In this case, it's what's returned by CreateFile.

With MS's C libary, you can use _get_osfhandle to return what you need from a C/unix file descriptor (returned by fileno). I don't know what other C libraries provide, if anything.

Thanks ikegami, after add _get_osfhandle function, I can get the addr mapping. Before I copy the contents of the address point to to a new SV, Is there a easy way to print the content of the address by perl directly?

use strict;
use warnings;
use Fcntl;
use Inline C => Config => LIBS => '-lkernel32', BUILD_NOISY => 1, type
+maps => 'typemap';
use Inline C => <<'END_OF_C_CODE';

#include <windows.h>
#include <winbase.h>
#include <io.h>
HANDLE get_handle(int fileno){
return _get_osfhandle(fileno);
}
void*
map_region(int filehandle, DWORD size, DWORD prot){
    HANDLE hMap = CreateFileMapping((HANDLE)filehandle, NULL, prot, 0,
+ size, NULL);
    LPVOID addr = MapViewOfFile(hMap, FILE_MAP_ALL_ACCESS, 0, 0, size)
+;
    CloseHandle(hMap);
    return addr;
}
int
unmap_region(void* addr, DWORD size){
    return UnmapViewOfFile(addr);
}
END_OF_C_CODE
my $test_file = 'test_mmap.bin';

sysopen(my $fh, $test_file, O_RDWR|O_CREAT|O_TRUNC)
  or die "can't open: $!";
binmode $fh;
my $size = 4096;
my $addr = map_region(get_handle(fileno($fh)), $size, 0x04)
  or die "mmap failed!!:  $^E ";

my $test_str = "Hello Windows mmap!";
syswrite($fh, $test_str);
print $addr;  #How print the contents without XS? 

unmap_region($addr, $size) or die "fail to unmap";

sysseek($fh, 0, 0);
my $buf;
sysread($fh, $buf, length($test_str));
print "validate: ", ($buf eq $test_str ? "success" : "failed"), "\n";

close $fh;
unlink $test_file;
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The fileno() return value is a C file descriptor value and the HANDLE is, as ikegami stated, what CreateFile() returns. CreateFile() is a Windows system function. You're mixing two different APIs. Instead of using CreateFileMapping() maybe you could try using mmap().

There's already a File::Map on CPAN which says that it works on both Windows and *NIX which may be of use unless you're reimplementing for pedagogical intent.

And it's used by PDL::IO::FastRaw to have memory-mapped scientific data.

Sorry for OT'ing your post, but I thought an example of mmap on *nix, tested in Linux, could be useful for those lucky linux users:

use strict;
use warnings;
use Fcntl;
use Inline C => Config => LIBS => '', BUILD_NOISY => 1;
use Inline C => <<'END_OF_C_CODE';

#include <sys/mman.h>
#include <stdio.h>
#include <errno.h>

int unmap_region(void *m, int sz){
    if( munmap(m, sz) != 0 ){
        fprintf(stderr, "unmap_region() : error, call to munmap() has 
+failed for memory address %p and size %ld : %s\n", m, sz, strerror(er
+rno));
        return 0; // failed
    }
    return 1; // success
}
void *map_region(int fd, int sz){
        char *map = (char *)mmap(NULL, sz, PROT_READ|PROT_WRITE, MAP_F
+ILE|MAP_SHARED, fd, 0);
        if (map == MAP_FAILED){
        fprintf(stderr, "map has failed for size %ld : %s\n", sz, stre
+rror(errno));
        return (void *)NULL; // failed
    }
    return map; // success
}
END_OF_C_CODE

my $test_file = 'test_mmap.bin';

sysopen(my $fh, $test_file, O_RDWR|O_CREAT|O_TRUNC)
  or die "can't open file '$test_file' : $!";
binmode $fh;
my $size = 4096;
my $addr = map_region(fileno($fh), $size)
  or die "mmap failed!!:  $^E ";

my $test_str = "Hello Linux mmap!";
syswrite($fh, $test_str);

unmap_region($addr, $size) or die "fail to unmap";

close($fh);

open($fh, '<', $test_file) or die "failed to open file '$test_file'/2,
+ $!";
my $contents;
{ local $/ = undef; $contents = <$fh> } close $fh;
print "Sucess, contents of the mmap'ed file '$test_file':\n${contents}
+\n--end contents.\n";
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