Bincompat helloworld g++

[Antonio-88]

Added bincompat-c++-hello
Added bincompat-c++-http

[Copilot]

Pull request overview

Adds two new Unikraft binary-compatibility examples that run Linux-ELF C++ programs via the ELF loader: a minimal “hello” and a simple HTTP server, including rootfs build artifacts, platform run scripts, and scripted test harnesses.

Changes:

• Introduce bincompat-c++-hello: C++ “Bye, World!” ELF + QEMU/Firecracker build/run/test scripts.
• Introduce bincompat-c++-http: statically-linked HTTP server ELF + QEMU/Firecracker build/run/test scripts.
• Add documentation and helper scripts (setup.sh, .scripts/*, Firecracker JSON configs) to automate setup/build/run/test flows.

Reviewed changes

Copilot reviewed 41 out of 41 changed files in this pull request and generated 9 comments.

Show a summary per file

File	Description
bincompat-c++-http/setup.sh	Creates workdir/ and symlinks required repo(s) into it.
bincompat-c++-http/rootfs/Makefile	Builds the Linux-ELF HTTP server binary for inclusion in the initrd.
bincompat-c++-http/rootfs/http_server.cpp	Implements a simple socket-based HTTP server returning “Bye, World!”.
bincompat-c++-http/rootfs/.gitignore	Ignores the built http_server binary in rootfs.
bincompat-c++-http/README.md	Documents build/run workflow for the HTTP server on Unikraft ELF loader.
bincompat-c++-http/fc.x86_64.json	Firecracker config to boot the ELF loader with initrd and run /http_server.
bincompat-c++-http/.scripts/test/wrapper.sh	Test wrapper intended to validate the app behavior after starting a VM.
bincompat-c++-http/.scripts/test/README.md	Documents the scripted test flow for this app.
bincompat-c++-http/.scripts/test/common.sh	Common test helpers (cleanup, start instance, curl/ping checks).
bincompat-c++-http/.scripts/test/all.sh	Runs build+run smoke tests for qemu/fc variants and logs output.
bincompat-c++-http/.scripts/test/.gitignore	Ignores test logs directory.
bincompat-c++-http/.scripts/run/qemu.x86_64	Starts QEMU with networking and runs /http_server under elfloader.
bincompat-c++-http/.scripts/run/fc.x86_64	Starts Firecracker using fc.x86_64.json.
bincompat-c++-http/.scripts/README.md	Documents .scripts build/run usage.
bincompat-c++-http/.scripts/common.sh	Sets elfloader base app and provides helper to build it.
bincompat-c++-http/.scripts/build/rootfs.x86_64	Builds rootfs ELF and packages initrd.cpio.
bincompat-c++-http/.scripts/build/qemu.x86_64	Builds rootfs + qemu kernel for base elfloader app.
bincompat-c++-http/.scripts/build/kernel.qemu.x86_64	Builds elfloader base kernel for QEMU.
bincompat-c++-http/.scripts/build/kernel.fc.x86_64	Builds elfloader base kernel for Firecracker.
bincompat-c++-http/.scripts/build/fc.x86_64	Builds rootfs + fc kernel for base elfloader app.
bincompat-c++-http/.gitignore	Ignores local build outputs (workdir/, initrd.cpio).
bincompat-c++-hello/setup.sh	Creates workdir/ and symlinks required repo(s) into it.
bincompat-c++-hello/rootfs/Makefile	Builds the Linux-ELF C++ hello binary for inclusion in the initrd.
bincompat-c++-hello/rootfs/helloworld.cpp	Implements the “Bye, World!” C++ hello program.
bincompat-c++-hello/rootfs/.gitignore	Ignores the built hello-c++ binary in rootfs.
bincompat-c++-hello/README.md	Documents build/run workflow for the C++ hello app on Unikraft ELF loader.
bincompat-c++-hello/fc.x86_64.json	Firecracker config to boot the ELF loader and run /hello-c++.
bincompat-c++-hello/.scripts/test/wrapper.sh	Test wrapper that checks for expected output.
bincompat-c++-hello/.scripts/test/README.md	Documents the scripted test flow for this app.
bincompat-c++-hello/.scripts/test/common.sh	Common test helpers (cleanup, start instance, curl/ping checks).
bincompat-c++-hello/.scripts/test/all.sh	Runs build+run smoke tests for qemu/fc variants and logs output.
bincompat-c++-hello/.scripts/test/.gitignore	Ignores test logs directory.
bincompat-c++-hello/.scripts/run/qemu.x86_64	Starts QEMU and runs /hello-c++ under elfloader.
bincompat-c++-hello/.scripts/run/fc.x86_64	Starts Firecracker using fc.x86_64.json.
bincompat-c++-hello/.scripts/common.sh	Sets elfloader base app and provides helper to build it.
bincompat-c++-hello/.scripts/build/rootfs.x86_64	Builds rootfs ELF and packages initrd.cpio.
bincompat-c++-hello/.scripts/build/qemu.x86_64	Builds rootfs + qemu kernel for base elfloader app.
bincompat-c++-hello/.scripts/build/kernel.qemu.x86_64	Builds elfloader base kernel for QEMU.
bincompat-c++-hello/.scripts/build/kernel.fc.x86_64	Builds elfloader base kernel for Firecracker.
bincompat-c++-hello/.scripts/build/fc.x86_64	Builds rootfs + fc kernel for base elfloader app.
bincompat-c++-hello/.gitignore	Ignores local build outputs (workdir).

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[Copilot]

Pull request overview

Copilot reviewed 41 out of 41 changed files in this pull request and generated no new comments.

Suppressed comments (7)

bincompat-c++-http/README.md:4

• The README claims this app is based on elfloader-net, but the linked README points to ../elfloader-basic/README.md, which is inconsistent and likely confusing for users following setup instructions.
  bincompat-c++-http/README.md:37
• The Quick Setup section links to a non-existent "Close QEMU" section (#close-qemu). This link is broken and duplicates the guidance already covered by the "Forcefully Terminating a Machine" section.
  bincompat-c++-http/fc.x86_64.json:6
• This Firecracker config points to ../elfloader-basic/..., but this app (and its scripts) are based on elfloader-net. As written, the run script’s base-kernel check can pass while Firecracker boots a different (or missing) kernel.
  bincompat-c++-http/.scripts/test/wrapper.sh:18
• The test starts ping/curl immediately after spawning the VM, which is likely to be flaky because the guest network stack and HTTP server may not be ready yet. Other HTTP app wrappers wait briefly before probing (e.g. cpp-http/.scripts/test/wrapper.sh:28-31).
  bincompat-c++-http/rootfs/Makefile:1
• Hardcoding CXX = g++ prevents users from overriding the compiler via environment/CLI (and differs from other rootfs Makefiles in this repo which rely on $(CXX) without setting it, e.g. elfloader-basic/rootfs/Makefile). Consider using ?= so CXX=/path/to/compiler make ... works.
  bincompat-c++-hello/rootfs/Makefile:1
• Hardcoding CXX = g++ prevents overriding the compiler via environment/CLI. For consistency with other rootfs Makefiles (which rely on $(CXX) without setting it), prefer ?= here.

CXX = g++

bincompat-c++-http/rootfs/http_server.cpp:7

• std::string is used below, but <string> isn’t included. Relying on transitive includes from <iostream> is non-portable and can break with different standard library implementations/toolchains.