qemu/linux-user/semihost.c

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/*
* ARM Compatible Semihosting Console Support.
*
* Copyright (c) 2019 Linaro Ltd
*
* Currently ARM and RISC-V are unique in having support for
* semihosting support in linux-user. So for now we implement the
* common console API but just for arm and risc-v linux-user.
*
* SPDX-License-Identifier: GPL-2.0-or-later
*/
#include "qemu/osdep.h"
#include "semihosting/console.h"
#include "qemu.h"
#include <termios.h>
int qemu_semihosting_console_outs(CPUArchState *env, target_ulong addr)
{
int len = target_strlen(addr);
void *s;
if (len < 0){
qemu_log_mask(LOG_GUEST_ERROR,
"%s: passed inaccessible address " TARGET_FMT_lx,
__func__, addr);
return 0;
}
s = lock_user(VERIFY_READ, addr, (long)(len + 1), 1);
g_assert(s); /* target_strlen has already verified this will work */
len = write(STDERR_FILENO, s, len);
unlock_user(s, addr, 0);
return len;
}
void qemu_semihosting_console_outc(CPUArchState *env, target_ulong addr)
{
char c;
if (get_user_u8(c, addr)) {
qemu_log_mask(LOG_GUEST_ERROR,
"%s: passed inaccessible address " TARGET_FMT_lx,
__func__, addr);
} else {
if (write(STDERR_FILENO, &c, 1) != 1) {
qemu_log_mask(LOG_UNIMP, "%s: unexpected write to stdout failure",
__func__);
}
}
}
/*
* For linux-user we can safely block. However as we want to return as
* soon as a character is read we need to tweak the termio to disable
* line buffering. We restore the old mode afterwards in case the
* program is expecting more normal behaviour. This is slow but
* nothing using semihosting console reading is expecting to be fast.
*/
target_ulong qemu_semihosting_console_inc(CPUArchState *env)
{
uint8_t c;
struct termios old_tio, new_tio;
/* Disable line-buffering and echo */
tcgetattr(STDIN_FILENO, &old_tio);
new_tio = old_tio;
new_tio.c_lflag &= (~ICANON & ~ECHO);
tcsetattr(STDIN_FILENO, TCSANOW, &new_tio);
c = getchar();
/* restore config */
tcsetattr(STDIN_FILENO, TCSANOW, &old_tio);
return (target_ulong) c;
}