GHC 6.4/mingw32: files larger than 4 GB andhFileSize/hSetFileSize/c_stat

Bulat Ziganshin bulatz at
Tue Apr 12 10:21:54 EDT 2005

Hello Simon,

mingw32 have 32-bit off_t type; access to large files are supported
with special functions and structures defined in msvcrrt.dll:

_CRTIMP __int64 __cdecl _lseeki64(int, __int64, int);
_CRTIMP __int64 __cdecl _telli64(int);
_CRTIMP int __cdecl  _fstati64(int, struct _stati64 *);
_CRTIMP int __cdecl  _stati64(const char *, struct _stati64 *);
struct _stati64 {
    __int64 st_size;

so, we need either
1) define COff to __int64 instead of off_t and rewrite existing
functions to work with 64 bit filesizes
2) define new set of low-level functions to work with 64 bit
filesizes. define high-level functions in terms of these 64-bit
functions on Win32

what solution will be better? in the first case COff no longer will be
equal to off_t, what some applications can imply. in the second case
we will add a lot of duplicating code

is there any other (GHC-supported) environments supporting 64 bit
filesizes, but having only 32-bit off_t?

(sorry for my bad English, i'm too far from native speaker)

Friday, April 08, 2005, 3:33:36 PM, you wrote:

SPJ> By all means.  If someone cares to send us a patch, we'll incorporate
SPJ> it.

SPJ> | While GHC I/O library on mingw32 platform perfectly reads and writes
SPJ> | files larger than 4 GB, functions hFileSize/c_fstat,
SPJ> | hSetFileSize/c_ftruncate and c_stat are still tied to C functions
SPJ> | returning 32 bit values and as a result truncate larger sizes to their
SPJ> | low 32 bits. Can this behaviour be fixed in the next bug-fix version?

Best regards,
 Bulat                            mailto:bulatz at

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