1 //
2 // initcon.cpp
3 //
4 // Copyright (c) Microsoft Corporation. All rights reserved.
5 //
6 // Defines the global console output handle and the __dcrt_lowio_initialize_console_output() and
7 // __dcrt_terminate_console_output() functions, which initialize and close that handle.
8 // Also defines functions that can be used instead of the Console API to enable retry behavior
9 // in case the cached console handle is freed.
10
11 #include <corecrt_internal_lowio.h>
12
13 _CRT_LINKER_FORCE_INCLUDE(__dcrt_console_output_terminator);
14
15 // The global console output handle.
16 static HANDLE __dcrt_lowio_console_output_handle = _console_uninitialized_handle;
17
18 // Initializes the global console output handle
__dcrt_lowio_initialize_console_output()19 static void __dcrt_lowio_initialize_console_output()
20 {
21 __dcrt_lowio_console_output_handle = CreateFileW(
22 L"CONOUT$",
23 GENERIC_WRITE,
24 FILE_SHARE_READ | FILE_SHARE_WRITE,
25 nullptr,
26 OPEN_EXISTING,
27 0,
28 nullptr);
29 }
30
__dcrt_lowio_ensure_console_output_initialized()31 extern "C" BOOL __cdecl __dcrt_lowio_ensure_console_output_initialized()
32 {
33 if (__dcrt_lowio_console_output_handle == _console_uninitialized_handle)
34 {
35 __dcrt_lowio_initialize_console_output();
36 }
37
38 if (__dcrt_lowio_console_output_handle == _console_invalid_handle)
39 {
40 return FALSE;
41 }
42 return TRUE;
43 }
44
45 // Closes the global console output handle
__dcrt_terminate_console_output()46 extern "C" void __cdecl __dcrt_terminate_console_output()
47 {
48 if ( __dcrt_lowio_console_output_handle != _console_invalid_handle
49 && __dcrt_lowio_console_output_handle != _console_uninitialized_handle)
50 {
51 CloseHandle(__dcrt_lowio_console_output_handle);
52 }
53 }
54
55 template <typename Func>
console_output_reopen_and_retry(Func const & fp)56 static BOOL console_output_reopen_and_retry(Func const& fp) throw()
57 {
58 BOOL result = fp();
59 if (!result && GetLastError() == ERROR_INVALID_HANDLE) {
60 __dcrt_terminate_console_output();
61 __dcrt_lowio_initialize_console_output();
62 result = fp();
63 }
64 return result;
65 }
66
__dcrt_write_console(_In_ void const * lpBuffer,_In_ DWORD nNumberOfCharsToWrite,_Out_ LPDWORD lpNumberOfCharsWritten)67 extern "C" BOOL __cdecl __dcrt_write_console(
68 _In_ void const * lpBuffer,
69 _In_ DWORD nNumberOfCharsToWrite,
70 _Out_ LPDWORD lpNumberOfCharsWritten
71 )
72 {
73 return console_output_reopen_and_retry(
74 [lpBuffer, nNumberOfCharsToWrite, lpNumberOfCharsWritten]()
75 {
76 return ::WriteConsoleW(
77 __dcrt_lowio_console_output_handle,
78 lpBuffer,
79 nNumberOfCharsToWrite,
80 lpNumberOfCharsWritten,
81 nullptr);
82 });
83 }
84