#!/usr/bin/env perl
# Copyright 2018 The Go Authors. All rights reserved.
# Use of this source code is governed by a BSD-style
# license that can be found in the LICENSE file.

# This program reads a file containing function prototypes
# (like syscall_aix.go) and generates system call bodies.
# The prototypes are marked by lines beginning with "//sys"
# and read like func declarations if //sys is replaced by func, but:
#	* The parameter lists must give a name for each argument.
#	  This includes return parameters.
#	* The parameter lists must give a type for each argument:
#	  the (x, y, z int) shorthand is not allowed.
#	* If the return parameter is an error number, it must be named err.
#	* If go func name needs to be different than its libc name,
#	* or the function is not in libc, name could be specified
#	* at the end, after "=" sign, like
#	  //sys getsockopt(s int, level int, name int, val uintptr, vallen *_Socklen) (err error) = libsocket.getsockopt

# This program will generate three files and handle both gc and gccgo implementation:
#   - zsyscall_aix_ppc64.go: the common part of each implementation (error handler, pointer creation)
#   - zsyscall_aix_ppc64_gc.go: gc part with //go_cgo_import_dynamic and a call to syscall6
#   - zsyscall_aix_ppc64_gccgo.go: gccgo part with C function and conversion to C type.

# The generated code looks like this
#
# zsyscall_aix_ppc64.go
# func asyscall(...) (n int, err error) {
#	  // Pointer Creation
#	  r1, e1 := callasyscall(...)
#	  // Type Conversion
#	  // Error Handler
#	  return
# }
#
# zsyscall_aix_ppc64_gc.go
# //go:cgo_import_dynamic libc_asyscall asyscall "libc.a/shr_64.o"
# //go:linkname libc_asyscall libc_asyscall
# var asyscall syscallFunc
#
# func callasyscall(...) (r1 uintptr, e1 Errno) {
#	  r1, _, e1 = syscall6(uintptr(unsafe.Pointer(&libc_asyscall)), "nb_args", ... )
#	  return
# }
#
# zsyscall_aix_ppc64_ggcgo.go
# /*
#  int asyscall(...)
#
# */
# import "C"
#
# func callasyscall(...) (r1 uintptr, e1 Errno) {
#	  r1 = uintptr(C.asyscall(...))
#	  e1 = syscall.GetErrno()
#	  return
# }


use strict;

my $cmdline = "mksyscall_aix_ppc64.pl " . join(' ', @ARGV);
my $errors = 0;
my $_32bit = "";
my $tags = "";  # build tags
my $aix = 0;
my $solaris = 0;

binmode STDOUT;

if($ARGV[0] eq "-b32") {
	$_32bit = "big-endian";
	shift;
} elsif($ARGV[0] eq "-l32") {
	$_32bit = "little-endian";
	shift;
}
if($ARGV[0] eq "-aix") {
	$aix = 1;
	shift;
}
if($ARGV[0] eq "-tags") {
	shift;
	$tags = $ARGV[0];
	shift;
}

if($ARGV[0] =~ /^-/) {
	print STDERR "usage: mksyscall_aix.pl [-b32 | -l32] [-tags x,y] [file ...]\n";
	exit 1;
}

sub parseparamlist($) {
	my ($list) = @_;
	$list =~ s/^\s*//;
	$list =~ s/\s*$//;
	if($list eq "") {
		return ();
	}
	return split(/\s*,\s*/, $list);
}

sub parseparam($) {
	my ($p) = @_;
	if($p !~ /^(\S*) (\S*)$/) {
		print STDERR "$ARGV:$.: malformed parameter: $p\n";
		$errors = 1;
		return ("xx", "int");
	}
	return ($1, $2);
}

my $package = "";
# GCCGO
my $textgccgo = "";
my $c_extern = "/*\n#include <stdint.h>\n";
# GC
my $textgc = "";
my $dynimports = "";
my $linknames = "";
my @vars = ();
# COMMUN
my $textcommon = "";

while(<>) {
	chomp;
	s/\s+/ /g;
	s/^\s+//;
	s/\s+$//;
	$package = $1 if !$package && /^package (\S+)$/;
	my $nonblock = /^\/\/sysnb /;
	next if !/^\/\/sys / && !$nonblock;

	# Line must be of the form
	# func Open(path string, mode int, perm int) (fd int, err error)
	# Split into name, in params, out params.
	if(!/^\/\/sys(nb)? (\w+)\(([^()]*)\)\s*(?:\(([^()]+)\))?\s*(?:=\s*(?:(\w*)\.)?(\w*))?$/) {
		print STDERR "$ARGV:$.: malformed //sys declaration\n";
		$errors = 1;
		next;
	}
	my ($nb, $func, $in, $out, $modname, $sysname) = ($1, $2, $3, $4, $5, $6);

	# Split argument lists on comma.
	my @in = parseparamlist($in);
	my @out = parseparamlist($out);

	$in = join(', ', @in);
	$out = join(', ', @out);

	if($sysname eq "") {
		$sysname = "$func";
	}

	my $onlyCommon = 0;
	if ($func eq "readlen" || $func eq "writelen" || $func eq "FcntlInt" || $func eq "FcntlFlock") {
		# This function call another syscall which is already implemented.
		# Therefore, the gc and gccgo part must not be generated.
		$onlyCommon = 1
	}

	# Try in vain to keep people from editing this file.
	# The theory is that they jump into the middle of the file
	# without reading the header.

	$textcommon .= "// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT\n\n";
	if (!$onlyCommon) {
		$textgccgo .= "// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT\n\n";
		$textgc .= "// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT\n\n";
	}


	# Check if value return, err return available
	my $errvar = "";
	my $retvar = "";
	my $rettype = "";
	foreach my $p (@out) {
		my ($name, $type) = parseparam($p);
		if($type eq "error") {
			$errvar = $name;
		} else {
			$retvar = $name;
			$rettype = $type;
		}
	}


	$sysname =~ s/([a-z])([A-Z])/${1}_$2/g;
	$sysname =~ y/A-Z/a-z/; # All libc functions are lowercase.

	# GCCGO Prototype return type
	my $C_rettype = "";
	if($rettype eq "unsafe.Pointer") {
		$C_rettype = "uintptr_t";
	} elsif($rettype eq "uintptr") {
		$C_rettype = "uintptr_t";
	} elsif($rettype =~ /^_/) {
		$C_rettype = "uintptr_t";
	} elsif($rettype eq "int") {
		$C_rettype = "int";
	} elsif($rettype eq "int32") {
		$C_rettype = "int";
	} elsif($rettype eq "int64") {
		$C_rettype = "long long";
	} elsif($rettype eq "uint32") {
		$C_rettype = "unsigned int";
	} elsif($rettype eq "uint64") {
		$C_rettype = "unsigned long long";
	} else {
		$C_rettype = "int";
	}
	if($sysname eq "exit") {
		$C_rettype = "void";
	}

	# GCCGO Prototype arguments type
	my @c_in = ();
	foreach my $i (0 .. $#in) {
		my ($name, $type) = parseparam($in[$i]);
		if($type =~ /^\*/) {
			push @c_in, "uintptr_t";
			} elsif($type eq "string") {
			push @c_in, "uintptr_t";
		} elsif($type =~ /^\[\](.*)/) {
			push @c_in, "uintptr_t", "size_t";
		} elsif($type eq "unsafe.Pointer") {
			push @c_in, "uintptr_t";
		} elsif($type eq "uintptr") {
			push @c_in, "uintptr_t";
		} elsif($type =~ /^_/) {
			push @c_in, "uintptr_t";
		} elsif($type eq "int") {
			if (($i == 0 || $i == 2) && $func eq "fcntl"){
				# These fcntl arguments needs to be uintptr to be able to call FcntlInt and FcntlFlock
				push @c_in, "uintptr_t";
			} else {
				push @c_in, "int";
			}
		} elsif($type eq "int32") {
			push @c_in, "int";
		} elsif($type eq "int64") {
			push @c_in, "long long";
		} elsif($type eq "uint32") {
			push @c_in, "unsigned int";
		} elsif($type eq "uint64") {
			push @c_in, "unsigned long long";
		} else {
			push @c_in, "int";
		}
	}

	if (!$onlyCommon){
		# GCCGO Prototype Generation
		# Imports of system calls from libc
		$c_extern .= "$C_rettype $sysname";
		my $c_in = join(', ', @c_in);
		$c_extern .= "($c_in);\n";
	}

	# GC Library name
	if($modname eq "") {
		$modname = "libc.a/shr_64.o";
	} else {
		print STDERR "$func: only syscall using libc are available\n";
		$errors = 1;
		next;
	}
	my $sysvarname = "libc_${sysname}";

	if (!$onlyCommon){
		# GC Runtime import of function to allow cross-platform builds.
		$dynimports .= "//go:cgo_import_dynamic ${sysvarname} ${sysname} \"$modname\"\n";
		# GC Link symbol to proc address variable.
		$linknames .= "//go:linkname ${sysvarname} ${sysvarname}\n";
		# GC Library proc address variable.
		push @vars, $sysvarname;
	}

	my $strconvfunc ="BytePtrFromString";
	my $strconvtype = "*byte";

	# Go function header.
	if($out ne "") {
		$out = " ($out)";
	}
	if($textcommon ne "") {
		$textcommon .= "\n"
	}

	$textcommon .= sprintf "func %s(%s)%s {\n", $func, join(', ', @in), $out ;

	# Prepare arguments to call.
	my @argscommun = (); # Arguments in the commun part
	my @argscall = ();   # Arguments for call prototype
	my @argsgc = ();     # Arguments for gc call (with syscall6)
	my @argsgccgo = ();  # Arguments for gccgo call (with C.name_of_syscall)
	my $n = 0;
	my $arg_n = 0;
	foreach my $p (@in) {
		my ($name, $type) = parseparam($p);
		if($type =~ /^\*/) {
			push @argscommun, "uintptr(unsafe.Pointer($name))";
			push @argscall, "$name uintptr";
			push @argsgc, "$name";
			push @argsgccgo, "C.uintptr_t($name)";
		} elsif($type eq "string" && $errvar ne "") {
			$textcommon .= "\tvar _p$n $strconvtype\n";
			$textcommon .= "\t_p$n, $errvar = $strconvfunc($name)\n";
			$textcommon .= "\tif $errvar != nil {\n\t\treturn\n\t}\n";

			push @argscommun, "uintptr(unsafe.Pointer(_p$n))";
			push @argscall, "_p$n uintptr ";
			push @argsgc, "_p$n";
			push @argsgccgo, "C.uintptr_t(_p$n)";
			$n++;
		} elsif($type eq "string") {
			print STDERR "$ARGV:$.: $func uses string arguments, but has no error return\n";
			$textcommon .= "\tvar _p$n $strconvtype\n";
			$textcommon .= "\t_p$n, $errvar = $strconvfunc($name)\n";
			$textcommon .= "\tif $errvar != nil {\n\t\treturn\n\t}\n";

			push @argscommun, "uintptr(unsafe.Pointer(_p$n))";
			push @argscall, "_p$n uintptr";
			push @argsgc, "_p$n";
			push @argsgccgo, "C.uintptr_t(_p$n)";
			$n++;
		} elsif($type =~ /^\[\](.*)/) {
			# Convert slice into pointer, length.
			# Have to be careful not to take address of &a[0] if len == 0:
			# pass nil in that case.
			$textcommon .= "\tvar _p$n *$1\n";
			$textcommon .= "\tif len($name) > 0 {\n\t\t_p$n = \&$name\[0]\n\t}\n";
			push @argscommun, "uintptr(unsafe.Pointer(_p$n))", "len($name)";
			push @argscall, "_p$n uintptr", "_lenp$n int";
			push @argsgc, "_p$n", "uintptr(_lenp$n)";
			push @argsgccgo, "C.uintptr_t(_p$n)", "C.size_t(_lenp$n)";
			$n++;
		} elsif($type eq "int64" && $_32bit ne "") {
			print STDERR "$ARGV:$.: $func uses int64 with 32 bits mode. Case not yet implemented\n";
			# if($_32bit eq "big-endian") {
			# 	push @args, "uintptr($name >> 32)", "uintptr($name)";
			# } else {
			# 	push @args, "uintptr($name)", "uintptr($name >> 32)";
			# }
			# $n++;
		} elsif($type eq "bool") {
			print STDERR "$ARGV:$.: $func uses bool. Case not yet implemented\n";
			# $text .= "\tvar _p$n uint32\n";
			# $text .= "\tif $name {\n\t\t_p$n = 1\n\t} else {\n\t\t_p$n = 0\n\t}\n";
			# push @args, "_p$n";
			# $n++;
		} elsif($type =~ /^_/ ||$type eq "unsafe.Pointer") {
			push @argscommun, "uintptr($name)";
			push @argscall, "$name uintptr";
			push @argsgc, "$name";
			push @argsgccgo, "C.uintptr_t($name)";
		} elsif($type eq "int") {
			if (($arg_n == 0 || $arg_n == 2) && ($func eq "fcntl" || $func eq "FcntlInt" || $func eq "FcntlFlock")) {
				# These fcntl arguments need to be uintptr to be able to call FcntlInt and FcntlFlock
				push @argscommun, "uintptr($name)";
				push @argscall, "$name uintptr";
				push @argsgc, "$name";
				push @argsgccgo, "C.uintptr_t($name)";
			} else {
				push @argscommun, "$name";
				push @argscall, "$name int";
				push @argsgc, "uintptr($name)";
				push @argsgccgo, "C.int($name)";
			}
		} elsif($type eq "int32") {
			push @argscommun, "$name";
			push @argscall, "$name int32";
			push @argsgc, "uintptr($name)";
			push @argsgccgo, "C.int($name)";
		} elsif($type eq "int64") {
			push @argscommun, "$name";
			push @argscall, "$name int64";
			push @argsgc, "uintptr($name)";
			push @argsgccgo, "C.longlong($name)";
		} elsif($type eq "uint32") {
			push @argscommun, "$name";
			push @argscall, "$name uint32";
			push @argsgc, "uintptr($name)";
			push @argsgccgo, "C.uint($name)";
		} elsif($type eq "uint64") {
			push @argscommun, "$name";
			push @argscall, "$name uint64";
			push @argsgc, "uintptr($name)";
			push @argsgccgo, "C.ulonglong($name)";
		} elsif($type eq "uintptr") {
			push @argscommun, "$name";
			push @argscall, "$name uintptr";
			push @argsgc, "$name";
			push @argsgccgo, "C.uintptr_t($name)";
		} else {
			push @argscommun, "int($name)";
			push @argscall, "$name int";
			push @argsgc, "uintptr($name)";
			push @argsgccgo, "C.int($name)";
		}
		$arg_n++;
	}
	my $nargs = @argsgc;

	# COMMUN function generation
	my $argscommun = join(', ', @argscommun);
	my $callcommun = "call$sysname($argscommun)";
	my @ret = ("_", "_");
	my $body = "";
	my $do_errno = 0;
	for(my $i=0; $i<@out; $i++) {
		my $p = $out[$i];
		my ($name, $type) = parseparam($p);
		my $reg = "";
		if($name eq "err") {
			$reg = "e1";
			$ret[1] = $reg;
			$do_errno = 1;
		} else {
			$reg = "r0";
			$ret[0] = $reg;
		}
		if($type eq "bool") {
			$reg = "$reg != 0";
		}
		if($reg ne "e1") {
			$body .= "\t$name = $type($reg)\n";
		}
	}
	if ($ret[0] eq "_"  && $ret[1] eq "_") {
		$textcommon .= "\t$callcommun\n";
	} else {
		$textcommon .= "\t$ret[0], $ret[1] := $callcommun\n";
	}
	$textcommon .= $body;

	if ($do_errno) {
		$textcommon .= "\tif e1 != 0 {\n";
		$textcommon .= "\t\terr = errnoErr(e1)\n";
		$textcommon .= "\t}\n";
	}
	$textcommon .= "\treturn\n";
	$textcommon .= "}\n";

	if ($onlyCommon){
		next
	}
	# CALL Prototype
	my $callProto = sprintf "func call%s(%s) (r1 uintptr, e1 Errno) {\n", $sysname, join(', ', @argscall);

	# GC function generation
	my $asm = "syscall6";
	if ($nonblock) {
		$asm = "rawSyscall6";
	}

	if(@argsgc <= 6) {
		while(@argsgc < 6) {
			push @argsgc, "0";
		}
	} else {
		print STDERR "$ARGV:$.: too many arguments to system call\n";
	}
	my $argsgc = join(', ', @argsgc);
	my $callgc = "$asm(uintptr(unsafe.Pointer(&$sysvarname)), $nargs, $argsgc)";

	$textgc .= $callProto;
	$textgc .= "\tr1, _, e1 = $callgc\n";
	$textgc .= "\treturn\n}\n";

	# GCCGO function generation
	my $argsgccgo = join(', ', @argsgccgo);
	my $callgccgo = "C.$sysname($argsgccgo)";
	$textgccgo .= $callProto;
	$textgccgo .= "\tr1 = uintptr($callgccgo)\n";
	$textgccgo .= "\te1 = syscall.GetErrno()\n";
	$textgccgo .= "\treturn\n}\n";
}

if($errors) {
	exit 1;
}

# Print zsyscall_aix_ppc64.go
open(my $fcommun, '>', 'zsyscall_aix_ppc64.go');
my $tofcommun = <<EOF;
// $cmdline
// Code generated by the command above; see README.md. DO NOT EDIT.

// +build $tags

package $package

import (
	"unsafe"
)

EOF

$tofcommun .= "import \"golang.org/x/sys/unix\"\n" if $package ne "unix";

$tofcommun .=<<EOF;

$textcommon
EOF
print $fcommun $tofcommun;


# Print zsyscall_aix_ppc64_gc.go
open(my $fgc, '>', 'zsyscall_aix_ppc64_gc.go');
my $tofgc = <<EOF;
// $cmdline
// Code generated by the command above; see README.md. DO NOT EDIT.

// +build $tags
// +build !gccgo

package $package

import (
	"unsafe"
)


EOF

$tofgc .= "import \"golang.org/x/sys/unix\"\n" if $package ne "unix";

my $vardecls = "\t" . join(",\n\t", @vars);
$vardecls .= " syscallFunc";

$tofgc .=<<EOF;
$dynimports
$linknames
type syscallFunc uintptr

var (
$vardecls
)

// Implemented in runtime/syscall_aix.go.
func rawSyscall6(trap, nargs, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2 uintptr, err Errno)
func syscall6(trap, nargs, a1, a2, a3, a4, a5, a6 uintptr) (r1, r2 uintptr, err Errno)

$textgc
EOF
print $fgc $tofgc;

# Print zsyscall_aix_ppc64_gc.go
open(my $fgccgo, '>', 'zsyscall_aix_ppc64_gccgo.go');
my $tofgccgo = <<EOF;
// $cmdline
// Code generated by the command above; see README.md. DO NOT EDIT.

// +build $tags
// +build gccgo

package $package


$c_extern
*/
import "C"
import (
	"syscall"
)


EOF

$tofgccgo .= "import \"golang.org/x/sys/unix\"\n" if $package ne "unix";

$tofgccgo .=<<EOF;

$textgccgo
EOF
print $fgccgo $tofgccgo;
exit 0;