github.com/code-reading/golang@v0.0.0-20220303082512-ba5bc0e589a3/go/src/syscall/mksyscall.pl (about) 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 $arm = 0; # 64-bit value should use (even, odd)-pair 33 my $libc = 0; 34 my $tags = ""; # build tags 35 my $newtags = ""; # new style build tags 36 my $extraimports = ""; 37 38 if($ARGV[0] eq "-b32") { 39 $_32bit = "big-endian"; 40 shift; 41 } elsif($ARGV[0] eq "-l32") { 42 $_32bit = "little-endian"; 43 shift; 44 } 45 if($ARGV[0] eq "-plan9") { 46 $plan9 = 1; 47 shift; 48 } 49 if($ARGV[0] eq "-darwin") { 50 $darwin = 1; 51 $libc = 1; 52 shift; 53 } 54 if($ARGV[0] eq "-openbsd") { 55 $openbsd = 1; 56 shift; 57 } 58 if($ARGV[0] eq "-netbsd") { 59 $netbsd = 1; 60 shift; 61 } 62 if($ARGV[0] eq "-dragonfly") { 63 $dragonfly = 1; 64 shift; 65 } 66 if($ARGV[0] eq "-arm") { 67 $arm = 1; 68 shift; 69 } 70 if($ARGV[0] eq "-libc") { 71 $libc = 1; 72 shift; 73 } 74 if($ARGV[0] eq "-tags") { 75 shift; 76 $tags = $ARGV[0]; 77 shift; 78 } 79 80 if($ARGV[0] =~ /^-/) { 81 print STDERR "usage: mksyscall.pl [-b32 | -l32] [-tags x,y] [file ...]\n"; 82 exit 1; 83 } 84 85 if($libc) { 86 $extraimports = 'import "internal/abi"'; 87 } 88 89 sub parseparamlist($) { 90 my ($list) = @_; 91 $list =~ s/^\s*//; 92 $list =~ s/\s*$//; 93 if($list eq "") { 94 return (); 95 } 96 return split(/\s*,\s*/, $list); 97 } 98 99 sub parseparam($) { 100 my ($p) = @_; 101 if($p !~ /^(\S*) (\S*)$/) { 102 print STDERR "$ARGV:$.: malformed parameter: $p\n"; 103 $errors = 1; 104 return ("xx", "int"); 105 } 106 return ($1, $2); 107 } 108 109 # set of trampolines we've already generated 110 my %trampolines; 111 112 my $text = ""; 113 while(<>) { 114 chomp; 115 s/\s+/ /g; 116 s/^\s+//; 117 s/\s+$//; 118 my $nonblock = /^\/\/sysnb /; 119 next if !/^\/\/sys / && !$nonblock; 120 121 # Line must be of the form 122 # func Open(path string, mode int, perm int) (fd int, errno error) 123 # Split into name, in params, out params. 124 if(!/^\/\/sys(nb)? (\w+)\(([^()]*)\)\s*(?:\(([^()]+)\))?\s*(?:=\s*((?i)_?SYS_[A-Z0-9_]+))?$/) { 125 print STDERR "$ARGV:$.: malformed //sys declaration\n"; 126 $errors = 1; 127 next; 128 } 129 my ($func, $in, $out, $sysname) = ($2, $3, $4, $5); 130 131 # Split argument lists on comma. 132 my @in = parseparamlist($in); 133 my @out = parseparamlist($out); 134 135 # Try in vain to keep people from editing this file. 136 # The theory is that they jump into the middle of the file 137 # without reading the header. 138 $text .= "// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT\n\n"; 139 140 if (($darwin && $func eq "ptrace1") || (($openbsd && $libc) && $func eq "ptrace")) { 141 # The ptrace function is called from forkAndExecInChild where stack 142 # growth is forbidden. 143 $text .= "//go:nosplit\n" 144 } 145 146 # Go function header. 147 my $out_decl = @out ? sprintf(" (%s)", join(', ', @out)) : ""; 148 $text .= sprintf "func %s(%s)%s {\n", $func, join(', ', @in), $out_decl; 149 150 # Check if err return available 151 my $errvar = ""; 152 foreach my $p (@out) { 153 my ($name, $type) = parseparam($p); 154 if($type eq "error") { 155 $errvar = $name; 156 last; 157 } 158 } 159 160 # Prepare arguments to Syscall. 161 my @args = (); 162 my $n = 0; 163 foreach my $p (@in) { 164 my ($name, $type) = parseparam($p); 165 if($type =~ /^\*/) { 166 push @args, "uintptr(unsafe.Pointer($name))"; 167 } elsif($type eq "string" && $errvar ne "") { 168 $text .= "\tvar _p$n *byte\n"; 169 $text .= "\t_p$n, $errvar = BytePtrFromString($name)\n"; 170 $text .= "\tif $errvar != nil {\n\t\treturn\n\t}\n"; 171 push @args, "uintptr(unsafe.Pointer(_p$n))"; 172 $n++; 173 } elsif($type eq "string") { 174 print STDERR "$ARGV:$.: $func uses string arguments, but has no error return\n"; 175 $text .= "\tvar _p$n *byte\n"; 176 $text .= "\t_p$n, _ = BytePtrFromString($name)\n"; 177 push @args, "uintptr(unsafe.Pointer(_p$n))"; 178 $n++; 179 } elsif($type =~ /^\[\](.*)/) { 180 # Convert slice into pointer, length. 181 # Have to be careful not to take address of &a[0] if len == 0: 182 # pass dummy pointer in that case. 183 # Used to pass nil, but some OSes or simulators reject write(fd, nil, 0). 184 $text .= "\tvar _p$n unsafe.Pointer\n"; 185 $text .= "\tif len($name) > 0 {\n\t\t_p$n = unsafe.Pointer(\&${name}[0])\n\t}"; 186 $text .= " else {\n\t\t_p$n = unsafe.Pointer(&_zero)\n\t}"; 187 $text .= "\n"; 188 push @args, "uintptr(_p$n)", "uintptr(len($name))"; 189 $n++; 190 } elsif($type eq "int64" && ($openbsd || $netbsd)) { 191 if (!$libc) { 192 push @args, "0"; 193 } 194 if($libc && $arm && @args % 2) { 195 # arm abi specifies 64 bit argument must be 64 bit aligned. 196 push @args, "0" 197 } 198 if($_32bit eq "big-endian") { 199 push @args, "uintptr($name>>32)", "uintptr($name)"; 200 } elsif($_32bit eq "little-endian") { 201 push @args, "uintptr($name)", "uintptr($name>>32)"; 202 } else { 203 push @args, "uintptr($name)"; 204 } 205 } elsif($type eq "int64" && $dragonfly) { 206 if ($func !~ /^extp(read|write)/i) { 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" && $_32bit ne "") { 217 if(@args % 2 && $arm) { 218 # arm abi specifies 64-bit argument uses 219 # (even, odd) pair 220 push @args, "0" 221 } 222 if($_32bit eq "big-endian") { 223 push @args, "uintptr($name>>32)", "uintptr($name)"; 224 } else { 225 push @args, "uintptr($name)", "uintptr($name>>32)"; 226 } 227 } else { 228 push @args, "uintptr($name)"; 229 } 230 } 231 232 # Determine which form to use; pad args with zeros. 233 my $asm = "Syscall"; 234 if ($nonblock) { 235 if ($errvar eq "" && $ENV{'GOOS'} eq "linux") { 236 $asm = "rawSyscallNoError"; 237 } else { 238 $asm = "RawSyscall"; 239 } 240 } 241 if ($libc) { 242 # Call unexported syscall functions (which take 243 # libc functions instead of syscall numbers). 244 $asm = lcfirst($asm); 245 } 246 if(@args <= 3) { 247 while(@args < 3) { 248 push @args, "0"; 249 } 250 } elsif(@args <= 6) { 251 $asm .= "6"; 252 while(@args < 6) { 253 push @args, "0"; 254 } 255 } elsif(@args <= 9) { 256 $asm .= "9"; 257 while(@args < 9) { 258 push @args, "0"; 259 } 260 } else { 261 print STDERR "$ARGV:$.: too many arguments to system call\n"; 262 } 263 264 if ($darwin || ($openbsd && $libc)) { 265 # Use extended versions for calls that generate a 64-bit result. 266 my ($name, $type) = parseparam($out[0]); 267 if ($type eq "int64" || ($type eq "uintptr" && $_32bit eq "")) { 268 $asm .= "X"; 269 } 270 } 271 272 # System call number. 273 my $funcname = ""; 274 if($sysname eq "") { 275 $sysname = "SYS_$func"; 276 $sysname =~ s/([a-z])([A-Z])/${1}_$2/g; # turn FooBar into Foo_Bar 277 $sysname =~ y/a-z/A-Z/; 278 if($libc) { 279 $sysname =~ y/A-Z/a-z/; 280 $sysname = substr $sysname, 4; 281 $funcname = "libc_$sysname"; 282 } 283 } 284 if($libc) { 285 if($funcname eq "") { 286 $sysname = substr $sysname, 4; 287 $funcname = "libc_$sysname"; 288 } 289 $sysname = "abi.FuncPCABI0(${funcname}_trampoline)"; 290 } 291 292 # Actual call. 293 my $args = join(', ', @args); 294 my $call = "$asm($sysname, $args)"; 295 296 # Assign return values. 297 my $body = ""; 298 my @ret = ("_", "_", "_"); 299 my $do_errno = 0; 300 for(my $i=0; $i<@out; $i++) { 301 my $p = $out[$i]; 302 my ($name, $type) = parseparam($p); 303 my $reg = ""; 304 if($name eq "err" && !$plan9) { 305 $reg = "e1"; 306 $ret[2] = $reg; 307 $do_errno = 1; 308 } elsif($name eq "err" && $plan9) { 309 $ret[0] = "r0"; 310 $ret[2] = "e1"; 311 next; 312 } else { 313 $reg = sprintf("r%d", $i); 314 $ret[$i] = $reg; 315 } 316 if($type eq "bool") { 317 $reg = "$reg != 0"; 318 } 319 if($type eq "int64" && $_32bit ne "") { 320 # 64-bit number in r1:r0 or r0:r1. 321 if($i+2 > @out) { 322 print STDERR "$ARGV:$.: not enough registers for int64 return\n"; 323 } 324 if($_32bit eq "big-endian") { 325 $reg = sprintf("int64(r%d)<<32 | int64(r%d)", $i, $i+1); 326 } else { 327 $reg = sprintf("int64(r%d)<<32 | int64(r%d)", $i+1, $i); 328 } 329 $ret[$i] = sprintf("r%d", $i); 330 $ret[$i+1] = sprintf("r%d", $i+1); 331 } 332 if($reg ne "e1" || $plan9) { 333 $body .= "\t$name = $type($reg)\n"; 334 } 335 } 336 if ($ret[0] eq "_" && $ret[1] eq "_" && $ret[2] eq "_") { 337 $text .= "\t$call\n"; 338 } else { 339 if ($errvar eq "" && $ENV{'GOOS'} eq "linux") { 340 # raw syscall without error on Linux, see golang.org/issue/22924 341 $text .= "\t$ret[0], $ret[1] := $call\n"; 342 } else { 343 $text .= "\t$ret[0], $ret[1], $ret[2] := $call\n"; 344 } 345 } 346 $text .= $body; 347 348 if ($plan9 && $ret[2] eq "e1") { 349 $text .= "\tif int32(r0) == -1 {\n"; 350 $text .= "\t\terr = e1\n"; 351 $text .= "\t}\n"; 352 } elsif ($do_errno) { 353 $text .= "\tif e1 != 0 {\n"; 354 $text .= "\t\terr = errnoErr(e1)\n"; 355 $text .= "\t}\n"; 356 } 357 $text .= "\treturn\n"; 358 $text .= "}\n\n"; 359 if($libc) { 360 if (not exists $trampolines{$funcname}) { 361 $trampolines{$funcname} = 1; 362 # The assembly trampoline that jumps to the libc routine. 363 $text .= "func ${funcname}_trampoline()\n\n"; 364 # Tell the linker that funcname can be found in libSystem using varname without the libc_ prefix. 365 my $basename = substr $funcname, 5; 366 my $libc = "libc.so"; 367 if ($darwin) { 368 $libc = "/usr/lib/libSystem.B.dylib"; 369 } 370 $text .= "//go:cgo_import_dynamic $funcname $basename \"$libc\"\n\n"; 371 } 372 } 373 } 374 375 chomp $text; 376 chomp $text; 377 378 if($errors) { 379 exit 1; 380 } 381 382 # TODO: this assumes tags are just simply comma separated. For now this is all the uses. 383 $newtags = $tags =~ s/,/ && /r; 384 385 print <<EOF; 386 // $cmdline 387 // Code generated by the command above; DO NOT EDIT. 388 389 //go:build $newtags 390 // +build $tags 391 392 package syscall 393 394 import "unsafe" 395 $extraimports 396 397 $text 398 EOF 399 exit 0;