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_solaris.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 err.
15#	* If go func name needs to be different than its libc name,
16#	* or the function is not in libc, name could be specified
17#	* at the end, after "=" sign, like
18#	  //sys getsockopt(s int, level int, name int, val uintptr, vallen *_Socklen) (err error) = libsocket.getsockopt
19
20use strict;
21
22my $cmdline = "mksyscall_libc.pl " . join(' ', @ARGV);
23my $errors = 0;
24my $_32bit = "";
25my $tags = "";  # build tags
26my $aix = 0;
27my $solaris = 0;
28
29binmode STDOUT;
30
31if($ARGV[0] eq "-b32") {
32	$_32bit = "big-endian";
33	shift;
34} elsif($ARGV[0] eq "-l32") {
35	$_32bit = "little-endian";
36	shift;
37}
38if($ARGV[0] eq "-aix") {
39	$aix = 1;
40	shift;
41}
42if($ARGV[0] eq "-solaris") {
43	$solaris = 1;
44	shift;
45}
46if($ARGV[0] eq "-tags") {
47	shift;
48	$tags = $ARGV[0];
49	shift;
50}
51
52
53if($ARGV[0] =~ /^-/) {
54	print STDERR "usage: mksyscall_libc.pl [-b32 | -l32] [-aix | -solaris] [-tags x,y] [file ...]\n";
55	exit 1;
56}
57
58sub parseparamlist($) {
59	my ($list) = @_;
60	$list =~ s/^\s*//;
61	$list =~ s/\s*$//;
62	if($list eq "") {
63		return ();
64	}
65	return split(/\s*,\s*/, $list);
66}
67
68sub parseparam($) {
69	my ($p) = @_;
70	if($p !~ /^(\S*) (\S*)$/) {
71		print STDERR "$ARGV:$.: malformed parameter: $p\n";
72		$errors = 1;
73		return ("xx", "int");
74	}
75	return ($1, $2);
76}
77
78my $package = "";
79my $text = "";
80my $dynimports = "";
81my $linknames = "";
82my @vars = ();
83while(<>) {
84	chomp;
85	s/\s+/ /g;
86	s/^\s+//;
87	s/\s+$//;
88	$package = $1 if !$package && /^package (\S+)$/;
89	my $nonblock = /^\/\/sysnb /;
90	next if !/^\/\/sys / && !$nonblock;
91
92	my $syscalldot = "";
93	$syscalldot = "syscall." if $package ne "syscall";
94
95	# Line must be of the form
96	#	func Open(path string, mode int, perm int) (fd int, err error)
97	# Split into name, in params, out params.
98	if(!/^\/\/sys(nb)? (\w+)\(([^()]*)\)\s*(?:\(([^()]+)\))?\s*(?:=\s*(?:(\w*)\.)?(\w*))?$/) {
99		print STDERR "$ARGV:$.: malformed //sys declaration\n";
100		$errors = 1;
101		next;
102	}
103	my ($nb, $func, $in, $out, $modname, $sysname) = ($1, $2, $3, $4, $5, $6);
104
105	# Split argument lists on comma.
106	my @in = parseparamlist($in);
107	my @out = parseparamlist($out);
108
109	# Try in vain to keep people from editing this file.
110	# The theory is that they jump into the middle of the file
111	# without reading the header.
112	$text .= "// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT\n\n";
113
114	# So file name.
115	if($aix) {
116		if($modname eq "") {
117			$modname = "libc.a/shr_64.o";
118		} else {
119			print STDERR "$func: only syscall using libc are available\n";
120			$errors = 1;
121			next;
122		}
123
124	}
125	if($solaris) {
126		if($modname eq "") {
127			$modname = "libc";
128		}
129		$modname .= ".so";
130
131	}
132
133	# System call name.
134	if($sysname eq "") {
135		$sysname = "$func";
136	}
137
138	# System call pointer variable name.
139	my $sysvarname = "libc_${sysname}";
140
141	my $strconvfunc = "BytePtrFromString";
142	my $strconvtype = "*byte";
143
144	$sysname =~ y/A-Z/a-z/; # All libc functions are lowercase.
145
146	# Runtime import of function to allow cross-platform builds.
147	$dynimports .= "//go:cgo_import_dynamic ${sysvarname} ${sysname} \"$modname\"\n";
148	# Link symbol to proc address variable.
149	$linknames .= "//go:linkname ${sysvarname} ${sysvarname}\n";
150	# Library proc address variable.
151	push @vars, $sysvarname;
152
153	# Go function header.
154	$out = join(', ', @out);
155	if($out ne "") {
156		$out = " ($out)";
157	}
158	if($text ne "") {
159		$text .= "\n"
160	}
161	$text .= sprintf "func %s(%s)%s {\n", $func, join(', ', @in), $out;
162
163	# Check if err return available
164	my $errvar = "";
165	foreach my $p (@out) {
166		my ($name, $type) = parseparam($p);
167		if($type eq "error") {
168			$errvar = $name;
169			last;
170		}
171	}
172
173	# Prepare arguments to Syscall.
174	my @args = ();
175	my $n = 0;
176	foreach my $p (@in) {
177		my ($name, $type) = parseparam($p);
178		if($type =~ /^\*/) {
179			push @args, "uintptr(unsafe.Pointer($name))";
180		} elsif($type eq "string" && $errvar ne "") {
181			$text .= "\tvar _p$n $strconvtype\n";
182			$text .= "\t_p$n, $errvar = $strconvfunc($name)\n";
183			$text .= "\tif $errvar != nil {\n\t\treturn\n\t}\n";
184			push @args, "uintptr(unsafe.Pointer(_p$n))";
185			$n++;
186		} elsif($type eq "string") {
187			print STDERR "$ARGV:$.: $func uses string arguments, but has no error return\n";
188			$text .= "\tvar _p$n $strconvtype\n";
189			$text .= "\t_p$n, _ = $strconvfunc($name)\n";
190			push @args, "uintptr(unsafe.Pointer(_p$n))";
191			$n++;
192		} elsif($type =~ /^\[\](.*)/) {
193			# Convert slice into pointer, length.
194			# Have to be careful not to take address of &a[0] if len == 0:
195			# pass nil in that case.
196			$text .= "\tvar _p$n *$1\n";
197			$text .= "\tif len($name) > 0 {\n\t\t_p$n = \&$name\[0]\n\t}\n";
198			push @args, "uintptr(unsafe.Pointer(_p$n))", "uintptr(len($name))";
199			$n++;
200		} elsif($type eq "int64" && $_32bit ne "") {
201			if($_32bit eq "big-endian") {
202				push @args, "uintptr($name >> 32)", "uintptr($name)";
203			} else {
204				push @args, "uintptr($name)", "uintptr($name >> 32)";
205			}
206		} elsif($type eq "bool") {
207 			$text .= "\tvar _p$n uint32\n";
208			$text .= "\tif $name {\n\t\t_p$n = 1\n\t} else {\n\t\t_p$n = 0\n\t}\n";
209			push @args, "uintptr(_p$n)";
210			$n++;
211		} else {
212			push @args, "uintptr($name)";
213		}
214	}
215	my $nargs = @args;
216
217	my $asmfuncname="";
218	my $asmrawfuncname="";
219
220	if($aix){
221		$asmfuncname="syscall6";
222		$asmrawfuncname="rawSyscall6";
223	} else {
224		$asmfuncname="sysvicall6";
225		$asmrawfuncname="rawSysvicall6";
226	}
227
228	# Determine which form to use; pad args with zeros.
229	my $asm = "${syscalldot}${asmfuncname}";
230	if ($nonblock) {
231		$asm = "${syscalldot}${asmrawfuncname}";
232	}
233	if(@args <= 6) {
234		while(@args < 6) {
235			push @args, "0";
236		}
237	} else {
238		print STDERR "$ARGV:$.: too many arguments to system call\n";
239	}
240
241	# Actual call.
242	my $args = join(', ', @args);
243	my $call = "$asm(uintptr(unsafe.Pointer(&$sysvarname)), $nargs, $args)";
244
245	# Assign return values.
246	my $body = "";
247	my $failexpr = "";
248	my @ret = ("_", "_", "_");
249	my @pout= ();
250	my $do_errno = 0;
251	for(my $i=0; $i<@out; $i++) {
252		my $p = $out[$i];
253		my ($name, $type) = parseparam($p);
254		my $reg = "";
255		if($name eq "err") {
256			$reg = "e1";
257			$ret[2] = $reg;
258			$do_errno = 1;
259		} else {
260			$reg = sprintf("r%d", $i);
261			$ret[$i] = $reg;
262		}
263		if($type eq "bool") {
264			$reg = "$reg != 0";
265		}
266		if($type eq "int64" && $_32bit ne "") {
267			# 64-bit number in r1:r0 or r0:r1.
268			if($i+2 > @out) {
269				print STDERR "$ARGV:$.: not enough registers for int64 return\n";
270			}
271			if($_32bit eq "big-endian") {
272				$reg = sprintf("int64(r%d)<<32 | int64(r%d)", $i, $i+1);
273			} else {
274				$reg = sprintf("int64(r%d)<<32 | int64(r%d)", $i+1, $i);
275			}
276			$ret[$i] = sprintf("r%d", $i);
277			$ret[$i+1] = sprintf("r%d", $i+1);
278		}
279		if($reg ne "e1") {
280			$body .= "\t$name = $type($reg)\n";
281		}
282	}
283	if ($ret[0] eq "_" && $ret[1] eq "_" && $ret[2] eq "_") {
284		$text .= "\t$call\n";
285	} else {
286		$text .= "\t$ret[0], $ret[1], $ret[2] := $call\n";
287	}
288	$text .= $body;
289
290	if ($do_errno) {
291		$text .= "\tif e1 != 0 {\n";
292		$text .= "\t\terr = errnoErr(e1)\n";
293		$text .= "\t}\n";
294	}
295	$text .= "\treturn\n";
296	$text .= "}\n";
297}
298
299if($errors) {
300	exit 1;
301}
302
303print <<EOF;
304// $cmdline
305// Code generated by the command above; DO NOT EDIT.
306
307// +build $tags
308
309package $package
310
311import "unsafe"
312EOF
313
314print "import \"syscall\"\n" if $package ne "syscall";
315
316my $vardecls = "\t" . join(",\n\t", @vars);
317$vardecls .= " libcFunc";
318
319chomp($_=<<EOF);
320
321$dynimports
322$linknames
323type libcFunc uintptr
324
325var (
326$vardecls
327)
328
329$text
330EOF
331print $_;
332exit 0;
333