win32-console-wrapper.c

/*
 * conredir, a hack to get working console IO with Windows GUI applications
 *
 * Copyright (c) 2013, Martin Herkt
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <stdio.h>
#include <windows.h>

// copied from osdep/io.h since this file is standalone
#define MP_PATH_MAX (32000)

int wmain(int argc, wchar_t **argv, wchar_t **envp);

static void cr_perror(void)
{
    LPWSTR error = NULL;
    DWORD len = FormatMessageW(FORMAT_MESSAGE_ALLOCATE_BUFFER |
                               FORMAT_MESSAGE_FROM_SYSTEM |
                               FORMAT_MESSAGE_IGNORE_INSERTS,
                               NULL, GetLastError(),
                               LANG_USER_DEFAULT,
                               (LPWSTR)&error, 0, NULL);

    HANDLE out = GetStdHandle(STD_ERROR_HANDLE);
    if (out != INVALID_HANDLE_VALUE && GetConsoleMode(out, &(DWORD){0}))
        WriteConsoleW(out, error, len, NULL, NULL);
    LocalFree(error);
}

static DWORD cr_runproc(wchar_t *name, wchar_t *cmdline)
{
    DWORD retval = 1;

    // Copy the list of inherited CRT file descriptors to the new process
    STARTUPINFOW our_si = {sizeof(our_si)};
    GetStartupInfoW(&our_si);

    // Don't redirect std streams if they are attached to a console. Let mpv
    // attach to the console directly in this case. In theory, it should work
    // out of the box because "console-like" handles should be managed by Windows
    // internally, which works for INPUT and OUTPUT, but in certain cases,
    // not for ERROR.
    DWORD mode;
    HANDLE hStdInput  = GetStdHandle(STD_INPUT_HANDLE);
    HANDLE hStdOutput = GetStdHandle(STD_OUTPUT_HANDLE);
    HANDLE hStdError  = GetStdHandle(STD_ERROR_HANDLE);
    STARTUPINFOW si = {
        .cb          = sizeof(si),
        .lpReserved2 = our_si.lpReserved2,
        .cbReserved2 = our_si.cbReserved2,
        .hStdInput   = GetConsoleMode(hStdInput, &mode)  ? NULL : hStdInput,
        .hStdOutput  = GetConsoleMode(hStdOutput, &mode) ? NULL : hStdOutput,
        .hStdError   = GetConsoleMode(hStdError, &mode)  ? NULL : hStdError,
    };
    si.dwFlags = (si.hStdInput || si.hStdOutput || si.hStdError) ? STARTF_USESTDHANDLES : 0;
    PROCESS_INFORMATION pi = {0};
    if (!CreateProcessW(name, cmdline, NULL, NULL, TRUE, 0, NULL, NULL, &si, &pi)) {
        cr_perror();
    } else {
        WaitForSingleObject(pi.hProcess, INFINITE);
        GetExitCodeProcess(pi.hProcess, &retval);
        CloseHandle(pi.hProcess);
        CloseHandle(pi.hThread);
    }

    return retval;
}

int mainCRTStartup(void);
int mainCRTStartup(void)
{
    wchar_t *cmd = GetCommandLineW();
    wchar_t *exe = LocalAlloc(LMEM_FIXED, MP_PATH_MAX * sizeof(wchar_t));
    DWORD len = GetModuleFileNameW(NULL, exe, MP_PATH_MAX);
    if (len < 4 || len == MP_PATH_MAX)
          ExitProcess(1);

    exe[len - 3] = L'e';
    exe[len - 2] = L'x';
    exe[len - 1] = L'e';

    // Set an environment variable so the child process can tell whether it
    // was started from this wrapper and attach to the console accordingly
    SetEnvironmentVariableW(L"_started_from_console", L"yes");

    ExitProcess(cr_runproc(exe, cmd));
}