;      /* "cannot happen" */
                if (wday < 0)
                        wday += DAYSPERWEEK;
                snprintf(result, size, "M%d.%d.%d",
                        rp->r_month + 1, week, wday);
        }
        if (rp->r_todisgmt)
                tod += gmtoff;
        if (rp->r_todisstd && rp->r_stdoff == 0)
                tod += dstoff;
        if (tod != 2 * SECSPERMIN * MINSPERHOUR) {
                strlcat(result, "/", size);
                ep = end(result, size);
                if (stringoffset(ep, size - (ep - result), tod) != 0)
                        return -1;
                if (tod < 0) {
                        if (compat < 2013)
                                compat = 2013;
                } else if (SECSPERDAY <= tod) {
                        if (compat < 1994)
                                compat = 1994;
                }
        }
        return compat;
}

static int
rule_cmp(struct rule const *a, struct rule const *b)
{
        if (!a)
                return -!!b;
        if (!b)
                return 1;
        if (a->r_hiyear != b->r_hiyear)
                return a->r_hiyear < b->r_hiyear ? -1 : 1;
        if (a->r_month - b->r_month != 0)
                return a->r_month - b->r_month;
        return a->r_dayofmonth - b->r_dayofmonth;
}

enum { YEAR_BY_YEAR_ZONE = 1 };

static int
stringzone(char *result, size_t size, const struct zone *zpfirst, int zonecount)
{
        const struct zone       *zp;
        struct rule             *rp, *stdrp, *dstrp;
        int                     i, c, compat = 0;
        const char              *abbrvar;
        char                    *ep;
        struct rule             stdr, dstr;

        result[0] = '\0';
        zp = zpfirst + zonecount - 1;
        stdrp = dstrp = NULL;
        for (i = 0; i < zp->z_nrules; ++i) {
                rp = &zp->z_rules[i];
                if (rp->r_hiwasnum || rp->r_hiyear != ZIC_MAX)
                        continue;
                if (rp->r_stdoff == 0) {
                        if (stdrp == NULL)
                                stdrp = rp;
                        else
                                return -1;
                } else {
                        if (dstrp == NULL)
                                dstrp = rp;
                        else
                                return -1;
                }
        }
        if (stdrp == NULL && dstrp == NULL) {
                /*
                ** There are no rules running through "max".
                ** Find the latest std rule in stdabbrrp
                ** and latest rule of any type in stdrp.
                */
                struct rule *stdabbrrp = NULL;
                for (i = 0; i < zp->z_nrules; ++i) {
                        rp = &zp->z_rules[i];
                        if (rp->r_stdoff == 0 && rule_cmp(stdabbrrp, rp) < 0)
                                stdabbrrp = rp;
                        if (rule_cmp(stdrp, rp) < 0)
                                stdrp = rp;
                }
                /*
                ** Horrid special case: if year is 2037,
                ** presume this is a zone handled on a year-by-year basis;
                ** do not try to apply a rule to the zone.
                */
                if (stdrp != NULL && stdrp->r_hiyear == 2037)
                        return YEAR_BY_YEAR_ZONE;

                if (stdrp != NULL && stdrp->r_stdoff != 0) {
                        /* Perpetual DST.  */
                        dstr.r_month = TM_JANUARY;
                        dstr.r_dycode = DC_DOM;
                        dstr.r_dayofmonth = 1;
                        dstr.r_tod = 0;
                        dstr.r_todisstd = dstr.r_todisgmt = FALSE;
                        dstr.r_stdoff = stdrp->r_stdoff;
                        dstr.r_abbrvar = stdrp->r_abbrvar;
                        stdr.r_month = TM_DECEMBER;
                        stdr.r_dycode = DC_DOM;
                        stdr.r_dayofmonth = 31;
                        stdr.r_tod = SECSPERDAY + stdrp->r_stdoff;
                        stdr.r_todisstd = stdr.r_todisgmt = FALSE;
                        stdr.r_stdoff = 0;
                        stdr.r_abbrvar
                          = (stdabbrrp ? stdabbrrp->r_abbrvar : "");
                        dstrp = &dstr;
                        stdrp = &stdr;
                }
        }
        if (stdrp == NULL && (zp->z_nrules != 0 || zp->z_stdoff != 0))
                return -1;
        abbrvar = (stdrp == NULL) ? "" : stdrp->r_abbrvar;
        doabbr(result, size, zp, abbrvar, 0, TRUE);
        ep = end(result, size);
        if (stringoffset(ep, size - (ep - result), -zp->z_gmtoff) != 0) {
                result[0] = '\0';
                return -1;
        }
        if (dstrp == NULL)
                return compat;
        ep = end(result, size);
        doabbr(ep, size - (ep - result), zp, dstrp->r_abbrvar, dstrp->r_stdoff,
            TRUE);
        if (dstrp->r_stdoff != SECSPERMIN * MINSPERHOUR) {
                ep = end(result, size);
                if (stringoffset(ep, size - (ep - result),
                        -(zp->z_gmtoff + dstrp->r_stdoff)) != 0) {
                                result[0] = '\0';
                                return -1;
                }
        }
        strlcat(result, ",", size);
        c = stringrule(result, size, dstrp, dstrp->r_stdoff, zp->z_gmtoff);
        if (c < 0) {
                result[0] = '\0';
                return -1;
        }
        if (compat < c)
                compat = c;
        strlcat(result, ",", size);
        c = stringrule(result, size, stdrp, dstrp->r_stdoff, zp->z_gmtoff);
        if (c < 0) {
                result[0] = '\0';
                return -1;
        }
        if (compat < c)
                compat = c;
        return compat;
}

static void
outzone(const struct zone *zpfirst, int zonecount)
{
        const struct zone       *zp;
        struct rule             *rp;
        int                     i, j, usestart, useuntil, type;
        zic_t                   starttime = 0, untiltime = 0;
        zic_t                   gmtoff, stdoff, startoff, year;
        int                     startttisstd = FALSE, startttisgmt = FALSE;
        char                    *startbuf, *ab, *envvar;
        int                     max_abbr_len, max_envvar_len;
        int                     prodstic; /* all rules are min to max */
        int                     compat, do_extend;
        char                    version;

        max_abbr_len = 2 + max_format_len + max_abbrvar_len;
        max_envvar_len = 2 * max_abbr_len + 5 * 9;
        startbuf = emalloc(max_abbr_len + 1);
        ab = emalloc(max_abbr_len + 1);
        envvar = emalloc(max_envvar_len + 1);
        /*
        ** Now. . .finally. . .generate some useful data!
        */
        timecnt = 0;
        typecnt = 0;
        charcnt = 0;
        prodstic = zonecount == 1;
        /*
        ** Thanks to Earl Chew
        ** for noting the need to unconditionally initialize startttisstd.
        */
        min_year = max_year = EPOCH_YEAR;
        if (leapseen) {
                updateminmax(leapminyear);
                updateminmax(leapmaxyear + (leapmaxyear < ZIC_MAX));
        }
        for (i = 0; i < zonecount; ++i) {
                zp = &zpfirst[i];
                if (i < zonecount - 1)
                        updateminmax(zp->z_untilrule.r_loyear);
                for (j = 0; j < zp->z_nrules; ++j) {
                        rp = &zp->z_rules[j];
                        if (rp->r_lowasnum)
                                updateminmax(rp->r_loyear);
                        if (rp->r_hiwasnum)
                                updateminmax(rp->r_hiyear);
                        if (rp->r_lowasnum || rp->r_hiwasnum)
                                prodstic = FALSE;
                }
        }
        /*
        ** Generate lots of data if a rule can't cover all future times.
        */
        compat = stringzone(envvar, max_envvar_len + 1, zpfirst, zonecount);
        version = compat < 2013 ? ZIC_VERSION_PRE_2013 : ZIC_VERSION;
        do_extend = compat < 0 || compat == YEAR_BY_YEAR_ZONE;
        if (noise) {
                if (!*envvar)
                        warning("no POSIX environment variable for zone %s",
                                zpfirst->z_name);
                else if (compat != 0 && compat != YEAR_BY_YEAR_ZONE) {
                        /* Circa-COMPAT clients, and earlier clients, might
                           not work for this zone when given dates before
                           1970 or after 2038.  */
                        warning("%s: pre-%d clients may mishandle"
                                  " distant timestamps",
                                zpfirst->z_name, compat);
                }
        }
        if (do_extend) {
                /*
                ** Search through a couple of extra years past the obvious
                ** 400, to avoid edge cases.  For example, suppose a non-POSIX
                ** rule applies from 2012 onwards and has transitions in March
                ** and September, plus some one-off transitions in November
                ** 2013.  If zic looked only at the last 400 years, it would
                ** set max_year=2413, with the intent that the 400 years 2014
                ** through 2413 will be repeated.  The last transition listed
                ** in the tzfile would be in 2413-09, less than 400 years
                ** after the last one-off transition in 2013-11.  Two years
                ** might be overkill, but with the kind of edge cases
                ** available we're not sure that one year would suffice.
                */
                enum { years_of_observations = YEARSPERREPEAT + 2 };

                if (min_year >= ZIC_MIN + years_of_observations)
                        min_year -= years_of_observations;
                else
                        min_year = ZIC_MIN;
                if (max_year <= ZIC_MAX - years_of_observations)
                        max_year += years_of_observations;
                else
                        max_year = ZIC_MAX;
                /*
                ** Regardless of any of the above,
                ** for a "proDSTic" zone which specifies that its rules
                ** always have and always will be in effect,
                ** we only need one cycle to define the zone.
                */
                if (prodstic) {
                        min_year = 1900;
                        max_year = min_year + years_of_observations;
                }
        }
        /*
        ** For the benefit of older systems,
        ** generate data from 1900 through 2037.
        */
        if (min_year > 1900)
                min_year = 1900;
        if (max_year < 2037)
                max_year = 2037;
        for (i = 0; i < zonecount; ++i) {
                /*
                ** A guess that may well be corrected later.
                */
                stdoff = 0;
                zp = &zpfirst[i];
                usestart = i > 0 && (zp - 1)->z_untiltime > min_time;
                useuntil = i < (zonecount - 1);
                if (useuntil && zp->z_untiltime <= min_time)
                        continue;
                gmtoff = zp->z_gmtoff;
                eat(zp->z_filename, zp->z_linenum);
                *startbuf = '\0';
                startoff = zp->z_gmtoff;
                if (zp->z_nrules == 0) {
                        stdoff = zp->z_stdoff;
                        doabbr(startbuf, max_abbr_len + 1, zp, NULL,
                            stdoff, FALSE);
                        type = addtype(oadd(zp->z_gmtoff, stdoff),
                                startbuf, stdoff != 0, startttisstd,
                                startttisgmt);
                        if (usestart) {
                                addtt(starttime, type);
                                usestart = FALSE;
                        } else if (stdoff != 0)
                                addtt(min_time, type);
                } else for (year = min_year; year <= max_year; ++year) {
                        if (useuntil && year > zp->z_untilrule.r_hiyear)
                                break;
                        /*
                        ** Mark which rules to do in the current year.
                        ** For those to do, calculate rpytime(rp, year);
                        */
                        for (j = 0; j < zp->z_nrules; ++j) {
                                rp = &zp->z_rules[j];
                                eats(zp->z_filename, zp->z_linenum,
                                        rp->r_filename, rp->r_linenum);
                                rp->r_todo = year >= rp->r_loyear &&
                                    year <= rp->r_hiyear;
                                if (rp->r_todo)
                                        rp->r_temp = rpytime(rp, year);
                        }
                        for ( ; ; ) {
                                int     k;
                                zic_t   jtime, ktime = 0;
                                zic_t   offset;

                                if (useuntil) {
                                        /*
                                        ** Turn untiltime into UT
                                        ** assuming the current gmtoff and
                                        ** stdoff values.
                                        */
                                        untiltime = zp->z_untiltime;
                                        if (!zp->z_untilrule.r_todisgmt)
                                                untiltime = tadd(untiltime,
                                                        -gmtoff);
                                        if (!zp->z_untilrule.r_todisstd)
                                                untiltime = tadd(untiltime,
                                                        -stdoff);
                                }
                                /*
                                ** Find the rule (of those to do, if any)
                                ** that takes effect earliest in the year.
                                */
                                k = -1;
                                for (j = 0; j < zp->z_nrules; ++j) {
                                        rp = &zp->z_rules[j];
                                        if (!rp->r_todo)
                                                continue;
                                        eats(zp->z_filename, zp->z_linenum,
                                                rp->r_filename, rp->r_linenum);
                                        offset = rp->r_todisgmt ? 0 : gmtoff;
                                        if (!rp->r_todisstd)
                                                offset = oadd(offset, stdoff);
                                        jtime = rp->r_temp;
                                        if (jtime == min_time ||
                                                jtime == max_time)
                                                        continue;
                                        jtime = tadd(jtime, -offset);
                                        if (k < 0 || jtime < ktime) {
                                                k = j;
                                                ktime = jtime;
                                        }
                                }
                                if (k < 0)
                                        break;  /* go on to next year */
                                rp = &zp->z_rules[k];
                                rp->r_todo = FALSE;
                                if (useuntil && ktime >= untiltime)
                                        break;
                                stdoff = rp->r_stdoff;
                                if (usestart && ktime == starttime)
                                        usestart = FALSE;
                                if (usestart) {
                                        if (ktime < starttime) {
                                                startoff = oadd(zp->z_gmtoff,
                                                    stdoff);
                                                doabbr(startbuf,
                                                    max_abbr_len + 1,
                                                    zp,
                                                    rp->r_abbrvar,
                                                    rp->r_stdoff,
                                                    FALSE);
                                                continue;
                                        }
                                        if (*startbuf == '\0' &&
                                            startoff == oadd(zp->z_gmtoff,
                                            stdoff)) {
                                                doabbr(startbuf,
                                                    max_abbr_len + 1,
                                                    zp,
                                                    rp->r_abbrvar,
                                                    rp->r_stdoff,
                                                    FALSE);
                                        }
                                }
                                eats(zp->z_filename, zp->z_linenum,
                                    rp->r_filename, rp->r_linenum);
                                doabbr(ab, max_abbr_len + 1, zp,
                                    rp->r_abbrvar, rp->r_stdoff, FALSE);
                                offset = oadd(zp->z_gmtoff, rp->r_stdoff);
                                type = addtype(offset, ab, rp->r_stdoff != 0,
                                    rp->r_todisstd, rp->r_todisgmt);
                                addtt(ktime, type);
                        }
                }
                if (usestart) {
                        if (*startbuf == '\0' &&
                            zp->z_format != NULL &&
                            strchr(zp->z_format, '%') == NULL &&
                            strchr(zp->z_format, '/') == NULL)
                                strlcpy(startbuf, zp->z_format, max_abbr_len + 1);
                        eat(zp->z_filename, zp->z_linenum);
                        if (*startbuf == '\0')
                                error("can't determine time zone abbreviation to use just after until time");
                        else
                                addtt(starttime,
                                    addtype(startoff, startbuf,
                                    startoff != zp->z_gmtoff,
                                    startttisstd, startttisgmt));
                }
                /*
                ** Now we may get to set starttime for the next zone line.
                */
                if (useuntil) {
                        startttisstd = zp->z_untilrule.r_todisstd;
                        startttisgmt = zp->z_untilrule.r_todisgmt;
                        starttime = zp->z_untiltime;
                        if (!startttisstd)
                                starttime = tadd(starttime, -stdoff);
                        if (!startttisgmt)
                                starttime = tadd(starttime, -gmtoff);
                }
        }
        if (do_extend) {
                /*
                ** If we're extending the explicitly listed observations
                ** for 400 years because we can't fill the POSIX-TZ field,
                ** check whether we actually ended up explicitly listing
                ** observations through that period.  If there aren't any
                ** near the end of the 400-year period, add a redundant
                ** one at the end of the final year, to make it clear
                ** that we are claiming to have definite knowledge of
                ** the lack of transitions up to that point.
                */
                struct rule xr;
                struct attype *lastat;
                xr.r_month = TM_JANUARY;
                xr.r_dycode = DC_DOM;
                xr.r_dayofmonth = 1;
                xr.r_tod = 0;
                for (lastat = &attypes[0], i = 1; i < timecnt; i++)
                        if (attypes[i].at > lastat->at)
                                lastat = &attypes[i];
                if (lastat->at < rpytime(&xr, max_year - 1)) {
                        /*
                        ** Create new type code for the redundant entry,
                        ** to prevent it being optimised away.
                        */
                        if (typecnt >= TZ_MAX_TYPES) {
                                error("too many local time types");
                                exit(EXIT_FAILURE);
                        }
                        gmtoffs[typecnt] = gmtoffs[lastat->type];
                        isdsts[typecnt] = isdsts[lastat->type];
                        ttisstds[typecnt] = ttisstds[lastat->type];
                        ttisgmts[typecnt] = ttisgmts[lastat->type];
                        abbrinds[typecnt] = abbrinds[lastat->type];
                        ++typecnt;
                        addtt(rpytime(&xr, max_year + 1), typecnt-1);
                }
        }
        writezone(zpfirst->z_name, envvar, version);
        free(startbuf);
        free(ab);
        free(envvar);
}

static void
addtt(const zic_t starttime, int type)
{
        size_t len;

        if (starttime <= min_time ||
            (timecnt == 1 && attypes[0].at < min_time)) {
                gmtoffs[0] = gmtoffs[type];
                isdsts[0] = isdsts[type];
                ttisstds[0] = ttisstds[type];
                ttisgmts[0] = ttisgmts[type];
                if (abbrinds[type] != 0) {
                        len = strlen(&chars[abbrinds[type]]) + 1;
                        memmove(chars, &chars[abbrinds[type]], len);
                }
                abbrinds[0] = 0;
                charcnt = strlen(chars) + 1;
                typecnt = 1;
                timecnt = 0;
                type = 0;
        }
        if (timecnt >= TZ_MAX_TIMES) {
                error("too many transitions?!");
                exit(EXIT_FAILURE);
        }
        attypes[timecnt].at = starttime;
        attypes[timecnt].type = type;
        ++timecnt;
}

static int
addtype(zic_t gmtoff, const char *abbr, int isdst, int ttisstd, int ttisgmt)
{
        int     i, j;

        if (isdst != TRUE && isdst != FALSE) {
                error("internal error - addtype called with bad isdst");
                exit(EXIT_FAILURE);
        }
        if (ttisstd != TRUE && ttisstd != FALSE) {
                error("internal error - addtype called with bad ttisstd");
                exit(EXIT_FAILURE);
        }
        if (ttisgmt != TRUE && ttisgmt != FALSE) {
                error("internal error - addtype called with bad ttisgmt");
                exit(EXIT_FAILURE);
        }
        /*
        ** See if there's already an entry for this zone type.
        ** If so, just return its index.
        */
        for (i = 0; i < typecnt; ++i) {
                if (gmtoff == gmtoffs[i] && isdst == isdsts[i] &&
                    strcmp(abbr, &chars[abbrinds[i]]) == 0 &&
                    ttisstd == ttisstds[i] &&
                    ttisgmt == ttisgmts[i])
                        return i;
        }
        /*
        ** There isn't one; add a new one, unless there are already too
        ** many.
        */
        if (typecnt >= TZ_MAX_TYPES) {
                error("too many local time types");
                exit(EXIT_FAILURE);
        }
        if (! (-1L - 2147483647L <= gmtoff && gmtoff <= 2147483647L)) {
                error("UT offset out of range");
                exit(EXIT_FAILURE);
        }
        gmtoffs[i] = gmtoff;
        isdsts[i] = isdst;
        ttisstds[i] = ttisstd;
        ttisgmts[i] = ttisgmt;

        for (j = 0; j < charcnt; ++j)
                if (strcmp(&chars[j], abbr) == 0)
                        break;
        if (j == charcnt)
                newabbr(abbr);
        abbrinds[i] = j;
        ++typecnt;
        return i;
}

static void
leapadd(zic_t t, int positive, int rolling, int count)
{
        int     i, j;

        if (leapcnt + (positive ? count : 1) > TZ_MAX_LEAPS) {
                error("too many leap seconds");
                exit(EXIT_FAILURE);
        }
        for (i = 0; i < leapcnt; ++i)
                if (t <= trans[i]) {
                        if (t == trans[i]) {
                                error("repeated leap second moment");
                                exit(EXIT_FAILURE);
                        }
                        break;
                }
        do {
                for (j = leapcnt; j > i; --j) {
                        trans[j] = trans[j - 1];
                        corr[j] = corr[j - 1];
                        roll[j] = roll[j - 1];
                }
                trans[i] = t;
                corr[i] = positive ? 1 : -count;
                roll[i] = rolling;
                ++leapcnt;
        } while (positive && --count != 0);
}

static void
adjleap(void)
{
        int     i;
        zic_t   last = 0;

        /*
        ** propagate leap seconds forward
        */
        for (i = 0; i < leapcnt; ++i) {
                trans[i] = tadd(trans[i], last);
                last = corr[i] += last;
        }
}

/* this function is not strncasecmp */
static __pure int
itsabbr(const char *sabbr, const char *sword)
{
        const unsigned char *abbr = sabbr;
        const unsigned char *word = sword;

        if (tolower(*abbr) != tolower(*word))
                return FALSE;
        while (*++abbr != '\0')
                do {
                        ++word;
                        if (*word == '\0')
                                return FALSE;
                } while (tolower(*word) != tolower(*abbr));
        return TRUE;
}

static __pure const struct lookup *
byword(const char *word, const struct lookup *table)
{
        const struct lookup     *foundlp;
        const struct lookup     *lp;

        if (word == NULL || table == NULL)
                return NULL;
        /*
        ** Look for exact match.
        */
        for (lp = table; lp->l_word != NULL; ++lp)
                if (strcasecmp(word, lp->l_word) == 0)
                        return lp;
        /*
        ** Look for inexact match.
        */
        foundlp = NULL;
        for (lp = table; lp->l_word != NULL; ++lp)
                if (itsabbr(word, lp->l_word)) {
                        if (foundlp == NULL)
                                foundlp = lp;
                        else
                                return NULL;    /* multiple inexact matches */
                }
        return foundlp;
}

static char **
getfields(char *cp)
{
        char            *dp;
        char            **array;
        int             nsubs;

        if (cp == NULL)
                return NULL;
        array = ereallocarray(NULL, strlen(cp) + 1, sizeof *array);
        nsubs = 0;
        for ( ; ; ) {
                while (isascii((unsigned char)*cp) &&
                    isspace((unsigned char)*cp))
                        ++cp;
                if (*cp == '\0' || *cp == '#')
                        break;
                array[nsubs++] = dp = cp;
                do {
                        if ((*dp = *cp++) != '"') {
                                ++dp;
                        } else {
                                while ((*dp = *cp++) != '"') {
                                        if (*dp != '\0')
                                                ++dp;
                                        else {
                                                error("Odd number of quotation marks");
                                                exit(EXIT_FAILURE);
                                        }
                                }
                        }
                } while (*cp != '\0' && *cp != '#' &&
                    (!isascii((unsigned char)*cp) || !isspace((unsigned char)*cp)));
                if (isascii((unsigned char)*cp) && isspace((unsigned char)*cp))
                        ++cp;
                *dp = '\0';
        }
        array[nsubs] = NULL;
        return array;
}

static __pure zic_t
oadd(zic_t t1, zic_t t2)
{
        if (t1 < 0 ? t2 < ZIC_MIN - t1 : ZIC_MAX - t1 < t2) {
                error("time overflow");
                exit(EXIT_FAILURE);
        }
        return t1 + t2;
}

static __pure zic_t
tadd(zic_t t1, zic_t t2)
{
        if (t1 == max_time && t2 > 0)
                return max_time;
        if (t1 == min_time && t2 < 0)
                return min_time;
        if (t1 < 0 ? t2 < min_time - t1 : max_time - t1 < t2) {
                error("time overflow");
                exit(EXIT_FAILURE);
        }
        return t1 + t2;
}

/*
** Given a rule, and a year, compute the date - in seconds since January 1,
** 1970, 00:00 LOCAL time - in that year that the rule refers to.
*/
static zic_t
rpytime(const struct rule *rp, zic_t wantedy)
{
        int     m, i;
        zic_t   dayoff;                 /* with a nod to Margaret O. */
        zic_t   t, y;

        if (wantedy == ZIC_MIN)
                return min_time;
        if (wantedy == ZIC_MAX)
                return max_time;
        dayoff = 0;
        m = TM_JANUARY;
        y = EPOCH_YEAR;
        while (wantedy != y) {
                if (wantedy > y) {
                        i = len_years[isleap(y)];
                        ++y;
                } else {
                        --y;
                        i = -len_years[isleap(y)];
                }
                dayoff = oadd(dayoff, i);
        }
        while (m != rp->r_month) {
                i = len_months[isleap(y)][m];
                dayoff = oadd(dayoff, i);
                ++m;
        }
        i = rp->r_dayofmonth;
        if (m == TM_FEBRUARY && i == 29 && !isleap(y)) {
                if (rp->r_dycode == DC_DOWLEQ)
                        --i;
                else {
                        error("use of 2/29 in non leap-year");
                        exit(EXIT_FAILURE);
                }
        }
        --i;
        dayoff = oadd(dayoff, i);
        if (rp->r_dycode == DC_DOWGEQ || rp->r_dycode == DC_DOWLEQ) {
                zic_t   wday = EPOCH_WDAY;

                /*
                ** Don't trust mod of negative numbers.
                */
                if (dayoff >= 0)
                        wday = (wday + dayoff) % DAYSPERWEEK;
                else {
                        wday -= ((-dayoff) % DAYSPERWEEK);
                        if (wday < 0)
                                wday += DAYSPERWEEK;
                }
                while (wday != rp->r_wday)
                        if (rp->r_dycode == DC_DOWGEQ) {
                                dayoff = oadd(dayoff, 1);
                                if (++wday >= DAYSPERWEEK)
                                        wday = 0;
                                ++i;
                        } else {
                                dayoff = oadd(dayoff, -1);
                                if (--wday < 0)
                                        wday = DAYSPERWEEK - 1;
                                --i;
                        }
        }
        if (dayoff < min_time / SECSPERDAY)
                return min_time;
        if (dayoff > max_time / SECSPERDAY)
                return max_time;
        t = (zic_t) dayoff * SECSPERDAY;
        return tadd(t, rp->r_tod);
}

static void
newabbr(const char *string)
{
        int     i;

        if (strcmp(string, GRANDPARENTED) != 0) {
                const char *    cp;
                const char *    mp;

                cp = string;
                mp = NULL;
                while (isascii((unsigned char)*cp) &&
                    (isalnum((unsigned char)*cp) || *cp == '-' || *cp == '+'))
                        ++cp;
                if (noise && cp - string > 3)
                        mp = "time zone abbreviation has more than 3 characters";
                if (cp - string > ZIC_MAX_ABBR_LEN_WO_WARN)
                        mp = "time zone abbreviation has too many characters";
                if (*cp != '\0')
                        mp = "time zone abbreviation differs from POSIX standard";
                if (mp != NULL)
                        warning("%s (%s)", mp, string);
        }
        i = strlen(string) + 1;
        if (charcnt + i > TZ_MAX_CHARS) {
                error("too many, or too long, time zone abbreviations");
                exit(EXIT_FAILURE);
        }
        strlcpy(&chars[charcnt], string, sizeof(chars) - charcnt);
        charcnt += i;
}

static int
mkdirs(char *argname)
{
        char *  name;
        char *  cp;

        if (argname == NULL || *argname == '\0')
                return 0;
        cp = name = ecpyalloc(argname);
        while ((cp = strchr(cp + 1, '/')) != 0) {
                *cp = '\0';
                if (!itsdir(name)) {
                        /*
                        ** It doesn't seem to exist, so we try to create it.
                        ** Creation may fail because of the directory being
                        ** created by some other multiprocessor, so we get
                        ** to do extra checking.
                        */
                        if (mkdir(name, MKDIR_UMASK) != 0) {
                                const char *e = strerror(errno);

                                if (errno != EEXIST || !itsdir(name)) {
                                        fprintf(stderr,
                                            "%s: Can't create directory %s: %s\n",
                                            __progname, name, e);
                                        free(name);
                                        return -1;
                                }
                        }
                }
                *cp = '/';
        }
        free(name);
        return 0;
}