GopherProxy

	zoneinfo.c - 9base - revived minimalist port of Plan 9 userland to Unix
	git clone git://git.suckless.org/9base
	Log
	Files
	Refs
	README
	LICENSE
	---
	zoneinfo.c (3092B)
	---
	1 #include <u.h>
	2 #include <libc.h>
	3
	4 /*
	5 * Access local time entries of zoneinfo files.
	6 * Formats 0 and 2 are supported, and 4-byte timestamps
	7 *
	8 * Copyright © 2008 M. Teichgräber
	9 * Contributed under the terms of the Lucent Public License 1.02.
	10 */
	11 #include "zoneinfo.h"
	12
	13 static
	14 struct Zoneinfo
	15 {
	16 int timecnt; /* # of transition times */
	17 int typecnt; /* # of local time types */
	18 int charcnt; /* # of characters of time zo…
	19
	20 uchar *ptime;
	21 uchar *ptype;
	22 uchar *ptt;
	23 uchar *pzone;
	24 } z;
	25
	26 static uchar *tzdata;
	27
	28 static
	29 uchar*
	30 readtzfile(char *file)
	31 {
	32 uchar *p;
	33 int fd;
	34 Dir *d;
	35
	36 fd = open(file, OREAD);
	37 if (fd<0)
	38 return nil;
	39 d = dirfstat(fd);
	40 if (d==nil)
	41 return nil;
	42 p = malloc(d->length);
	43 if (p!=nil)
	44 readn(fd, p, d->length);
	45 free(d);
	46 close(fd);
	47 return p;
	48 }
	49 static char *zonefile;
	50 void
	51 tzfile(char *f)
	52 {
	53 if (tzdata!=nil) {
	54 free(tzdata);
	55 tzdata = nil;
	56 }
	57 z.timecnt = 0;
	58 zonefile = f;
	59 }
	60
	61 static
	62 long
	63 get4(uchar *p)
	64 {
	65 return (p[0]<<24)+(p[1]<<16)+(p[2]<<8)+p[3];
	66 }
	67
	68 enum {
	69 TTinfosz = 4+1+1,
	70 };
	71
	72 static
	73 int
	74 parsehead(void)
	75 {
	76 uchar *p;
	77 int ver;
	78
	79 ver = tzdata[4];
	80 if (ver!=0)
	81 if (ver!='2')
	82 return -1;
	83
	84 p = tzdata + 4 + 1 + 15;
	85
	86 z.timecnt = get4(p+3*4);
	87 z.typecnt = get4(p+4*4);
	88 if (z.typecnt==0)
	89 return -1;
	90 z.charcnt = get4(p+5*4);
	91 z.ptime = p+6*4;
	92 z.ptype = z.ptime + z.timecnt*4;
	93 z.ptt = z.ptype + z.timecnt;
	94 z.pzone = z.ptt + z.typecnt*TTinfosz;
	95 return 0;
	96 }
	97
	98 static
	99 void
	100 ttinfo(Tinfo *ti, int tti)
	101 {
	102 uchar *p;
	103 int i;
	104
	105 i = z.ptype[tti];
	106 assert(i<z.typecnt);
	107 p = z.ptt + i*TTinfosz;
	108 ti->tzoff = get4(p);
	109 ti->dlflag = p[4];
	110 assert(p[5]<z.charcnt);
	111 ti->zone = (char*)z.pzone + p[5];
	112 }
	113
	114 static
	115 void
	116 readtimezone(void)
	117 {
	118 char *tmp;
	119
	120 z.timecnt = 0;
	121 switch (zonefile==nil) {
	122 default:
	123 if ((tmp=getenv("timezone"))!=nil) {
	124 tzdata = readtzfile(tmp);
	125 free(tmp);
	126 break;
	127 }
	128 zonefile = "/etc/localtime";
	129 /* fall through */
	130 case 0:
	131 tzdata = readtzfile(zonefile);
	132 }
	133 if (tzdata==nil)
	134 return;
	135
	136 if (strncmp("TZif", (char*)tzdata, 4)!=0)
	137 goto errfree;
	138
	139 if (parsehead()==-1) {
	140 errfree:
	141 free(tzdata);
	142 tzdata = nil;
	143 z.timecnt = 0;
	144 return;
	145 }
	146 }
	147
	148 static
	149 tlong
	150 gett4(uchar *p)
	151 {
	152 long l;
	153
	154 l = get4(p);
	155 if (l<0)
	156 return 0;
	157 return l;
	158 }
	159 int
	160 zonetinfo(Tinfo *ti, int i)
	161 {
	162 if (tzdata==nil)
	163 readtimezone();
	164 if (i<0 \|\| i>=z.timecnt)
	165 return -1;
	166 ti->t = gett4(z.ptime + 4*i);
	167 ttinfo(ti, i);
	168 return i;
	169 }
	170
	171 int
	172 zonelookuptinfo(Tinfo *ti, tlong t)
	173 {
	174 uchar *p;
	175 int i;
	176 tlong oldtt, tt;
	177
	178 if (tzdata==nil)
	179 readtimezone();
	180 oldtt = 0;
	181 p = z.ptime;
	182 for (i=0; i<z.timecnt; i++) {
	183 tt = gett4(p);
	184 if (t<tt)
	185 break;
	186 oldtt = tt;
	187 p += 4;
	188 }
	189 if (i>0) {
	190 ttinfo(ti, i-1);
	191 ti->t = oldtt;
	192 // fprint(2, "t:%ld off:%d dflag:%d %s\n", (long)ti->t, t…
	193 return i-1;
	194 }
	195 return -1;
	196 }
	197
	198 void
	199 zonedump(int fd)
	200 {
	201 int i;
	202 uchar *p;
	203 tlong t;
	204 Tinfo ti;
	205
	206 if (tzdata==nil)
	207 readtimezone();
	208 p = z.ptime;
	209 for (i=0; i<z.timecnt; i++) {
	210 t = gett4(p);
	211 ttinfo(&ti, i);
	212 fprint(fd, "%ld\t%d\t%d\t%s\n", (long)t, ti.tzoff, ti.dl…
	213 p += 4;
	214 }
	215 }