![Cosmopolitan Honeybadger](usr/share/img/honeybadger.png) # Cosmopolitan [Cosmopolitan Libc](https://justine.lol/cosmopolitan/index.html) makes C a build-once run-anywhere language, like Java, except it doesn't need an interpreter or virtual machine. Instead, it reconfigures stock GCC and Clang to output a POSIX-approved polyglot format that runs natively on Linux + Mac + Windows + FreeBSD + OpenBSD + NetBSD + BIOS with the best possible performance and the tiniest footprint imaginable. ## Background For an introduction to this project, please read the [αcτµαlly pδrταblε εxεcµταblε](https://justine.lol/ape.html) blog post and [cosmopolitan libc](https://justine.lol/cosmopolitan/index.html) website. We also have [API documentation](https://justine.lol/cosmopolitan/documentation.html). ## Getting Started If you're doing your development work on Linux or BSD then you need just five files to get started. Here's what you do on Linux: ```sh wget https://justine.lol/cosmopolitan/cosmopolitan.zip unzip cosmopolitan.zip printf 'main() { printf("hello world\\n"); }\n' >hello.c gcc -g -Os -static -nostdlib -nostdinc -fno-pie -no-pie -mno-red-zone \ -fno-omit-frame-pointer -pg -mnop-mcount \ -o hello.com.dbg hello.c -fuse-ld=bfd -Wl,-T,ape.lds \ -include cosmopolitan.h crt.o ape-no-modify-self.o cosmopolitan.a objcopy -S -O binary hello.com.dbg hello.com ``` You now have a portable program. ```sh ./hello.com bash -c './hello.com' # zsh/fish workaround (we patched them in 2021) ``` Since we used the `ape-no-modify-self.o` bootloader (rather than `ape.o`) your executable will not modify itself when it's run. What it'll instead do, is extract a 4kb program to `${TMPDIR:-/tmp}` that maps your program into memory without needing to copy it. It's possible to install the APE loader systemwide as follows. ```sh # (1) linux systems that want binfmt_misc ape/apeinstall.sh # (2) for linux/freebsd/netbsd/openbsd systems cp build/bootstrap/ape.elf /usr/bin/ape # (3) for mac os x systems cp build/bootstrap/ape.macho /usr/bin/ape ``` If you followed steps (2) and (3) then there's going to be a slight constant-time startup latency each time you run an APE binary. Your system might also prevent your APE program from being installed to a system directory as a setuid binary or a script interpreter. To solve that, you can use the following flag to turn your binary into the platform local format (ELF or Mach-O): ```sh $ file hello.com hello.com: DOS/MBR boot sector ./hello.com --assimilate $ file hello.com hello.com: ELF 64-bit LSB executable ``` There's also some other useful flags that get baked into your binary by default: ```sh ./hello.com --strace # log system calls to stderr ./hello.com --ftrace # log function calls to stderr ``` If you want your `hello.com` program to be much tinier, more on the order of 16kb rather than 60kb, then all you have to do is use instead. See . ### MacOS If you're developing on MacOS you can install the GNU compiler collection for x86_64-elf via homebrew: ```sh brew install x86_64-elf-gcc ``` Then in the above scripts just replace `gcc` and `objcopy` with `x86_64-elf-gcc` and `x86_64-elf-objcopy` to compile your APE binary. ### Windows If you're developing on Windows then you need to download an x86_64-pc-linux-gnu toolchain beforehand. See the [Compiling on Windows](https://justine.lol/cosmopolitan/windows-compiling.html) tutorial. It's needed because the ELF object format is what makes universal binaries possible. Cosmopolitan officially only builds on Linux. However, one highly experimental (and currently broken) thing you could try, is building the entire cosmo repository from source using the cross9 toolchain. ``` mkdir -p o/third_party rm -rf o/third_party/gcc wget https://justine.lol/linux-compiler-on-windows/cross9.zip unzip cross9.zip mv cross9 o/third_party/gcc build/bootstrap/make.com ``` ## Source Builds Cosmopolitan can be compiled from source on any Linux distro. First, you need to download or clone the repository. ```sh wget https://justine.lol/cosmopolitan/cosmopolitan.tar.gz tar xf cosmopolitan.tar.gz # see releases page cd cosmopolitan ``` This will build the entire repository and run all the tests: ```sh build/bootstrap/make.com -j16 o//examples/hello.com find o -name \*.com | xargs ls -rShal | less ``` If you get an error running make.com then it's probably because you have WINE installed to `binfmt_misc`. You can fix that by installing the the APE loader as an interpreter. It'll improve build performance too! ```sh ape/apeinstall.sh ``` Since the Cosmopolitan repository is very large, you might only want to build a particular thing. Cosmopolitan's build config does a good job at having minimal deterministic builds. For example, if you wanted to build only hello.com then you could do that as follows: ```sh build/bootstrap/make.com -j16 o//examples/hello.com ``` Sometimes it's desirable to build a subset of targets, without having to list out each individual one. You can do that by asking make to build a directory name. For example, if you wanted to build only the targets and subtargets of the chibicc package including its tests, you would say: ```sh build/bootstrap/make.com -j16 o//third_party/chibicc o//third_party/chibicc/chibicc.com --help ``` Cosmopolitan provides a variety of build modes. For example, if you want really tiny binaries (as small as 12kb in size) then you'd say: ```sh build/bootstrap/make.com -j16 MODE=tiny ``` Here's some other build modes you can try: ```sh build/bootstrap/make.com -j16 MODE=dbg # asan + ubsan + debug build/bootstrap/make.com -j16 MODE=asan # production memory safety build/bootstrap/make.com -j16 MODE=opt # -march=native optimizations build/bootstrap/make.com -j16 MODE=rel # traditional release binaries build/bootstrap/make.com -j16 MODE=optlinux # optimal linux-only performance build/bootstrap/make.com -j16 MODE=tinylinux # tiniest linux-only 4kb binaries ``` For further details, see [//build/config.mk](build/config.mk). ## GDB Here's the recommended `~/.gdbinit` config: ``` set host-charset UTF-8 set target-charset UTF-8 set target-wide-charset UTF-8 set osabi none set complaints 0 set confirm off set history save on set history filename ~/.gdb_history define asm layout asm layout reg end define src layout src layout reg end src ``` You normally run the `.com.dbg` file under gdb. If you need to debug the `.com` file itself, then you can load the debug symbols independently as ``` gdb foo.com -ex 'add-symbol-file foo.com.dbg 0x401000' ``` ## Support Vector | Platform | Min Version | Circa | | :--- | ---: | ---: | | AMD | K8 Venus | 2005 | | Intel | Core | 2006 | | New Technology | Vista | 2006 | | GNU/Systemd | 2.6.18 | 2007 | | XNU's Not UNIX! | 15.6 | 2018 | | FreeBSD | 13 | 2020 | | OpenBSD | 6.4 | 2018 | | NetBSD | 9.2 | 2021 |