1 //
2 // close.cpp
3 //
4 // Copyright (c) Microsoft Corporation. All rights reserved.
5 //
6 // Defines _close(), which closes a file.
7 //
8 #include <corecrt_internal_lowio.h>
9 #include <corecrt_internal_ptd_propagation.h>
10
11
12
13 // Closes the underlying OS file handle, if and only if nt needs to be closed.
14 // Returns 0 on success; returns the OS error on failure.
close_os_handle_nolock(int const fh)15 static DWORD close_os_handle_nolock(int const fh) throw()
16 {
17 // If the underlying handle is INVALID_HANDLE_VALUE, don't try to acutally
18 // close it:
19 if (_get_osfhandle(fh) == (intptr_t)INVALID_HANDLE_VALUE)
20 {
21 return 0;
22 }
23
24 // If the file handle is stdout or stderr, and if stdout and stderr are
25 // mapped to the same OS file handle, skip the CloseHandle without error.
26 //
27 // stdout and stderr are the only handles for which this support is
28 // provided. Other handles may be mapped to the same OS file handle only
29 // at the programmer's risk.
30 bool is_other_std_handle_open =
31 fh == 1 && (_osfile(2) & FOPEN) ||
32 fh == 2 && (_osfile(1) & FOPEN);
33
34 if (is_other_std_handle_open && _get_osfhandle(1) == _get_osfhandle(2))
35 {
36 return 0;
37 }
38
39 // Otherwise, we can go ahead and close the handle:
40 if (CloseHandle(reinterpret_cast<HANDLE>(_get_osfhandle(fh))))
41 {
42 return 0;
43 }
44
45 return GetLastError();
46 }
47
48
49
50 // Closes the file associated with the given file handle. On success, returns 0.
51 // On failure, returns -1 and sets errno.
_close_internal(int const fh,__crt_cached_ptd_host & ptd)52 extern "C" int __cdecl _close_internal(int const fh, __crt_cached_ptd_host& ptd)
53 {
54 _UCRT_CHECK_FH_CLEAR_OSSERR_RETURN(ptd, fh, EBADF, -1);
55 _UCRT_VALIDATE_CLEAR_OSSERR_RETURN(ptd, (fh >= 0 && (unsigned)fh < (unsigned)_nhandle), EBADF, -1);
56 _UCRT_VALIDATE_CLEAR_OSSERR_RETURN(ptd, (_osfile(fh) & FOPEN), EBADF, -1);
57
58 return __acrt_lowio_lock_fh_and_call(fh, [&]()
59 {
60 if (_osfile(fh) & FOPEN)
61 {
62 return _close_nolock_internal(fh, ptd);
63 }
64 else
65 {
66 ptd.get_errno().set(EBADF);
67 _ASSERTE(("Invalid file descriptor. File possibly closed by a different thread",0));
68 return -1;
69 }
70 });
71 }
72
_close(int const fh)73 extern "C" int __cdecl _close(int const fh)
74 {
75 __crt_cached_ptd_host ptd;
76 return _close_internal(fh, ptd);
77 }
78
79
80
_close_nolock_internal(int const fh,__crt_cached_ptd_host & ptd)81 extern "C" int __cdecl _close_nolock_internal(int const fh, __crt_cached_ptd_host& ptd)
82 {
83 DWORD const close_os_handle_error = close_os_handle_nolock(fh);
84
85 _free_osfhnd(fh);
86 _osfile(fh) = 0;
87
88 if (close_os_handle_error != 0)
89 {
90 __acrt_errno_map_os_error_ptd(close_os_handle_error, ptd);
91 return -1;
92 }
93
94 return 0;
95 }
96
_close_nolock(int const fh)97 extern "C" int __cdecl _close_nolock(int const fh)
98 {
99 __crt_cached_ptd_host ptd;
100 return _close_nolock_internal(fh, ptd);
101 }
102