-D_FILE_OFFSET_BITS

[Russell Coker <russell@coker.com.au>]

I've just started trying to get SE Linux going on ARM.  The Makefile for one 
of the important utility programs (the program to find all the files on the 
file system and relabel them to the correct security context) uses 
-D_FILE_OFFSET_BITS=64 (it needs to stat() every file on the file system 
including those over 2G in size).

When I compile this on debussy it fails, among other problems the code wants 
to use >> operations for hashing an ino_t.

I've attached a little test program I use for creating large files with holes.  
On my x86 systems I used to be able to create large files with the attached 
program (although recently it has started giving signal 25 when I try).

On debussy my hole program refuses to create large files, but "cat /dev/zero 
>> file" will bring a file over the 2G limit without any problems.

Any tips on getting large file support portable (or on ./configure tests to do 
it right)?

Currently I'm just using -D_FILE_OFFSET_BITS=32 and it seems to work OK.

-- 
http://www.coker.com.au/selinux/   My NSA Security Enhanced Linux packages
http://www.coker.com.au/bonnie++/  Bonnie++ hard drive benchmark
http://www.coker.com.au/postal/    Postal SMTP/POP benchmark
http://www.coker.com.au/~russell/  My home page

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <linux/unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

#if ! ( defined __USE_LARGEFILE64 || defined __USE_FILE_OFFSET64 )
_syscall5 (int,  _llseek,  uint,  fd, ulong, hi, ulong, lo,
           loff_t *, res, uint, wh);
#endif

int main(int argc, char *argv[])
{
  if(!argv[1] || !argv[2])
  {
    printf("usage: hole filename size\n");
    return 1;
  }
  int fd = open(argv[1], O_RDWR | O_CREAT | O_TRUNC, S_IRUSR | S_IWUSR);
  if(fd == -1)
  {
    printf("Can't open %s\n", argv[2]);
    return 1;
  }
  long long size = atoll(argv[2]);
  printf("Seeking to %lld\n", size);
  loff_t retval;
#if defined __USE_FILE_OFFSET64
    retval = lseek(fd, size, SEEK_SET);
#elif defined __USE_LARGEFILE64
    retval = lseek64(fd, size, SEEK_SET);
#else
    loff_t result;
    unsigned long high = int(size >> 32);
    printf("high:%d\n", high);
    retval = _llseek (fd, high,
                      ((unsigned long long) size) & 0xffffffff,
                      &result, SEEK_SET);
    if(retval == 0)
      retval = result;
#endif
  if(retval != size)
  {
    printf("Can't seek to %lld\n", size);
    return 1;
  }
  char c = 'A';
  if(write(fd, (void *)&c, 1) != 1)
  {
    printf("Can't write to file.\n");
    return 1;
  }
  close(fd);
  return 0;
}