Grab control file info and war dependencies from a debian file

debian.kt

package com.netflix.debian

import org.apache.commons.compress.archivers.*
import org.apache.commons.compress.compressors.CompressorStreamFactory
import java.io.*

fun main(args: Array<String>) {
    val libPattern = "WEB-INF/lib/(.+)\\.jar".toRegex()

    FileInputStream("pisces.deb").archiveStream { entry, debIn ->
        when (entry.name) {
            "control.tar.gz" ->
                debIn.unzippedEntry().archiveStream { controlEntry, controlIn ->
                    if (controlEntry.name == "./control") {
                        controlIn.reader().readText().splitToSequence("\n").forEach { println(it) }
                    }
                }
            "data.tar.gz" ->
                debIn.unzippedEntry().archiveStream { dataEntry, dataIn ->
                    if (dataEntry.name.matches("./apps/tomcat/webapps/.+\\.war".toRegex())) {
                        dataIn.archiveStream { warEntry, warIn ->
                            val jar = libPattern.match(warEntry.name)?.groups?.get(1)?.value
                            if (jar is String) {
                                println(jar)
                            }
                        }
                    }
                }
        }
    }.close()
}

fun InputStream.unzippedEntry() = CompressorStreamFactory().createCompressorInputStream(BufferedInputStream(this))

fun InputStream.archiveStream(archivePredicate: (ArchiveEntry, InputStream) -> Unit): InputStream {
    val buffered = buffered()
    val arIn = ArchiveStreamFactory().createArchiveInputStream(buffered)
    while (true) {
        val arEntry = arIn.nextEntry ?: break
        archivePredicate.invoke(arEntry, arIn)
    }
    return buffered
}

Makes some assumptions about the location of the war, but you get the idea... Extension functions are amazing to take a really unfriendly library like commons-compress and make it functional-like.