mirror of https://github.com/jart/cosmopolitan.git synced 2025-01-31 11:37:35 +00:00

Justine Tunney 226aaf3547 Improve memory safety

This commit makes numerous refinements to cosmopolitan memory handling.

The default stack size has been reduced from 2mb to 128kb. A new macro
is now provided so you can easily reconfigure the stack size to be any
value you want. Work around the breaking change by adding to your main:

    STATIC_STACK_SIZE(0x00200000);  // 2mb stack

If you're not sure how much stack you need, then you can use:

    STATIC_YOINK("stack_usage_logging");

After which you can `sort -nr o/$MODE/stack.log`. Based on the unit test
suite, nothing in the Cosmopolitan repository (except for Python) needs
a stack size greater than 30kb. There are also new macros for detecting
the size and address of the stack at runtime, e.g. GetStackAddr(). We
also now support sigaltstack() so if you want to see nice looking crash
reports whenever a stack overflow happens, you can put this in main():

    ShowCrashReports();

Under `make MODE=dbg` and `make MODE=asan` the unit testing framework
will now automatically print backtraces of memory allocations when
things like memory leaks happen. Bugs are now fixed in ASAN global
variable overrun detection. The memtrack and asan runtimes also handle
edge cases now. The new tools helped to identify a few memory leaks,
which are fixed by this change.

This change should fix an issue reported in #288 with ARG_MAX limits.
Fixing this doubled the performance of MKDEPS.COM and AR.COM yet again.

2021-10-13 17:27:13 -07:00

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Cosmopolitan

Cosmopolitan Libc 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 blog post and cosmopolitan libc website. We also have API documentation.

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:

wget https://justine.lol/cosmopolitan/cosmopolitan-amalgamation-1.0.zip
unzip cosmopolitan-amalgamation-1.0.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.o cosmopolitan.a
objcopy -S -O binary hello.com.dbg hello.com

You now have a portable program. Please note that your APE binary will assimilate itself as a conventional resident of your platform after the first run, so it can be fast and efficient for subsequent executions.

./hello.com
bash -c './hello.com'  # zsh/fish workaround (we upstreamed patches)

So if you intend to copy the binary to Windows or Mac then please do that before you run it, not after.

MacOS

If you're developing on MacOS you can install the GNU compiler collection for x86_64-elf via homebrew:

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 tutorial. It's needed because the ELF object format is what makes universal binaries possible.

Source Builds

Cosmopolitan can be compiled from source on any Linux distro. GNU make needs to be installed beforehand. This is a freestanding hermetic repository that bootstraps using a vendored static gcc9 executable. No further dependencies are required.

wget https://justine.lol/cosmopolitan/cosmopolitan-1.0.tar.gz
tar xf cosmopolitan-1.0.tar.gz  # see releases page
cd cosmopolitan
make -j16
o//examples/hello.com
find o -name \*.com | xargs ls -rShal | less

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	12	2018
OpenBSD	6.4	2018
NetBSD	9.1	2020
GNU Make	4.0	2015

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