1 files changed, 201 insertions, 0 deletions
diff --git a/internal/media/ffmpeg/wasm.go b/internal/media/ffmpeg/wasm.go
new file mode 100644
index 000000000..ff5506f2a
--- /dev/null
+++ b/internal/media/ffmpeg/wasm.go
@@ -0,0 +1,201 @@
+// GoToSocial
+// Copyright (C) GoToSocial Authors admin@gotosocial.org
+// SPDX-License-Identifier: AGPL-3.0-or-later
+//
+// This program is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Affero General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// This program is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+// GNU Affero General Public License for more details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+package ffmpeg
+
+import (
+	"context"
+	"io"
+	"os"
+
+	ffmpeglib "codeberg.org/gruf/go-ffmpreg/embed/ffmpeg"
+	ffprobelib "codeberg.org/gruf/go-ffmpreg/embed/ffprobe"
+	"github.com/tetratelabs/wazero"
+	"github.com/tetratelabs/wazero/imports/wasi_snapshot_preview1"
+	"github.com/tetratelabs/wazero/sys"
+)
+
+// Use all core features required by ffmpeg / ffprobe
+// (these should be the same but we OR just in case).
+const corefeatures = ffprobelib.CoreFeatures |
+	ffmpeglib.CoreFeatures
+
+var (
+	// shared WASM runtime instance.
+	runtime wazero.Runtime
+
+	// ffmpeg / ffprobe compiled WASM.
+	ffmpeg  wazero.CompiledModule
+	ffprobe wazero.CompiledModule
+)
+
+// Args encapsulates the passing of common
+// configuration options to run an instance
+// of a compiled WebAssembly module that is
+// run in a typical CLI manner.
+type Args struct {
+
+	// Optional further module configuration function.
+	// (e.g. to mount filesystem dir, set env vars, etc).
+	Config func(wazero.ModuleConfig) wazero.ModuleConfig
+
+	// Standard FDs.
+	Stdin  io.Reader
+	Stdout io.Writer
+	Stderr io.Writer
+
+	// CLI args.
+	Args []string
+}
+
+// run will run the given compiled
+// WebAssembly module using given args,
+// using the global wazero runtime.
+func run(
+	ctx context.Context,
+	cmod wazero.CompiledModule,
+	args Args,
+) (
+	uint32, // exit code
+	error,
+) {
+	// Prefix module name as argv0 to args.
+	cargs := make([]string, len(args.Args)+1)
+	copy(cargs[1:], args.Args)
+	cargs[0] = cmod.Name()
+
+	// Create base module config.
+	modcfg := wazero.NewModuleConfig()
+	modcfg = modcfg.WithArgs(cargs...)
+	modcfg = modcfg.WithStdin(args.Stdin)
+	modcfg = modcfg.WithStdout(args.Stdout)
+	modcfg = modcfg.WithStderr(args.Stderr)
+
+	if args.Config != nil {
+		// Pass through config fn.
+		modcfg = args.Config(modcfg)
+	}
+
+	// Instantiate the module from precompiled wasm module data.
+	mod, err := runtime.InstantiateModule(ctx, cmod, modcfg)
+
+	if mod != nil {
+		// Ensure closed.
+		_ = mod.Close(ctx)
+	}
+
+	// Try extract exit code.
+	switch err := err.(type) {
+	case *sys.ExitError:
+		return err.ExitCode(), nil
+	default:
+		return 0, err
+	}
+}
+
+// compileFfmpeg ensures the ffmpeg WebAssembly has been
+// pre-compiled into memory. If already compiled is a no-op.
+func compileFfmpeg(ctx context.Context) error {
+	if ffmpeg != nil {
+		return nil
+	}
+
+	// Ensure runtime already initialized.
+	if err := initRuntime(ctx); err != nil {
+		return err
+	}
+
+	// Compile the ffmpeg WebAssembly module into memory.
+	cmod, err := runtime.CompileModule(ctx, ffmpeglib.B)
+	if err != nil {
+		return err
+	}
+
+	// Set module.
+	ffmpeg = cmod
+	return nil
+}
+
+// compileFfprobe ensures the ffprobe WebAssembly has been
+// pre-compiled into memory. If already compiled is a no-op.
+func compileFfprobe(ctx context.Context) error {
+	if ffprobe != nil {
+		return nil
+	}
+
+	// Ensure runtime already initialized.
+	if err := initRuntime(ctx); err != nil {
+		return err
+	}
+
+	// Compile the ffprobe WebAssembly module into memory.
+	cmod, err := runtime.CompileModule(ctx, ffprobelib.B)
+	if err != nil {
+		return err
+	}
+
+	// Set module.
+	ffprobe = cmod
+	return nil
+}
+
+// initRuntime initializes the global wazero.Runtime,
+// if already initialized this function is a no-op.
+func initRuntime(ctx context.Context) error {
+	if runtime != nil {
+		return nil
+	}
+
+	var cache wazero.CompilationCache
+
+	if dir := os.Getenv("GTS_WAZERO_COMPILATION_CACHE"); dir != "" {
+		var err error
+
+		// Use on-filesystem compilation cache given by env.
+		cache, err = wazero.NewCompilationCacheWithDir(dir)
+		if err != nil {
+			return err
+		}
+	}
+
+	// Prepare config with cache.
+	cfg := wazero.NewRuntimeConfig()
+	cfg = cfg.WithCoreFeatures(corefeatures)
+	cfg = cfg.WithCompilationCache(cache)
+
+	// Instantiate runtime with prepared config.
+	rt := wazero.NewRuntimeWithConfig(ctx, cfg)
+
+	// Prepare default "env" host module.
+	env := rt.NewHostModuleBuilder("env")
+
+	// Instantiate host "env" module.
+	_, err := env.Instantiate(ctx)
+	if err != nil {
+		return err
+	}
+
+	// Instantiate wasi snapshot preview features in runtime.
+	_, err = wasi_snapshot_preview1.Instantiate(ctx, rt)
+	if err != nil {
+		return err
+	}
+
+	// Set runtime.
+	runtime = rt
+	return nil
+}