embeddir

An example of using the zig build system to aid in embeddeding multiple files in an executable.

Toby Jaffey, https://mastodon.me.uk/@tobyjaffey

Zig has @embedFile (https://ziglang.org/documentation/master/#embedFile) which embeds the contents of a file in the executable at compile time. In some situations, it's useful to embed all files from a directory without hardcoding their names into the source code.

How does it work?

In build.zig, we add a custom function addAssetsOption(). This opens the assets directory, lists files and passes the list to the main program in a module called assets in a field called files.

...
    options.addOption([]const []const u8, "files", files.items);
    exe.step.dependOn(&options.step);

    const assets = b.createModule(.{
        .source_file = options.getSource(),
        .dependencies = &.{},
    });
    exe.addModule("assets", assets);
...

In src/main, we build a ComptimeStringMap using assets.files as the keys and the result of @embedFile() on each key as the value.

At runtime, the data can then be accessed by filename using:

const data = embeddedFilesMap.get(filename).?;

The list of files can be found in assets.files