Initial public snapshot

With code from Bill. Thanks Bill!

1 files changed, 91 insertions, 0 deletions

diff --git a/src/abi.h b/src/abi.h
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+++ b/src/abi.h
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+/*
+ * Copyright © 2021 Michael Smith <mikesmiffy128@gmail.com>
+ *
+ * Permission to use, copy, modify, and/or distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+ * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+ * AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+ * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+ * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+ * OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+ * PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#ifndef INC_ABI_H
+#define INC_ABI_H
+
+#include "intdefs.h"
+
+/*
+ * This file defines miscellaneous C++ ABI stuff. Looking at it may cause
+ * brain damage and/or emotional trauma.
+ */
+
+#ifdef _WIN32 // Windows RTTI stuff, obviously only used on Windows.
+
+// MSVC RTTI is quite a black box, but thankfully there's some useful sources:
+// - https://doxygen.reactos.org/d0/dcf/cxx_8h_source.html
+// - https://blog.quarkslab.com/visual-c-rtti-inspection.html
+// - https://www.geoffchappell.com/studies/msvc/language/predefined/
+// - https://docs.rs/pelite/0.5.0/src/pelite/pe32/msvc.rs.html
+
+// By the way, while I'm here I'd just like to point out how ridiculous this
+// layout is. Whoever decided to put this many levels of indirection over what
+// should be a small lookup table is an absolute nutcase. I hope that individual
+// has gotten some help by now, mostly for the sake of others.
+
+struct msvc_rtti_descriptor {
+	void *vtab;
+	void *unknown; // ???
+	// XXX: pretty sure this is supposed to be flexible, but too lazy to write
+	// the stupid union init macros to make that fully portable
+	char classname[80];
+};
+
+// "pointer to member displacement"
+struct msvc_pmd { int mdisp, pdisp, vdisp; };
+
+struct msvc_basedesc {
+	struct msvc_rtti_descriptor *desc;
+	uint nbases;
+	struct msvc_pmd where;
+	uint attr;
+};
+
+struct msvc_rtti_hierarchy {
+	uint sig;
+	uint attrs;
+	uint nbaseclasses;
+	struct msvc_basedesc **baseclasses;
+};
+
+struct msvc_rtti_locator {
+	uint sig;
+	int baseoff;
+	// ctor offset, or some flags; reactos and rust pelite say different things?
+	int unknown;
+	struct msvc_rtti_descriptor *desc;
+	struct msvc_rtti_hierarchy *hier;
+};
+
+// I mean seriously look at this crap!
+#define DEF_MSVC_BASIC_RTTI(mod, name, vtab, typestr) \
+mod struct msvc_rtti_locator name; \
+static struct msvc_rtti_descriptor _desc_##name = {(vtab) + 1, 0, typestr}; \
+static struct msvc_basedesc _basedesc_##name = {&_desc_##name, 0, {0, 0, 0}, 0}; \
+mod struct msvc_rtti_locator name = { \
+	0, 0, 0, \
+	&_desc_##name, \
+	&(struct msvc_rtti_hierarchy){ \
+		0, 1 /* per engine */, 1, (struct msvc_basedesc *[]){&_basedesc_##name} \
+	} \
+};
+
+#endif
+
+#endif
+
+// vi: sw=4 ts=4 noet tw=80 cc=80