#!perl
use strict;
use Config;
use File::Temp;

my $SYS_re = qr/\bSYS_\w+|\bNR_syscalls\b/;
my @SYS_names;
{
    my $tmp = File::Temp->new;
    print $tmp "#include <sys/syscall.h>\n";
    my $cmd = "$Config{cpp} -dM $Config{cppflags} $tmp";
    open my $pipe, "$cmd |" or die "failed: $cmd";
    local $_;
    while (<$pipe>) {
	next unless s/^\s*#\s*define\s+//;
	my ($sym) = split;
	next unless $sym =~ $SYS_re;
	push @SYS_names, $sym;
    }
    close $pipe or die "failed: $cmd";
}

die "No $SYS_re names in <sys/syscall.h>"
    unless @SYS_names;

my $SYS_prefix = "PERL_syscall__";
my %SYS_kv;
{
    my $tmp = File::Temp->new;
    print $tmp "#include <sys/syscall.h>\n";
    for (@SYS_names) {
	print $tmp "$SYS_prefix$_ $_\n";
    }
    my $cmd = "$Config{cpp} $Config{cppflags} $tmp";
    open my $pipe, "$cmd |" or die "failed: $cmd";
    local $_;
    while (<$pipe>) {
	next unless s/^$SYS_prefix//;
	/^($SYS_re)\s+(\S.*)/ or die "bad cpp output: $_\n";
	$SYS_kv{$1} = $2;
    }
    close $pipe or die "failed: $cmd";
}

die "No $SYS_re names in <sys/syscall.h>"
    unless %SYS_kv;

unlink "sys_syscall.ph";
open my $fh, ">sys_syscall.ph" or die "Cannot open sys_syscall.ph: $!";
print $fh "# Automatically generated, do not edit.\n";
print $fh "use strict;\n";
for my $k (sort keys %SYS_kv) {
    my $v = $SYS_kv{$k};
    print $fh "sub $k () { $v }\n";
}
print $fh "1;\n";
close $fh or die "Cannot close sys_syscall.ph: $!";
require "./sys_syscall.ph";