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 $darwin = 0;
29my $openbsd = 0;
30my $netbsd = 0;
31my $dragonfly = 0;
32my $arm = 0; # 64-bit value should use (even, odd)-pair
33my $libc = 0;
34my $tags = "";  # build tags
35my $newtags = ""; # new style build tags
36my $stdimports = 'import "unsafe"';
37my $extraimports = "";
38
39if($ARGV[0] eq "-b32") {
40	$_32bit = "big-endian";
41	shift;
42} elsif($ARGV[0] eq "-l32") {
43	$_32bit = "little-endian";
44	shift;
45}
46if($ARGV[0] eq "-plan9") {
47	$plan9 = 1;
48	shift;
49}
50if($ARGV[0] eq "-darwin") {
51	$darwin = 1;
52	$libc = 1;
53	shift;
54}
55if($ARGV[0] eq "-openbsd") {
56	$openbsd = 1;
57	shift;
58}
59if($ARGV[0] eq "-netbsd") {
60	$netbsd = 1;
61	shift;
62}
63if($ARGV[0] eq "-dragonfly") {
64	$dragonfly = 1;
65	shift;
66}
67if($ARGV[0] eq "-arm") {
68	$arm = 1;
69	shift;
70}
71if($ARGV[0] eq "-libc") {
72	$libc = 1;
73	shift;
74}
75if($ARGV[0] eq "-tags") {
76	shift;
77	$tags = $ARGV[0];
78	shift;
79}
80
81if($ARGV[0] =~ /^-/) {
82	print STDERR "usage: mksyscall.pl [-b32 | -l32] [-tags x,y] [file ...]\n";
83	exit 1;
84}
85
86if($libc) {
87	$extraimports = 'import "internal/abi"';
88}
89if($darwin) {
90	$extraimports .= "\nimport \"runtime\"";
91}
92
93sub parseparamlist($) {
94	my ($list) = @_;
95	$list =~ s/^\s*//;
96	$list =~ s/\s*$//;
97	if($list eq "") {
98		return ();
99	}
100	return split(/\s*,\s*/, $list);
101}
102
103sub parseparam($) {
104	my ($p) = @_;
105	if($p !~ /^(\S*) (\S*)$/) {
106		print STDERR "$ARGV:$.: malformed parameter: $p\n";
107		$errors = 1;
108		return ("xx", "int");
109	}
110	return ($1, $2);
111}
112
113# set of trampolines we've already generated
114my %trampolines;
115
116my $text = "";
117while(<>) {
118	chomp;
119	s/\s+/ /g;
120	s/^\s+//;
121	s/\s+$//;
122	my $nonblock = /^\/\/sysnb /;
123	next if !/^\/\/sys / && !$nonblock;
124
125	# Line must be of the form
126	#	func Open(path string, mode int, perm int) (fd int, errno error)
127	# Split into name, in params, out params.
128	if(!/^\/\/sys(nb)? (\w+)\(([^()]*)\)\s*(?:\(([^()]+)\))?\s*(?:=\s*((?i)_?SYS_[A-Z0-9_]+))?$/) {
129		print STDERR "$ARGV:$.: malformed //sys declaration\n";
130		$errors = 1;
131		next;
132	}
133	my ($func, $in, $out, $sysname) = ($2, $3, $4, $5);
134
135	# Split argument lists on comma.
136	my @in = parseparamlist($in);
137	my @out = parseparamlist($out);
138
139	# Try in vain to keep people from editing this file.
140	# The theory is that they jump into the middle of the file
141	# without reading the header.
142	$text .= "// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT\n\n";
143
144	if ((($darwin || ($openbsd && $libc)) && $func =~ /^ptrace(Ptr)?$/)) {
145		# The ptrace function is called from forkAndExecInChild where stack
146		# growth is forbidden.
147		$text .= "//go:nosplit\n"
148	}
149
150	# Go function header.
151	my $out_decl = @out ? sprintf(" (%s)", join(', ', @out)) : "";
152	$text .= sprintf "func %s(%s)%s {\n", $func, join(', ', @in), $out_decl;
153
154	# Disable ptrace on iOS.
155	if ($darwin && $func =~ /^ptrace(Ptr)?$/) {
156		$text .= "\tif runtime.GOOS == \"ios\" {\n";
157		$text .= "\t\tpanic(\"unimplemented\")\n";
158		$text .= "\t}\n";
159	}
160
161	# Check if err return available
162	my $errvar = "";
163	foreach my $p (@out) {
164		my ($name, $type) = parseparam($p);
165		if($type eq "error") {
166			$errvar = $name;
167			last;
168		}
169	}
170
171	# Prepare arguments to Syscall.
172	my @args = ();
173	my $n = 0;
174	foreach my $p (@in) {
175		my ($name, $type) = parseparam($p);
176		if($type =~ /^\*/) {
177			push @args, "uintptr(unsafe.Pointer($name))";
178		} elsif($type eq "string" && $errvar ne "") {
179			$text .= "\tvar _p$n *byte\n";
180			$text .= "\t_p$n, $errvar = BytePtrFromString($name)\n";
181			$text .= "\tif $errvar != nil {\n\t\treturn\n\t}\n";
182			push @args, "uintptr(unsafe.Pointer(_p$n))";
183			$n++;
184		} elsif($type eq "string") {
185			print STDERR "$ARGV:$.: $func uses string arguments, but has no error return\n";
186			$text .= "\tvar _p$n *byte\n";
187			$text .= "\t_p$n, _ = BytePtrFromString($name)\n";
188			push @args, "uintptr(unsafe.Pointer(_p$n))";
189			$n++;
190		} elsif($type =~ /^\[\](.*)/) {
191			# Convert slice into pointer, length.
192			# Have to be careful not to take address of &a[0] if len == 0:
193			# pass dummy pointer in that case.
194			# Used to pass nil, but some OSes or simulators reject write(fd, nil, 0).
195			$text .= "\tvar _p$n unsafe.Pointer\n";
196			$text .= "\tif len($name) > 0 {\n\t\t_p$n = unsafe.Pointer(\&${name}[0])\n\t}";
197			$text .= " else {\n\t\t_p$n = unsafe.Pointer(&_zero)\n\t}";
198			$text .= "\n";
199			push @args, "uintptr(_p$n)", "uintptr(len($name))";
200			$n++;
201		} elsif($type eq "int64" && ($openbsd || $netbsd)) {
202			if (!$libc) {
203				push @args, "0";
204			}
205			if($libc && $arm && @args % 2) {
206				# arm abi specifies 64 bit argument must be 64 bit aligned.
207				push @args, "0"
208			}
209			if($_32bit eq "big-endian") {
210				push @args, "uintptr($name>>32)", "uintptr($name)";
211			} elsif($_32bit eq "little-endian") {
212				push @args, "uintptr($name)", "uintptr($name>>32)";
213			} else {
214				push @args, "uintptr($name)";
215			}
216		} elsif($type eq "int64" && $dragonfly) {
217			if ($func !~ /^extp(read|write)/i) {
218				push @args, "0";
219			}
220			if($_32bit eq "big-endian") {
221				push @args, "uintptr($name>>32)", "uintptr($name)";
222			} elsif($_32bit eq "little-endian") {
223				push @args, "uintptr($name)", "uintptr($name>>32)";
224			} else {
225				push @args, "uintptr($name)";
226			}
227		} elsif($type eq "int64" && $_32bit ne "") {
228			if(@args % 2 && $arm) {
229				# arm abi specifies 64-bit argument uses
230				# (even, odd) pair
231				push @args, "0"
232			}
233			if($_32bit eq "big-endian") {
234				push @args, "uintptr($name>>32)", "uintptr($name)";
235			} else {
236				push @args, "uintptr($name)", "uintptr($name>>32)";
237			}
238		} else {
239			push @args, "uintptr($name)";
240		}
241	}
242
243	# Determine which form to use; pad args with zeros.
244	my $asm = "Syscall";
245	if ($nonblock) {
246		if ($errvar eq "" && $ENV{'GOOS'} eq "linux") {
247			$asm = "rawSyscallNoError";
248		} else {
249			$asm = "RawSyscall";
250		}
251	}
252	if ($libc) {
253		# Call unexported syscall functions (which take
254		# libc functions instead of syscall numbers).
255		$asm = lcfirst($asm);
256	}
257	if(@args <= 3) {
258		while(@args < 3) {
259			push @args, "0";
260		}
261	} elsif(@args <= 6) {
262		$asm .= "6";
263		while(@args < 6) {
264			push @args, "0";
265		}
266	} elsif(@args <= 9) {
267		$asm .= "9";
268		while(@args < 9) {
269			push @args, "0";
270		}
271	} else {
272		print STDERR "$ARGV:$.: too many arguments to system call\n";
273	}
274
275	if ($darwin || ($openbsd && $libc)) {
276		# Use extended versions for calls that generate a 64-bit result.
277		my ($name, $type) = parseparam($out[0]);
278		if ($type eq "int64" || ($type eq "uintptr" && $_32bit eq "")) {
279			$asm .= "X";
280		}
281	}
282
283	# System call number.
284	my $funcname = "";
285	if($sysname eq "") {
286		$sysname = "SYS_$func";
287		$sysname =~ s/([a-z])([A-Z])/${1}_$2/g;	# turn FooBar into Foo_Bar
288		$sysname =~ y/a-z/A-Z/;
289		if($libc) {
290			$sysname =~ y/A-Z/a-z/;
291			$sysname = substr $sysname, 4;
292			$funcname = "libc_$sysname";
293		}
294	}
295	if($libc) {
296		if($funcname eq "") {
297			$sysname = substr $sysname, 4;
298			$sysname =~ y/A-Z/a-z/;
299			$funcname = "libc_$sysname";
300		}
301		$sysname = "abi.FuncPCABI0(${funcname}_trampoline)";
302	}
303
304	# Actual call.
305	my $args = join(', ', @args);
306	my $call = "$asm($sysname, $args)";
307
308	# Assign return values.
309	my $body = "";
310	my @ret = ("_", "_", "_");
311	my $do_errno = 0;
312	for(my $i=0; $i<@out; $i++) {
313		my $p = $out[$i];
314		my ($name, $type) = parseparam($p);
315		my $reg = "";
316		if($name eq "err" && !$plan9) {
317			$reg = "e1";
318			$ret[2] = $reg;
319			$do_errno = 1;
320		} elsif($name eq "err" && $plan9) {
321			$ret[0] = "r0";
322			$ret[2] = "e1";
323			next;
324		} else {
325			$reg = sprintf("r%d", $i);
326			$ret[$i] = $reg;
327		}
328		if($type eq "bool") {
329			$reg = "$reg != 0";
330		}
331		if($type eq "int64" && $_32bit ne "") {
332			# 64-bit number in r1:r0 or r0:r1.
333			if($i+2 > @out) {
334				print STDERR "$ARGV:$.: not enough registers for int64 return\n";
335			}
336			if($_32bit eq "big-endian") {
337				$reg = sprintf("int64(r%d)<<32 | int64(r%d)", $i, $i+1);
338			} else {
339				$reg = sprintf("int64(r%d)<<32 | int64(r%d)", $i+1, $i);
340			}
341			$ret[$i] = sprintf("r%d", $i);
342			$ret[$i+1] = sprintf("r%d", $i+1);
343		}
344		if($reg ne "e1" || $plan9) {
345			$body .= "\t$name = $type($reg)\n";
346		}
347	}
348	if ($ret[0] eq "_" && $ret[1] eq "_" && $ret[2] eq "_") {
349		$text .= "\t$call\n";
350	} else {
351		if ($errvar eq "" && $ENV{'GOOS'} eq "linux") {
352			# raw syscall without error on Linux, see golang.org/issue/22924
353			$text .= "\t$ret[0], $ret[1] := $call\n";
354		} else {
355			$text .= "\t$ret[0], $ret[1], $ret[2] := $call\n";
356		}
357	}
358	$text .= $body;
359
360	if ($plan9 && $ret[2] eq "e1") {
361		$text .= "\tif int32(r0) == -1 {\n";
362		$text .= "\t\terr = e1\n";
363		$text .= "\t}\n";
364	} elsif ($do_errno) {
365		$text .= "\tif e1 != 0 {\n";
366		$text .= "\t\terr = errnoErr(e1)\n";
367		$text .= "\t}\n";
368	}
369	$text .= "\treturn\n";
370	$text .= "}\n\n";
371	if($libc) {
372		if (not exists $trampolines{$funcname}) {
373			$trampolines{$funcname} = 1;
374			# The assembly trampoline that jumps to the libc routine.
375			$text .= "func ${funcname}_trampoline()\n\n";
376			# Tell the linker that funcname can be found in libSystem using varname without the libc_ prefix.
377			my $basename = substr $funcname, 5;
378			my $libc = "libc.so";
379			if ($darwin) {
380				$libc = "/usr/lib/libSystem.B.dylib";
381			}
382			$text .= "//go:cgo_import_dynamic $funcname $basename \"$libc\"\n\n";
383		}
384	}
385}
386
387chomp $text;
388chomp $text;
389
390if($errors) {
391	exit 1;
392}
393
394if($extraimports ne "") {
395    $stdimports .= "\n$extraimports";
396}
397
398# TODO: this assumes tags are just simply comma separated. For now this is all the uses.
399$newtags = $tags =~ s/,/ && /r;
400
401print <<EOF;
402// $cmdline
403// Code generated by the command above; DO NOT EDIT.
404
405//go:build $newtags
406
407package syscall
408
409$stdimports
410
411$text
412EOF
413exit 0;
414