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