Name: dbT83986 Date: 08/15/99


Uncompressing a file using java.util.zip.GZIPInputStream fails if the uncompressed file is 2GB or larger (it works for files up to 2,147,483,647 bytes). I suspect that the problem is an overflow, presumably of a variable somewhere in GZIPInputStream that should be declared as long, but is declared as int.

Here is the program that exhibits the problem:

import java.io.FileInputStream;
import java.io.IOException;
import java.util.zip.GZIPInputStream;

public class TestGZIP {
    public static void main(String[] args) {
        try {
            FileInputStream fis = new FileInputStream(args[0]);
            GZIPInputStream gis = new GZIPInputStream(fis);
            while (gis.read() != -1) {}
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

Here is a program for producing a large file (full of zeroes) of a specific length:

import java.io.FileOutputStream;
import java.io.IOException;

public class WriteZeros {
    public static void main(String[] args) throws IOException {
        byte[] buf = new byte[8192];
        long n = Long.parseLong(args[0]);
        FileOutputStream fos = new FileOutputStream(args[1]);
        long m = n / buf.length;
        for (long i = 0; i < m; i++) {
            fos.write(buf, 0, buf.length);
        }
        fos.write(buf, 0, (int)(n % buf.length));
        fos.close();
    }
}

% java WriteZeros 2147483647 twogigminusone
% gzip twogigminusone
% java TestGZIP twogigminusone.gz
% java WriteZeros 2147483648 twogig
% gzip twogig
% java TestGZIP twogig.gz
java.io.IOException: Corrupt GZIP trailer
        at java.util.zip.GZIPInputStream.readTrailer (GZIPInputStream.java:173) (pc 85)
        at java.util.zip.GZIPInputStream.read (GZIPInputStream.java:90) (pc 23)
        at java.util.zip.InflaterInputStream.read (pc 8)
        at TestGZIP.main (TestGZIP.java:10) (pc 24)
(Review ID: 93899)
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