LXR qemu/linux-user/semihost.c

   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 */
  26int 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
  47int qemu_semihosting_console_write(void *buf, int len)
  48{
  49    return fwrite(buf, 1, len, stderr);
  50}
  51