Support Linux binfmt_misc and APE loading on Apple

The "no modify self" variant of Actually Portable Executable is now
supported on all platforms. If you use `$(APE_NO_MODIFY_SELF)` then
ld.bfd will embed a 4096 byte ELF binary and a 4096 byte Macho file
which are installed on the fly to ${TMPDIR:-/tmp}, which enables us
launch the executable, without needing to copy the whole executable

To prevent it from copying a tiny executable to your temp directory
you need to install the `ape` command (renamed from ape-loader), to
a system path. For example:

    # FreeBSD / NetBSD / OpenBSD
    make -j8 o//ape/ape
    cp o//ape/ape /usr/bin/ape

    # Mac OS
    # make -j8 o//ape/ape.macho
    curl https://justine.lol/ape.macho >/usr/bin/ape
    chmod +x /usr/bin/ape

On Linux you can get even more performance with the new binfmt_misc
support which makes launching non-modifying APE binaries as fast as
launching ELF executables. Running the following command:

    # Linux
    ape/apeinstall.sh

Will copy APE loader to /usr/bin/ape and register with binfmt_misc
Lastly, this change also fixes a really interesting race condition
with OpenBSD thread joining.
This commit is contained in:
Justine Tunney 2022-05-21 07:52:58 -07:00
parent 7838edae88
commit db0d8dd806
31 changed files with 1089 additions and 305 deletions

View file

@ -21,6 +21,7 @@
#include "libc/calls/sigbits.h"
#include "libc/calls/strace.internal.h"
#include "libc/intrin/cmpxchg.h"
#include "libc/intrin/lockcmpxchg.h"
#include "libc/intrin/spinlock.h"
#include "libc/log/libfatal.internal.h"
#include "libc/macros.internal.h"
@ -131,9 +132,7 @@ static privileged bool __sig_deliver(bool restartable, int sig, int si_code,
// since sigaction() is @asyncsignalsafe we only restore it if the
// user didn't change it during the signal handler. we also don't
// need to do anything if this was a oneshot signal or nodefer.
_spinlock(&__sig_lock);
_cmpxchg(__sighandrvas + sig, (int32_t)(intptr_t)SIG_DFL, rva);
_spunlock(&__sig_lock);
_lockcmpxchg(__sighandrvas + sig, (int32_t)(intptr_t)SIG_DFL, rva);
}
if (!restartable) {