Remove the VLA from handle_connection()

[mixi]

This fixes a segfault on musl libc with reasonable sized buffers, as
musl's default thread stack size is quite small (128k since 1.1.21).

A similar bug exists on glibc with large enough buffers (reproducable
with e.g. 16MB on my test system).

This fixes #108.

[mixi]

I also now implemented the memory savings on glibc by requesting a reasonably small thread stack as proposed in #108.

[dashezup]

it only receives 8 bytes on f3c7a29 (tested on musl), no matter if -B is set or not.

============================================================
[Fiche][STATUS] Sat Apr  3 10:09:30 2021
[Fiche][STATUS] Incoming connection from: 127.0.0.1 (localhost.localdomain).
[Fiche][STATUS] Received 8 bytes, saved to: hmxd.
============================================================

or it's still wip? @ me when you need me to test it.

[mixi]

@dashezup: That was me missing that sizeof(buffer) was being used to determine the size of the buffer (works with a static buffer / a VLA, doesn't work with a dynamically allocated buffer). It should be fixed now.

[dashezup]

Nice 👍 , I've tested fcfcff9 on musl, it works properly, I can upload very huge text (like 1G, probably memory was full and can't add more in that case)

[mixi]

NOTE: This was broken before moving the cleanup to the exit label because it called free(c) before dereferencing c.

[mixi]

That was me changing the 16k of requested thread stack to the musl default of 128k. That should probably be safer and still less than the glibc default.