This makes breaking changes to add underscores to many non-standard
function names provided by the c library. MODE=tiny is now tinier and
we now use smaller locks that are better for tiny apps in this mode.
Some headers have been renamed to be in the same folder as the build
package, so it'll be easier to know which build dependency is needed.
Certain old misguided interfaces have been removed. Intel intrinsics
headers are now listed in libc/isystem (but not in the amalgamation)
to help further improve open source compatibility. Header complexity
has also been reduced. Lastly, more shell scripts are now available.
This change reconciles our pledge() implementation with the OpenBSD
kernel source code. We now a polyfill that's much closer to OpenBSD's
behavior. For example, it was discovered that "stdio" permits threads.
There were a bunch of Linux system calls that needed to be added, like
sched_yield(). The exec / execnative category division is now dropped.
We're instead using OpenBSD's "prot_exec" promise for launching APE
binaries and dynamic shared objects. We also now filter clone() flags.
The pledge.com command has been greatly improved. It now does unveiling
by default when Landlock is available. It's now smart enough to unveil a
superset of paths that OpenBSD automatically unveils with pledge(), such
as /etc/localtime. pledge.com also now checks if the executable being
launched is a dynamic shared object, in which case it unveils libraries.
These changes now make it possible to pledge curl on ubuntu 20.04 glibc:
pledge.com -p 'stdio rpath prot_exec inet dns tty sendfd recvfd' \
curl -s https://justine.lol/hello.txt
Here's what pledging curl on Alpine 3.16 with Musl Libc looks like:
pledge.com -p 'stdio rpath prot_exec dns inet' \
curl -s https://justine.lol/hello.txt
Here's what pledging curl.com w/ ape loader looks like:
pledge.com -p 'stdio rpath prot_exec dns inet' \
o//examples/curl.com https://justine.lol/hello.txt
The most secure sandbox, is curl.com converted to static ELF:
o//tool/build/assimilate.com o//examples/curl.com
pledge.com -p 'stdio rpath dns inet' \
o//examples/curl.com https://justine.lol/hello.txt
A weird corner case needed to be handled when resolving symbolic links
during the unveiling process, that's arguably a Landlock bug. It's not
surprising since Musl and Glibc are also inconsistent here too.
We had previously not enabled TLS in MODE=tiny in order to keep the
smallest example programs (e.g. life.com) just 16kb in size. But it
was error prone doing that, so now we just always enable it because
this change uses hacks to ensure it won't increase life.com's size.
This change also fixes a bug on NetBSD, where signal handlers would
break thread local storage if SA_SIGINFO was being used. This looks
like it might be a bug in NetBSD, but it's got a simple workaround.
Calls to lock/unlock functions are now NOPs by default. The first time
clone() is called, they get turned into CALL instructions. Doing this
caused funcctions like fputc() to shrink from 85 bytes to 45+4 bytes.
Since the ANSI solution of `(__threaded && lock())` inlines os much
superfluous binary content into functions all over the place.
