cinterop

cinterop is a tool that facilitates interoperability between the programming languages Java and C. It is part of the Kotlin multiplatform development ecosystem, allowing Kotlin code to seamlessly call into and be called from native C libraries. This enables developers to leverage existing C codebases within their Kotlin projects, which can be particularly useful for accessing low-level system APIs, performance-critical libraries, or code written in C.

The primary mechanism cinterop uses is by generating Kotlin bindings for C headers. When you provide cinterop with one or more C header files, it analyzes them and produces Kotlin declarations that mirror the C functions, structs, unions, and enums. These generated bindings allow Kotlin code to interact with the C code as if it were native Kotlin code. This includes calling C functions, allocating and accessing memory for C data structures, and handling data type conversions between Kotlin and C.

Beyond simple function calls, cinterop supports more advanced scenarios. It can handle complex C data types, memory management, and even callbacks from C to Kotlin. The tool is configured through a build script, typically within a Gradle project, where you specify the native libraries and header files to be processed. This integration makes it a powerful component for Kotlin projects that require interaction with the native world, whether for performance, platform-specific features, or reusing existing C code.