dev-util/b2: fix crash on Apple M1 due to undefined behavior.

Currently, the build system dev-util/b2-4.9.3, notably used
by Boost, crashes on Apple M1 w/ macOS with a Segmentation
Fault. This prevents one from using the tool, and also making
building Boost impossible. It's also notable since it contains
the keyword "~x64-macos", so it should receive first-class
macOS support.

It has been determined that when the NULL-terminated variadic
function call_rule() is invoked, the value 0 is passed as the
last argument to act as a terminator. However, this is an
integer value, which is incompatible with the pointer data type
expected by call_rule().

This is undefined behavior in C, correct operation is not guaranteed.
In fact, it causes b2 to crash on Apple M1 when GCC is used - the
loop is not terminated when it should, instead, it keeps
running, creating the following error:

    lol_add failed due to reached limit of 19 elements

In some cases, it can even corrupt the internal state of the
program, creating an infinite loop.

This commit fixes the problem by explicitly casting the value 0
to the correct pointer type (OBJECT *).

Since the existence of the bug doesn't prevent one from installing
the package, it can lurk inside the system and remain undetected,
furthermore, it's technically a C programming bug, other platforms
could've been affected as well in theory. Thus, we also bump the
package version.

Closes: https://bugs.gentoo.org/895524
Signed-off-by: Yifeng Li <tomli@tomli.me>
Closes: https://github.com/gentoo/gentoo/pull/29681
Signed-off-by: Sam James <sam@gentoo.org>

2 files changed, 122 insertions, 0 deletions

diff --git a/dev-util/b2/b2-4.9.3-r1.ebuild b/dev-util/b2/b2-4.9.3-r1.ebuild
new file mode 100644
index 000000000000..7ce4a20f5de2
--- /dev/null
+++ b/dev-util/b2/b2-4.9.3-r1.ebuild
@@ -0,0 +1,67 @@
+# Copyright 1999-2023 Gentoo Authors
+# Distributed under the terms of the GNU General Public License v2
+
+EAPI=8
+
+inherit edo flag-o-matic toolchain-funcs
+
+MY_PV="$(ver_rs 1- _)"
+
+DESCRIPTION="A system for large project software construction, simple to use and powerful"
+HOMEPAGE="https://www.bfgroup.xyz/b2/"
+SRC_URI="https://github.com/bfgroup/b2/archive/refs/tags/${PV}.tar.gz -> ${P}.tar.gz"
+S="${WORKDIR}/${P}/src"
+
+LICENSE="Boost-1.0"
+SLOT="0"
+KEYWORDS="~alpha amd64 arm arm64 hppa ~ia64 ~loong ~m68k ~mips ppc ppc64 ~riscv ~s390 sparc x86 ~x64-cygwin ~amd64-linux ~x86-linux ~ppc-macos ~x64-macos ~sparc-solaris ~sparc64-solaris ~x64-solaris ~x86-solaris"
+IUSE="examples"
+RESTRICT="test"
+
+RDEPEND="!dev-util/boost-build"
+
+PATCHES=(
+	"${FILESDIR}"/${PN}-4.9.2-disable_python_rpath.patch
+	"${FILESDIR}"/${PN}-4.9.2-darwin-gentoo-toolchain.patch
+	"${FILESDIR}"/${PN}-4.9.2-add-none-feature-options.patch
+	"${FILESDIR}"/${PN}-4.9.2-no-implicit-march-flags.patch
+	"${FILESDIR}"/${PN}-4.9.2-odr.patch
+	"${FILESDIR}"/${PN}-4.9.3-fix-apple-m1-crash-by-explicit-pointer-cast.patch
+)
+
+src_configure() {
+	# need to enable LFS explicitly for 64-bit offsets on 32-bit hosts (#761100)
+	append-lfs-flags
+}
+
+src_compile() {
+	cd engine || die
+
+	# upstream doesn't want separate flags for CPPFLAGS/LDFLAGS
+	# https://github.com/bfgroup/b2/pull/187#issuecomment-1335688424
+	edo ${CONFIG_SHELL:-${BASH}} ./build.sh cxx --cxx="$(tc-getCXX)" --cxxflags="${CXXFLAGS} ${CPPFLAGS} ${LDFLAGS}" -d+2 --without-python
+}
+
+src_test() {
+	# Forget tests, b2 is a lost cause
+	:
+}
+
+src_install() {
+	dobin engine/b2
+
+	insinto /usr/share/b2/src
+	doins -r "${FILESDIR}/site-config.jam" \
+		bootstrap.jam build-system.jam ../example/user-config.jam \
+		build kernel options tools util
+
+	find "${ED}"/usr/share/b2/src -iname '*.py' -delete || die
+
+	dodoc ../notes/{changes,release_procedure,build_dir_option,relative_source_paths}.txt
+
+	if use examples; then
+		docinto examples
+		dodoc -r ../example/.
+		docompress -x /usr/share/doc/${PF}/examples
+	fi
+}
diff --git a/dev-util/b2/files/b2-4.9.3-fix-apple-m1-crash-by-explicit-pointer-cast.patch b/dev-util/b2/files/b2-4.9.3-fix-apple-m1-crash-by-explicit-pointer-cast.patch
new file mode 100644
index 000000000000..753c60fd14ce
--- /dev/null
+++ b/dev-util/b2/files/b2-4.9.3-fix-apple-m1-crash-by-explicit-pointer-cast.patch
@@ -0,0 +1,55 @@
+https://github.com/bfgroup/b2/issues/152
+https://github.com/bfgroup/b2/pull/214
+https://bugs.gentoo.org/895524
+
+From 62dc6ff74a0b9717b4a8dd61ce06770e6fb7c177 Mon Sep 17 00:00:00 2001
+From: Yifeng Li <tomli@tomli.me>
+Date: Mon, 20 Feb 2023 09:52:32 +0000
+Subject: [PATCH] Fix #152 crash on Apple M1 by casting 0 to (OBJECT *)
+ explicitly.
+
+Currently, when the NULL-terminated variadic function call_rule()
+is invoked, the value "0" is passed as the last argument to act
+as a terminator. However, this is an integer value, which is
+incompatible with the pointer data type expected by call_rule().
+
+This is undefined behavior in C, correct operation is not
+guaranteed. In fact, it causes b2 to crash on Apple M1 when GCC
+is used - the loop is not terminated when it should, instead, it
+keeps running, creating the following error:
+
+> lol_add failed due to reached limit of 19 elements
+
+In some cases, it can even corrupt the internal state of the program,
+creating an infinite loop.
+
+This commit fixes the problem by explicitly casting the value 0 to
+the correct pointer type (OBJECT *).
+
+Signed-off-by: Yifeng Li <tomli@tomli.me>
+---
+ src/engine/modules/property-set.cpp | 4 ++--
+ 1 file changed, 2 insertions(+), 2 deletions(-)
+
+diff --git a/src/engine/modules/property-set.cpp b/src/engine/modules/property-set.cpp
+index 6e190a7639..b0d3c2dab8 100644
+--- src/engine/modules/property-set.cpp
++++ src/engine/modules/property-set.cpp
+@@ -162,7 +162,7 @@ LIST * property_set_create( FRAME * frame, int flags )
+         OBJECT * rulename = object_new( "new" );
+         OBJECT * varname = object_new( "self.raw" );
+         LIST * val = call_rule( rulename, frame,
+-            list_new( object_new( "property-set" ) ), 0 );
++            list_new( object_new( "property-set" ) ), (OBJECT *) 0 );
+         LISTITER iter, end;
+         object_free( rulename );
+         pos->value = object_copy( list_front( val ) );
+@@ -183,7 +183,7 @@ LIST * property_set_create( FRAME * frame, int flags )
+                 import_module( imports, frame->module );
+                 rulename = object_new( "errors.error" );
+                 call_rule( rulename, frame,
+-                    list_new( object_new( message->value ) ), 0 );
++                    list_new( object_new( message->value ) ), (OBJECT *) 0 );
+                 /* unreachable */
+                 string_free( message );
+                 list_free( imports );