mage: Improve error messages and resource handling

This commit includes minor developer tooling improvements:
- Improves the checksum mismatch error message for better diagnostics.
- Fix spurious "error closing" logs when double-closing files explicitely and with `defer`

Author: orestisfl

dev-tools/mage/downloads/utils.go

@@ -110,7 +110,7 @@ func verifyChecksum(checksumFile string) error {
 	}
 
 	if expectedChecksum != actualChecksum {
-		return fmt.Errorf("checksum of file %s does not match expected checksum of %s", fileName, actualChecksum)
+		return fmt.Errorf("%s checksum mismatch: expected=%s actual=%s", fileName, expectedChecksum, actualChecksum)
 	}
 
 	return nil

dev-tools/mage/pkgtypes.go

@@ -9,6 +9,7 @@ import (
 	"archive/zip"
 	"bytes"
 	"compress/gzip"
+	"errors"
 	"fmt"
 	"hash/fnv"
 	"io"
@@ -666,27 +667,15 @@ func PackageTarGz(spec PackageSpec) error {
 	if err != nil {
 		return err
 	}
-	defer func() {
-		if err := outFile.Close(); err != nil {
-			log.Printf("failed to close output file: %v", err)
-		}
-	}()
+	defer closeOrLog(outFile, "output file")
 
 	// Create a gzip writer to our output file
 	gzWriter := gzip.NewWriter(outFile)
-	defer func() {
-		if err := gzWriter.Close(); err != nil {
-			log.Printf("failed to close gzip writer: %v", err)
-		}
-	}()
+	defer closeOrLog(gzWriter, "gzip writer")
 
 	// Create a new tar archive.
 	w := tar.NewWriter(gzWriter)
-	defer func() {
-		if err := w.Close(); err != nil {
-			log.Printf("failed to close tar writer: %v", err)
-		}
-	}()
+	defer closeOrLog(gzWriter, "tar writer")
 
 	// // Replace the darwin-universal by darwin-x86_64 and darwin-arm64. Also
 	// // keep the other files.
@@ -759,6 +748,14 @@ func PackageTarGz(spec PackageSpec) error {
 	return nil
 }
 
+func closeOrLog(closer io.Closer, what string) {
+	err := closer.Close()
+	if err == nil || errors.Is(err, os.ErrClosed) {
+		return
+	}
+	log.Printf("failed to close %s: %v", what, err)
+}
+
 // PackageDeb packages a deb file. This requires Docker to execute FPM.
 func PackageDeb(spec PackageSpec) error {
 	return runFPM(spec, Deb)
@@ -953,7 +950,7 @@ func addFileToZip(ar *zip.Writer, baseDir string, pkgFile PackageFile) error {
 		if err != nil {
 			return err
 		}
-		defer file.Close()
+		defer closeOrLog(file, "zip input file")
 
 		if _, err = io.Copy(w, file); err != nil {
 			return err
@@ -1034,7 +1031,7 @@ func addFileToTar(ar *tar.Writer, baseDir string, pkgFile PackageFile) error {
 		if err != nil {
 			return err
 		}
-		defer file.Close()
+		defer closeOrLog(file, "tar input file")
 
 		if _, err = io.Copy(ar, file); err != nil {
 			return err