qemu

1
/*
2
 * ARM Compatible Semihosting Console Support.
3
 *
4
 * Copyright (c) 2019 Linaro Ltd
5
 *
6
 * Currently ARM and RISC-V are unique in having support for
7
 * semihosting support in linux-user. So for now we implement the
8
 * common console API but just for arm and risc-v linux-user.
9
 *
10
 * SPDX-License-Identifier: GPL-2.0-or-later
11
 */
12

13
#include "qemu/osdep.h"
14
#include "semihosting/console.h"
15
#include "qemu.h"
16
#include "user-internals.h"
17
#include <termios.h>
18

19
/*
20
 * For linux-user we can safely block. However as we want to return as
21
 * soon as a character is read we need to tweak the termio to disable
22
 * line buffering. We restore the old mode afterwards in case the
23
 * program is expecting more normal behaviour. This is slow but
24
 * nothing using semihosting console reading is expecting to be fast.
25
 */
26
int qemu_semihosting_console_read(CPUState *cs, void *buf, int len)
27
{
28
    int ret;
29
    struct termios old_tio, new_tio;
30

31
    /* Disable line-buffering and echo */
32
    tcgetattr(STDIN_FILENO, &old_tio);
33
    new_tio = old_tio;
34
    new_tio.c_lflag &= (~ICANON & ~ECHO);
35
    new_tio.c_cc[VMIN] = 1;
36
    new_tio.c_cc[VTIME] = 0;
37
    tcsetattr(STDIN_FILENO, TCSANOW, &new_tio);
38

39
    ret = fread(buf, 1, len, stdin);
40

41
    /* restore config */
42
    tcsetattr(STDIN_FILENO, TCSANOW, &old_tio);
43

44
    return ret;
45
}
46

47
int qemu_semihosting_console_write(void *buf, int len)
48
{
49
    return fwrite(buf, 1, len, stderr);
50
}
51