1#!/usr/bin/env perl
2# Copyright 2009 The Go Authors. All rights reserved.
3# Use of this source code is governed by a BSD-style
4# license that can be found in the LICENSE file.
5
6# This program reads a file containing function prototypes
7# (like syscall_darwin.go) and generates system call bodies.
8# The prototypes are marked by lines beginning with "//sys"
9# and read like func declarations if //sys is replaced by func, but:
10#	* The parameter lists must give a name for each argument.
11#	  This includes return parameters.
12#	* The parameter lists must give a type for each argument:
13#	  the (x, y, z int) shorthand is not allowed.
14#	* If the return parameter is an error number, it must be named errno.
15
16# A line beginning with //sysnb is like //sys, except that the
17# goroutine will not be suspended during the execution of the system
18# call.  This must only be used for system calls which can never
19# block, as otherwise the system call could cause all goroutines to
20# hang.
21
22use strict;
23
24my $cmdline = "mksyscall.pl " . join(' ', @ARGV);
25my $errors = 0;
26my $_32bit = "";
27my $plan9 = 0;
28my $openbsd = 0;
29my $netbsd = 0;
30my $dragonfly = 0;
31my $arm = 0; # 64-bit value should use (even, odd)-pair
32my $tags = "";  # build tags
33
34if($ARGV[0] eq "-b32") {
35	$_32bit = "big-endian";
36	shift;
37} elsif($ARGV[0] eq "-l32") {
38	$_32bit = "little-endian";
39	shift;
40}
41if($ARGV[0] eq "-plan9") {
42	$plan9 = 1;
43	shift;
44}
45if($ARGV[0] eq "-openbsd") {
46	$openbsd = 1;
47	shift;
48}
49if($ARGV[0] eq "-netbsd") {
50	$netbsd = 1;
51	shift;
52}
53if($ARGV[0] eq "-dragonfly") {
54	$dragonfly = 1;
55	shift;
56}
57if($ARGV[0] eq "-arm") {
58	$arm = 1;
59	shift;
60}
61if($ARGV[0] eq "-tags") {
62	shift;
63	$tags = $ARGV[0];
64	shift;
65}
66
67if($ARGV[0] =~ /^-/) {
68	print STDERR "usage: mksyscall.pl [-b32 | -l32] [-tags x,y] [file ...]\n";
69	exit 1;
70}
71
72# Check that we are using the new build system if we should
73if($ENV{'GOOS'} eq "linux" && $ENV{'GOARCH'} ne "sparc64") {
74	if($ENV{'GOLANG_SYS_BUILD'} ne "docker") {
75		print STDERR "In the new build system, mksyscall should not be called directly.\n";
76		print STDERR "See README.md\n";
77		exit 1;
78	}
79}
80
81
82sub parseparamlist($) {
83	my ($list) = @_;
84	$list =~ s/^\s*//;
85	$list =~ s/\s*$//;
86	if($list eq "") {
87		return ();
88	}
89	return split(/\s*,\s*/, $list);
90}
91
92sub parseparam($) {
93	my ($p) = @_;
94	if($p !~ /^(\S*) (\S*)$/) {
95		print STDERR "$ARGV:$.: malformed parameter: $p\n";
96		$errors = 1;
97		return ("xx", "int");
98	}
99	return ($1, $2);
100}
101
102my $text = "";
103while(<>) {
104	chomp;
105	s/\s+/ /g;
106	s/^\s+//;
107	s/\s+$//;
108	my $nonblock = /^\/\/sysnb /;
109	next if !/^\/\/sys / && !$nonblock;
110
111	# Line must be of the form
112	#	func Open(path string, mode int, perm int) (fd int, errno error)
113	# Split into name, in params, out params.
114	if(!/^\/\/sys(nb)? (\w+)\(([^()]*)\)\s*(?:\(([^()]+)\))?\s*(?:=\s*((?i)SYS_[A-Z0-9_]+))?$/) {
115		print STDERR "$ARGV:$.: malformed //sys declaration\n";
116		$errors = 1;
117		next;
118	}
119	my ($func, $in, $out, $sysname) = ($2, $3, $4, $5);
120
121	# Split argument lists on comma.
122	my @in = parseparamlist($in);
123	my @out = parseparamlist($out);
124
125	# Try in vain to keep people from editing this file.
126	# The theory is that they jump into the middle of the file
127	# without reading the header.
128	$text .= "// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT\n\n";
129
130	# Go function header.
131	my $out_decl = @out ? sprintf(" (%s)", join(', ', @out)) : "";
132	$text .= sprintf "func %s(%s)%s {\n", $func, join(', ', @in), $out_decl;
133
134	# Check if err return available
135	my $errvar = "";
136	foreach my $p (@out) {
137		my ($name, $type) = parseparam($p);
138		if($type eq "error") {
139			$errvar = $name;
140			last;
141		}
142	}
143
144	# Prepare arguments to Syscall.
145	my @args = ();
146	my $n = 0;
147	foreach my $p (@in) {
148		my ($name, $type) = parseparam($p);
149		if($type =~ /^\*/) {
150			push @args, "uintptr(unsafe.Pointer($name))";
151		} elsif($type eq "string" && $errvar ne "") {
152			$text .= "\tvar _p$n *byte\n";
153			$text .= "\t_p$n, $errvar = BytePtrFromString($name)\n";
154			$text .= "\tif $errvar != nil {\n\t\treturn\n\t}\n";
155			push @args, "uintptr(unsafe.Pointer(_p$n))";
156			$n++;
157		} elsif($type eq "string") {
158			print STDERR "$ARGV:$.: $func uses string arguments, but has no error return\n";
159			$text .= "\tvar _p$n *byte\n";
160			$text .= "\t_p$n, _ = BytePtrFromString($name)\n";
161			push @args, "uintptr(unsafe.Pointer(_p$n))";
162			$n++;
163		} elsif($type =~ /^\[\](.*)/) {
164			# Convert slice into pointer, length.
165			# Have to be careful not to take address of &a[0] if len == 0:
166			# pass dummy pointer in that case.
167			# Used to pass nil, but some OSes or simulators reject write(fd, nil, 0).
168			$text .= "\tvar _p$n unsafe.Pointer\n";
169			$text .= "\tif len($name) > 0 {\n\t\t_p$n = unsafe.Pointer(\&${name}[0])\n\t}";
170			$text .= " else {\n\t\t_p$n = unsafe.Pointer(&_zero)\n\t}";
171			$text .= "\n";
172			push @args, "uintptr(_p$n)", "uintptr(len($name))";
173			$n++;
174		} elsif($type eq "int64" && ($openbsd || $netbsd)) {
175			push @args, "0";
176			if($_32bit eq "big-endian") {
177				push @args, "uintptr($name>>32)", "uintptr($name)";
178			} elsif($_32bit eq "little-endian") {
179				push @args, "uintptr($name)", "uintptr($name>>32)";
180			} else {
181				push @args, "uintptr($name)";
182			}
183		} elsif($type eq "int64" && $dragonfly) {
184			if ($func !~ /^extp(read|write)/i) {
185				push @args, "0";
186			}
187			if($_32bit eq "big-endian") {
188				push @args, "uintptr($name>>32)", "uintptr($name)";
189			} elsif($_32bit eq "little-endian") {
190				push @args, "uintptr($name)", "uintptr($name>>32)";
191			} else {
192				push @args, "uintptr($name)";
193			}
194		} elsif($type eq "int64" && $_32bit ne "") {
195			if(@args % 2 && $arm) {
196				# arm abi specifies 64-bit argument uses
197				# (even, odd) pair
198				push @args, "0"
199			}
200			if($_32bit eq "big-endian") {
201				push @args, "uintptr($name>>32)", "uintptr($name)";
202			} else {
203				push @args, "uintptr($name)", "uintptr($name>>32)";
204			}
205		} else {
206			push @args, "uintptr($name)";
207		}
208	}
209
210	# Determine which form to use; pad args with zeros.
211	my $asm = "Syscall";
212	if ($nonblock) {
213		if ($errvar eq "" && $ENV{'GOOS'} eq "linux") {
214			$asm = "RawSyscallNoError";
215		} else {
216			$asm = "RawSyscall";
217		}
218	} else {
219		if ($errvar eq "" && $ENV{'GOOS'} eq "linux") {
220			$asm = "SyscallNoError";
221		}
222	}
223	if(@args <= 3) {
224		while(@args < 3) {
225			push @args, "0";
226		}
227	} elsif(@args <= 6) {
228		$asm .= "6";
229		while(@args < 6) {
230			push @args, "0";
231		}
232	} elsif(@args <= 9) {
233		$asm .= "9";
234		while(@args < 9) {
235			push @args, "0";
236		}
237	} else {
238		print STDERR "$ARGV:$.: too many arguments to system call\n";
239	}
240
241	# System call number.
242	if($sysname eq "") {
243		$sysname = "SYS_$func";
244		$sysname =~ s/([a-z])([A-Z])/${1}_$2/g;	# turn FooBar into Foo_Bar
245		$sysname =~ y/a-z/A-Z/;
246	}
247
248	# Actual call.
249	my $args = join(', ', @args);
250	my $call = "$asm($sysname, $args)";
251
252	# Assign return values.
253	my $body = "";
254	my @ret = ("_", "_", "_");
255	my $do_errno = 0;
256	for(my $i=0; $i<@out; $i++) {
257		my $p = $out[$i];
258		my ($name, $type) = parseparam($p);
259		my $reg = "";
260		if($name eq "err" && !$plan9) {
261			$reg = "e1";
262			$ret[2] = $reg;
263			$do_errno = 1;
264		} elsif($name eq "err" && $plan9) {
265			$ret[0] = "r0";
266			$ret[2] = "e1";
267			next;
268		} else {
269			$reg = sprintf("r%d", $i);
270			$ret[$i] = $reg;
271		}
272		if($type eq "bool") {
273			$reg = "$reg != 0";
274		}
275		if($type eq "int64" && $_32bit ne "") {
276			# 64-bit number in r1:r0 or r0:r1.
277			if($i+2 > @out) {
278				print STDERR "$ARGV:$.: not enough registers for int64 return\n";
279			}
280			if($_32bit eq "big-endian") {
281				$reg = sprintf("int64(r%d)<<32 | int64(r%d)", $i, $i+1);
282			} else {
283				$reg = sprintf("int64(r%d)<<32 | int64(r%d)", $i+1, $i);
284			}
285			$ret[$i] = sprintf("r%d", $i);
286			$ret[$i+1] = sprintf("r%d", $i+1);
287		}
288		if($reg ne "e1" || $plan9) {
289			$body .= "\t$name = $type($reg)\n";
290		}
291	}
292	if ($ret[0] eq "_" && $ret[1] eq "_" && $ret[2] eq "_") {
293		$text .= "\t$call\n";
294	} else {
295		if ($errvar eq "" && $ENV{'GOOS'} eq "linux") {
296			# raw syscall without error on Linux, see golang.org/issue/22924
297			$text .= "\t$ret[0], $ret[1] := $call\n";
298		} else {
299			$text .= "\t$ret[0], $ret[1], $ret[2] := $call\n";
300		}
301	}
302	$text .= $body;
303
304	if ($plan9 && $ret[2] eq "e1") {
305		$text .= "\tif int32(r0) == -1 {\n";
306		$text .= "\t\terr = e1\n";
307		$text .= "\t}\n";
308	} elsif ($do_errno) {
309		$text .= "\tif e1 != 0 {\n";
310		$text .= "\t\terr = errnoErr(e1)\n";
311		$text .= "\t}\n";
312	}
313	$text .= "\treturn\n";
314	$text .= "}\n\n";
315}
316
317chomp $text;
318chomp $text;
319
320if($errors) {
321	exit 1;
322}
323
324print <<EOF;
325// $cmdline
326// Code generated by the command above; see README.md. DO NOT EDIT.
327
328// +build $tags
329
330package unix
331
332import (
333	"syscall"
334	"unsafe"
335)
336
337var _ syscall.Errno
338
339$text
340EOF
341exit 0;
342