huwcampbell.com
Reactos
1//
2// eof.cpp
3//
4// Copyright (c) Microsoft Corporation. All rights reserved.
5//
6// Defines _eof(), which tests whether a file is at EOF.
7//
8#include <corecrt_internal_lowio.h>
9
10
11
12// Tests if a file is at EOF. Returns:
13// * 1 if at EOF
14// * 0 if not at EOF
15// * -1 on failure (errno is set)
16extern "C" int __cdecl _eof(int const fh)
17{
18 _CHECK_FH_CLEAR_OSSERR_RETURN(fh, EBADF, -1);
19 _VALIDATE_CLEAR_OSSERR_RETURN((fh >= 0 && (unsigned)fh < (unsigned)_nhandle), EBADF, -1);
20 _VALIDATE_CLEAR_OSSERR_RETURN((_osfile(fh) & FOPEN), EBADF, -1);
21
22 return __acrt_lowio_lock_fh_and_call(fh, [&]()
23 {
24 if ((_osfile(fh) & FOPEN) == 0)
25 {
26 errno = EBADF;
27 _doserrno = 0;
28 _ASSERTE(("Invalid file descriptor. File possibly closed by a different thread",0));
29 return -1;
30 }
31
32 __int64 const here = _lseeki64_nolock(fh, 0ll, SEEK_CUR);
33 if (here == -1ll)
34 return -1;
35
36
37 __int64 const end = _lseeki64_nolock(fh, 0ll, SEEK_END);
38 if (end == -1ll)
39 return -1;
40
41 // Now we can test if we're at the end:
42 if (here == end)
43 return 1;
44
45 // If we aren't at the end, we need to reset the stream to its original
46 // state before we return:
47 _lseeki64_nolock(fh, here, SEEK_SET);
48 return 0;
49 });
50}