Text file
src/syscall/mksyscall_libc.pl
Documentation: syscall
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 $newtags = ""; # new style build tags
27my $aix = 0;
28my $solaris = 0;
29
30binmode STDOUT;
31
32if($ARGV[0] eq "-b32") {
33 $_32bit = "big-endian";
34 shift;
35} elsif($ARGV[0] eq "-l32") {
36 $_32bit = "little-endian";
37 shift;
38}
39if($ARGV[0] eq "-aix") {
40 $aix = 1;
41 shift;
42}
43if($ARGV[0] eq "-solaris") {
44 $solaris = 1;
45 shift;
46}
47if($ARGV[0] eq "-tags") {
48 shift;
49 $tags = $ARGV[0];
50 shift;
51}
52
53
54if($ARGV[0] =~ /^-/) {
55 print STDERR "usage: mksyscall_libc.pl [-b32 | -l32] [-aix | -solaris] [-tags x,y] [file ...]\n";
56 exit 1;
57}
58
59sub parseparamlist($) {
60 my ($list) = @_;
61 $list =~ s/^\s*//;
62 $list =~ s/\s*$//;
63 if($list eq "") {
64 return ();
65 }
66 return split(/\s*,\s*/, $list);
67}
68
69sub parseparam($) {
70 my ($p) = @_;
71 if($p !~ /^(\S*) (\S*)$/) {
72 print STDERR "$ARGV:$.: malformed parameter: $p\n";
73 $errors = 1;
74 return ("xx", "int");
75 }
76 return ($1, $2);
77}
78
79my $package = "";
80my $text = "";
81my $dynimports = "";
82my $linknames = "";
83my @vars = ();
84while(<>) {
85 chomp;
86 s/\s+/ /g;
87 s/^\s+//;
88 s/\s+$//;
89 $package = $1 if !$package && /^package (\S+)$/;
90 my $nonblock = /^\/\/sysnb /;
91 next if !/^\/\/sys / && !$nonblock;
92
93 my $syscalldot = "";
94 $syscalldot = "syscall." if $package ne "syscall";
95
96 # Line must be of the form
97 # func Open(path string, mode int, perm int) (fd int, err error)
98 # Split into name, in params, out params.
99 if(!/^\/\/sys(nb)? (\w+)\(([^()]*)\)\s*(?:\(([^()]+)\))?\s*(?:=\s*(?:(\w*)\.)?(\w*))?$/) {
100 print STDERR "$ARGV:$.: malformed //sys declaration\n";
101 $errors = 1;
102 next;
103 }
104 my ($nb, $func, $in, $out, $modname, $sysname) = ($1, $2, $3, $4, $5, $6);
105
106 # Split argument lists on comma.
107 my @in = parseparamlist($in);
108 my @out = parseparamlist($out);
109
110 # Try in vain to keep people from editing this file.
111 # The theory is that they jump into the middle of the file
112 # without reading the header.
113 $text .= "// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT\n\n";
114
115 # So file name.
116 if($aix) {
117 if($modname eq "") {
118 $modname = "libc.a/shr_64.o";
119 } else {
120 print STDERR "$func: only syscall using libc are available\n";
121 $errors = 1;
122 next;
123 }
124
125 }
126 if($solaris) {
127 if($modname eq "") {
128 $modname = "libc";
129 }
130 $modname .= ".so";
131
132 }
133
134 # System call name.
135 if($sysname eq "") {
136 $sysname = "$func";
137 }
138
139 # System call pointer variable name.
140 my $sysvarname = "libc_${sysname}";
141
142 my $strconvfunc = "BytePtrFromString";
143 my $strconvtype = "*byte";
144
145 $sysname =~ y/A-Z/a-z/; # All libc functions are lowercase.
146
147 # Runtime import of function to allow cross-platform builds.
148 if($dynimports !~ /\s+${sysvarname}\s+/) {
149 $dynimports .= "//go:cgo_import_dynamic ${sysvarname} ${sysname} \"$modname\"\n";
150 # Link symbol to proc address variable.
151 $linknames .= "//go:linkname ${sysvarname} ${sysvarname}\n";
152 # Library proc address variable.
153 push @vars, $sysvarname;
154 }
155
156 # Go function header.
157 $out = join(', ', @out);
158 if($out ne "") {
159 $out = " ($out)";
160 }
161 if($text ne "") {
162 $text .= "\n"
163 }
164 $text .= sprintf "func %s(%s)%s {\n", $func, join(', ', @in), $out;
165
166 # Check if err return available
167 my $errvar = "";
168 foreach my $p (@out) {
169 my ($name, $type) = parseparam($p);
170 if($type eq "error") {
171 $errvar = $name;
172 last;
173 }
174 }
175
176 # Prepare arguments to Syscall.
177 my @args = ();
178 my $n = 0;
179 foreach my $p (@in) {
180 my ($name, $type) = parseparam($p);
181 if($type =~ /^\*/) {
182 push @args, "uintptr(unsafe.Pointer($name))";
183 } elsif($type eq "string" && $errvar ne "") {
184 $text .= "\tvar _p$n $strconvtype\n";
185 $text .= "\t_p$n, $errvar = $strconvfunc($name)\n";
186 $text .= "\tif $errvar != nil {\n\t\treturn\n\t}\n";
187 push @args, "uintptr(unsafe.Pointer(_p$n))";
188 $n++;
189 } elsif($type eq "string") {
190 print STDERR "$ARGV:$.: $func uses string arguments, but has no error return\n";
191 $text .= "\tvar _p$n $strconvtype\n";
192 $text .= "\t_p$n, _ = $strconvfunc($name)\n";
193 push @args, "uintptr(unsafe.Pointer(_p$n))";
194 $n++;
195 } elsif($type =~ /^\[\](.*)/) {
196 # Convert slice into pointer, length.
197 # Have to be careful not to take address of &a[0] if len == 0:
198 # pass nil in that case.
199 $text .= "\tvar _p$n *$1\n";
200 $text .= "\tif len($name) > 0 {\n\t\t_p$n = \&$name\[0]\n\t}\n";
201 push @args, "uintptr(unsafe.Pointer(_p$n))", "uintptr(len($name))";
202 $n++;
203 } elsif($type eq "int64" && $_32bit ne "") {
204 if($_32bit eq "big-endian") {
205 push @args, "uintptr($name >> 32)", "uintptr($name)";
206 } else {
207 push @args, "uintptr($name)", "uintptr($name >> 32)";
208 }
209 } elsif($type eq "bool") {
210 $text .= "\tvar _p$n uint32\n";
211 $text .= "\tif $name {\n\t\t_p$n = 1\n\t} else {\n\t\t_p$n = 0\n\t}\n";
212 push @args, "uintptr(_p$n)";
213 $n++;
214 } else {
215 push @args, "uintptr($name)";
216 }
217 }
218 my $nargs = @args;
219
220 my $asmfuncname="";
221 my $asmrawfuncname="";
222
223 if($aix){
224 $asmfuncname="syscall6";
225 $asmrawfuncname="rawSyscall6";
226 } else {
227 $asmfuncname="sysvicall6";
228 $asmrawfuncname="rawSysvicall6";
229 }
230
231 # Determine which form to use; pad args with zeros.
232 my $asm = "${syscalldot}${asmfuncname}";
233 if ($nonblock) {
234 $asm = "${syscalldot}${asmrawfuncname}";
235 }
236 if(@args <= 6) {
237 while(@args < 6) {
238 push @args, "0";
239 }
240 } else {
241 print STDERR "$ARGV:$.: too many arguments to system call\n";
242 }
243
244 # Actual call.
245 my $args = join(', ', @args);
246 my $call = "$asm(uintptr(unsafe.Pointer(&$sysvarname)), $nargs, $args)";
247
248 # Assign return values.
249 my $body = "";
250 my $failexpr = "";
251 my @ret = ("_", "_", "_");
252 my @pout= ();
253 my $do_errno = 0;
254 for(my $i=0; $i<@out; $i++) {
255 my $p = $out[$i];
256 my ($name, $type) = parseparam($p);
257 my $reg = "";
258 if($name eq "err") {
259 $reg = "e1";
260 $ret[2] = $reg;
261 $do_errno = 1;
262 } else {
263 $reg = sprintf("r%d", $i);
264 $ret[$i] = $reg;
265 }
266 if($type eq "bool") {
267 $reg = "$reg != 0";
268 }
269 if($type eq "int64" && $_32bit ne "") {
270 # 64-bit number in r1:r0 or r0:r1.
271 if($i+2 > @out) {
272 print STDERR "$ARGV:$.: not enough registers for int64 return\n";
273 }
274 if($_32bit eq "big-endian") {
275 $reg = sprintf("int64(r%d)<<32 | int64(r%d)", $i, $i+1);
276 } else {
277 $reg = sprintf("int64(r%d)<<32 | int64(r%d)", $i+1, $i);
278 }
279 $ret[$i] = sprintf("r%d", $i);
280 $ret[$i+1] = sprintf("r%d", $i+1);
281 }
282 if($reg ne "e1") {
283 $body .= "\t$name = $type($reg)\n";
284 }
285 }
286 if ($ret[0] eq "_" && $ret[1] eq "_" && $ret[2] eq "_") {
287 $text .= "\t$call\n";
288 } else {
289 $text .= "\t$ret[0], $ret[1], $ret[2] := $call\n";
290 }
291 $text .= $body;
292
293 if ($do_errno) {
294 $text .= "\tif e1 != 0 {\n";
295 $text .= "\t\terr = errnoErr(e1)\n";
296 $text .= "\t}\n";
297 }
298 $text .= "\treturn\n";
299 $text .= "}\n";
300}
301
302if($errors) {
303 exit 1;
304}
305
306# TODO: this assumes tags are just simply comma separated. For now this is all the uses.
307$newtags = $tags =~ s/,/ && /r;
308
309print <<EOF;
310// $cmdline
311// Code generated by the command above; DO NOT EDIT.
312
313//go:build $newtags
314
315package $package
316
317import "unsafe"
318EOF
319
320print "import \"syscall\"\n" if $package ne "syscall";
321
322my $vardecls = "\t" . join(",\n\t", @vars);
323$vardecls .= " libcFunc";
324
325chomp($_=<<EOF);
326
327$dynimports
328$linknames
329type libcFunc uintptr
330
331var (
332$vardecls
333)
334
335$text
336EOF
337print $_;
338exit 0;
View as plain text