Text file src/pkg/syscall/mksyscall.pl
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
22 use strict;
23
24 my $cmdline = "mksyscall.pl " . join(' ', @ARGV);
25 my $errors = 0;
26 my $_32bit = "";
27 my $plan9 = 0;
28 my $darwin = 0;
29 my $openbsd = 0;
30 my $netbsd = 0;
31 my $dragonfly = 0;
32 my $nacl = 0;
33 my $arm = 0; # 64-bit value should use (even, odd)-pair
34 my $tags = ""; # build tags
35
36 if($ARGV[0] eq "-b32") {
37 $_32bit = "big-endian";
38 shift;
39 } elsif($ARGV[0] eq "-l32") {
40 $_32bit = "little-endian";
41 shift;
42 }
43 if($ARGV[0] eq "-plan9") {
44 $plan9 = 1;
45 shift;
46 }
47 if($ARGV[0] eq "-darwin") {
48 $darwin = 1;
49 shift;
50 }
51 if($ARGV[0] eq "-openbsd") {
52 $openbsd = 1;
53 shift;
54 }
55 if($ARGV[0] eq "-netbsd") {
56 $netbsd = 1;
57 shift;
58 }
59 if($ARGV[0] eq "-dragonfly") {
60 $dragonfly = 1;
61 shift;
62 }
63 if($ARGV[0] eq "-nacl") {
64 $nacl = 1;
65 shift;
66 }
67 if($ARGV[0] eq "-arm") {
68 $arm = 1;
69 shift;
70 }
71 if($ARGV[0] eq "-tags") {
72 shift;
73 $tags = $ARGV[0];
74 shift;
75 }
76
77 if($ARGV[0] =~ /^-/) {
78 print STDERR "usage: mksyscall.pl [-b32 | -l32] [-tags x,y] [file ...]\n";
79 exit 1;
80 }
81
82 sub parseparamlist($) {
83 my ($list) = @_;
84 $list =~ s/^\s*//;
85 $list =~ s/\s*$//;
86 if($list eq "") {
87 return ();
88 }
89 return split(/\s*,\s*/, $list);
90 }
91
92 sub parseparam($) {
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
102 # set of trampolines we've already generated
103 my %trampolines;
104
105 my $text = "";
106 while(<>) {
107 chomp;
108 s/\s+/ /g;
109 s/^\s+//;
110 s/\s+$//;
111 my $nonblock = /^\/\/sysnb /;
112 next if !/^\/\/sys / && !$nonblock;
113
114 # Line must be of the form
115 # func Open(path string, mode int, perm int) (fd int, errno error)
116 # Split into name, in params, out params.
117 if(!/^\/\/sys(nb)? (\w+)\(([^()]*)\)\s*(?:\(([^()]+)\))?\s*(?:=\s*((?i)_?SYS_[A-Z0-9_]+))?$/) {
118 print STDERR "$ARGV:$.: malformed //sys declaration\n";
119 $errors = 1;
120 next;
121 }
122 my ($func, $in, $out, $sysname) = ($2, $3, $4, $5);
123
124 # Split argument lists on comma.
125 my @in = parseparamlist($in);
126 my @out = parseparamlist($out);
127
128 # Try in vain to keep people from editing this file.
129 # The theory is that they jump into the middle of the file
130 # without reading the header.
131 $text .= "// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT\n\n";
132
133 if ($darwin && $func eq "ptrace") {
134 # The ptrace function is called from forkAndExecInChild where stack
135 # growth is forbidden.
136 $text .= "//go:nosplit\n"
137 }
138
139 # Go function header.
140 my $out_decl = @out ? sprintf(" (%s)", join(', ', @out)) : "";
141 $text .= sprintf "func %s(%s)%s {\n", $func, join(', ', @in), $out_decl;
142
143 # Check if err return available
144 my $errvar = "";
145 foreach my $p (@out) {
146 my ($name, $type) = parseparam($p);
147 if($type eq "error") {
148 $errvar = $name;
149 last;
150 }
151 }
152
153 # Prepare arguments to Syscall.
154 my @args = ();
155 my $n = 0;
156 foreach my $p (@in) {
157 my ($name, $type) = parseparam($p);
158 if($type =~ /^\*/) {
159 push @args, "uintptr(unsafe.Pointer($name))";
160 } elsif($type eq "string" && $errvar ne "") {
161 $text .= "\tvar _p$n *byte\n";
162 $text .= "\t_p$n, $errvar = BytePtrFromString($name)\n";
163 $text .= "\tif $errvar != nil {\n\t\treturn\n\t}\n";
164 push @args, "uintptr(unsafe.Pointer(_p$n))";
165 $n++;
166 } elsif($type eq "string") {
167 print STDERR "$ARGV:$.: $func uses string arguments, but has no error return\n";
168 $text .= "\tvar _p$n *byte\n";
169 $text .= "\t_p$n, _ = BytePtrFromString($name)\n";
170 push @args, "uintptr(unsafe.Pointer(_p$n))";
171 $n++;
172 } elsif($type =~ /^\[\](.*)/) {
173 # Convert slice into pointer, length.
174 # Have to be careful not to take address of &a[0] if len == 0:
175 # pass dummy pointer in that case.
176 # Used to pass nil, but some OSes or simulators reject write(fd, nil, 0).
177 $text .= "\tvar _p$n unsafe.Pointer\n";
178 $text .= "\tif len($name) > 0 {\n\t\t_p$n = unsafe.Pointer(\&${name}[0])\n\t}";
179 $text .= " else {\n\t\t_p$n = unsafe.Pointer(&_zero)\n\t}";
180 $text .= "\n";
181 push @args, "uintptr(_p$n)", "uintptr(len($name))";
182 $n++;
183 } elsif($type eq "int64" && ($openbsd || $netbsd)) {
184 push @args, "0";
185 if($_32bit eq "big-endian") {
186 push @args, "uintptr($name>>32)", "uintptr($name)";
187 } elsif($_32bit eq "little-endian") {
188 push @args, "uintptr($name)", "uintptr($name>>32)";
189 } else {
190 push @args, "uintptr($name)";
191 }
192 } elsif($type eq "int64" && $dragonfly) {
193 if ($func !~ /^extp(read|write)/i) {
194 push @args, "0";
195 }
196 if($_32bit eq "big-endian") {
197 push @args, "uintptr($name>>32)", "uintptr($name)";
198 } elsif($_32bit eq "little-endian") {
199 push @args, "uintptr($name)", "uintptr($name>>32)";
200 } else {
201 push @args, "uintptr($name)";
202 }
203 } elsif($type eq "int64" && $_32bit ne "") {
204 if(@args % 2 && $arm) {
205 # arm abi specifies 64-bit argument uses
206 # (even, odd) pair
207 push @args, "0"
208 }
209 if($_32bit eq "big-endian") {
210 push @args, "uintptr($name>>32)", "uintptr($name)";
211 } else {
212 push @args, "uintptr($name)", "uintptr($name>>32)";
213 }
214 } else {
215 push @args, "uintptr($name)";
216 }
217 }
218
219 # Determine which form to use; pad args with zeros.
220 my $asm = "Syscall";
221 if ($nonblock) {
222 if ($errvar eq "" && $ENV{'GOOS'} eq "linux") {
223 $asm = "rawSyscallNoError";
224 } else {
225 $asm = "RawSyscall";
226 }
227 }
228 if ($darwin) {
229 # Call unexported syscall functions (which take
230 # libc functions instead of syscall numbers).
231 $asm = lcfirst($asm);
232 }
233 if(@args <= 3) {
234 while(@args < 3) {
235 push @args, "0";
236 }
237 } elsif(@args <= 6) {
238 $asm .= "6";
239 while(@args < 6) {
240 push @args, "0";
241 }
242 } elsif(@args <= 9) {
243 $asm .= "9";
244 while(@args < 9) {
245 push @args, "0";
246 }
247 } else {
248 print STDERR "$ARGV:$.: too many arguments to system call\n";
249 }
250
251 if ($darwin) {
252 # Use extended versions for calls that generate a 64-bit result.
253 my ($name, $type) = parseparam($out[0]);
254 if ($type eq "int64" || ($type eq "uintptr" && $_32bit eq "")) {
255 $asm .= "X";
256 }
257 }
258
259 # System call number.
260 my $funcname = "";
261 if($sysname eq "") {
262 $sysname = "SYS_$func";
263 $sysname =~ s/([a-z])([A-Z])/${1}_$2/g; # turn FooBar into Foo_Bar
264 $sysname =~ y/a-z/A-Z/;
265 if($nacl) {
266 $sysname =~ y/A-Z/a-z/;
267 }
268 if($darwin) {
269 $sysname =~ y/A-Z/a-z/;
270 $sysname = substr $sysname, 4;
271 $funcname = "libc_$sysname";
272 }
273 }
274 if($darwin) {
275 if($funcname eq "") {
276 $sysname = substr $sysname, 4;
277 $funcname = "libc_$sysname";
278 }
279 $sysname = "funcPC(${funcname}_trampoline)";
280 }
281
282 # Actual call.
283 my $args = join(', ', @args);
284 my $call = "$asm($sysname, $args)";
285
286 # Assign return values.
287 my $body = "";
288 my @ret = ("_", "_", "_");
289 my $do_errno = 0;
290 for(my $i=0; $i<@out; $i++) {
291 my $p = $out[$i];
292 my ($name, $type) = parseparam($p);
293 my $reg = "";
294 if($name eq "err" && !$plan9) {
295 $reg = "e1";
296 $ret[2] = $reg;
297 $do_errno = 1;
298 } elsif($name eq "err" && $plan9) {
299 $ret[0] = "r0";
300 $ret[2] = "e1";
301 next;
302 } else {
303 $reg = sprintf("r%d", $i);
304 $ret[$i] = $reg;
305 }
306 if($type eq "bool") {
307 $reg = "$reg != 0";
308 }
309 if($type eq "int64" && $_32bit ne "") {
310 # 64-bit number in r1:r0 or r0:r1.
311 if($i+2 > @out) {
312 print STDERR "$ARGV:$.: not enough registers for int64 return\n";
313 }
314 if($_32bit eq "big-endian") {
315 $reg = sprintf("int64(r%d)<<32 | int64(r%d)", $i, $i+1);
316 } else {
317 $reg = sprintf("int64(r%d)<<32 | int64(r%d)", $i+1, $i);
318 }
319 $ret[$i] = sprintf("r%d", $i);
320 $ret[$i+1] = sprintf("r%d", $i+1);
321 }
322 if($reg ne "e1" || $plan9) {
323 $body .= "\t$name = $type($reg)\n";
324 }
325 }
326 if ($ret[0] eq "_" && $ret[1] eq "_" && $ret[2] eq "_") {
327 $text .= "\t$call\n";
328 } else {
329 if ($errvar eq "" && $ENV{'GOOS'} eq "linux") {
330 # raw syscall without error on Linux, see golang.org/issue/22924
331 $text .= "\t$ret[0], $ret[1] := $call\n";
332 } else {
333 $text .= "\t$ret[0], $ret[1], $ret[2] := $call\n";
334 }
335 }
336 $text .= $body;
337
338 if ($plan9 && $ret[2] eq "e1") {
339 $text .= "\tif int32(r0) == -1 {\n";
340 $text .= "\t\terr = e1\n";
341 $text .= "\t}\n";
342 } elsif ($do_errno) {
343 $text .= "\tif e1 != 0 {\n";
344 $text .= "\t\terr = errnoErr(e1)\n";
345 $text .= "\t}\n";
346 }
347 $text .= "\treturn\n";
348 $text .= "}\n\n";
349 if($darwin) {
350 if (not exists $trampolines{$funcname}) {
351 $trampolines{$funcname} = 1;
352 # The assembly trampoline that jumps to the libc routine.
353 $text .= "func ${funcname}_trampoline()\n";
354 # Map syscall.funcname to just plain funcname.
355 # (The jump to this function is in the assembly trampoline, generated by mksyscallasm_darwin.go.)
356 $text .= "//go:linkname $funcname $funcname\n";
357 # Tell the linker that funcname can be found in libSystem using varname without the libc_ prefix.
358 my $basename = substr $funcname, 5;
359 $text .= "//go:cgo_import_dynamic $funcname $basename \"/usr/lib/libSystem.B.dylib\"\n\n";
360 }
361 }
362 }
363
364 chomp $text;
365 chomp $text;
366
367 if($errors) {
368 exit 1;
369 }
370
371 print <<EOF;
372 // $cmdline
373 // Code generated by the command above; DO NOT EDIT.
374
375 // +build $tags
376
377 package syscall
378
379 import "unsafe"
380
381 $text
382 EOF
383 exit 0;
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