Subversion Repositories planix.SVN

#include <u.h>
#include <libc.h>

#define TZSIZE  150
static  void    readtimezone(void);
static  int     rd_name(char**, char*);
static  int     rd_long(char**, long*);
static
struct
{
        char    stname[4];
        char    dlname[4];
        long    stdiff;
        long    dldiff;
        long    dlpairs[TZSIZE];
} timezone;

#define SEC2MIN 60L
#define SEC2HOUR (60L*SEC2MIN)
#define SEC2DAY (24L*SEC2HOUR)

/*
 *  days per month plus days/year
 */
static  int     dmsize[] =
{
        365, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
};
static  int     ldmsize[] =
{
        366, 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31
};

/*
 *  return the days/month for the given year
 */
static int *
yrsize(int y)
{
        if((y%4) == 0 && ((y%100) != 0 || (y%400) == 0))
                return ldmsize;
        else
                return dmsize;
}

/*
 * compute seconds since Jan 1 1970 GMT
 * and convert to our timezone.
 */
long
tm2sec(Tm *tm)
{
        long secs;
        int i, yday, year, *d2m;

        if(strcmp(tm->zone, "GMT") != 0 && timezone.stname[0] == 0)
                readtimezone();
        secs = 0;

        /*
         *  seconds per year
         */
        year = tm->year + 1900;
        for(i = 1970; i < year; i++){
                d2m = yrsize(i);
                secs += d2m[0] * SEC2DAY;
        }

        /*
         *  if mday is set, use mon and mday to compute yday
         */
        if(tm->mday){
                yday = 0;
                d2m = yrsize(year);
                for(i=0; i<tm->mon; i++)
                        yday += d2m[i+1];
                yday += tm->mday-1;
        }else{
                yday = tm->yday;
        }
        secs += yday * SEC2DAY;

        /*
         * hours, minutes, seconds
         */
        secs += tm->hour * SEC2HOUR;
        secs += tm->min * SEC2MIN;
        secs += tm->sec;

        /*
         * Only handles zones mentioned in /env/timezone,
         * but things get too ambiguous otherwise.
         */
        if(strcmp(tm->zone, timezone.stname) == 0)
                secs -= timezone.stdiff;
        else if(strcmp(tm->zone, timezone.dlname) == 0)
                secs -= timezone.dldiff;
        if(secs < 0)
                secs = 0;
        return secs;
}

static
void
readtimezone(void)
{
        char buf[TZSIZE*11+30], *p;
        int i;

        memset(buf, 0, sizeof(buf));
        i = open("/env/timezone", 0);
        if(i < 0)
                goto error;
        if(read(i, buf, sizeof(buf)) >= sizeof(buf))
                goto error;
        close(i);
        p = buf;
        if(rd_name(&p, timezone.stname))
                goto error;
        if(rd_long(&p, &timezone.stdiff))
                goto error;
        if(rd_name(&p, timezone.dlname))
                goto error;
        if(rd_long(&p, &timezone.dldiff))
                goto error;
        for(i=0; i<TZSIZE; i++) {
                if(rd_long(&p, &timezone.dlpairs[i]))
                        goto error;
                if(timezone.dlpairs[i] == 0)
                        return;
        }

error:
        timezone.stdiff = 0;
        strcpy(timezone.stname, "GMT");
        timezone.dlpairs[0] = 0;
}

static int
rd_name(char **f, char *p)
{
        int c, i;

        for(;;) {
                c = *(*f)++;
                if(c != ' ' && c != '\n')
                        break;
        }
        for(i=0; i<3; i++) {
                if(c == ' ' || c == '\n')
                        return 1;
                *p++ = c;
                c = *(*f)++;
        }
        if(c != ' ' && c != '\n')
                return 1;
        *p = 0;
        return 0;
}

static int
rd_long(char **f, long *p)
{
        int c, s;
        long l;

        s = 0;
        for(;;) {
                c = *(*f)++;
                if(c == '-') {
                        s++;
                        continue;
                }
                if(c != ' ' && c != '\n')
                        break;
        }
        if(c == 0) {
                *p = 0;
                return 0;
        }
        l = 0;
        for(;;) {
                if(c == ' ' || c == '\n')
                        break;
                if(c < '0' || c > '9')
                        return 1;
                l = l*10 + c-'0';
                c = *(*f)++;
        }
        if(s)
                l = -l;
        *p = l;
        return 0;
}