github.com/c12o16h1/go/src@v0.0.0-20200114212001-5a151c0f00ed/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 $tags = "";  # build tags
    34  
    35  if($ARGV[0] eq "-b32") {
    36  	$_32bit = "big-endian";
    37  	shift;
    38  } elsif($ARGV[0] eq "-l32") {
    39  	$_32bit = "little-endian";
    40  	shift;
    41  }
    42  if($ARGV[0] eq "-plan9") {
    43  	$plan9 = 1;
    44  	shift;
    45  }
    46  if($ARGV[0] eq "-darwin") {
    47  	$darwin = 1;
    48  	shift;
    49  }
    50  if($ARGV[0] eq "-openbsd") {
    51  	$openbsd = 1;
    52  	shift;
    53  }
    54  if($ARGV[0] eq "-netbsd") {
    55  	$netbsd = 1;
    56  	shift;
    57  }
    58  if($ARGV[0] eq "-dragonfly") {
    59  	$dragonfly = 1;
    60  	shift;
    61  }
    62  if($ARGV[0] eq "-arm") {
    63  	$arm = 1;
    64  	shift;
    65  }
    66  if($ARGV[0] eq "-tags") {
    67  	shift;
    68  	$tags = $ARGV[0];
    69  	shift;
    70  }
    71  
    72  if($ARGV[0] =~ /^-/) {
    73  	print STDERR "usage: mksyscall.pl [-b32 | -l32] [-tags x,y] [file ...]\n";
    74  	exit 1;
    75  }
    76  
    77  sub parseparamlist($) {
    78  	my ($list) = @_;
    79  	$list =~ s/^\s*//;
    80  	$list =~ s/\s*$//;
    81  	if($list eq "") {
    82  		return ();
    83  	}
    84  	return split(/\s*,\s*/, $list);
    85  }
    86  
    87  sub parseparam($) {
    88  	my ($p) = @_;
    89  	if($p !~ /^(\S*) (\S*)$/) {
    90  		print STDERR "$ARGV:$.: malformed parameter: $p\n";
    91  		$errors = 1;
    92  		return ("xx", "int");
    93  	}
    94  	return ($1, $2);
    95  }
    96  
    97  # set of trampolines we've already generated
    98  my %trampolines;
    99  
   100  my $text = "";
   101  while(<>) {
   102  	chomp;
   103  	s/\s+/ /g;
   104  	s/^\s+//;
   105  	s/\s+$//;
   106  	my $nonblock = /^\/\/sysnb /;
   107  	next if !/^\/\/sys / && !$nonblock;
   108  
   109  	# Line must be of the form
   110  	#	func Open(path string, mode int, perm int) (fd int, errno error)
   111  	# Split into name, in params, out params.
   112  	if(!/^\/\/sys(nb)? (\w+)\(([^()]*)\)\s*(?:\(([^()]+)\))?\s*(?:=\s*((?i)_?SYS_[A-Z0-9_]+))?$/) {
   113  		print STDERR "$ARGV:$.: malformed //sys declaration\n";
   114  		$errors = 1;
   115  		next;
   116  	}
   117  	my ($func, $in, $out, $sysname) = ($2, $3, $4, $5);
   118  
   119  	# Split argument lists on comma.
   120  	my @in = parseparamlist($in);
   121  	my @out = parseparamlist($out);
   122  
   123  	# Try in vain to keep people from editing this file.
   124  	# The theory is that they jump into the middle of the file
   125  	# without reading the header.
   126  	$text .= "// THIS FILE IS GENERATED BY THE COMMAND AT THE TOP; DO NOT EDIT\n\n";
   127  
   128  	if ($darwin && $func eq "ptrace") {
   129  		# The ptrace function is called from forkAndExecInChild where stack
   130  		# growth is forbidden.
   131  		$text .= "//go:nosplit\n"
   132  	}
   133  
   134  	# Go function header.
   135  	my $out_decl = @out ? sprintf(" (%s)", join(', ', @out)) : "";
   136  	$text .= sprintf "func %s(%s)%s {\n", $func, join(', ', @in), $out_decl;
   137  
   138  	# Check if err return available
   139  	my $errvar = "";
   140  	foreach my $p (@out) {
   141  		my ($name, $type) = parseparam($p);
   142  		if($type eq "error") {
   143  			$errvar = $name;
   144  			last;
   145  		}
   146  	}
   147  
   148  	# Prepare arguments to Syscall.
   149  	my @args = ();
   150  	my $n = 0;
   151  	foreach my $p (@in) {
   152  		my ($name, $type) = parseparam($p);
   153  		if($type =~ /^\*/) {
   154  			push @args, "uintptr(unsafe.Pointer($name))";
   155  		} elsif($type eq "string" && $errvar ne "") {
   156  			$text .= "\tvar _p$n *byte\n";
   157  			$text .= "\t_p$n, $errvar = BytePtrFromString($name)\n";
   158  			$text .= "\tif $errvar != nil {\n\t\treturn\n\t}\n";
   159  			push @args, "uintptr(unsafe.Pointer(_p$n))";
   160  			$n++;
   161  		} elsif($type eq "string") {
   162  			print STDERR "$ARGV:$.: $func uses string arguments, but has no error return\n";
   163  			$text .= "\tvar _p$n *byte\n";
   164  			$text .= "\t_p$n, _ = BytePtrFromString($name)\n";
   165  			push @args, "uintptr(unsafe.Pointer(_p$n))";
   166  			$n++;
   167  		} elsif($type =~ /^\[\](.*)/) {
   168  			# Convert slice into pointer, length.
   169  			# Have to be careful not to take address of &a[0] if len == 0:
   170  			# pass dummy pointer in that case.
   171  			# Used to pass nil, but some OSes or simulators reject write(fd, nil, 0).
   172  			$text .= "\tvar _p$n unsafe.Pointer\n";
   173  			$text .= "\tif len($name) > 0 {\n\t\t_p$n = unsafe.Pointer(\&${name}[0])\n\t}";
   174  			$text .= " else {\n\t\t_p$n = unsafe.Pointer(&_zero)\n\t}";
   175  			$text .= "\n";
   176  			push @args, "uintptr(_p$n)", "uintptr(len($name))";
   177  			$n++;
   178  		} elsif($type eq "int64" && ($openbsd || $netbsd)) {
   179  			push @args, "0";
   180  			if($_32bit eq "big-endian") {
   181  				push @args, "uintptr($name>>32)", "uintptr($name)";
   182  			} elsif($_32bit eq "little-endian") {
   183  				push @args, "uintptr($name)", "uintptr($name>>32)";
   184  			} else {
   185  				push @args, "uintptr($name)";
   186  			}
   187  		} elsif($type eq "int64" && $dragonfly) {
   188  			if ($func !~ /^extp(read|write)/i) {
   189  				push @args, "0";
   190  			}
   191  			if($_32bit eq "big-endian") {
   192  				push @args, "uintptr($name>>32)", "uintptr($name)";
   193  			} elsif($_32bit eq "little-endian") {
   194  				push @args, "uintptr($name)", "uintptr($name>>32)";
   195  			} else {
   196  				push @args, "uintptr($name)";
   197  			}
   198  		} elsif($type eq "int64" && $_32bit ne "") {
   199  			if(@args % 2 && $arm) {
   200  				# arm abi specifies 64-bit argument uses
   201  				# (even, odd) pair
   202  				push @args, "0"
   203  			}
   204  			if($_32bit eq "big-endian") {
   205  				push @args, "uintptr($name>>32)", "uintptr($name)";
   206  			} else {
   207  				push @args, "uintptr($name)", "uintptr($name>>32)";
   208  			}
   209  		} else {
   210  			push @args, "uintptr($name)";
   211  		}
   212  	}
   213  
   214  	# Determine which form to use; pad args with zeros.
   215  	my $asm = "Syscall";
   216  	if ($nonblock) {
   217  		if ($errvar eq "" && $ENV{'GOOS'} eq "linux") {
   218  			$asm = "rawSyscallNoError";
   219  		} else {
   220  			$asm = "RawSyscall";
   221  		}
   222  	}
   223  	if ($darwin) {
   224  		# Call unexported syscall functions (which take
   225  		# libc functions instead of syscall numbers).
   226  		$asm = lcfirst($asm);
   227  	}
   228  	if(@args <= 3) {
   229  		while(@args < 3) {
   230  			push @args, "0";
   231  		}
   232  	} elsif(@args <= 6) {
   233  		$asm .= "6";
   234  		while(@args < 6) {
   235  			push @args, "0";
   236  		}
   237  	} elsif(@args <= 9) {
   238  		$asm .= "9";
   239  		while(@args < 9) {
   240  			push @args, "0";
   241  		}
   242  	} else {
   243  		print STDERR "$ARGV:$.: too many arguments to system call\n";
   244  	}
   245  
   246  	if ($darwin) {
   247  		# Use extended versions for calls that generate a 64-bit result.
   248  		my ($name, $type) = parseparam($out[0]);
   249  		if ($type eq "int64" || ($type eq "uintptr" && $_32bit eq "")) {
   250  			$asm .= "X";
   251  		}
   252  	}
   253  
   254  	# System call number.
   255  	my $funcname = "";
   256  	if($sysname eq "") {
   257  		$sysname = "SYS_$func";
   258  		$sysname =~ s/([a-z])([A-Z])/${1}_$2/g;	# turn FooBar into Foo_Bar
   259  		$sysname =~ y/a-z/A-Z/;
   260  		if($darwin) {
   261  			$sysname =~ y/A-Z/a-z/;
   262  			$sysname = substr $sysname, 4;
   263  			$funcname = "libc_$sysname";
   264  		}
   265  	}
   266  	if($darwin) {
   267  		if($funcname eq "") {
   268  			$sysname = substr $sysname, 4;
   269  			$funcname = "libc_$sysname";
   270  		}
   271  		$sysname = "funcPC(${funcname}_trampoline)";
   272  	}
   273  
   274  	# Actual call.
   275  	my $args = join(', ', @args);
   276  	my $call = "$asm($sysname, $args)";
   277  
   278  	# Assign return values.
   279  	my $body = "";
   280  	my @ret = ("_", "_", "_");
   281  	my $do_errno = 0;
   282  	for(my $i=0; $i<@out; $i++) {
   283  		my $p = $out[$i];
   284  		my ($name, $type) = parseparam($p);
   285  		my $reg = "";
   286  		if($name eq "err" && !$plan9) {
   287  			$reg = "e1";
   288  			$ret[2] = $reg;
   289  			$do_errno = 1;
   290  		} elsif($name eq "err" && $plan9) {
   291  			$ret[0] = "r0";
   292  			$ret[2] = "e1";
   293  			next;
   294  		} else {
   295  			$reg = sprintf("r%d", $i);
   296  			$ret[$i] = $reg;
   297  		}
   298  		if($type eq "bool") {
   299  			$reg = "$reg != 0";
   300  		}
   301  		if($type eq "int64" && $_32bit ne "") {
   302  			# 64-bit number in r1:r0 or r0:r1.
   303  			if($i+2 > @out) {
   304  				print STDERR "$ARGV:$.: not enough registers for int64 return\n";
   305  			}
   306  			if($_32bit eq "big-endian") {
   307  				$reg = sprintf("int64(r%d)<<32 | int64(r%d)", $i, $i+1);
   308  			} else {
   309  				$reg = sprintf("int64(r%d)<<32 | int64(r%d)", $i+1, $i);
   310  			}
   311  			$ret[$i] = sprintf("r%d", $i);
   312  			$ret[$i+1] = sprintf("r%d", $i+1);
   313  		}
   314  		if($reg ne "e1" || $plan9) {
   315  			$body .= "\t$name = $type($reg)\n";
   316  		}
   317  	}
   318  	if ($ret[0] eq "_" && $ret[1] eq "_" && $ret[2] eq "_") {
   319  		$text .= "\t$call\n";
   320  	} else {
   321  		if ($errvar eq "" && $ENV{'GOOS'} eq "linux") {
   322  			# raw syscall without error on Linux, see golang.org/issue/22924
   323  			$text .= "\t$ret[0], $ret[1] := $call\n";
   324  		} else {
   325  			$text .= "\t$ret[0], $ret[1], $ret[2] := $call\n";
   326  		}
   327  	}
   328  	$text .= $body;
   329  
   330  	if ($plan9 && $ret[2] eq "e1") {
   331  		$text .= "\tif int32(r0) == -1 {\n";
   332  		$text .= "\t\terr = e1\n";
   333  		$text .= "\t}\n";
   334  	} elsif ($do_errno) {
   335  		$text .= "\tif e1 != 0 {\n";
   336  		$text .= "\t\terr = errnoErr(e1)\n";
   337  		$text .= "\t}\n";
   338  	}
   339  	$text .= "\treturn\n";
   340  	$text .= "}\n\n";
   341  	if($darwin) {
   342  		if (not exists $trampolines{$funcname}) {
   343  			$trampolines{$funcname} = 1;
   344  			# The assembly trampoline that jumps to the libc routine.
   345  			$text .= "func ${funcname}_trampoline()\n";
   346  			# Map syscall.funcname to just plain funcname.
   347  			# (The jump to this function is in the assembly trampoline, generated by mksyscallasm_darwin.go.)
   348  			$text .= "//go:linkname $funcname $funcname\n";
   349  			# Tell the linker that funcname can be found in libSystem using varname without the libc_ prefix.
   350  			my $basename = substr $funcname, 5;
   351  			$text .= "//go:cgo_import_dynamic $funcname $basename \"/usr/lib/libSystem.B.dylib\"\n\n";
   352  		}
   353  	}
   354  }
   355  
   356  chomp $text;
   357  chomp $text;
   358  
   359  if($errors) {
   360  	exit 1;
   361  }
   362  
   363  print <<EOF;
   364  // $cmdline
   365  // Code generated by the command above; DO NOT EDIT.
   366  
   367  // +build $tags
   368  
   369  package syscall
   370  
   371  import "unsafe"
   372  
   373  $text
   374  EOF
   375  exit 0;