What to do when size of the struct differs on 32 and 64 bit?
Vitaliy Margolen
wine-devel at kievinfo.com
Wed Aug 13 00:44:20 CDT 2008
While debugging some force-feedback issues ran into an interesting problem.
The size of one struct from include/linux differs between 32-bit and 64-bit.
That wouldn't be a major problem except that size is the part of the ioctl()
request. Which results in EINVAL.
In more details:
input.h:
#define EVIOCSFF _IOC(_IOC_WRITE, 'E', 0x80, sizeof(struct ff_effect))
The simple test program:
#include <linux/input.h>
#include <stdio.h>
int main(int argc, char * argv[])
{
printf("sizeof(struct ff_effect) = %d EVIOCSFF=%#x\n", sizeof(struct
ff_effect), EVIOCSFF);
return 0;
}
$ gcc test_size.c -o test_size && ./test_size
sizeof(struct ff_effect) = 48 EVIOCSFF=0x40304580
$ gcc -m32 test_size.c -o test_size32 && ./test_size32
sizeof(struct ff_effect) = 44 EVIOCSFF=0x402c4580
The question is what do we do about it? I'm sure there are might be more
cases like that.
Vitaliy
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