Compiling

Note: Compiling sqlite3 to WebAssembly is not necessary for users of this package, just grab the .wasm from the latest release on GitHub.

This section describes how to compile the WebAssembly modules from source. This uses a LLVM-based toolchain with components of the WASI SDK for C runtime components.

Setup

Linux

On Linux, you need a LLVM based toolchain capable of compiling to WebAssembly. On Arch Linux, the wasi-compiler-rt and wasi-libc packages are enough for this. On other distros, you may have to download the sysroot and compiler builtins from their respective package managers or directly from the WASI SDK releases.

With wasi in /usr/share/wasi-sysroot and the default clang compiler having the required builtins, you can setup the build with:

cmake -S src -B .dart_tool/sqlite3_build

macOS

On macOS, install a WebAssembly-capable C compiler. If you're using Homebrew, you can use

brew install cmake llvm binaryen wasi-libc wasi-runtimes

Then, set up the build with

cmake -Dwasi_sysroot=/opt/homebrew/share/wasi-sysroot -Dclang=/opt/homebrew/opt/llvm/bin/clang -S src -B .dart_tool/sqlite3_build

Building

In this directory, run:

cmake --build .dart_tool/sqlite3_build/ -t output -j

The output target copies sqlite3.wasm and sqlite3.debug.wasm to out/.

(Of course, you can also run the build in any other directory than .dart_tool/sqite3_build if you want to).

Customizing the WASM module

The build scripts in this repository, which are also used for the default distribution of sqlite3.wasm attached to releases, are designed to mirror the options used by sqlite3_flutter_libs. If you want to use different options, or include custom extensions in the WASM module, you can customize the build setup.

To use regular sqlite3 sources with different compile-time options, alter assets/wasm/sqlite_cfg.h and re-run the build as described in compiling. Including additional extensions written in C is possible by adapting the CMakeLists.txt in assets/wasm.

A simple example demonstrating how to include Rust-based extensions is included in example/custom_wasm_build. The readme in that directory explains the build process in detail, but you still need the WASI/Clang toolchains described in the setup section.