func NewProcess()

in packages/@jsii/go-runtime/jsii-runtime-go/internal/kernel/process/process.go [64:144]
67 lines of code
12 McCabe index (conditional complexity)

func NewProcess(compatibleVersions string) (*Process, error) {
	p := Process{}

	if constraints, err := semver.NewConstraint(compatibleVersions); err != nil {
		return nil, err
	} else {
		p.compatibleVersions = constraints
	}

	if custom := os.Getenv(JSII_RUNTIME); custom != "" {
		var (
			command string
			args    []string
		)
		// Sub-shelling in order to avoid having to parse arguments
		if runtime.GOOS == "windows" {
			// On windows, we use %ComSpec% if set, or cmd.exe
			if cmd := os.Getenv("ComSpec"); cmd != "" {
				command = cmd
			} else {
				command = "cmd.exe"
			}
			// The /d option disables Registry-defined AutoRun, it's safer to enable
			// The /s option tells cmd.exe the command is quoted as if it were typed into a prompt
			// The /c option tells cmd.exe to run the specified command and exit immediately
			args = []string{"/d", "/s", "/c", custom}
		} else {
			// On other OS'es, we use $SHELL and fall back to "/bin/sh"
			if shell := os.Getenv("SHELL"); shell != "" {
				command = shell
			} else {
				command = "/bin/sh"
			}
			args = []string{"-c", custom}
		}
		p.cmd = exec.Command(command, args...)
	} else if tmpdir, err := ioutil.TempDir("", "jsii-runtime.*"); err != nil {
		return nil, err
	} else {
		p.tmpdir = tmpdir
		if entrypoint, err := embedded.ExtractRuntime(tmpdir); err != nil {
			p.Close()
			return nil, err
		} else {
			if node := os.Getenv(JSII_NODE); node != "" {
				p.cmd = exec.Command(node, entrypoint)
			} else {
				p.cmd = exec.Command("node", entrypoint)
			}
		}
	}

	// Setting up environment - if duplicate keys are found, the last value is used, so we are careful with ordering. In
	// particular, we are setting NODE_OPTIONS only if `os.Environ()` does not have another value... So the user can
	// control the environment... However, JSII_AGENT must always be controlled by this process.
	p.cmd.Env = append([]string{"NODE_OPTIONS=--max-old-space-size=4069"}, os.Environ()...)
	p.cmd.Env = append(p.cmd.Env, fmt.Sprintf("JSII_AGENT=%v/%v/%v", runtime.Version(), runtime.GOOS, runtime.GOARCH))

	if stdin, err := p.cmd.StdinPipe(); err != nil {
		p.Close()
		return nil, err
	} else {
		p.stdin = stdin
		p.requests = json.NewEncoder(stdin)
	}
	if stdout, err := p.cmd.StdoutPipe(); err != nil {
		p.Close()
		return nil, err
	} else {
		p.stdout = stdout
		p.responses = json.NewDecoder(stdout)
	}
	if stderr, err := p.cmd.StderrPipe(); err != nil {
		p.Close()
		return nil, err
	} else {
		p.stderr = stderr
	}

	return &p, nil
}