github.com/megatontech/mynoteforgo@v0.0.0-20200507084910-5d0c6ea6e890/源码/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 $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 # Go function header. 134 my $out_decl = @out ? sprintf(" (%s)", join(', ', @out)) : ""; 135 $text .= sprintf "func %s(%s)%s {\n", $func, join(', ', @in), $out_decl; 136 137 # Check if err return available 138 my $errvar = ""; 139 foreach my $p (@out) { 140 my ($name, $type) = parseparam($p); 141 if($type eq "error") { 142 $errvar = $name; 143 last; 144 } 145 } 146 147 # Prepare arguments to Syscall. 148 my @args = (); 149 my $n = 0; 150 foreach my $p (@in) { 151 my ($name, $type) = parseparam($p); 152 if($type =~ /^\*/) { 153 push @args, "uintptr(unsafe.Pointer($name))"; 154 } elsif($type eq "string" && $errvar ne "") { 155 $text .= "\tvar _p$n *byte\n"; 156 $text .= "\t_p$n, $errvar = BytePtrFromString($name)\n"; 157 $text .= "\tif $errvar != nil {\n\t\treturn\n\t}\n"; 158 push @args, "uintptr(unsafe.Pointer(_p$n))"; 159 $n++; 160 } elsif($type eq "string") { 161 print STDERR "$ARGV:$.: $func uses string arguments, but has no error return\n"; 162 $text .= "\tvar _p$n *byte\n"; 163 $text .= "\t_p$n, _ = BytePtrFromString($name)\n"; 164 push @args, "uintptr(unsafe.Pointer(_p$n))"; 165 $n++; 166 } elsif($type =~ /^\[\](.*)/) { 167 # Convert slice into pointer, length. 168 # Have to be careful not to take address of &a[0] if len == 0: 169 # pass dummy pointer in that case. 170 # Used to pass nil, but some OSes or simulators reject write(fd, nil, 0). 171 $text .= "\tvar _p$n unsafe.Pointer\n"; 172 $text .= "\tif len($name) > 0 {\n\t\t_p$n = unsafe.Pointer(\&${name}[0])\n\t}"; 173 $text .= " else {\n\t\t_p$n = unsafe.Pointer(&_zero)\n\t}"; 174 $text .= "\n"; 175 push @args, "uintptr(_p$n)", "uintptr(len($name))"; 176 $n++; 177 } elsif($type eq "int64" && ($openbsd || $netbsd)) { 178 push @args, "0"; 179 if($_32bit eq "big-endian") { 180 push @args, "uintptr($name>>32)", "uintptr($name)"; 181 } elsif($_32bit eq "little-endian") { 182 push @args, "uintptr($name)", "uintptr($name>>32)"; 183 } else { 184 push @args, "uintptr($name)"; 185 } 186 } elsif($type eq "int64" && $dragonfly) { 187 if ($func !~ /^extp(read|write)/i) { 188 push @args, "0"; 189 } 190 if($_32bit eq "big-endian") { 191 push @args, "uintptr($name>>32)", "uintptr($name)"; 192 } elsif($_32bit eq "little-endian") { 193 push @args, "uintptr($name)", "uintptr($name>>32)"; 194 } else { 195 push @args, "uintptr($name)"; 196 } 197 } elsif($type eq "int64" && $_32bit ne "") { 198 if(@args % 2 && $arm) { 199 # arm abi specifies 64-bit argument uses 200 # (even, odd) pair 201 push @args, "0" 202 } 203 if($_32bit eq "big-endian") { 204 push @args, "uintptr($name>>32)", "uintptr($name)"; 205 } else { 206 push @args, "uintptr($name)", "uintptr($name>>32)"; 207 } 208 } else { 209 push @args, "uintptr($name)"; 210 } 211 } 212 213 # Determine which form to use; pad args with zeros. 214 my $asm = "Syscall"; 215 if ($nonblock) { 216 if ($errvar eq "" && $ENV{'GOOS'} eq "linux") { 217 $asm = "rawSyscallNoError"; 218 } else { 219 $asm = "RawSyscall"; 220 } 221 } 222 if ($darwin) { 223 # Call unexported syscall functions (which take 224 # libc functions instead of syscall numbers). 225 $asm = lcfirst($asm); 226 } 227 if(@args <= 3) { 228 while(@args < 3) { 229 push @args, "0"; 230 } 231 } elsif(@args <= 6) { 232 $asm .= "6"; 233 while(@args < 6) { 234 push @args, "0"; 235 } 236 } elsif(@args <= 9) { 237 $asm .= "9"; 238 while(@args < 9) { 239 push @args, "0"; 240 } 241 } else { 242 print STDERR "$ARGV:$.: too many arguments to system call\n"; 243 } 244 245 if ($darwin) { 246 # Use extended versions for calls that generate a 64-bit result. 247 my ($name, $type) = parseparam($out[0]); 248 if ($type eq "int64" || ($type eq "uintptr" && $_32bit eq "")) { 249 $asm .= "X"; 250 } 251 } 252 253 # System call number. 254 my $funcname = ""; 255 if($sysname eq "") { 256 $sysname = "SYS_$func"; 257 $sysname =~ s/([a-z])([A-Z])/${1}_$2/g; # turn FooBar into Foo_Bar 258 $sysname =~ y/a-z/A-Z/; 259 if($nacl) { 260 $sysname =~ y/A-Z/a-z/; 261 } 262 if($darwin) { 263 $sysname =~ y/A-Z/a-z/; 264 $sysname = substr $sysname, 4; 265 $funcname = "libc_$sysname"; 266 } 267 } 268 if($darwin) { 269 if($funcname eq "") { 270 $sysname = substr $sysname, 4; 271 $funcname = "libc_$sysname"; 272 } 273 $sysname = "funcPC(${funcname}_trampoline)"; 274 } 275 276 # Actual call. 277 my $args = join(', ', @args); 278 my $call = "$asm($sysname, $args)"; 279 280 # Assign return values. 281 my $body = ""; 282 my @ret = ("_", "_", "_"); 283 my $do_errno = 0; 284 for(my $i=0; $i<@out; $i++) { 285 my $p = $out[$i]; 286 my ($name, $type) = parseparam($p); 287 my $reg = ""; 288 if($name eq "err" && !$plan9) { 289 $reg = "e1"; 290 $ret[2] = $reg; 291 $do_errno = 1; 292 } elsif($name eq "err" && $plan9) { 293 $ret[0] = "r0"; 294 $ret[2] = "e1"; 295 next; 296 } else { 297 $reg = sprintf("r%d", $i); 298 $ret[$i] = $reg; 299 } 300 if($type eq "bool") { 301 $reg = "$reg != 0"; 302 } 303 if($type eq "int64" && $_32bit ne "") { 304 # 64-bit number in r1:r0 or r0:r1. 305 if($i+2 > @out) { 306 print STDERR "$ARGV:$.: not enough registers for int64 return\n"; 307 } 308 if($_32bit eq "big-endian") { 309 $reg = sprintf("int64(r%d)<<32 | int64(r%d)", $i, $i+1); 310 } else { 311 $reg = sprintf("int64(r%d)<<32 | int64(r%d)", $i+1, $i); 312 } 313 $ret[$i] = sprintf("r%d", $i); 314 $ret[$i+1] = sprintf("r%d", $i+1); 315 } 316 if($reg ne "e1" || $plan9) { 317 $body .= "\t$name = $type($reg)\n"; 318 } 319 } 320 if ($ret[0] eq "_" && $ret[1] eq "_" && $ret[2] eq "_") { 321 $text .= "\t$call\n"; 322 } else { 323 if ($errvar eq "" && $ENV{'GOOS'} eq "linux") { 324 # raw syscall without error on Linux, see golang.org/issue/22924 325 $text .= "\t$ret[0], $ret[1] := $call\n"; 326 } else { 327 $text .= "\t$ret[0], $ret[1], $ret[2] := $call\n"; 328 } 329 } 330 $text .= $body; 331 332 if ($plan9 && $ret[2] eq "e1") { 333 $text .= "\tif int32(r0) == -1 {\n"; 334 $text .= "\t\terr = e1\n"; 335 $text .= "\t}\n"; 336 } elsif ($do_errno) { 337 $text .= "\tif e1 != 0 {\n"; 338 $text .= "\t\terr = errnoErr(e1)\n"; 339 $text .= "\t}\n"; 340 } 341 $text .= "\treturn\n"; 342 $text .= "}\n\n"; 343 if($darwin) { 344 if (not exists $trampolines{$funcname}) { 345 $trampolines{$funcname} = 1; 346 # The assembly trampoline that jumps to the libc routine. 347 $text .= "func ${funcname}_trampoline()\n"; 348 # Map syscall.funcname to just plain funcname. 349 # (The jump to this function is in the assembly trampoline, generated by mksyscallasm_darwin.go.) 350 $text .= "//go:linkname $funcname $funcname\n"; 351 # Tell the linker that funcname can be found in libSystem using varname without the libc_ prefix. 352 my $basename = substr $funcname, 5; 353 $text .= "//go:cgo_import_dynamic $funcname $basename \"/usr/lib/libSystem.B.dylib\"\n"; 354 } 355 } 356 } 357 358 chomp $text; 359 chomp $text; 360 361 if($errors) { 362 exit 1; 363 } 364 365 print <<EOF; 366 // $cmdline 367 // Code generated by the command above; DO NOT EDIT. 368 369 // +build $tags 370 371 package syscall 372 373 import "unsafe" 374 375 $text 376 EOF 377 exit 0;