Handle possible signals from POSIX APIs (mmap, read, ...)

[edubart]

Context

There are some POSIX functions we call that may raise signals in unusual situations.

For example mmap() may raise SIGBUS when a mapped file is overwritten while it's mapped, this may happen when the user overwrites a rootfs while a running emulator is using it.

The write() and read() functions used in console TTY may also raise signals such as SIGPIPE when its file descriptor is closed by the host.

When any of these signals happens the application exits unexpectedly or even crashes, while in the ideal situation an internal error could have been raised, making it possible to handle it programatically.

Possible solutions

We should review all POSIX and Linux functions we call in the emulator and review if we properly handle all possible signals for them and make the machine exit gracefully or with an error instead of a crash or unexpected exit. In the case of Lua APIs we could raise a Lua error.

Definition of Done

• Handle possible signals for mmap()
• Handle possible signals for read()
• Handle possible signals for write()
• Raise Lua errors instead of exiting