Re: [Qemu-devel] [PATCH] qemu-char: fix terminal crash when using "-monitor stdio -nographic"

[Li Liu <john.liuli@huawei.com>]

On 2014/8/27 14:44, Markus Armbruster wrote:
> "john.liuli" <john.liuli@huawei.com> writes:
> 
>> From: Li Liu <john.liuli@huawei.com>
>>
>> Eeay to reproduce, just try "qemu -monitor stdio -nographic"
>> and type "quit", then the terminal will be crashed.
>>
>> There are two pathes try to call tcgetattr of stdio in vl.c:
>>
>> 1) Monitor_parse(optarg, "readline");
>>    .....
>>    qemu_opts_foreach(qemu_find_opts("chardev"),
>>                      chardev_init_func, NULL, 1) != 0)
>>
>> 2) if (default_serial)
>>    add_device_config(DEV_SERIAL, "stdio");
>>    ....
>>    if (foreach_device_config(DEV_SERIAL, serial_parse) < 0)
>>
>> Both of them will trigger qemu_chr_open_stdio which will disable
>> ECHO attributes. First one has updated the attributes of stdio
>> by calling qemu_chr_fe_set_echo(chr, false). And the tty
>> attributes has been saved in oldtty. Then the second path will
>> redo such actions, and the oldtty is overlapped. So till "quit",
>> term_exit can't recove the correct attributes.
>>
>> Signed-off-by: Li Liu <john.liuli@huawei.com>
> 
> Yes, failure to restore tty settings is a bug.
> 
> But is having multiple character devices use the same terminal valid?

I'm not sure. But I have found such comments in vl.c
"According to documentation and historically, -nographic redirects
serial port, parallel port and monitor to stdio"

Best regards
Li.

> If no, can we catch and reject the attempt?
> 
> [...]
> 
>