Streaming AB OTA on Android

gistfile1.txt

                var h = URL(otaUrl).openConnection() as HttpsURLConnection
                var zis = ZipInputStream(h.inputStream)
                var props = ""
                var offset  = 0L
                val FIXED_HEADER_SIZE = 30
                var payload_offset = 0L
                var payload_size = 0L

                while(true) {
                    val entry = zis.nextEntry
                    if(entry == null) break
                    val size = entry.size

                    val n = entry.name.length
                    val m = if (entry.extra == null) 0 else entry.extra.size
                    val headerSize = FIXED_HEADER_SIZE + n + m
                    offset += headerSize

                    l("Entry $entry")

                    if (entry.name.equals("payload.bin")) {
                        payload_offset = offset
                        payload_size = entry.compressedSize
                        val nextEntryOffset = payload_offset + entry.compressedSize
                        zis.close()
                        l("Payload starts at $payload_offset ends at $nextEntryOffset")
                        h = URL(otaUrl).openConnection() as HttpsURLConnection
                        h.setRequestProperty("Range", "bytes=$nextEntryOffset-")
                        zis = ZipInputStream(h.inputStream)
                    }
                    offset += entry.compressedSize

                    if(entry.name == "payload_properties.txt") {
                        val barr = ByteArray(size.toInt())
                        zis.read(barr)
                        props = String(barr, Charsets.UTF_8)
                        l("Payload properties is $props")
                    }
                    zis.closeEntry()
                }

                l("Got payload offset $payload_offset")

                val p = props
                    .split("\n")
                    .filter { it.contains("=") }
                    .map { it.trim() }
                    .toTypedArray()
                l("props")
                for(i in p) {
                    l("- $i")
                }
                val svc = Class.forName("android.os.UpdateEngine")
                    .getConstructor().newInstance()
                svc.javaClass
                    .getMethod("applyPayload", String::class.java, Long::class.java, Long::class.java, Array<String>::class.java)
                    .invoke(svc, otaUrl, payload_offset, payload_size, p)