unix_console.cpp

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/*
Copyright (C) 1997-2001 Id Software, Inc.

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.

*/

#include "../../common/common.h"
#include "../system.h"
#include <unistd.h>
#include <signal.h>
#include <termios.h>
#include <fcntl.h>
#include <sys/time.h>

typedef struct {
    uint32_t    cursor;
    char        buffer[256];
} consoleHistory_t;

static bool stdinActive;
/* general flag to tell about tty console mode */
static bool ttyConsoleActivated = false;

/* some key codes that the terminal may be using, initialised on start up */
static int TTY_erase;
static int TTY_eof;

static struct termios TTY_tc;

static consoleHistory_t ttyConsoleHistory;

/* This is somewhat of a duplicate of the graphical console history
 * but it's safer more modular to have our own here */
#define CON_HISTORY 32
static consoleHistory_t ttyEditLines[CON_HISTORY];
static int histCurrent = -1, histCount = 0;

static void CON_FlushIn (void)
{
    char key;
    while (read(STDIN_FILENO, &key, 1) != -1)
        ;
}

static void Sys_TTYDeleteCharacter (void)
{
    char key = '\b';
    write(STDOUT_FILENO, &key, 1) || 0;
    key = ' ';
    write(STDOUT_FILENO, &key, 1) || 0;
    key = '\b';
    write(STDOUT_FILENO, &key, 1) || 0;
}

static void Sys_TTYConsoleHide (void)
{
    if (ttyConsoleHistory.cursor > 0) {
        for (unsigned int i = 0; i < ttyConsoleHistory.cursor; i++)
            Sys_TTYDeleteCharacter();
    }
    Sys_TTYDeleteCharacter(); /* Delete "]" */
}

static void Sys_TTYConsoleShow (void)
{
    write(STDOUT_FILENO, "]", 1) || 0;
    if (ttyConsoleHistory.cursor) {
        for (unsigned int i = 0; i < ttyConsoleHistory.cursor; i++) {
            write(STDOUT_FILENO, ttyConsoleHistory.buffer + i, 1) || 0;
        }
    }
}

static void Sys_TTYConsoleHistoryAdd (consoleHistory_t* field)
{
    const size_t size = lengthof(ttyEditLines);

    assert(histCount <= size);
    assert(histCount >= 0);
    assert(histCurrent >= -1);
    assert(histCurrent <= histCount);
    /* make some room */
    for (int i = size - 1; i > 0; i--)
        ttyEditLines[i] = ttyEditLines[i - 1];

    ttyEditLines[0] = *field;
    if (histCount < size)
        histCount++;

    histCurrent = -1; /* re-init */
}

static consoleHistory_t* Sys_TTYConsoleHistoryPrevious (void)
{
    assert(histCount <= lengthof(ttyEditLines));
    assert(histCount >= 0);
    assert(histCurrent >= -1);
    assert(histCurrent <= histCount);

    const int histPrev = histCurrent + 1;
    if (histPrev >= histCount)
        return nullptr;

    histCurrent++;
    return &(ttyEditLines[histCurrent]);
}

static consoleHistory_t* Sys_TTYConsoleHistoryNext (void)
{
    assert(histCount <= CON_HISTORY);
    assert(histCount >= 0);
    assert(histCurrent >= -1);
    assert(histCurrent <= histCount);
    if (histCurrent >= 0)
        histCurrent--;

    if (histCurrent == -1)
        return nullptr;

    return &(ttyEditLines[histCurrent]);
}

static void Sys_TTYConsoleSigCont (int signum)
{
    Sys_ConsoleInit();
}

void Sys_ShowConsole (bool show)
{
    static int ttyConsoleHide = 0;

    if (!ttyConsoleActivated)
        return;

    if (show) {
        assert(ttyConsoleHide > 0);
        ttyConsoleHide--;
        if (ttyConsoleHide == 0)
            Sys_TTYConsoleShow();
    } else {
        if (ttyConsoleHide == 0)
            Sys_TTYConsoleHide();
        ttyConsoleHide++;
    }
}

void Sys_ConsoleShutdown (void)
{
    if (ttyConsoleActivated) {
        Sys_TTYDeleteCharacter(); /* Delete "]" */
        tcsetattr(STDIN_FILENO, TCSADRAIN, &TTY_tc);
    }

    /* Restore blocking to stdin reads */
    fcntl(STDIN_FILENO, F_SETFL, fcntl(STDIN_FILENO, F_GETFL, 0) & ~O_NONBLOCK);
}

static void Sys_TTYConsoleHistoryClear (consoleHistory_t* edit)
{
    OBJZERO(*edit);
}

static bool Sys_IsATTY (void)
{
    const char* term = getenv("TERM");
    return isatty(STDIN_FILENO) && !(term && (Q_streq(term, "raw") || Q_streq(term, "dumb")));
}

void Sys_ConsoleInit (void)
{
    /* If the process is backgrounded (running non interactively)
     * then SIGTTIN or SIGTOU is emitted, if not caught, turns into a SIGSTP */
    signal(SIGTTIN, SIG_IGN);
    signal(SIGTTOU, SIG_IGN);

    /* If SIGCONT is received, reinitialize console */
    signal(SIGCONT, Sys_TTYConsoleSigCont);

    /* Make stdin reads non-blocking */
    fcntl(STDIN_FILENO, F_SETFL, fcntl(STDIN_FILENO, F_GETFL, 0) | O_NONBLOCK);

    if (!Sys_IsATTY()) {
        Com_Printf("tty console mode disabled\n");
        ttyConsoleActivated = false;
        stdinActive = true;
        return;
    }

    Sys_TTYConsoleHistoryClear(&ttyConsoleHistory);
    tcgetattr(STDIN_FILENO, &TTY_tc);
    TTY_erase = TTY_tc.c_cc[VERASE];
    TTY_eof = TTY_tc.c_cc[VEOF];
    struct termios tc = TTY_tc;

    /*
     * ECHO: don't echo input characters.
     * ICANON: enable canonical mode. This enables the special characters EOF, EOL,
     *   EOL2, ERASE, KILL, REPRINT, STATUS, and WERASE, and buffers by lines.
     * ISIG: when any of the characters INTR, QUIT, SUSP or DSUSP are received,
     *   generate the corresponding sig­nal.
     */
    tc.c_lflag &= ~(ECHO | ICANON);

    /*
     * ISTRIP strip off bit 8
     * INPCK enable input parity checking
     */
    tc.c_iflag &= ~(ISTRIP | INPCK);
    tc.c_cc[VMIN] = 1;
    tc.c_cc[VTIME] = 0;
    tcsetattr(STDIN_FILENO, TCSADRAIN, &tc);
    ttyConsoleActivated = true;
}

const char* Sys_ConsoleInput (void)
{
    /* we use this when sending back commands */
    static char text[256];

    if (ttyConsoleActivated) {
        char key;
        int avail = read(STDIN_FILENO, &key, 1);
        if (avail != -1) {
            /* we have something
             * backspace?
             * NOTE TTimo testing a lot of values .. seems it's the only way to get it to work everywhere */
            if (key == TTY_erase || key == 127 || key == 8) {
                if (ttyConsoleHistory.cursor > 0) {
                    ttyConsoleHistory.cursor--;
                    ttyConsoleHistory.buffer[ttyConsoleHistory.cursor] = '\0';
                    Sys_TTYDeleteCharacter();
                }
                return nullptr;
            }
            /* check if this is a control char */
            if (key && key < ' ') {
                if (key == '\n') {
                    /* push it in history */
                    Sys_TTYConsoleHistoryAdd(&ttyConsoleHistory);
                    Q_strncpyz(text, ttyConsoleHistory.buffer, sizeof(text));
                    Sys_TTYConsoleHistoryClear(&ttyConsoleHistory);
                    key = '\n';
                    write(1, &key, 1) || 0;
                    write(1, "]", 1) || 0;
                    return text;
                }
                if (key == '\t') {
                    const size_t size = sizeof(ttyConsoleHistory.buffer);
                    const char* s = ttyConsoleHistory.buffer;
                    char* target = ttyConsoleHistory.buffer;
                    Sys_ShowConsole(false);
                    Com_ConsoleCompleteCommand(s, target, size, &ttyConsoleHistory.cursor, 0);
                    Sys_ShowConsole(true);
                    return nullptr;
                }
                avail = read(STDIN_FILENO, &key, 1);
                if (avail != -1) {
                    /* VT 100 keys */
                    if (key == '[' || key == 'O') {
                        consoleHistory_t* history;
                        avail = read(STDIN_FILENO, &key, 1);
                        if (avail != -1) {
                            switch (key) {
                            case 'A':
                                history = Sys_TTYConsoleHistoryPrevious();
                                if (history) {
                                    Sys_ShowConsole(false);
                                    ttyConsoleHistory = *history;
                                    Sys_ShowConsole(true);
                                }
                                CON_FlushIn();
                                return nullptr;
                                break;
                            case 'B':
                                history = Sys_TTYConsoleHistoryNext();
                                Sys_ShowConsole(false);
                                if (history) {
                                    ttyConsoleHistory = *history;
                                } else {
                                    Sys_TTYConsoleHistoryClear(&ttyConsoleHistory);
                                }
                                Sys_ShowConsole(true);
                                CON_FlushIn();
                                return nullptr;
                                break;
                            case 'C':
                                return nullptr;
                            case 'D':
                                return nullptr;
                            }
                        }
                    }
                }
                CON_FlushIn();
                return nullptr;
            }
            if (ttyConsoleHistory.cursor >= sizeof(text) - 1)
                return nullptr;
            /* push regular character */
            ttyConsoleHistory.buffer[ttyConsoleHistory.cursor] = key;
            ttyConsoleHistory.cursor++;
            /* print the current line (this is differential) */
            write(STDOUT_FILENO, &key, 1) || 0;
        }

        return nullptr;
    } else if (stdinActive) {
        fd_set fdset;
        struct timeval timeout;

        FD_ZERO(&fdset);
        FD_SET(STDIN_FILENO, &fdset); /* stdin */
        timeout.tv_sec = 0;
        timeout.tv_usec = 0;
        if (select(STDIN_FILENO + 1, &fdset, nullptr, nullptr, &timeout) == -1
                || !FD_ISSET(STDIN_FILENO, &fdset))
            return nullptr;

        const int len = read(STDIN_FILENO, text, sizeof(text));
        if (len == 0) { /* eof! */
            stdinActive = false;
            return nullptr;
        }

        if (len < 1)
            return nullptr;
        text[len - 1] = 0; /* rip off the /n and terminate */

        return text;
    }
    return nullptr;
}

void Sys_ConsoleOutput (const char* string)
{
    /* BUG: for some reason, NDELAY also affects stdout (1) when used on stdin (0). */
    const int origflags = fcntl(STDOUT_FILENO, F_GETFL, 0);

    fcntl(STDOUT_FILENO, F_SETFL, origflags & ~FNDELAY);
    while (*string) {
        const ssize_t written = write(STDOUT_FILENO, string, strlen(string));
        if (written <= 0)
            break; /* sorry, I cannot do anything about this error - without an output */
        string += written;
    }
    fcntl(STDOUT_FILENO, F_SETFL, origflags);
}