kmp-zip

ZIP input/output streams with Java-compatible byte-array streams, DEFLATE via zlib, adapters for common I/O libraries, and comprehensive ZipEntry metadata plus streaming APIs.

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JVMKotlin/NativeWasm
GitHub stars5
Authorshenrik242
Open issues1
LicenseMozilla Public License 2.0
Creation date3 months ago
Last activityabout 2 months ago
Latest release0.11.2 (7 days ago)
GitHub repositoryGitHub pages

kmp-zip

Kotlin Multiplatform ZIP and GZIP library for JVM and iOS targets.

Provides ByteArrayInputStream, ByteArrayOutputStream, ZipInputStream, ZipOutputStream, GzipInputStream, and GzipOutputStream with a common API across platforms. On JVM, the implementations delegate to java.io and java.util.zip. On iOS/Native, they are pure Kotlin implementations using platform.zlib for DEFLATE compression and decompression.

Modules

Artifact Description
no.synth:kmp-zip Core I/O, ZIP, and GZIP streams
no.synth:kmp-zip-kotlinx kotlinx-io Source/Sink adapters (both directions) for the core streams
no.synth:kmp-zip-okio OkIO BufferedSource/BufferedSink/Source/Sink adapters (both directions) for the core streams

Targets

  • JVM (also consumable from Android projects)
  • iosX64, iosArm64, iosSimulatorArm64

Installation

Published on Maven Central. No special repository configuration needed.

kotlin {
    sourceSets {
        commonMain {
            dependencies {
                implementation("no.synth:kmp-zip:0.8.0")

                // Optional: kotlinx-io adapters
                implementation("no.synth:kmp-zip-kotlinx:0.8.0")

                // Optional: OkIO adapters
                implementation("no.synth:kmp-zip-okio:0.8.0")
            }
        }
    }
}

API

kmp-zip — no.synth.kmpzip.io

Type Description
InputStream Abstract class — read(), read(ByteArray, off, len), available(), skip(), close(), etc.
OutputStream Abstract class — write(Int), write(ByteArray, off, len), flush(), close()
ByteArrayInputStream Reads from a ByteArray. Full Java-compatible API.
ByteArrayOutputStream Auto-growing buffer with toByteArray(), size(), reset(), writeTo()
InputStream.readBytes() Extension that reads all remaining bytes

kmp-zip — no.synth.kmpzip.zip

Type Description
ZipInputStream(InputStream) Reads ZIP entries — nextEntry, closeEntry(), read(), readBytes()
ZipInputStream(ByteArray) Convenience factory
ZipOutputStream(OutputStream) Writes ZIP entries — putNextEntry(), closeEntry(), write(), finish(), setMethod(), setLevel()
ZipEntry Entry metadata — name, size, compressedSize, crc, method, isDirectory, time, comment, extra
ZipConstants STORED = 0, DEFLATED = 8

kmp-zip — no.synth.kmpzip.gzip

Type Description
GzipInputStream(InputStream) Decompresses a GZIP stream — read(), available(), close()
GzipInputStream(ByteArray) Convenience factory
GzipOutputStream(OutputStream) Compresses data in GZIP format — write(), finish(), flush(), close()

kmp-zip-kotlinx — no.synth.kmpzip.kotlinx

Type Description
SourceInputStream(Source) Wraps a kotlinx-io Source as an InputStream
SinkOutputStream(Sink) Wraps a kotlinx-io Sink as an OutputStream
InputStreamSource(InputStream) Wraps an InputStream as a kotlinx-io RawSource
OutputStreamSink(OutputStream) Wraps an OutputStream as a kotlinx-io RawSink
Source.asInputStream() Extension shorthand
Sink.asOutputStream() Extension shorthand
InputStream.asSource() Extension shorthand
OutputStream.asSink() Extension shorthand
ZipInputStream(Source) Factory — creates a ZipInputStream from a Source
ZipOutputStream(Sink) Factory — creates a ZipOutputStream from a Sink
GzipInputStream(Source) Factory — creates a GzipInputStream from a Source
GzipOutputStream(Sink) Factory — creates a GzipOutputStream from a Sink

kmp-zip-okio — no.synth.kmpzip.okio

Type Description
SourceInputStream(BufferedSource) Wraps an OkIO BufferedSource as an InputStream
SinkOutputStream(BufferedSink) Wraps an OkIO BufferedSink as an OutputStream
InputStreamSource(InputStream) Wraps an InputStream as an OkIO Source
OutputStreamSink(OutputStream) Wraps an OutputStream as an OkIO Sink
BufferedSource.asInputStream() Extension shorthand
BufferedSink.asOutputStream() Extension shorthand
InputStream.asSource() Extension shorthand
OutputStream.asSink() Extension shorthand
ZipInputStream(BufferedSource) Factory — creates a ZipInputStream from a BufferedSource
ZipOutputStream(BufferedSink) Factory — creates a ZipOutputStream from a BufferedSink
GzipInputStream(BufferedSource) Factory — creates a GzipInputStream from a BufferedSource
GzipOutputStream(BufferedSink) Factory — creates a GzipOutputStream from a BufferedSink

Usage

Read a ZIP from a ByteArray

ZipInputStream(zipBytes).use { zis ->
    while (true) {
        val entry = zis.nextEntry ?: break
        println("${entry.name}: ${zis.readBytes().decodeToString()}")
    }
}

Create a ZIP into a ByteArray

val buf = ByteArrayOutputStream()
ZipOutputStream(buf).use { zos ->
    zos.putNextEntry(ZipEntry("hello.txt"))
    zos.write("Hello, world!".encodeToByteArray())
    zos.closeEntry()
}
val zipBytes = buf.toByteArray()

GZIP compress and decompress

// Compress
val buf = ByteArrayOutputStream()
GzipOutputStream(buf).use { gzos ->
    gzos.write("Hello, world!".encodeToByteArray())
}
val gzipped = buf.toByteArray()

// Decompress
val text = GzipInputStream(gzipped).use { gzis ->
    gzis.readBytes().decodeToString()
}

kotlinx-io: read/write ZIPs via Source/Sink

import kotlinx.io.Buffer
import no.synth.kmpzip.kotlinx.ZipInputStream
import no.synth.kmpzip.kotlinx.ZipOutputStream

val buffer = Buffer()

// Write
ZipOutputStream(buffer).use { zos ->
    zos.putNextEntry(ZipEntry("hello.txt"))
    zos.write("Hello from kotlinx-io!".encodeToByteArray())
    zos.closeEntry()
}

// Read
ZipInputStream(buffer).use { zis ->
    val entry = zis.nextEntry ?: error("Expected entry")
    println("${entry.name}: ${zis.readBytes().decodeToString()}")
}

OkIO: read/write ZIPs via BufferedSource/BufferedSink

import okio.Buffer
import no.synth.kmpzip.okio.ZipInputStream
import no.synth.kmpzip.okio.ZipOutputStream

val buffer = Buffer()

// Write
ZipOutputStream(buffer).use { zos ->
    zos.putNextEntry(ZipEntry("hello.txt"))
    zos.write("Hello from OkIO!".encodeToByteArray())
    zos.closeEntry()
}

// Read
ZipInputStream(buffer).use { zis ->
    val entry = zis.nextEntry ?: error("Expected entry")
    println("${entry.name}: ${zis.readBytes().decodeToString()}")
}

Stream data from a ZIP entry via Source

The InputStream.asSource() adapter lets you read a ZIP entry through a Source, which is useful for streaming deserialization (e.g. kotlinx-serialization's decodeFromBufferedSource).

OkIO:

import okio.buffer
import no.synth.kmpzip.okio.ZipInputStream
import no.synth.kmpzip.okio.asSource

ZipInputStream(source).use { zis ->
    val entry = zis.nextEntry
    if (entry != null) {
        val entrySource = zis.asSource().buffer()
        // Stream directly from the ZIP entry — e.g. Json.decodeFromBufferedSource(serializer, entrySource)
        println("${entry.name}: ${entrySource.readUtf8()}")
    }
}

kotlinx-io:

import kotlinx.io.buffered
import kotlinx.io.readString
import no.synth.kmpzip.kotlinx.ZipInputStream
import no.synth.kmpzip.kotlinx.asSource

ZipInputStream(source).use { zis ->
    val entry = zis.nextEntry
    if (entry != null) {
        val entrySource = zis.asSource().buffered()
        // Stream directly from the ZIP entry — e.g. Json.decodeFromBufferedSource(serializer, entrySource)
        println("${entry.name}: ${entrySource.readString()}")
    }
}

Stream data directly into a ZIP entry via Sink

The OutputStream.asSink() adapter lets you write into a ZIP entry through a Sink, which is useful for streaming serialization (e.g. kotlinx-serialization's encodeToSink).

OkIO:

import okio.buffer
import no.synth.kmpzip.okio.ZipOutputStream
import no.synth.kmpzip.okio.asSink

ZipOutputStream(sink).use { zos ->
    zos.putNextEntry(ZipEntry("data.json"))
    val entrySink = zos.asSink().buffer()
    // Stream directly into the ZIP entry — e.g. Json.encodeToSink(serializer, value, entrySink)
    entrySink.writeUtf8("""{"hello": "world"}""")
    entrySink.flush()
    zos.closeEntry()
}

kotlinx-io:

import kotlinx.io.buffered
import kotlinx.io.writeString
import no.synth.kmpzip.kotlinx.ZipOutputStream
import no.synth.kmpzip.kotlinx.asSink

ZipOutputStream(sink).use { zos ->
    zos.putNextEntry(ZipEntry("data.json"))
    val entrySink = zos.asSink().buffered()
    // Stream directly into the ZIP entry — e.g. Json.encodeToSink(serializer, value, entrySink)
    entrySink.writeString("""{"hello": "world"}""")
    entrySink.flush()
    zos.closeEntry()
}

Building

Requires JDK 21 and Xcode (for iOS targets).

./gradlew build                      # Full build
./gradlew jvmTest                    # JVM tests
./gradlew iosSimulatorArm64Test      # iOS simulator tests

Publishing

Tagging a release triggers the GitHub Actions workflow to publish to Maven Central:

git tag v0.8.0
git push origin v0.8.0

License

Mozilla Public License 2.0 (MPL-2.0)

JVMKotlin/NativeWasm
GitHub stars5
Authorshenrik242
Open issues1
LicenseMozilla Public License 2.0
Creation date3 months ago
Last activityabout 2 months ago
Latest release0.11.2 (7 days ago)
GitHub repositoryGitHub pages

kmp-zip

Kotlin Multiplatform ZIP and GZIP library for JVM and iOS targets.

Provides ByteArrayInputStream, ByteArrayOutputStream, ZipInputStream, ZipOutputStream, GzipInputStream, and GzipOutputStream with a common API across platforms. On JVM, the implementations delegate to java.io and java.util.zip. On iOS/Native, they are pure Kotlin implementations using platform.zlib for DEFLATE compression and decompression.

Modules

Artifact Description
no.synth:kmp-zip Core I/O, ZIP, and GZIP streams
no.synth:kmp-zip-kotlinx kotlinx-io Source/Sink adapters (both directions) for the core streams
no.synth:kmp-zip-okio OkIO BufferedSource/BufferedSink/Source/Sink adapters (both directions) for the core streams

Targets

  • JVM (also consumable from Android projects)
  • iosX64, iosArm64, iosSimulatorArm64

Installation

Published on Maven Central. No special repository configuration needed.

kotlin {
    sourceSets {
        commonMain {
            dependencies {
                implementation("no.synth:kmp-zip:0.8.0")

                // Optional: kotlinx-io adapters
                implementation("no.synth:kmp-zip-kotlinx:0.8.0")

                // Optional: OkIO adapters
                implementation("no.synth:kmp-zip-okio:0.8.0")
            }
        }
    }
}

API

kmp-zip — no.synth.kmpzip.io

Type Description
InputStream Abstract class — read(), read(ByteArray, off, len), available(), skip(), close(), etc.
OutputStream Abstract class — write(Int), write(ByteArray, off, len), flush(), close()
ByteArrayInputStream Reads from a ByteArray. Full Java-compatible API.
ByteArrayOutputStream Auto-growing buffer with toByteArray(), size(), reset(), writeTo()
InputStream.readBytes() Extension that reads all remaining bytes

kmp-zip — no.synth.kmpzip.zip

Type Description
ZipInputStream(InputStream) Reads ZIP entries — nextEntry, closeEntry(), read(), readBytes()
ZipInputStream(ByteArray) Convenience factory
ZipOutputStream(OutputStream) Writes ZIP entries — putNextEntry(), closeEntry(), write(), finish(), setMethod(), setLevel()
ZipEntry Entry metadata — name, size, compressedSize, crc, method, isDirectory, time, comment, extra
ZipConstants STORED = 0, DEFLATED = 8

kmp-zip — no.synth.kmpzip.gzip

Type Description
GzipInputStream(InputStream) Decompresses a GZIP stream — read(), available(), close()
GzipInputStream(ByteArray) Convenience factory
GzipOutputStream(OutputStream) Compresses data in GZIP format — write(), finish(), flush(), close()

kmp-zip-kotlinx — no.synth.kmpzip.kotlinx

Type Description
SourceInputStream(Source) Wraps a kotlinx-io Source as an InputStream
SinkOutputStream(Sink) Wraps a kotlinx-io Sink as an OutputStream
InputStreamSource(InputStream) Wraps an InputStream as a kotlinx-io RawSource
OutputStreamSink(OutputStream) Wraps an OutputStream as a kotlinx-io RawSink
Source.asInputStream() Extension shorthand
Sink.asOutputStream() Extension shorthand
InputStream.asSource() Extension shorthand
OutputStream.asSink() Extension shorthand
ZipInputStream(Source) Factory — creates a ZipInputStream from a Source
ZipOutputStream(Sink) Factory — creates a ZipOutputStream from a Sink
GzipInputStream(Source) Factory — creates a GzipInputStream from a Source
GzipOutputStream(Sink) Factory — creates a GzipOutputStream from a Sink

kmp-zip-okio — no.synth.kmpzip.okio

Type Description
SourceInputStream(BufferedSource) Wraps an OkIO BufferedSource as an InputStream
SinkOutputStream(BufferedSink) Wraps an OkIO BufferedSink as an OutputStream
InputStreamSource(InputStream) Wraps an InputStream as an OkIO Source
OutputStreamSink(OutputStream) Wraps an OutputStream as an OkIO Sink
BufferedSource.asInputStream() Extension shorthand
BufferedSink.asOutputStream() Extension shorthand
InputStream.asSource() Extension shorthand
OutputStream.asSink() Extension shorthand
ZipInputStream(BufferedSource) Factory — creates a ZipInputStream from a BufferedSource
ZipOutputStream(BufferedSink) Factory — creates a ZipOutputStream from a BufferedSink
GzipInputStream(BufferedSource) Factory — creates a GzipInputStream from a BufferedSource
GzipOutputStream(BufferedSink) Factory — creates a GzipOutputStream from a BufferedSink

Usage

Read a ZIP from a ByteArray

ZipInputStream(zipBytes).use { zis ->
    while (true) {
        val entry = zis.nextEntry ?: break
        println("${entry.name}: ${zis.readBytes().decodeToString()}")
    }
}

Create a ZIP into a ByteArray

val buf = ByteArrayOutputStream()
ZipOutputStream(buf).use { zos ->
    zos.putNextEntry(ZipEntry("hello.txt"))
    zos.write("Hello, world!".encodeToByteArray())
    zos.closeEntry()
}
val zipBytes = buf.toByteArray()

GZIP compress and decompress

// Compress
val buf = ByteArrayOutputStream()
GzipOutputStream(buf).use { gzos ->
    gzos.write("Hello, world!".encodeToByteArray())
}
val gzipped = buf.toByteArray()

// Decompress
val text = GzipInputStream(gzipped).use { gzis ->
    gzis.readBytes().decodeToString()
}

kotlinx-io: read/write ZIPs via Source/Sink

import kotlinx.io.Buffer
import no.synth.kmpzip.kotlinx.ZipInputStream
import no.synth.kmpzip.kotlinx.ZipOutputStream

val buffer = Buffer()

// Write
ZipOutputStream(buffer).use { zos ->
    zos.putNextEntry(ZipEntry("hello.txt"))
    zos.write("Hello from kotlinx-io!".encodeToByteArray())
    zos.closeEntry()
}

// Read
ZipInputStream(buffer).use { zis ->
    val entry = zis.nextEntry ?: error("Expected entry")
    println("${entry.name}: ${zis.readBytes().decodeToString()}")
}

OkIO: read/write ZIPs via BufferedSource/BufferedSink

import okio.Buffer
import no.synth.kmpzip.okio.ZipInputStream
import no.synth.kmpzip.okio.ZipOutputStream

val buffer = Buffer()

// Write
ZipOutputStream(buffer).use { zos ->
    zos.putNextEntry(ZipEntry("hello.txt"))
    zos.write("Hello from OkIO!".encodeToByteArray())
    zos.closeEntry()
}

// Read
ZipInputStream(buffer).use { zis ->
    val entry = zis.nextEntry ?: error("Expected entry")
    println("${entry.name}: ${zis.readBytes().decodeToString()}")
}

Stream data from a ZIP entry via Source

The InputStream.asSource() adapter lets you read a ZIP entry through a Source, which is useful for streaming deserialization (e.g. kotlinx-serialization's decodeFromBufferedSource).

OkIO:

import okio.buffer
import no.synth.kmpzip.okio.ZipInputStream
import no.synth.kmpzip.okio.asSource

ZipInputStream(source).use { zis ->
    val entry = zis.nextEntry
    if (entry != null) {
        val entrySource = zis.asSource().buffer()
        // Stream directly from the ZIP entry — e.g. Json.decodeFromBufferedSource(serializer, entrySource)
        println("${entry.name}: ${entrySource.readUtf8()}")
    }
}

kotlinx-io:

import kotlinx.io.buffered
import kotlinx.io.readString
import no.synth.kmpzip.kotlinx.ZipInputStream
import no.synth.kmpzip.kotlinx.asSource

ZipInputStream(source).use { zis ->
    val entry = zis.nextEntry
    if (entry != null) {
        val entrySource = zis.asSource().buffered()
        // Stream directly from the ZIP entry — e.g. Json.decodeFromBufferedSource(serializer, entrySource)
        println("${entry.name}: ${entrySource.readString()}")
    }
}

Stream data directly into a ZIP entry via Sink

The OutputStream.asSink() adapter lets you write into a ZIP entry through a Sink, which is useful for streaming serialization (e.g. kotlinx-serialization's encodeToSink).

OkIO:

import okio.buffer
import no.synth.kmpzip.okio.ZipOutputStream
import no.synth.kmpzip.okio.asSink

ZipOutputStream(sink).use { zos ->
    zos.putNextEntry(ZipEntry("data.json"))
    val entrySink = zos.asSink().buffer()
    // Stream directly into the ZIP entry — e.g. Json.encodeToSink(serializer, value, entrySink)
    entrySink.writeUtf8("""{"hello": "world"}""")
    entrySink.flush()
    zos.closeEntry()
}

kotlinx-io:

import kotlinx.io.buffered
import kotlinx.io.writeString
import no.synth.kmpzip.kotlinx.ZipOutputStream
import no.synth.kmpzip.kotlinx.asSink

ZipOutputStream(sink).use { zos ->
    zos.putNextEntry(ZipEntry("data.json"))
    val entrySink = zos.asSink().buffered()
    // Stream directly into the ZIP entry — e.g. Json.encodeToSink(serializer, value, entrySink)
    entrySink.writeString("""{"hello": "world"}""")
    entrySink.flush()
    zos.closeEntry()
}

Building

Requires JDK 21 and Xcode (for iOS targets).

./gradlew build                      # Full build
./gradlew jvmTest                    # JVM tests
./gradlew iosSimulatorArm64Test      # iOS simulator tests

Publishing

Tagging a release triggers the GitHub Actions workflow to publish to Maven Central:

git tag v0.8.0
git push origin v0.8.0

License

Mozilla Public License 2.0 (MPL-2.0)