* Re: faking time
2002-02-11 11:49 faking time SA products
` (3 preceding siblings ...)
2002-02-11 23:08 ` Kilobug
@ 2002-02-12 3:47 ` Theodore Tso
2002-02-12 8:33 ` Andreas Ferber
2002-02-12 6:00 ` David Schwartz
2002-02-12 6:09 ` Nick 'Sharkey' Moore
6 siblings, 1 reply; 12+ messages in thread
From: Theodore Tso @ 2002-02-12 3:47 UTC (permalink / raw)
To: SA products; +Cc: linux-kernel
[-- Attachment #1: Type: text/plain, Size: 810 bytes --]
On Mon, Feb 11, 2002 at 11:49:39AM +0000, SA products wrote:
>
> Dear Kernel list,
>
> I want to fake the time returned by the time() system call so that
> for a limited number of user space programs the time can be set to
> the future or the past without affecting other applications and
> without affecting system time-- Ideally I would like to install a
> loadable module to accomplish this- Any hints ? Any starting points?
Here's an LD_PRELOAD shared library that will do the trick... just
export the environment variable FAKETIME with the time that you'd
like, and then export the LD_PRELOAD environment variable to point
that the faketime.so library, and then execute your program. All
programs that have these two environment variables set will have their
time faked out accordingly.
- Ted
[-- Attachment #2: faketime.c --]
[-- Type: text/x-csrc, Size: 27585 bytes --]
/* Convert struct partime into time_t. */
/* Copyright 1992, 1993, 1994, 1995 Paul Eggert
Distributed under license by the Free Software Foundation, Inc.
This file is part of RCS.
RCS is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.
RCS is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with RCS; see the file COPYING.
If not, write to the Free Software Foundation,
59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
Report problems and direct all questions to:
rcs-bugs@cs.purdue.edu
*/
#include <stdlib.h>
#include <time.h>
#include <sys/time.h>
#include <ctype.h>
#define P(x) x
#define TM_UNDEFINED (-1)
#define TM_DEFINED(x) (0 <= (x))
#define TM_UNDEFINED_ZONE ((long) -24 * 60 * 60)
#define TM_LOCAL_ZONE (TM_UNDEFINED_ZONE - 1)
struct partime {
/*
* This structure describes the parsed time.
* Only the following tm_* values in it are used:
* sec, min, hour, mday, mon, year, wday, yday.
* If TM_UNDEFINED(value), the parser never found the value.
* The tm_year field is the actual year, not the year - 1900;
* but see ymodulus below.
*/
struct tm tm;
/*
* If !TM_UNDEFINED(ymodulus),
* then tm.tm_year is actually modulo ymodulus.
*/
int ymodulus;
/*
* Week of year, ISO 8601 style.
* If TM_UNDEFINED(yweek), the parser never found yweek.
* Weeks start on Mondays.
* Week 1 includes Jan 4.
*/
int yweek;
/* Seconds east of UTC; or TM_LOCAL_ZONE or TM_UNDEFINED_ZONE. */
long zone;
};
static char *partime (char const *, struct partime *);
static char *parzone (char const *, long *);
static int isleap P((int));
static int month_days P((struct tm const*));
static time_t maketime P((struct partime const*,time_t));
/* Lookup tables for names of months, weekdays, time zones. */
#define NAME_LENGTH_MAXIMUM 4
struct name_val {
char name[NAME_LENGTH_MAXIMUM];
int val;
};
static char const *parse_decimal P((char const*,int,int,int,int,int*,int*));
static char const *parse_fixed P((char const*,int,int*));
static char const *parse_pattern_letter P((char const*,int,struct partime*));
static char const *parse_prefix P((char const*,struct partime*,int*));
static char const *parse_ranged P((char const*,int,int,int,int*));
static int lookup P((char const*,struct name_val const[]));
static int merge_partime P((struct partime*, struct partime const*));
static void undefine P((struct partime*));
static struct name_val const month_names[] = {
{"jan",0}, {"feb",1}, {"mar",2}, {"apr",3}, {"may",4}, {"jun",5},
{"jul",6}, {"aug",7}, {"sep",8}, {"oct",9}, {"nov",10}, {"dec",11},
{"", TM_UNDEFINED}
};
static struct name_val const weekday_names[] = {
{"sun",0}, {"mon",1}, {"tue",2}, {"wed",3}, {"thu",4}, {"fri",5}, {"sat",6},
{"", TM_UNDEFINED}
};
#define hr60nonnegative(t) ((t)/100 * 60 + (t)%100)
#define hr60(t) ((t)<0 ? -hr60nonnegative(-(t)) : hr60nonnegative(t))
#define zs(t,s) {s, hr60(t)}
#define zd(t,s,d) zs(t, s), zs((t)+100, d)
static struct name_val const zone_names[] = {
zs(-1000, "hst"), /* Hawaii */
zd(-1000,"hast","hadt"),/* Hawaii-Aleutian */
zd(- 900,"akst","akdt"),/* Alaska */
zd(- 800, "pst", "pdt"),/* Pacific */
zd(- 700, "mst", "mdt"),/* Mountain */
zd(- 600, "cst", "cdt"),/* Central */
zd(- 500, "est", "edt"),/* Eastern */
zd(- 400, "ast", "adt"),/* Atlantic */
zd(- 330, "nst", "ndt"),/* Newfoundland */
zs( 000, "utc"), /* Coordinated Universal */
zs( 000, "cut"), /* " */
zs( 000, "ut"), /* Universal */
zs( 000, "z"), /* Zulu (required by ISO 8601) */
zd( 000, "gmt", "bst"),/* Greenwich Mean, British Summer */
zs( 000, "wet"), /* Western Europe */
zs( 100, "met"), /* Middle Europe */
zs( 100, "cet"), /* Central Europe */
zs( 200, "eet"), /* Eastern Europe */
zs( 530, "ist"), /* India */
zd( 900, "jst", "jdt"),/* Japan */
zd( 900, "kst", "kdt"),/* Korea */
zd( 1200,"nzst","nzdt"),/* New Zealand */
{ "lt", 1 },
#if 0
/* The following names are duplicates or are not well attested. */
zs(-1100, "sst"), /* Samoa */
zs(-1000, "tht"), /* Tahiti */
zs(- 930, "mqt"), /* Marquesas */
zs(- 900, "gbt"), /* Gambier */
zd(- 900, "yst", "ydt"),/* Yukon - name is no longer used */
zs(- 830, "pit"), /* Pitcairn */
zd(- 500, "cst", "cdt"),/* Cuba */
zd(- 500, "ast", "adt"),/* Acre */
zd(- 400, "wst", "wdt"),/* Western Brazil */
zd(- 400, "ast", "adt"),/* Andes */
zd(- 400, "cst", "cdt"),/* Chile */
zs(- 300, "wgt"), /* Western Greenland */
zd(- 300, "est", "edt"),/* Eastern South America */
zs(- 300, "mgt"), /* Middle Greenland */
zd(- 200, "fst", "fdt"),/* Fernando de Noronha */
zs(- 100, "egt"), /* Eastern Greenland */
zs(- 100, "aat"), /* Atlantic Africa */
zs(- 100, "act"), /* Azores and Canaries */
zs( 000, "wat"), /* West Africa */
zs( 100, "cat"), /* Central Africa */
zd( 100, "mez","mesz"),/* Mittel-Europaeische Zeit */
zs( 200, "sat"), /* South Africa */
zd( 200, "ist", "idt"),/* Israel */
zs( 300, "eat"), /* East Africa */
zd( 300, "ast", "adt"),/* Arabia */
zd( 300, "msk", "msd"),/* Moscow */
zd( 330, "ist", "idt"),/* Iran */
zs( 400, "gst"), /* Gulf */
zs( 400, "smt"), /* Seychelles & Mascarene */
zd( 400, "esk", "esd"),/* Yekaterinburg */
zd( 400, "bsk", "bsd"),/* Baku */
zs( 430, "aft"), /* Afghanistan */
zd( 500, "osk", "osd"),/* Omsk */
zs( 500, "pkt"), /* Pakistan */
zd( 500, "tsk", "tsd"),/* Tashkent */
zs( 545, "npt"), /* Nepal */
zs( 600, "bgt"), /* Bangladesh */
zd( 600, "nsk", "nsd"),/* Novosibirsk */
zs( 630, "bmt"), /* Burma */
zs( 630, "cct"), /* Cocos */
zs( 700, "ict"), /* Indochina */
zs( 700, "jvt"), /* Java */
zd( 700, "isk", "isd"),/* Irkutsk */
zs( 800, "hkt"), /* Hong Kong */
zs( 800, "pst"), /* Philippines */
zs( 800, "sgt"), /* Singapore */
zd( 800, "cst", "cdt"),/* China */
zd( 800, "ust", "udt"),/* Ulan Bator */
zd( 800, "wst", "wst"),/* Western Australia */
zd( 800, "ysk", "ysd"),/* Yakutsk */
zs( 900, "blt"), /* Belau */
zs( 900, "mlt"), /* Moluccas */
zd( 900, "vsk", "vsd"),/* Vladivostok */
zd( 930, "cst", "cst"),/* Central Australia */
zs( 1000, "gst"), /* Guam */
zd( 1000, "gsk", "gsd"),/* Magadan */
zd( 1000, "est", "est"),/* Eastern Australia */
zd( 1100,"lhst","lhst"),/* Lord Howe */
zd( 1100, "psk", "psd"),/* Petropavlovsk-Kamchatski */
zs( 1100,"ncst"), /* New Caledonia */
zs( 1130,"nrft"), /* Norfolk */
zd( 1200, "ask", "asd"),/* Anadyr */
zs( 1245,"nz-chat"), /* Chatham */
zs( 1300, "tgt"), /* Tongatapu */
#endif
{"", -1}
};
static int
lookup (s, table)
char const *s;
struct name_val const table[];
/* Look for a prefix of S in TABLE, returning val for first matching entry. */
{
int j;
char buf[NAME_LENGTH_MAXIMUM];
for (j = 0; j < NAME_LENGTH_MAXIMUM; j++) {
unsigned char c = *s++;
buf[j] = isupper (c) ? tolower (c) : c;
if (!isalpha (c))
break;
}
for (; table[0].name[0]; table++)
for (j = 0; buf[j] == table[0].name[j]; )
if (++j == NAME_LENGTH_MAXIMUM || !table[0].name[j])
goto done;
done:
return table[0].val;
}
static void
undefine (t) struct partime *t;
/* Set *T to ``undefined'' values. */
{
t->tm.tm_sec = t->tm.tm_min = t->tm.tm_hour = t->tm.tm_mday = t->tm.tm_mon
= t->tm.tm_year = t->tm.tm_wday = t->tm.tm_yday
= t->ymodulus = t->yweek
= TM_UNDEFINED;
t->zone = TM_UNDEFINED_ZONE;
}
/*
* Array of patterns to look for in a date string.
* Order is important: we look for the first matching pattern
* whose values do not contradict values that we already know about.
* See `parse_pattern_letter' below for the meaning of the pattern codes.
*/
static char const * const patterns[] = {
/*
* These traditional patterns must come first,
* to prevent an ISO 8601 format from misinterpreting their prefixes.
*/
"E_n_y", "x", /* RFC 822 */
"E_n", "n_E", "n", "t:m:s_A", "t:m_A", "t_A", /* traditional */
"y/N/D$", /* traditional RCS */
/* ISO 8601:1988 formats, generalized a bit. */
"y-N-D$", "4ND$", "Y-N$",
"RND$", "-R=N$", "-R$", "--N=D$", "N=DT",
"--N$", "---D$", "DT",
"Y-d$", "4d$", "R=d$", "-d$", "dT",
"y-W-X", "yWX", "y=W",
"-r-W-X", "r-W-XT", "-rWX", "rWXT", "-W=X", "W=XT", "-W",
"-w-X", "w-XT", "---X$", "XT", "4$",
"T",
"h:m:s$", "hms$", "h:m$", "hm$", "h$", "-m:s$", "-ms$", "-m$", "--s$",
"Y", "Z",
0
};
static char const *
parse_prefix (str, t, pi) char const *str; struct partime *t; int *pi;
/*
* Parse an initial prefix of STR, setting *T accordingly.
* Return the first character after the prefix, or 0 if it couldn't be parsed.
* Start with pattern *PI; if success, set *PI to the next pattern to try.
* Set *PI to -1 if we know there are no more patterns to try;
* if *PI is initially negative, give up immediately.
*/
{
int i = *pi;
char const *pat;
unsigned char c;
if (i < 0)
return 0;
/* Remove initial noise. */
while (!isalnum (c = *str) && c != '-' && c != '+') {
if (!c) {
undefine (t);
*pi = -1;
return str;
}
str++;
}
/* Try a pattern until one succeeds. */
while ((pat = patterns[i++]) != 0) {
char const *s = str;
undefine (t);
do {
if (!(c = *pat++)) {
*pi = i;
return s;
}
} while ((s = parse_pattern_letter (s, c, t)) != 0);
}
return 0;
}
static char const *
parse_fixed (s, digits, res) char const *s; int digits, *res;
/*
* Parse an initial prefix of S of length DIGITS; it must be a number.
* Store the parsed number into *RES.
* Return the first character after the prefix, or 0 if it couldn't be parsed.
*/
{
int n = 0;
char const *lim = s + digits;
while (s < lim) {
unsigned d = *s++ - '0';
if (9 < d)
return 0;
n = 10*n + d;
}
*res = n;
return s;
}
static char const *
parse_ranged (s, digits, lo, hi, res) char const *s; int digits, lo, hi, *res;
/*
* Parse an initial prefix of S of length DIGITS;
* it must be a number in the range LO through HI.
* Store the parsed number into *RES.
* Return the first character after the prefix, or 0 if it couldn't be parsed.
*/
{
s = parse_fixed (s, digits, res);
return s && lo<=*res && *res<=hi ? s : 0;
}
static char const *
parse_decimal (s, digits, lo, hi, resolution, res, fres)
char const *s;
int digits, lo, hi, resolution, *res, *fres;
/*
* Parse an initial prefix of S of length DIGITS;
* it must be a number in the range LO through HI
* and it may be followed by a fraction that is to be computed using RESOLUTION.
* Store the parsed number into *RES; store the fraction times RESOLUTION,
* rounded to the nearest integer, into *FRES.
* Return the first character after the prefix, or 0 if it couldn't be parsed.
*/
{
s = parse_fixed (s, digits, res);
if (s && lo<=*res && *res<=hi) {
int f = 0;
if ((s[0]==',' || s[0]=='.') && isdigit ((unsigned char) s[1])) {
char const *s1 = ++s;
int num10 = 0, denom10 = 10, product;
while (isdigit ((unsigned char) *++s))
denom10 *= 10;
s = parse_fixed (s1, s - s1, &num10);
product = num10*resolution;
f = (product + (denom10>>1)) / denom10;
f -= f & (product%denom10 == denom10>>1); /* round to even */
if (f < 0 || product/resolution != num10)
return 0; /* overflow */
}
*fres = f;
return s;
}
return 0;
}
static char *
parzone (s, zone) char const *s; long *zone;
/*
* Parse an initial prefix of S; it must denote a time zone.
* Set *ZONE to the number of seconds east of GMT,
* or to TM_LOCAL_ZONE if it is the local time zone.
* Return the first character after the prefix, or 0 if it couldn't be parsed.
*/
{
char sign;
int hh, mm, ss;
int minutesEastOfUTC;
long offset, z;
/*
* The formats are LT, n, n DST, nDST, no, o
* where n is a time zone name
* and o is a time zone offset of the form [-+]hh[:mm[:ss]].
*/
switch (*s) {
case '-': case '+':
z = 0;
break;
default:
minutesEastOfUTC = lookup (s, zone_names);
if (minutesEastOfUTC == -1)
return 0;
/* Don't bother to check rest of spelling. */
while (isalpha ((unsigned char) *s))
s++;
/* Don't modify LT. */
if (minutesEastOfUTC == 1) {
*zone = TM_LOCAL_ZONE;
return (char *) s;
}
z = minutesEastOfUTC * 60L;
/* Look for trailing " DST". */
if (
(s[-1]=='T' || s[-1]=='t') &&
(s[-2]=='S' || s[-2]=='s') &&
(s[-3]=='D' || s[-3]=='t')
)
goto trailing_dst;
while (isspace ((unsigned char) *s))
s++;
if (
(s[0]=='D' || s[0]=='d') &&
(s[1]=='S' || s[1]=='s') &&
(s[2]=='T' || s[2]=='t')
) {
s += 3;
trailing_dst:
*zone = z + 60*60;
return (char *) s;
}
switch (*s) {
case '-': case '+': break;
default: return (char *) s;
}
}
sign = *s++;
if (!(s = parse_ranged (s, 2, 0, 23, &hh)))
return 0;
mm = ss = 0;
if (*s == ':')
s++;
if (isdigit ((unsigned char) *s)) {
if (!(s = parse_ranged (s, 2, 0, 59, &mm)))
return 0;
if (*s==':' && s[-3]==':' && isdigit ((unsigned char) s[1])) {
if (!(s = parse_ranged (s + 1, 2, 0, 59, &ss)))
return 0;
}
}
if (isdigit ((unsigned char) *s))
return 0;
offset = (hh*60 + mm)*60L + ss;
*zone = z + (sign=='-' ? -offset : offset);
/*
* ?? Are fractions allowed here?
* If so, they're not implemented.
*/
return (char *) s;
}
static char const *
parse_pattern_letter (s, c, t) char const *s; int c; struct partime *t;
/*
* Parse an initial prefix of S, matching the pattern whose code is C.
* Set *T accordingly.
* Return the first character after the prefix, or 0 if it couldn't be parsed.
*/
{
switch (c) {
case '$': /* The next character must be a non-digit. */
if (isdigit ((unsigned char) *s))
return 0;
break;
case '-': case '/': case ':':
/* These characters stand for themselves. */
if (*s++ != c)
return 0;
break;
case '4': /* 4-digit year */
s = parse_fixed (s, 4, &t->tm.tm_year);
break;
case '=': /* optional '-' */
s += *s == '-';
break;
case 'A': /* AM or PM */
/*
* This matches the regular expression [AaPp][Mm]?.
* It must not be followed by a letter or digit;
* otherwise it would match prefixes of strings like "PST".
*/
switch (*s++) {
case 'A': case 'a':
if (t->tm.tm_hour == 12)
t->tm.tm_hour = 0;
break;
case 'P': case 'p':
if (t->tm.tm_hour != 12)
t->tm.tm_hour += 12;
break;
default: return 0;
}
switch (*s) {
case 'M': case 'm': s++; break;
}
if (isalnum (*s))
return 0;
break;
case 'D': /* day of month [01-31] */
s = parse_ranged (s, 2, 1, 31, &t->tm.tm_mday);
break;
case 'd': /* day of year [001-366] */
s = parse_ranged (s, 3, 1, 366, &t->tm.tm_yday);
t->tm.tm_yday--;
break;
case 'E': /* extended day of month [1-9, 01-31] */
s = parse_ranged (s, (
isdigit ((unsigned char) s[0]) &&
isdigit ((unsigned char) s[1])
) + 1, 1, 31, &t->tm.tm_mday);
break;
case 'h': /* hour [00-23 followed by optional fraction] */
{
int frac;
s = parse_decimal (s, 2, 0, 23, 60*60, &t->tm.tm_hour, &frac);
t->tm.tm_min = frac / 60;
t->tm.tm_sec = frac % 60;
}
break;
case 'm': /* minute [00-59 followed by optional fraction] */
s = parse_decimal (s, 2, 0, 59, 60, &t->tm.tm_min, &t->tm.tm_sec);
break;
case 'n': /* month name [e.g. "Jan"] */
if (!TM_DEFINED (t->tm.tm_mon = lookup (s, month_names)))
return 0;
/* Don't bother to check rest of spelling. */
while (isalpha ((unsigned char) *s))
s++;
break;
case 'N': /* month [01-12] */
s = parse_ranged (s, 2, 1, 12, &t->tm.tm_mon);
t->tm.tm_mon--;
break;
case 'r': /* year % 10 (remainder in origin-0 decade) [0-9] */
s = parse_fixed (s, 1, &t->tm.tm_year);
t->ymodulus = 10;
break;
case_R:
case 'R': /* year % 100 (remainder in origin-0 century) [00-99] */
s = parse_fixed (s, 2, &t->tm.tm_year);
t->ymodulus = 100;
break;
case 's': /* second [00-60 followed by optional fraction] */
{
int frac;
s = parse_decimal (s, 2, 0, 60, 1, &t->tm.tm_sec, &frac);
t->tm.tm_sec += frac;
}
break;
case 'T': /* 'T' or 't' */
switch (*s++) {
case 'T': case 't': break;
default: return 0;
}
break;
case 't': /* traditional hour [1-9 or 01-12] */
s = parse_ranged (s, (
isdigit ((unsigned char) s[0]) && isdigit ((unsigned char) s[1])
) + 1, 1, 12, &t->tm.tm_hour);
break;
case 'w': /* 'W' or 'w' only (stands for current week) */
switch (*s++) {
case 'W': case 'w': break;
default: return 0;
}
break;
case 'W': /* 'W' or 'w', followed by a week of year [00-53] */
switch (*s++) {
case 'W': case 'w': break;
default: return 0;
}
s = parse_ranged (s, 2, 0, 53, &t->yweek);
break;
case 'X': /* weekday (1=Mon ... 7=Sun) [1-7] */
s = parse_ranged (s, 1, 1, 7, &t->tm.tm_wday);
t->tm.tm_wday--;
break;
case 'x': /* weekday name [e.g. "Sun"] */
if (!TM_DEFINED (t->tm.tm_wday = lookup (s, weekday_names)))
return 0;
/* Don't bother to check rest of spelling. */
while (isalpha ((unsigned char) *s))
s++;
break;
case 'y': /* either R or Y */
if (
isdigit ((unsigned char) s[0]) &&
isdigit ((unsigned char) s[1]) &&
!isdigit ((unsigned char) s[2])
)
goto case_R;
/* fall into */
case 'Y': /* year in full [4 or more digits] */
{
int len = 0;
while (isdigit ((unsigned char) s[len]))
len++;
if (len < 4)
return 0;
s = parse_fixed (s, len, &t->tm.tm_year);
}
break;
case 'Z': /* time zone */
s = parzone (s, &t->zone);
break;
case '_': /* possibly empty sequence of non-alphanumerics */
while (!isalnum (*s) && *s)
s++;
break;
default: /* bad pattern */
return 0;
}
return s;
}
static int
merge_partime (t, u) struct partime *t; struct partime const *u;
/*
* If there is no conflict, merge into *T the additional information in *U
* and return 0. Otherwise do nothing and return -1.
*/
{
# define conflict(a,b) ((a) != (b) && TM_DEFINED (a) && TM_DEFINED (b))
if (
conflict (t->tm.tm_sec, u->tm.tm_sec) ||
conflict (t->tm.tm_min, u->tm.tm_min) ||
conflict (t->tm.tm_hour, u->tm.tm_hour) ||
conflict (t->tm.tm_mday, u->tm.tm_mday) ||
conflict (t->tm.tm_mon, u->tm.tm_mon) ||
conflict (t->tm.tm_year, u->tm.tm_year) ||
conflict (t->tm.tm_wday, u->tm.tm_yday) ||
conflict (t->ymodulus, u->ymodulus) ||
conflict (t->yweek, u->yweek) ||
(
t->zone != u->zone &&
t->zone != TM_UNDEFINED_ZONE &&
u->zone != TM_UNDEFINED_ZONE
)
)
return -1;
# undef conflict
# define merge_(a,b) if (TM_DEFINED (b)) (a) = (b);
merge_ (t->tm.tm_sec, u->tm.tm_sec)
merge_ (t->tm.tm_min, u->tm.tm_min)
merge_ (t->tm.tm_hour, u->tm.tm_hour)
merge_ (t->tm.tm_mday, u->tm.tm_mday)
merge_ (t->tm.tm_mon, u->tm.tm_mon)
merge_ (t->tm.tm_year, u->tm.tm_year)
merge_ (t->tm.tm_wday, u->tm.tm_yday)
merge_ (t->ymodulus, u->ymodulus)
merge_ (t->yweek, u->yweek)
# undef merge_
if (u->zone != TM_UNDEFINED_ZONE) t->zone = u->zone;
return 0;
}
static char *
partime (s, t) char const *s; struct partime *t;
/*
* Parse a date/time prefix of S, putting the parsed result into *T.
* Return the first character after the prefix.
* The prefix may contain no useful information;
* in that case, *T will contain only undefined values.
*/
{
struct partime p;
undefine (t);
while (*s) {
int i = 0;
char const *s1;
do {
if (!(s1 = parse_prefix (s, &p, &i)))
return (char *) s;
} while (merge_partime (t, &p) != 0);
s = s1;
}
return (char *) s;
}
/*
* For maximum portability, use only localtime and gmtime.
* Make no assumptions about the time_t epoch or the range of time_t values.
* Avoid mktime because it's not universal and because there's no easy,
* portable way for mktime to yield the inverse of gmtime.
*/
#define TM_YEAR_ORIGIN 1900
static int
isleap(y)
int y;
{
return (y&3) == 0 && (y%100 != 0 || y%400 == 0);
}
static int const month_yday[] = {
/* days in year before start of months 0-12 */
0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365
};
/* Yield the number of days in TM's month. */
static int
month_days(tm)
struct tm const *tm;
{
int m = tm->tm_mon;
return month_yday[m+1] - month_yday[m]
+ (m==1 && isleap(tm->tm_year + TM_YEAR_ORIGIN));
}
/*
* Convert UNIXTIME to struct tm form.
* Use gmtime if available and if !LOCALZONE, localtime otherwise.
*/
static struct tm *
time2tm(time_t unixtime, int localzone)
{
struct tm *tm;
# if TZ_must_be_set
static char const *TZ;
if (!TZ && !(TZ = getenv("TZ")))
faterror("The TZ environment variable is not set; please set it to your timezone");
# endif
if (localzone || !(tm = gmtime(&unixtime)))
tm = localtime(&unixtime);
return tm;
}
/* Yield A - B, measured in seconds. */
static time_t
difftm(struct tm const *a, struct tm const *b)
{
int ay = a->tm_year + (TM_YEAR_ORIGIN - 1);
int by = b->tm_year + (TM_YEAR_ORIGIN - 1);
int difference_in_day_of_year = a->tm_yday - b->tm_yday;
int intervening_leap_days = (
((ay >> 2) - (by >> 2))
- (ay/100 - by/100)
+ ((ay/100 >> 2) - (by/100 >> 2))
);
time_t difference_in_years = ay - by;
time_t difference_in_days = (
difference_in_years*365
+ (intervening_leap_days + difference_in_day_of_year)
);
return
(
(
24*difference_in_days
+ (a->tm_hour - b->tm_hour)
)*60 + (a->tm_min - b->tm_min)
)*60 + (a->tm_sec - b->tm_sec);
}
/*
* Adjust time T by adding SECONDS. SECONDS must be at most 24 hours' worth.
* Adjust only T's year, mon, mday, hour, min and sec members;
* plus adjust wday if it is defined.
*/
static void
adjzone(struct tm *t, long seconds)
{
/*
* This code can be off by a second if SECONDS is not a multiple of 60,
* if T is local time, and if a leap second happens during this minute.
* But this bug has never occurred, and most likely will not ever occur.
* Liberia, the last country for which SECONDS % 60 was nonzero,
* switched to UTC in May 1972; the first leap second was in June 1972.
*/
int leap_second = t->tm_sec == 60;
long sec = seconds + (t->tm_sec - leap_second);
if (sec < 0) {
if ((t->tm_min -= (59-sec)/60) < 0) {
if ((t->tm_hour -= (59-t->tm_min)/60) < 0) {
t->tm_hour += 24;
if (TM_DEFINED(t->tm_wday) && --t->tm_wday < 0)
t->tm_wday = 6;
if (--t->tm_mday <= 0) {
if (--t->tm_mon < 0) {
--t->tm_year;
t->tm_mon = 11;
}
t->tm_mday = month_days(t);
}
}
t->tm_min += 24 * 60;
}
sec += 24L * 60 * 60;
} else
if (60 <= (t->tm_min += sec/60))
if (24 <= (t->tm_hour += t->tm_min/60)) {
t->tm_hour -= 24;
if (TM_DEFINED(t->tm_wday) && ++t->tm_wday == 7)
t->tm_wday = 0;
if (month_days(t) < ++t->tm_mday) {
if (11 < ++t->tm_mon) {
++t->tm_year;
t->tm_mon = 0;
}
t->tm_mday = 1;
}
}
t->tm_min %= 60;
t->tm_sec = (int) (sec%60) + leap_second;
}
/*
* Convert TM to time_t, using localtime if LOCALZONE and gmtime otherwise.
* Use only TM's year, mon, mday, hour, min, and sec members.
* Ignore TM's old tm_yday and tm_wday, but fill in their correct values.
* Yield -1 on failure (e.g. a member out of range).
* Posix 1003.1-1990 doesn't allow leap seconds, but some implementations
* have them anyway, so allow them if localtime/gmtime does.
*/
static time_t
tm2time(struct tm *tm, int localzone)
{
/* Cache the most recent t,tm pairs; 1 for gmtime, 1 for localtime. */
static time_t t_cache[2];
static struct tm tm_cache[2];
time_t d, gt;
struct tm const *gtm;
/*
* The maximum number of iterations should be enough to handle any
* combinations of leap seconds, time zone rule changes, and solar time.
* 4 is probably enough; we use a bigger number just to be safe.
*/
int remaining_tries = 8;
/* Avoid subscript errors. */
if (12 <= (unsigned)tm->tm_mon)
return -1;
tm->tm_yday = month_yday[tm->tm_mon] + tm->tm_mday
- (tm->tm_mon<2 || ! isleap(tm->tm_year + TM_YEAR_ORIGIN));
/* Make a first guess. */
gt = t_cache[localzone];
gtm = gt ? &tm_cache[localzone] : time2tm(gt,localzone);
/* Repeatedly use the error from the guess to improve the guess. */
while ((d = difftm(tm, gtm)) != 0) {
if (--remaining_tries == 0)
return -1;
gt += d;
gtm = time2tm(gt,localzone);
}
t_cache[localzone] = gt;
tm_cache[localzone] = *gtm;
/*
* Check that the guess actually matches;
* overflow can cause difftm to yield 0 even on differing times,
* or tm may have members out of range (e.g. bad leap seconds).
*/
if ( (tm->tm_year ^ gtm->tm_year)
| (tm->tm_mon ^ gtm->tm_mon)
| (tm->tm_mday ^ gtm->tm_mday)
| (tm->tm_hour ^ gtm->tm_hour)
| (tm->tm_min ^ gtm->tm_min)
| (tm->tm_sec ^ gtm->tm_sec))
return -1;
tm->tm_wday = gtm->tm_wday;
return gt;
}
/*
* Check *PT and convert it to time_t.
* If it is incompletely specified, use DEFAULT_TIME to fill it out.
* Use localtime if PT->zone is the special value TM_LOCAL_ZONE.
* Yield -1 on failure.
* ISO 8601 day-of-year and week numbers are not yet supported.
*/
static time_t
maketime(pt, default_time)
struct partime const *pt;
time_t default_time;
{
int localzone, wday;
struct tm tm;
struct tm *tm0 = 0;
time_t r;
tm0 = 0; /* Keep gcc -Wall happy. */
localzone = pt->zone==TM_LOCAL_ZONE;
tm = pt->tm;
if (TM_DEFINED(pt->ymodulus) || !TM_DEFINED(tm.tm_year)) {
/* Get tm corresponding to current time. */
tm0 = time2tm(default_time, localzone);
if (!localzone)
adjzone(tm0, pt->zone);
}
if (TM_DEFINED(pt->ymodulus))
tm.tm_year +=
(tm0->tm_year + TM_YEAR_ORIGIN)/pt->ymodulus * pt->ymodulus;
else if (!TM_DEFINED(tm.tm_year)) {
/* Set default year, month, day from current time. */
tm.tm_year = tm0->tm_year + TM_YEAR_ORIGIN;
if (!TM_DEFINED(tm.tm_mon)) {
tm.tm_mon = tm0->tm_mon;
if (!TM_DEFINED(tm.tm_mday))
tm.tm_mday = tm0->tm_mday;
}
}
/* Convert from partime year (Gregorian) to Posix year. */
tm.tm_year -= TM_YEAR_ORIGIN;
/* Set remaining default fields to be their minimum values. */
if (!TM_DEFINED(tm.tm_mon)) tm.tm_mon = 0;
if (!TM_DEFINED(tm.tm_mday)) tm.tm_mday = 1;
if (!TM_DEFINED(tm.tm_hour)) tm.tm_hour = 0;
if (!TM_DEFINED(tm.tm_min)) tm.tm_min = 0;
if (!TM_DEFINED(tm.tm_sec)) tm.tm_sec = 0;
if (!localzone)
adjzone(&tm, -pt->zone);
wday = tm.tm_wday;
/* Convert and fill in the rest of the tm. */
r = tm2time(&tm, localzone);
/* Check weekday. */
if (r != -1 && TM_DEFINED(wday) && wday != tm.tm_wday)
return -1;
return r;
}
/* Parse a free-format date in SOURCE, yielding a Unix format time. */
static time_t
str2time(char const *source, time_t default_time, long default_zone)
{
struct partime pt;
if (*partime(source, &pt))
return -1;
if (pt.zone == TM_UNDEFINED_ZONE)
pt.zone = default_zone;
return maketime(&pt, default_time);
}
time_t time(time_t *ptr)
{
time_t default_time = 0;
long default_zone = -5*60*60;
struct timeval tv;
time_t t;
char *s;
gettimeofday(&tv, 0);
default_time = tv.tv_sec;
s = getenv("FAKETIME");
if (s) {
t = str2time(s, default_time, default_zone);
if (t == -1)
t = default_time;
} else
t = default_time;
if (ptr)
*ptr = t;
return t;
}
[-- Attachment #3: Makefile --]
[-- Type: text/plain, Size: 219 bytes --]
all: faketime.so
faketime.o: faketime.c
cc -fpic -c -o faketime.o faketime.c
faketime.so: faketime.o
gcc -shared faketime.o -lc -Wl,-soname -Wl,faketime.so -o faketime.so
clean:
/bin/rm -f faketime.o faketime.so
^ permalink raw reply [flat|nested] 12+ messages in thread