initial

internal/bsdaily/verify.go

@@ -0,0 +1,63 @@
+package bsdaily
+
+import (
+	"fmt"
+	"log/slog"
+	"os/exec"
+	"strings"
+)
+
+func VerifyOutput(path string) error {
+	slog.Info("running zstdmt integrity check")
+	testCmd := exec.Command("zstdmt", "--test", path)
+	var testStderr strings.Builder
+	testCmd.Stderr = &testStderr
+	if err := testCmd.Run(); err != nil {
+		return fmt.Errorf("zstdmt --test failed: %w; stderr: %s", err, testStderr.String())
+	}
+	slog.Info("zstdmt integrity check passed")
+
+	slog.Info("verifying SQL content")
+	catCmd := exec.Command("zstdcat", path)
+	headCmd := exec.Command("head", "-20")
+
+	pipe, err := catCmd.StdoutPipe()
+	if err != nil {
+		return fmt.Errorf("creating zstdcat pipe: %w", err)
+	}
+	headCmd.Stdin = pipe
+
+	var headOut strings.Builder
+	headCmd.Stdout = &headOut
+
+	if err := headCmd.Start(); err != nil {
+		return fmt.Errorf("starting head: %w", err)
+	}
+	if err := catCmd.Start(); err != nil {
+		return fmt.Errorf("starting zstdcat: %w", err)
+	}
+
+	// head closes pipe early, zstdcat gets SIGPIPE - expected
+	_ = headCmd.Wait()
+	_ = catCmd.Wait()
+
+	content := headOut.String()
+	if len(content) == 0 {
+		return fmt.Errorf("decompressed content is empty")
+	}
+
+	hasSQLMarker := false
+	for _, marker := range []string{"BEGIN TRANSACTION", "CREATE TABLE", "INSERT INTO", "PRAGMA"} {
+		if strings.Contains(content, marker) {
+			hasSQLMarker = true
+			break
+		}
+	}
+	if !hasSQLMarker {
+		return fmt.Errorf("decompressed content does not look like SQL; first 200 bytes: %s",
+			content[:min(200, len(content))])
+	}
+
+	slog.Info("SQL content verification passed")
+	return nil
+}