path: root/wsutil/console_win32.c

/* console_win32.c
 * Console support for MSWindows
 *
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 2002, Jeffrey C. Foster <jfoste@woodward.com>
 *
 * SPDX-License-Identifier: GPL-2.0-or-later
 */

#ifdef _WIN32

#include <string.h>
#include <stdio.h>
#include <stdlib.h>

#include <glib.h>
#include <wsutil/file_util.h>

#include "console_win32.h"

#include <fcntl.h>
#include <conio.h>
#include <windows.h>
#include <tchar.h>

static bool has_console;  /* true if app has console */
static bool console_wait; /* "Press any key..." */
static bool stdin_capture = false; /* Don't grab stdin & stdout if true */

/*
 * Check whether a given standard handle needs to be redirected.
 *
 * If you run a Windows-subsystem program from cmd.exe on Windows XP,
 * and you haven't redirected the handle in question, GetStdHandle()
 * succeeds (so it doesn't return INVALID_HANDLE_VALUE or NULL), but
 * GetFile_type fails on the results with ERROR_INVALID_HANDLE.
 * In that case, redirection to a console is necessary.
 *
 * If you run it from the shell prompt in "mintty" in at least some
 * versions of Cygwin on Windows XP, and you haven't redirected the
 * handle in question, GetStdHandle() succeeds and returns a handle
 * that's a pipe or socket; it appears mintty reads from it and outputs
 * what it reads to the console.
 */
static bool
needs_redirection(int std_handle)
{
    HANDLE fd;
    DWORD handle_type;
    DWORD error;

    fd = GetStdHandle(std_handle);
    if (fd == NULL) {
        /*
         * No standard handle.  According to Microsoft's
         * documentation for GetStdHandle(), one reason for
         * this would be that the process is "a service on
         * an interactive desktop"; I'm not sure whether
         * such a process should be popping up a console.
         *
         * However, it also appears to be the case for
         * the standard input and standard error, but
         * *not* the standard output, for something run
         * with a double-click in Windows Explorer,
         * sow we'll say it needs redirection.
         */
        return true;
    }
    if (fd == INVALID_HANDLE_VALUE) {
        /*
         * OK, I'm not when this would happen; return
         * "no redirection" for now.
         */
        return false;
    }
    handle_type = GetFileType(fd);
    if (handle_type == FILE_TYPE_UNKNOWN) {
        error = GetLastError();
        if (error == ERROR_INVALID_HANDLE) {
            /*
             * OK, this appears to be the case where we're
             * running something in a mode that needs a
             * console.
             */
            return true;
        }
    }

    /*
     * Assume no redirection is needed for all other cases.
     */
    return false;
}

/*
 * If this application has no console window to which its standard output
 * would go, create one.
 */
void
create_console(void)
{
    bool must_redirect_stdin;
    bool must_redirect_stdout;
    bool must_redirect_stderr;

    if (stdin_capture) {
        /* We've been handed "-i -". Don't mess with stdio. */
        return;
    }

    if (has_console) {
        return;
    }

    /* Are the standard input, output, and error invalid handles? */
    must_redirect_stdin = needs_redirection(STD_INPUT_HANDLE);
    must_redirect_stdout = needs_redirection(STD_OUTPUT_HANDLE);
    must_redirect_stderr = needs_redirection(STD_ERROR_HANDLE);

    /* If none of them are invalid, we don't need to do anything. */
    if (!must_redirect_stdin && !must_redirect_stdout && !must_redirect_stderr)
        return;

    /* OK, at least one of them needs to be redirected to a console;
        try to attach to the parent process's console and, if that fails,
        try to create one. */
    /*
        * See if we have an existing console (i.e. we were run from a
        * command prompt).
        */
    if (!AttachConsole(ATTACH_PARENT_PROCESS)) {
        /* Probably not, as we couldn't attach to the parent process's
            console.
            Try to create a console.

            According to a comment on

http://msdn.microsoft.com/en-us/library/windows/desktop/ms681952(v=vs.85).aspx

            (which now redirects to a docs.microsoft.com page that is
            devoid of comments, and which is not available on the
            Wayback Machine)

            and according to

http://connect.microsoft.com/VisualStudio/feedback/details/689696/installing-security-update-kb2507938-prevents-console-allocation

            (which has disappeared, and isn't available on the Wayback
            Machine)

            and

https://answers.microsoft.com/en-us/windows/forum/windows_xp-windows_update/kb2567680-andor-kb2507938-breaks-attachconsole-api/e8191280-2d49-4be4-9918-18486fba0afa

even a failed attempt to attach to another process's console
will cause subsequent AllocConsole() calls to fail, possibly due
to bugs introduced by a security patch.  To work around this, we
do a FreeConsole() first. */
        FreeConsole();
        if (AllocConsole()) {
            /* That succeeded. */
            console_wait = true;
            SetConsoleTitle(_T("Wireshark Debug Console"));
        } else {
            /* On Windows XP, this still fails; FreeConsole() apparently
                doesn't clear the state, as it does on Windows 7. */
            return;   /* couldn't create console */
        }
    }

    if (must_redirect_stdin)
        ws_freopen("CONIN$", "r", stdin);
    if (must_redirect_stdout) {
        ws_freopen("CONOUT$", "w", stdout);
        fprintf(stdout, "\n");
    }
    if (must_redirect_stderr) {
        ws_freopen("CONOUT$", "w", stderr);
        fprintf(stderr, "\n");
    }

    /* Now register "destroy_console()" as a routine to be called just
        before the application exits, so that we can destroy the console
        after the user has typed a key (so that the console doesn't just
        disappear out from under them, giving the user no chance to see
        the message(s) we put in there). */
    atexit(destroy_console);

    /* Well, we have a console now. */
    has_console = true;
}

void
restore_pipes(void)
{
    bool must_redirect_stdin;
    bool must_redirect_stdout;
    bool must_redirect_stderr;

    HANDLE fd;

    if (stdin_capture) {
        /* We've been handed "-i -". Don't mess with stdio. */
        return;
    }

    if (has_console) {
        return;
    }

    /* Are the standard input, output, and error invalid handles? */
    must_redirect_stdin = needs_redirection(STD_INPUT_HANDLE);
    must_redirect_stdout = needs_redirection(STD_OUTPUT_HANDLE);
    must_redirect_stderr = needs_redirection(STD_ERROR_HANDLE);

    /* If none of them are invalid, we don't need to do anything. */
    if (!must_redirect_stdin && !must_redirect_stdout && !must_redirect_stderr)
        return;

    if (!must_redirect_stdin)
        fd = GetStdHandle(STD_INPUT_HANDLE);

    /* OK, at least one of them needs to be redirected to a console;
        try to attach to the parent process's console and, if that fails,
        cleanup and return. */
    /*
        * See if we have an existing console (i.e. we were run from a
        * command prompt).
        */
    if (!AttachConsole(ATTACH_PARENT_PROCESS)) {
        FreeConsole();
        return;   /* No parent - cleanup and exit */
    }

    if (must_redirect_stdin) {
        ws_freopen("CONIN$", "r", stdin);
    } else {
        SetStdHandle(STD_INPUT_HANDLE, fd);
    }
    if (must_redirect_stdout) {
        ws_freopen("CONOUT$", "w", stdout);
        fprintf(stdout, "\n");
    }
    if (must_redirect_stderr) {
        ws_freopen("CONOUT$", "w", stderr);
        fprintf(stderr, "\n");
    }

    /* Now register "destroy_console()" as a routine to be called just
        before the application exits, so that we can destroy the console
        after the user has typed a key (so that the console doesn't just
        disappear out from under them, giving the user no chance to see
        the message(s) we put in there). */
    atexit(destroy_console);

    /* Well, we have a console now. */
    has_console = true;
}

void
destroy_console(void)
{
    if (console_wait) {
        printf("\n\nPress any key to exit\n");
        _getch();
    }
    FreeConsole();
}

void
set_console_wait(bool set_console_wait)
{
    console_wait = set_console_wait;
}

bool
get_console_wait(void)
{
    return console_wait;
}

void
set_stdin_capture(bool set_stdin_capture)
{
    stdin_capture = set_stdin_capture;
}

bool
get_stdin_capture(void)
{
    return stdin_capture;
}

#endif /* _WIN32 */