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Text file src/syscall/mksyscall.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_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
    22use strict;
    23
    24my $cmdline = "mksyscall.pl " . join(' ', @ARGV);
    25my $errors = 0;
    26my $_32bit = "";
    27my $plan9 = 0;
    28my $darwin = 0;
    29my $openbsd = 0;
    30my $netbsd = 0;
    31my $dragonfly = 0;
    32my $nacl = 0;
    33my $arm = 0; # 64-bit value should use (even, odd)-pair
    34my $tags = "";  # build tags
    35
    36if($ARGV[0] eq "-b32") {
    37	$_32bit = "big-endian";
    38	shift;
    39} elsif($ARGV[0] eq "-l32") {
    40	$_32bit = "little-endian";
    41	shift;
    42}
    43if($ARGV[0] eq "-plan9") {
    44	$plan9 = 1;
    45	shift;
    46}
    47if($ARGV[0] eq "-darwin") {
    48	$darwin = 1;
    49	shift;
    50}
    51if($ARGV[0] eq "-openbsd") {
    52	$openbsd = 1;
    53	shift;
    54}
    55if($ARGV[0] eq "-netbsd") {
    56	$netbsd = 1;
    57	shift;
    58}
    59if($ARGV[0] eq "-dragonfly") {
    60	$dragonfly = 1;
    61	shift;
    62}
    63if($ARGV[0] eq "-nacl") {
    64	$nacl = 1;
    65	shift;
    66}
    67if($ARGV[0] eq "-arm") {
    68	$arm = 1;
    69	shift;
    70}
    71if($ARGV[0] eq "-tags") {
    72	shift;
    73	$tags = $ARGV[0];
    74	shift;
    75}
    76
    77if($ARGV[0] =~ /^-/) {
    78	print STDERR "usage: mksyscall.pl [-b32 | -l32] [-tags x,y] [file ...]\n";
    79	exit 1;
    80}
    81
    82sub parseparamlist($) {
    83	my ($list) = @_;
    84	$list =~ s/^\s*//;
    85	$list =~ s/\s*$//;
    86	if($list eq "") {
    87		return ();
    88	}
    89	return split(/\s*,\s*/, $list);
    90}
    91
    92sub parseparam($) {
    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
   103my %trampolines;
   104
   105my $text = "";
   106while(<>) {
   107	chomp;
   108	s/\s+/ /g;
   109	s/^\s+//;
   110	s/\s+$//;
   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
   358chomp $text;
   359chomp $text;
   360
   361if($errors) {
   362	exit 1;
   363}
   364
   365print <<EOF;
   366// $cmdline
   367// Code generated by the command above; DO NOT EDIT.
   368
   369// +build $tags
   370
   371package syscall
   372
   373import "unsafe"
   374
   375$text
   376EOF
   377exit 0;

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