grub/grub-core/lib/datetime.c
Javier Martinez Canillas aa096037ae normal: Move common datetime functions out of the normal module
The common datetime helper functions are currently included in the normal
module, but this makes any other module that calls these functions to have
a dependency with the normal module only for this reason.

Since the normal module does a lot of stuff, it calls functions from other
modules. But since other modules may depend on it for calling the datetime
helpers, this could lead to circular dependencies between modules.

As an example, when platform == xen the grub_get_datetime() function from
the datetime module calls to the grub_unixtime2datetime() helper function
from the normal module. Which leads to the following module dependency:

    datetime -> normal

and send_dhcp_packet() from the net module calls the grub_get_datetime()
function, which leads to the following module dependency:

    net -> datetime -> normal

but that means that the normal module is not allowed to depend on net or
any other module that depends on it due the transitive dependency caused
by datetime. A recent patch attempted to add support to fetch the config
file over the network, which leads to the following circular dependency:

    normal -> net -> datetime -> normal

So having the datetime helpers in the normal module makes it quite fragile
and easy to add circular dependencies like these, that break the build due
the genmoddep.awk script catching the issues.

Fix this by taking the datetime helper functions out of the normal module
and instead add them to the datetime module itself. Besides fixing these
issues, it makes more sense to have these helper functions there anyways.

Reported-by: Daniel Kiper <daniel.kiper@oracle.com>
Signed-off-by: Javier Martinez Canillas <javierm@redhat.com>
Reviewed-by: Daniel Kiper <daniel.kiper@oracle.com>
2020-02-18 15:12:06 +01:00

109 lines
3.1 KiB
C

/* datetime.c - Module for common datetime function. */
/*
* GRUB -- GRand Unified Bootloader
* Copyright (C) 2008 Free Software Foundation, Inc.
*
* GRUB 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 3 of the License, or
* (at your option) any later version.
*
* GRUB 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 GRUB. If not, see <http://www.gnu.org/licenses/>.
*/
#include <grub/datetime.h>
#include <grub/i18n.h>
static const char *const grub_weekday_names[] =
{
N_("Sunday"),
N_("Monday"),
N_("Tuesday"),
N_("Wednesday"),
N_("Thursday"),
N_("Friday"),
N_("Saturday"),
};
int
grub_get_weekday (struct grub_datetime *datetime)
{
unsigned a, y, m;
if (datetime->month <= 2)
a = 1;
else
a = 0;
y = datetime->year - a;
m = datetime->month + 12 * a - 2;
return (datetime->day + y + y / 4 - y / 100 + y / 400 + (31 * m / 12)) % 7;
}
const char *
grub_get_weekday_name (struct grub_datetime *datetime)
{
return _ (grub_weekday_names[grub_get_weekday (datetime)]);
}
#define SECPERMIN 60
#define SECPERHOUR (60*SECPERMIN)
#define SECPERDAY (24*SECPERHOUR)
#define DAYSPERYEAR 365
#define DAYSPER4YEARS (4*DAYSPERYEAR+1)
void
grub_unixtime2datetime (grub_int32_t nix, struct grub_datetime *datetime)
{
int i;
grub_uint8_t months[12] = {31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
/* In the period of validity of unixtime all years divisible by 4
are bissextile*/
/* Convenience: let's have 3 consecutive non-bissextile years
at the beginning of the counting date. So count from 1901. */
int days_epoch;
/* Number of days since 1st Januar, 1901. */
unsigned days;
/* Seconds into current day. */
unsigned secs_in_day;
/* Transform C divisions and modulos to mathematical ones */
if (nix < 0)
days_epoch = -(((unsigned) (SECPERDAY-nix-1)) / SECPERDAY);
else
days_epoch = ((unsigned) nix) / SECPERDAY;
secs_in_day = nix - days_epoch * SECPERDAY;
days = days_epoch + 69 * DAYSPERYEAR + 17;
datetime->year = 1901 + 4 * (days / DAYSPER4YEARS);
days %= DAYSPER4YEARS;
/* On 31st December of bissextile years 365 days from the beginning
of the year elapsed but year isn't finished yet */
if (days / DAYSPERYEAR == 4)
{
datetime->year += 3;
days -= 3*DAYSPERYEAR;
}
else
{
datetime->year += days / DAYSPERYEAR;
days %= DAYSPERYEAR;
}
for (i = 0; i < 12
&& days >= (i==1 && datetime->year % 4 == 0
? 29 : months[i]); i++)
days -= (i==1 && datetime->year % 4 == 0
? 29 : months[i]);
datetime->month = i + 1;
datetime->day = 1 + days;
datetime->hour = (secs_in_day / SECPERHOUR);
secs_in_day %= SECPERHOUR;
datetime->minute = secs_in_day / SECPERMIN;
datetime->second = secs_in_day % SECPERMIN;
}