Initial import

libc/crt/crt.S

@@ -0,0 +1,56 @@
+/*-*- mode:asm; indent-tabs-mode:t; tab-width:8; coding:utf-8               -*-│
+│vi: set et ft=asm ts=8 tw=8 fenc=utf-8                                     :vi│
+╞══════════════════════════════════════════════════════════════════════════════╡
+│ Copyright 2020 Justine Alexandra Roberts Tunney                              │
+│                                                                              │
+│ This program is free software; you can redistribute it and/or modify         │
+│ it under the terms of the GNU General Public License as published by         │
+│ the Free Software Foundation; version 2 of the License.                      │
+│                                                                              │
+│ This program is distributed in the hope that it will be useful, but          │
+│ WITHOUT ANY WARRANTY; without even the implied warranty of                   │
+│ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU             │
+│ General Public License for more details.                                     │
+│                                                                              │
+│ You should have received a copy of the GNU General Public License            │
+│ along with this program; if not, write to the Free Software                  │
+│ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA                │
+│ 02110-1301 USA                                                               │
+╚─────────────────────────────────────────────────────────────────────────────*/
+#include "libc/dce.h"
+#include "libc/macros.h"
+#include "libc/notice.inc"
+#include "libc/runtime/internal.h"
+.section .start,"ax",@progbits
+.yoink	__FILE__
+
+/	System Five userspace program entrypoint.
+/
+/	@param	rsp is [n,argv₀..argvₙ₋₁,0,envp₀..,0,auxv₀..,0,..]
+/	@note	FreeBSD is special (see freebsd/lib/csu/amd64/...)
+/	@noreturn
+_start_xnu:
+	movb	$XNU,hostos(%rip)
+	jmp	0f
+_start:	test	%rdi,%rdi
+	cmovnz	%rdi,%rsp
+	jz	0f
+	movb	$FREEBSD,hostos(%rip)
+0:	movslq	(%rsp),%r12			# argc
+	lea	8(%rsp),%r13			# argv
+	lea	24(%rsp,%r12,8),%r14		# envp
+	.weak	idata.iat,idata.iatend
+	ezlea	missingno,ax			# make win32 imps noop
+	ezlea	idata.iat,di
+	ezlea	idata.iatend,cx
+	sub	%rdi,%rcx
+	shr	$3,%ecx
+	rep stosq
+	xor	%eax,%eax			# find end of environ
+	or	$-1,%ecx
+	mov	%r14,%rdi
+	repnz scasq
+	mov	%rdi,%r15			# auxv
+	jmp	__executive
+	.endfn	_start,weak,hidden
+	.endfn	_start_xnu,weak,hidden

libc/crt/crt.mk

@@ -0,0 +1,30 @@
+#-*-mode:makefile-gmake;indent-tabs-mode:t;tab-width:8;coding:utf-8-*-┐
+#───vi: set et ft=make ts=8 tw=8 fenc=utf-8 :vi───────────────────────┘
+#
+# SYNOPSIS
+#
+#   Cosmopolitan C Runtime.
+#
+# OVERVIEW
+#
+#   This is a special object library defining the Cosmopolitan SysV
+#   userspace runtime entrypoint, i.e. _start(). The $(CRT) argument
+#   should come first in the link order when building ELF binaries;
+#   becauseo it's the lowest level function; it wraps main(); and it
+#   decides which runtime support libraries get schlepped into builds.
+#
+#   Please note that, when building an αcτµαlly pδrταblε εxεcµταblε,
+#   lower-level entrypoints exist and as such, $(CRT) will generally
+#   come second in link-order after $(APE).
+
+PKGS += CRT
+
+CRT_ARTIFACTS += CRT
+CRT = o/$(MODE)/libc/crt/crt.o
+CRT_FILES = libc/crt/crt.S
+CRT_SRCS = libc/crt/crt.S
+CRT_OBJS = o/$(MODE)/libc/crt/crt.o o/$(MODE)/libc/crt/crt.S.zip.o
+$(CRT_OBJS): $(BUILD_FILES) libc/crt/crt.mk
+
+.PHONY: o/$(MODE)/libc/crt
+o/$(MODE)/libc/crt: $(CRT)