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  */
  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 }