newlib-cygwin/winsup/mingw/mingwex/mingw-fseek.c

107 lines
3.1 KiB
C

/*
* Workaround for limitations on win9x where a file contents are
* not zero'd out if you seek past the end and then write.
* Copied from ming local-patch to binutils/bfd/libbfd.c written by
* Mumit Khan <khan@xraylith.wisc.edu>
*/
#include <windows.h>
#include <stdio.h>
#include <io.h>
#include <stdlib.h>
#define ZEROBLOCKSIZE 512
static int __mingw_fseek_called;
/* The fseek in Win9x runtime does not zero out the file if seeking past
the end; if you don't want random stuff from your disk included in your
output DLL/executable, use this version instead. On WinNT/Win2k, it
just calls runtime fseek().
CHECK/FIXME: Does this work for both text and binary modes?? */
int
__mingw_fseek (FILE *fp, long offset, int whence)
{
# undef fseek
__mingw_fseek_called = 1;
return fseek (fp, offset, whence);
}
int
__mingw_fseeko64 (FILE *fp, off64_t offset, int whence)
{
# undef fseeko64
__mingw_fseek_called = 1;
return fseeko64 (fp, offset, whence);
}
int
__mingw_fwrite (const void *buffer, size_t size, size_t count, FILE *fp)
{
# undef fwrite
if ((_osver & 0x8000) && __mingw_fseek_called)
{
ULARGE_INTEGER actual_length;
LARGE_INTEGER current_position = {{0LL}};
__mingw_fseek_called = 0;
fflush (fp);
actual_length.LowPart = GetFileSize ((HANDLE) _get_osfhandle (fileno (fp)),
&actual_length.HighPart);
if (actual_length.LowPart == 0xFFFFFFFF
&& GetLastError() != NO_ERROR )
return -1;
current_position.LowPart = SetFilePointer ((HANDLE) _get_osfhandle (fileno (fp)),
current_position.LowPart,
&current_position.HighPart,
FILE_CURRENT);
if (current_position.LowPart == 0xFFFFFFFF
&& GetLastError() != NO_ERROR )
return -1;
#ifdef DEBUG
printf ("__mingw_fwrite: current %I64u, actual %I64u\n",
current_position.QuadPart, actual_length.QuadPart);
#endif /* DEBUG */
if (current_position.QuadPart > actual_length.QuadPart)
{
static char __mingw_zeros[ZEROBLOCKSIZE];
long long numleft;
SetFilePointer ((HANDLE) _get_osfhandle (fileno (fp)),
0, 0, FILE_END);
numleft = current_position.QuadPart - actual_length.QuadPart;
#ifdef DEBUG
printf ("__mingw_fwrite: Seeking %I64d bytes past end\n", numleft);
#endif /* DEBUG */
while (numleft > 0LL)
{
DWORD nzeros = (numleft > ZEROBLOCKSIZE)
? ZEROBLOCKSIZE : numleft;
DWORD written;
if (! WriteFile ((HANDLE) _get_osfhandle (fileno (fp)),
__mingw_zeros, nzeros, &written, NULL))
{
/* Best we can hope for, or at least DJ says so. */
SetFilePointer ((HANDLE) _get_osfhandle (fileno (fp)),
0, 0, FILE_BEGIN);
return -1;
}
if (written < nzeros)
{
/* Likewise. */
SetFilePointer ((HANDLE) _get_osfhandle (fileno (fp)),
0, 0, FILE_BEGIN);
return -1;
}
numleft -= written;
}
FlushFileBuffers ((HANDLE) _get_osfhandle (fileno (fp)));
}
}
return fwrite (buffer, size, count, fp);
}