feat(plugin): Calculate SHA256 if it does not exist (#2935)

* feat(plugin): Calculate SHA256 if it does not exist

* Add logging

internal/ext/wasm/wasm.go

@@ -10,6 +10,7 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"log/slog"
 	"net/http"
 	"os"
 	"path/filepath"
@@ -52,20 +53,26 @@ func cacheDir() (string, error) {
 var flight singleflight.Group
 
 // Verify the provided sha256 is valid.
-func (r *Runner) parseChecksum() (string, error) {
-	if r.SHA256 == "" {
-		return "", fmt.Errorf("missing SHA-256 checksum")
+func (r *Runner) getChecksum(ctx context.Context) (string, error) {
+	if r.SHA256 != "" {
+		return r.SHA256, nil
 	}
-	return r.SHA256, nil
+	// TODO: Add a log line here about something
+	_, sum, err := r.fetch(ctx, r.URL)
+	if err != nil {
+		return "", err
+	}
+	slog.Warn("fetching WASM binary to calculate sha256. Set this value in sqlc.yaml to prevent unneeded work", "sha256", sum)
+	return sum, nil
 }
 
 func (r *Runner) loadModule(ctx context.Context, engine *wasmtime.Engine) (*wasmtime.Module, error) {
-	expected, err := r.parseChecksum()
+	expected, err := r.getChecksum(ctx)
 	if err != nil {
 		return nil, err
 	}
 	value, err, _ := flight.Do(expected, func() (interface{}, error) {
-		return r.loadSerializedModule(ctx, engine)
+		return r.loadSerializedModule(ctx, engine, expected)
 	})
 	if err != nil {
 		return nil, err
@@ -77,17 +84,13 @@ func (r *Runner) loadModule(ctx context.Context, engine *wasmtime.Engine) (*wasm
 	return wasmtime.NewModuleDeserialize(engine, data)
 }
 
-func (r *Runner) loadSerializedModule(ctx context.Context, engine *wasmtime.Engine) ([]byte, error) {
-	expected, err := r.parseChecksum()
-	if err != nil {
-		return nil, err
-	}
+func (r *Runner) loadSerializedModule(ctx context.Context, engine *wasmtime.Engine, expectedSha string) ([]byte, error) {
 	cacheDir, err := cache.PluginsDir()
 	if err != nil {
 		return nil, err
 	}
 
-	pluginDir := filepath.Join(cacheDir, expected)
+	pluginDir := filepath.Join(cacheDir, expectedSha)
 	modName := fmt.Sprintf("plugin_%s_%s_%s.module", runtime.GOOS, runtime.GOARCH, wasmtimeVersion)
 	modPath := filepath.Join(pluginDir, modName)
 	_, staterr := os.Stat(modPath)
@@ -99,7 +102,7 @@ func (r *Runner) loadSerializedModule(ctx context.Context, engine *wasmtime.Engi
 		return data, nil
 	}
 
-	wmod, err := r.loadWASM(ctx, cacheDir, expected)
+	wmod, err := r.loadWASM(ctx, cacheDir, expectedSha)
 	if err != nil {
 		return nil, err
 	}
@@ -126,53 +129,62 @@ func (r *Runner) loadSerializedModule(ctx context.Context, engine *wasmtime.Engi
 	return out, nil
 }
 
-func (r *Runner) loadWASM(ctx context.Context, cache string, expected string) ([]byte, error) {
-	pluginDir := filepath.Join(cache, expected)
-	pluginPath := filepath.Join(pluginDir, "plugin.wasm")
-	_, staterr := os.Stat(pluginPath)
-
+func (r *Runner) fetch(ctx context.Context, uri string) ([]byte, string, error) {
 	var body io.ReadCloser
+
 	switch {
-	case staterr == nil:
-		file, err := os.Open(pluginPath)
-		if err != nil {
-			return nil, fmt.Errorf("os.Open: %s %w", pluginPath, err)
-		}
-		body = file
 
-	case strings.HasPrefix(r.URL, "file://"):
-		file, err := os.Open(strings.TrimPrefix(r.URL, "file://"))
+	case strings.HasPrefix(uri, "file://"):
+		file, err := os.Open(strings.TrimPrefix(uri, "file://"))
 		if err != nil {
-			return nil, fmt.Errorf("os.Open: %s %w", r.URL, err)
+			return nil, "", fmt.Errorf("os.Open: %s %w", uri, err)
 		}
 		body = file
 
-	case strings.HasPrefix(r.URL, "https://"):
-		req, err := http.NewRequestWithContext(ctx, "GET", r.URL, nil)
+	case strings.HasPrefix(uri, "https://"):
+		req, err := http.NewRequestWithContext(ctx, "GET", uri, nil)
 		if err != nil {
-			return nil, fmt.Errorf("http.Get: %s %w", r.URL, err)
+			return nil, "", fmt.Errorf("http.Get: %s %w", uri, err)
 		}
 		req.Header.Set("User-Agent", fmt.Sprintf("sqlc/%s Go/%s (%s %s)", info.Version, runtime.Version(), runtime.GOOS, runtime.GOARCH))
 		resp, err := http.DefaultClient.Do(req)
 		if err != nil {
-			return nil, fmt.Errorf("http.Get: %s %w", r.URL, err)
+			return nil, "", fmt.Errorf("http.Get: %s %w", r.URL, err)
 		}
 		body = resp.Body
 
 	default:
-		return nil, fmt.Errorf("unknown scheme: %s", r.URL)
+		return nil, "", fmt.Errorf("unknown scheme: %s", r.URL)
 	}
 
 	defer body.Close()
 
 	wmod, err := io.ReadAll(body)
 	if err != nil {
-		return nil, fmt.Errorf("readall: %w", err)
+		return nil, "", fmt.Errorf("readall: %w", err)
 	}
 
 	sum := sha256.Sum256(wmod)
 	actual := fmt.Sprintf("%x", sum)
 
+	return wmod, actual, nil
+}
+
+func (r *Runner) loadWASM(ctx context.Context, cache string, expected string) ([]byte, error) {
+	pluginDir := filepath.Join(cache, expected)
+	pluginPath := filepath.Join(pluginDir, "plugin.wasm")
+	_, staterr := os.Stat(pluginPath)
+
+	uri := r.URL
+	if staterr == nil {
+		uri = "file://" + pluginPath
+	}
+
+	wmod, actual, err := r.fetch(ctx, uri)
+	if err != nil {
+		return nil, err
+	}
+
 	if expected != actual {
 		return nil, fmt.Errorf("invalid checksum: expected %s, got %s", expected, actual)
 	}