[feature/OFFICIALLY UNSUPPORTED] add nowasm build tag to disable building with WebAssembly (#3429)

* add experimental build-tag 'nowasm' which uses local ffmpeg / ffprobe

* updated experimental support message

* add comment to build script explaining build tag

* add nowasm build tags to moderncsqlite files

internal/media/ffmpeg/exec_nowasm.go

@@ -0,0 +1,142 @@
+// 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/>.
+
+//go:build nowasm
+
+package ffmpeg
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"io/fs"
+	"os/exec"
+
+	"codeberg.org/gruf/go-ffmpreg/wasm"
+	"github.com/tetratelabs/wazero"
+	"github.com/tetratelabs/wazero/sys"
+)
+
+func init() {
+	fmt.Println("!! you are using an unsupported build configuration of gotosocial with WebAssembly disabled !!")
+	fmt.Println("!! please do not file bug reports regarding media processing with this configuration !!")
+	fmt.Println("!! it is also less secure; this does not enforce version checks on ffmpeg / ffprobe versions !!")
+}
+
+// runCmd will run 'name' with the given arguments, returning exit code or error.
+func runCmd(ctx context.Context, name string, args wasm.Args) (uint32, error) {
+	cmd := exec.CommandContext(ctx, name, args.Args...) //nolint:gosec
+
+	// Set provided std files.
+	cmd.Stdin = args.Stdin
+	cmd.Stdout = args.Stdout
+	cmd.Stderr = args.Stderr
+
+	if args.Config != nil {
+		// Gather some information
+		// from module config func.
+		var cfg falseModuleConfig
+		_ = args.Config(&cfg)
+
+		// Extract from conf.
+		cmd.Env = cfg.env
+	}
+
+	// Run prepared command, catching err type.
+	switch err := cmd.Run(); err := err.(type) {
+
+	// Extract code from
+	// any exit error type.
+	case *exec.ExitError:
+		rc := err.ExitCode()
+		return uint32(rc), err
+
+	default:
+		return 0, err
+	}
+}
+
+type falseModuleConfig struct{ env []string }
+
+func (cfg *falseModuleConfig) WithArgs(...string) wazero.ModuleConfig {
+	return cfg // noop
+}
+
+func (cfg *falseModuleConfig) WithEnv(key string, value string) wazero.ModuleConfig {
+	cfg.env = append(cfg.env, key+"="+value)
+	return cfg // noop
+}
+
+func (cfg *falseModuleConfig) WithFS(fs.FS) wazero.ModuleConfig {
+	return cfg // noop
+}
+
+func (cfg *falseModuleConfig) WithFSConfig(wazero.FSConfig) wazero.ModuleConfig {
+	return cfg // noop
+}
+
+func (cfg *falseModuleConfig) WithName(string) wazero.ModuleConfig {
+	return cfg // noop
+}
+
+func (cfg *falseModuleConfig) WithStartFunctions(...string) wazero.ModuleConfig {
+	return cfg // noop
+}
+
+func (cfg *falseModuleConfig) WithStderr(io.Writer) wazero.ModuleConfig {
+	return cfg // noop
+}
+
+func (cfg *falseModuleConfig) WithStdin(io.Reader) wazero.ModuleConfig {
+	return cfg // noop
+}
+
+func (cfg *falseModuleConfig) WithStdout(io.Writer) wazero.ModuleConfig {
+	return cfg // noop
+}
+
+func (cfg *falseModuleConfig) WithWalltime(sys.Walltime, sys.ClockResolution) wazero.ModuleConfig {
+	return cfg // noop
+}
+
+func (cfg *falseModuleConfig) WithSysWalltime() wazero.ModuleConfig {
+	return cfg // noop
+}
+
+func (cfg *falseModuleConfig) WithNanotime(sys.Nanotime, sys.ClockResolution) wazero.ModuleConfig {
+	return cfg // noop
+}
+
+func (cfg *falseModuleConfig) WithSysNanotime() wazero.ModuleConfig {
+	return cfg // noop
+}
+
+func (cfg *falseModuleConfig) WithNanosleep(sys.Nanosleep) wazero.ModuleConfig {
+	return cfg // noop
+}
+
+func (cfg *falseModuleConfig) WithOsyield(sys.Osyield) wazero.ModuleConfig {
+	return cfg // noop
+}
+
+func (cfg *falseModuleConfig) WithSysNanosleep() wazero.ModuleConfig {
+	return cfg // noop
+}
+
+func (cfg *falseModuleConfig) WithRandSource(io.Reader) wazero.ModuleConfig {
+	return cfg // noop
+}