On 2018/11/14 21:46, sisyphus wrote:
> On Wed, Nov 14, 2018 at 10:20 PM Tetsuo Handa
> <penguin-ker...@i-love.sakura.ne.jp> wrote:
>
>> Even on 32bit environments (at least for Linux), lstat() calls 64bit version
>
Here is some test results on Linux.
32bits userspace on 32bits kernel:
# truncate -s 17592186044415 test
# perl -e 'use File::stat; my $sb = lstat("test"); printf("%s\n", $sb->size);'
17592186044415
# perl -e 'use File::stat; my $sb = lstat("test"); printf("%u\n", $sb->size);'
4294967295
32bits userspace on 64bits kernel:
# truncate -s 9223372036854775807 test
# perl -e 'use File::stat; my $sb = lstat("test"); printf("%s\n", $sb->size);'
9.22337203685478e+18
# perl -e 'use File::stat; my $sb = lstat("test"); printf("%u\n", $sb->size);'
4294967295
64bits userspace on 64bits kernel:
# truncate -s 9223372036854775807 test
# perl -e 'use File::stat; my $sb = lstat("test"); printf("%s\n", $sb->size);'
9223372036854775807
# perl -e 'use File::stat; my $sb = lstat("test"); printf("%u\n", $sb->size);'
9223372036854775807
> When I check on Windows, I find that the value is actually an NV (not an IV
> as I had expected).
> I expect it's the same for you, in which case it's a 53-bit double
> (unless $Config{nvsize} reports a value greater than 8).
>
> You can test for this using Devel::Peek:
>
64bits userspace on 64bits kernel:
NV is 8 bytes
SV = IV(0x1f98730) at 0x1f98740
REFCNT = 1
FLAGS = (IOK,pIOK)
IV = 9223372036854775807
32bits userspace on 64bits kernel:
NV is 8 bytes
SV = NV(0x95d7608) at 0x95b45b8
REFCNT = 1
FLAGS = (NOK,pNOK)
NV = 9.22337203685478e+18
Since accurate file size value is lost as soon as it is stored into $sb, doing
my $x = $sb->size;
$value = Math::BigInt->new("$x");
won't help. I will use "%s" without Math::BigInt.
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