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amiga-ixemul/utils/ixtimezone.c

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/*
* Written by Hans Verkuil (hans@wyst.hobby.nl)
*
* battclock.resource patch idea was shamelessly stolen from the unixclock
* utility written by Geert Uytterhoeven. unixclock is available on Aminet.
*/
#include <stdlib.h>
#include <stdio.h>
#include <time.h>
#include <ixemul.h>
#include <exec/memory.h>
#include <clib/exec_protos.h>
#include <dos/var.h>
#include <sys/time.h>
#include <proto/exec.h>
#include <proto/dos.h>
#include <proto/battclock.h>
#define LVOReadBattClock (-12)
#define LVOWriteBattClock (-18)
#ifdef __MORPHOS__
#define NewReadBattClock _NewReadBattClock
#define NewWriteBattClock _NewWriteBattClock
#define OldReadBattClock _OldReadBattClock
#define OldWriteBattClock _OldWriteBattClock
#define EndOfPatch _EndOfPatch
#define GMTOffset _GMTOffset
#endif
/* Flags. Currently only bit 0 is used to tell whether Daylight Saving Time
is in effect or not. However, ixtimezone only sets this flag, but it doesn't
test it. And neither does ixemul.library. In fact, the library completely
ignores the flag field. */
#define DST_ON 0x01
typedef struct
{
long offset;
unsigned char flags;
} ixtime;
struct Node *BattClockBase;
char VERSION[] = "\000$VER: ixtimezone 1.0 (10.11.95)";
/* battclock.resource patch code */
asm("
.text
.globl _NewReadBattClock
.globl _NewWriteBattClock
.globl _OldReadBattClock
.globl _OldWriteBattClock
.globl _GMTOffset
.globl _EndOfPatch
_NewReadBattClock:
.int 0x207a0014, 0x4e9090ba, 0x00164e75
/* Since the GNU assembler is currently unable to properly compile
PC-relative code, I'm using the hex-code directly. As soon as the
assembler can handle PC-relative code, the line above should be
replaced by:
move.l _OldReadBattClock(pc),a0
jsr (a0)
sub.l _GMTOffset(pc),d0
rts
*/
_NewWriteBattClock:
.int 0xd0ba0010, 0x207a0008
.short 0x4ed0
/* Since the GNU assembler is currently unable to properly compile
PC-relative code, I'm using the hex-code directly. As soon as the
assembler can handle PC-relative code, the line above should be
replaced by:
add.l _GMTOffset(pc),d0
move.l _OldWriteBattClock(pc),a0
jmp (a0)
*/
_OldReadBattClock:
.int 0
_OldWriteBattClock:
.int 0
_GMTOffset:
.int 0
_EndOfPatch:
");
extern char NewReadBattClock;
extern char NewWriteBattClock;
extern char OldReadBattClock;
extern char OldWriteBattClock;
extern long GMTOffset;
extern long EndOfPatch;
static ixtime *read_ixtime(void)
{
static ixtime t;
char buf[10];
/*
* Read the GMT offset. This environment variable is 5 bytes long. The
* first 4 form a long that contains the offset in seconds and the fifth
* byte contains flags.
*/
if (GetVar("IXGMTOFFSET", buf, 6, GVF_BINARY_VAR) == 5 && IoErr() == 5)
{
memcpy(&t.offset, buf, 4);
t.flags = buf[4];
return &t;
}
return NULL;
}
static void create_ixtime(ixtime *t, char *pathname)
{
FILE *f = fopen(pathname, "w");
if (f)
{
fwrite(t, 5, 1, f);
fclose(f);
}
}
static void write_ixtime(ixtime *t, int write_also_to_envarc)
{
ix_set_gmt_offset(t->offset);
create_ixtime(t, "/ENV/IXGMTOFFSET");
if (write_also_to_envarc)
create_ixtime(t, "/ENVARC/IXGMTOFFSET");
}
static void set_clock(long offset)
{
struct timeval tv;
gettimeofday(&tv, NULL);
tv.tv_sec += offset;
settimeofday(&tv, NULL);
}
static void reset_clock(void)
{
struct timeval tv;
tv.tv_usec = 0;
tv.tv_sec = ReadBattClock();
tv.tv_sec += (8*365+2) * 24 * 3600 + ix_get_gmt_offset();
settimeofday(&tv, NULL);
}
static long *get_function_addr(void)
{
return *((long **)((char *)BattClockBase + LVOReadBattClock + 2));
}
static void patch_batt_resource(long offset)
{
char *mem;
long size = (long)&EndOfPatch - (long)&NewReadBattClock;
long mem_offset;
long *oldread, *oldwrite, *gmt;
BattClockBase = (struct Node *)OpenResource("battclock.resource");
if (*(gmt = get_function_addr()) == 0x207a0014)
{
printf("battclock.resource was already patched.\n");
gmt = (long *)(((char *)&GMTOffset) + (long)((char *)gmt - &NewReadBattClock));
if (*gmt != offset)
{
*gmt = offset;
reset_clock();
}
return; /* already patched */
}
GMTOffset = offset;
mem = AllocMem(size, MEMF_PUBLIC);
mem_offset = mem - &NewReadBattClock;
memcpy(mem, &NewReadBattClock, size);
CacheClearE(mem, size, CACRF_ClearI); /* clear instruction cache */
oldread = (long *)(&OldReadBattClock + mem_offset);
oldwrite = (long *)(&OldWriteBattClock + mem_offset);
Disable();
*oldread = (long)SetFunction((struct Library *)BattClockBase, LVOReadBattClock, (void *)(&NewReadBattClock + mem_offset));
*oldwrite = (long)SetFunction((struct Library *)BattClockBase, LVOWriteBattClock, (void *)(&NewWriteBattClock + mem_offset));
Enable();
reset_clock();
printf("patched battclock.resource.\n");
}
static void remove_patch(void)
{
long *p, mem_offset, *oldread, *oldwrite;
long size = (long)&EndOfPatch - (long)&NewReadBattClock;
BattClockBase = (struct Node *)OpenResource("battclock.resource");
if (*(p = get_function_addr()) != 0x207a0014)
{
printf("battclock.resource wasn't patched.\n");
exit(0); /* not patched */
}
mem_offset = (char *)p - &NewReadBattClock;
oldread = (long *)(&OldReadBattClock + mem_offset);
oldwrite = (long *)(&OldWriteBattClock + mem_offset);
Disable();
SetFunction((struct Library *)BattClockBase, LVOReadBattClock, (void *)*oldread);
SetFunction((struct Library *)BattClockBase, LVOWriteBattClock, (void *)*oldwrite);
Enable();
FreeMem(p, size);
reset_clock();
printf("removed battclock.resource patch.\n");
exit(0);
}
static void test(void)
{
time_t t;
time(&t);
printf("GMT: %s", asctime(gmtime(&t)));
printf("Local: %s", asctime(localtime(&t)));
exit(0);
}
static void usage(void)
{
fprintf(stderr, "Usage: ixtimezone <option>
Where <option> is one of:
-test Show GMT and localtime
-get-offset Get GMT offset and patch ixemul.library
-check-dst As -get-offset, but also automatically adjust the Amiga
time if Daylight Saving Time has gone in effect (or vice
versa)
-patch-resource As -get-offset, but also patch the battclock.resource
-remove-patch Remove the battclock.resource patch\n");
exit(1);
}
int main(int argc, char **argv)
{
struct tm *local_tm, *gmt_tm;
int local_hms, gmt_hms;
time_t t, local_t, gmt_t;
ixtime *old, new;
int set_the_clock = 0, patch_resource = 0;
int write_to_envarc = 0;
if (argc != 2)
usage();
if (!strcmp(argv[1], "-test"))
test();
else if (!strcmp(argv[1], "-check-dst"))
set_the_clock = 1;
else if (!strcmp(argv[1], "-patch-resource"))
patch_resource = 1;
else if (!strcmp(argv[1], "-remove-patch"))
remove_patch();
else if (strcmp(argv[1], "-get-offset"))
usage();
/*
* Get current time, both GMT and local.
* We don't care if these values are correct or not, we are only interested
* in the difference between the two.
*/
time(&t);
gmt_tm = gmtime(&t);
gmt_hms = gmt_tm->tm_hour * 3600 + gmt_tm->tm_min * 60 + gmt_tm->tm_sec;
local_tm = localtime(&t);
local_hms = local_tm->tm_hour * 3600 + local_tm->tm_min * 60 + local_tm->tm_sec;
new.flags = (local_tm->tm_isdst ? DST_ON : 0);
new.offset = 0;
if (gmt_hms != local_hms)
{
/* They are not the same. So compute the difference between them */
local_tm->tm_isdst = 0; /* don't let these values influence the result! */
local_tm->tm_zone = NULL;
local_tm->tm_gmtoff = 0;
local_t = mktime(local_tm);
gmt_tm = gmtime(&t);
gmt_tm->tm_isdst = 0;
gmt_tm->tm_zone = NULL;
gmt_tm->tm_gmtoff = 0;
gmt_t = mktime(gmt_tm);
new.offset = gmt_t - local_t; /* obtain the difference */
}
old = read_ixtime();
if (old == NULL || old->offset != new.offset)
{
write_to_envarc = 1;
if (set_the_clock && old)
set_clock(old->offset - new.offset);
}
write_ixtime(&new, write_to_envarc);
if (patch_resource)
patch_batt_resource(new.offset);
return 0;
}
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