'uv_tty_init' prevents FD to be used by child processes

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Renato Maia

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Oct 19, 2020, 8:23:29 PM10/19/20
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I just noticed that using libuv 1.40.0 built in Linux 5.8.11, if I
create TTY handlers for a FD will prevent the FD to be used by child
processes, similar to what 'uv_disable_stdio_inheritance' does.

The attached code illustrates the behavior. The output is:

```
libuv 1.40.0
failcommand.c:25: uv_tty_init(loop, tty, 0, 0)
failcommand.c:25: uv_tty_init(loop, tty, 1, 0)
failcommand.c:25: uv_tty_init(loop, tty, 2, 0)
failcommand.c:30: system('echo "Hello, world!"') = Inappropriate ioctl
for device
failcommand.c:38: uv_close(tty) /* fd=0 */
failcommand.c:38: uv_close(tty) /* fd=1 */
failcommand.c:38: uv_close(tty) /* fd=2 */
```

Is this expected behavior? Is there a way to use TTY streams for
standard streams (STD{IN,OUT,ERR}) and still be able to create
processes that can use them?

Thanks in advance.

P.S.: I noticed some sections missing from the API documentation, but
which are present in the 'Show Source' link of the page. For instance,
'uv_tty_mode_t' and 'uv_tty_vtermstate_t' descriptions are missing in
http://docs.libuv.org/en/v1.x/tty.html. Should I report this
somewhere?

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Renato Maia

Renato Maia

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Oct 19, 2020, 8:26:34 PM10/19/20
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On Mon, Oct 19, 2020 at 9:23 PM Renato Maia <maia....@gmail.com> wrote:
> The attached code illustrates the behavior. The output is:

Sorry, I forgot to attach the file. Here it is.

--
Renato Maia
failcommand.c

Jameson Nash

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Oct 19, 2020, 11:06:32 PM10/19/20
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Yes, this is a known issue (https://github.com/libuv/libuv/issues/2062). In my experience, embedding applications should probably always pass `dup(0)` etc. to libuv to avoid these sorts of problems.

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