#!/usr/bin/perl -w

# A script to get around some shortcomings in elf2e32, namely:
# - Returning 0 even when there are errors.
# - Excluding symbols from the dso file even when they are present in the ELF file.
# - Including symbols in the the dso file even when they are not present in the ELF file.
# - Overwriting the old dso file even when there are no changes (increases build time).

use File::Copy;

my @args = ();
my @definput;
my @defoutput;
my @dso;
my @tmpdso;
foreach (@ARGV) {
    if (/^--definput/o) {
        @definput = split('=', $_);
    } elsif (/^--defoutput/o) {
        @defoutput = split('=', $_);
    } elsif (/^--dso/o) {
        @dso = split('=', $_);
    } elsif (/^--tmpdso/o) {
        @tmpdso = split('=', $_);
        $tmpdso[0] = "--dso";
    } else {
        push(@args, $_);
    }
}

@definput = () if (!@definput || ! -e $definput[1]);

if (@dso && !@tmpdso || !@dso && @tmpdso) {
    print("--dso and --tmpdso must be used together.\n");
    exit 1;
}

my $buildingLibrary = (@defoutput && @dso) ? 1 : 0;

my $fixupFile = "";
my $runCount = 0;
my $returnCode = 0;

while (1) {
    if (++$runCount > 2) {
        print("Internal error in $0, link succeeded, but exports may be wrong.\n");
        last;
    }

    my $elf2e32Pipe;
    my $elf2e32Cmd = "elf2e32 @args"
         . " " . join("=", @definput)
         . " " . join("=", @defoutput)
         . " " . join("=", @tmpdso);
    open($elf2e32Pipe, "$elf2e32Cmd 2>&1 |") or die ("Could not run elf2e32");

    my %fixupSymbols;
    my $foundBrokenSymbols = 0;
    my $errors = 0;
    while (<$elf2e32Pipe>) {
        print;
        if (/Error:/io) {
            $errors = 1;
        } elsif (/symbol ([a-z0-9_]+) absent in the DEF file, but present in the ELF file/io) {
            $fixupSymbols{$1} = 1;
            $foundBrokenSymbols = 1;
        } elsif (/[0-9]+ Frozen Export\(s\) missing from the ELF file/io) {
            $foundBrokenSymbols = 1;
        }
    }
    close($elf2e32Pipe);

    if ($errors) {
        $returnCode = 1;
        last;
    }

    if ($buildingLibrary) {
        my $tmpDefFile;
        my $defFile;
        open($defFile, "< $defoutput[1]") or die("Could not open $defoutput[1]");
        open($tmpDefFile, "> $defoutput[1].tmp") or die("Could not open $defoutput[1].tmp");
        $fixupFile = "$defoutput[1].tmp";
        while (<$defFile>) {
            s/\r//;
            s/\n//;
            next if (/; NEW:/);
            if (/([a-z0-9_]+) @/i) {
                if (exists($fixupSymbols{$1})) {
                    s/ ABSENT//;
                } elsif (s/; MISSING://) {
                    s/$/ ABSENT/;
                }
            }
            print($tmpDefFile "$_\n");
        }
        close($defFile);
        close($tmpDefFile);

        $definput[1] = "$defoutput[1].tmp";

        if (!$foundBrokenSymbols || $errors) {
            last;
        }

        print("Rerunning elf2e32 due to DEF file / ELF file mismatch\n");
    } else {
        last;
    }
};

if ($fixupFile) {
    unlink($defoutput[1]);
    move($fixupFile, $defoutput[1]);
}

exit $returnCode if ($returnCode != 0);

if ($buildingLibrary) {
    my $differenceFound = 0;

    if (-e $dso[1]) {
        my $dsoFile;
        my $tmpdsoFile;
        my $dsoBuf;
        my $tmpdsoBuf;
        open($dsoFile, "< $dso[1]") or die("Could not open $dso[1]");
        open($tmpdsoFile, "< $tmpdso[1]") or die("Could not open $tmpdso[1]");
        binmode($dsoFile);
        binmode($tmpdsoFile);
        while(read($dsoFile, $dsoBuf, 4096) && read($tmpdsoFile, $tmpdsoBuf, 4096)) {
            if ($dsoBuf ne $tmpdsoBuf) {
                $differenceFound = 1;
            }
        }
        close($tmpdsoFile);
        close($dsoFile);
    } else {
        $differenceFound = 1;
    }

    if ($differenceFound) {
        copy($tmpdso[1], $dso[1]);
    }
}