/**

 * $Id$

 * 

 * DC-load syscall implementation.

 *

 * Copyright (c) 2005 Nathan Keynes.

 *

 * 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.

 */

#include <stdio.h>

#include <unistd.h>

#include <fcntl.h>

#include "dream.h"

#include "mem.h"

#include "dreamcast.h"

#include "syscall.h"

#include "sh4/sh4.h"

#define SYS_READ 0

#define SYS_WRITE 1

#define SYS_OPEN 2

#define SYS_CLOSE 3

#define SYS_CREAT 4

#define SYS_LINK 5

#define SYS_UNLINK 6

#define SYS_CHDIR 7

#define SYS_CHMOD 8

#define SYS_LSEEK 9

#define SYS_FSTAT 10

#define SYS_TIME 11

#define SYS_STAT 12

#define SYS_UTIME 13

#define SYS_ASSIGNWRKMEM 14

#define SYS_EXIT 15

#define SYS_OPENDIR 16

#define SYS_CLOSEDIR 17

#define SYS_READDIR 18

#define SYS_GETHOSTINFO 19

#define SYS_MAGIC 0xDEADBEEF

#define SYS_MAGIC_ADDR 0x8c004004

#define SYSCALL_ADDR 0x8c004008

static gboolean dcload_allow_unsafe = FALSE;

void dcload_set_allow_unsafe( gboolean allow )

{

    dcload_allow_unsafe = allow;

}

#define MAX_OPEN_FDS 16

/**

 * Mapping from emulator fd to real fd (so we can limit read/write

 * to only fds we've explicitly granted access to).

 */

int open_fds[MAX_OPEN_FDS];

int dcload_alloc_fd() 

{

    int i;

    for( i=0; i<MAX_OPEN_FDS; i++ ) {

        if( open_fds[i] == -1 ) {

            return i;

        }

    }

    return -1;

}

void dcload_syscall( uint32_t syscall_id ) 

{

    // uint32_t syscall = sh4r.r[4];

    int fd;

    switch( sh4r.r[4] ) {

    case SYS_READ:

        fd = sh4r.r[5];

        if( fd < 0 || fd >= MAX_OPEN_FDS || open_fds[fd] == -1 ) {

            sh4r.r[0] = -1;

        } else {

            sh4ptr_t buf = mem_get_region( sh4r.r[6] );

            int length = sh4r.r[7];

            sh4r.r[0] = read( open_fds[fd], buf, length );

        }

        break;

    case SYS_WRITE:

        fd = sh4r.r[5];

        if( fd < 0 || fd >= MAX_OPEN_FDS || open_fds[fd] == -1 ) {

            sh4r.r[0] = -1;

        } else {

            sh4ptr_t buf = mem_get_region( sh4r.r[6] );

            int length = sh4r.r[7];

            sh4r.r[0] = write( open_fds[fd], buf, length );

        }

        break;

    case SYS_LSEEK:

        fd = sh4r.r[5];

        if( fd < 0 || fd >= MAX_OPEN_FDS || open_fds[fd] == -1 ) {

            sh4r.r[0] = -1;

        } else {

            sh4r.r[0] = lseek( open_fds[fd], sh4r.r[6], sh4r.r[7] );

        }

        break;

        /* Secure access only */

    case SYS_OPEN:

        if( dcload_allow_unsafe ) {

            fd = dcload_alloc_fd();

            if( fd == -1 ) {

                sh4r.r[0] = -1;

            } else {

                char *filename = (char *)mem_get_region( sh4r.r[5] );

                int realfd = open( filename, sh4r.r[6] );

                open_fds[fd] = realfd;

                sh4r.r[0] = realfd;

            }

        } else {

            ERROR( "Denying access to local filesystem" );

            sh4r.r[0] = -1;

        }

        break;

    case SYS_CLOSE:

        if( dcload_allow_unsafe ) {

            fd = sh4r.r[5];

            if( fd < 0 || fd >= MAX_OPEN_FDS || open_fds[fd] == -1 ) {

                sh4r.r[0] = -1;

            } else {

                if( open_fds[fd] > 2 ) {

                    sh4r.r[0] = close( open_fds[fd] );

                } else {

                    /* Don't actually close real fds 0-2 */

                    sh4r.r[0] = 0;

                }

                open_fds[fd] = -1;

            }

        }

        break;

    case SYS_EXIT:

        if( dcload_allow_unsafe ) {

            dreamcast_shutdown();

            exit( sh4r.r[5] );

        } else {

            dreamcast_stop();

        }

    default:

        sh4r.r[0] = -1;

    }

}

void dcload_install() 

{

    memset( &open_fds, -1, sizeof(open_fds) );

    open_fds[0] = 0;

    open_fds[1] = 1;

    open_fds[2] = 2;

    syscall_add_hook_vector( 0xF0, SYSCALL_ADDR, dcload_syscall );

    mem_write_long( SYS_MAGIC_ADDR, SYS_MAGIC );

}