when FFmpeg wasix build exit, the OS prompt is not restored properly

[ptitSeb]

Describe the bug

Using the ffmpeg wasix build, like with wasmer run wasmer/ffmpeg --mapdir /src:. -- -i /src/a.mp4 /src/a.avi will do the coversion, but when it's over, the program is like it's waiting for an input, while it's over. The OS prompt is not showing.

Steps to reproduce

wasmer run wasmer/ffmpeg --mapdir /src:. -- -i /src/a.mp4 /src/a.av

with a.mp4 existing...

Expected behavior

Prompt showing at this end of the conversion

Actual behavior

Prompt not showing at the end of the conversion

Additional context

[ptitSeb]

@john-sharratt Here is a way to reproduce the issue with a more minimum sample:
create main.c with

#include <stdio.h>
#include <unistd.h>
#include  <sys/time.h>

static int read_key()
{
    int ch;
    int n = 1;
    struct timeval tv;
    fd_set rfds;

    FD_ZERO(&rfds);
    FD_SET(0, &rfds);
    tv.tv_sec = 0;
    tv.tv_usec = 0;
    return select(1, &rfds, NULL, NULL, &tv);
}

int main(int argc, const char* argv[])
{
  int ch = read_key();
  printf("key = %d, bye\n", ch);
}

Build with

clang-15 --target=wasm32-wasi --sysroot=/home/seb/wasix-libc/sysroot32 -matomics -mbulk-memory -mmutable-globals -pthread -mthread-model posix -ftls-model=local-exec -fno-trapping-math -D_WASI_EMULATED_MMAN -D_WASI_EMULATED_SIGNAL -D_WASI_EMULATED_PROCESS_CLOCKS -O2 -g -flto -Wl,--shared-memory -Wl,--max-memory=4294967296 -Wl,--import-memory -Wl,--export-dynamic -Wl,--export=__heap_base -Wl,--export=__stack_pointer -Wl,--export=__data_end -Wl,--export=__wasm_init_tls -Wl,--export=__wasm_signal -Wl,--export=__tls_size -Wl,--export=__tls_align -Wl,--export=__tls_base -lwasi-emulated-mman -O2 -flto -g  main.c -o main.wasm

path/version to clang and path to sysroot need to be adapted of course.

Native version can be built with a simple gcc main.c -o main

The native version exit immediatly with

key = 0, bye

While the wasm version wait for a keypress.