Add resumable downloads, download paths, queue controls and history

internal/files/internal.go

@@ -0,0 +1,41 @@
+package files
+
+import (
+	"errors"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+const (
+	PartFileName      = ".download.part"
+	JobFileName       = ".job.json"
+	temporaryPrefix   = ".ddc-tmp-"
+	temporaryWildcard = temporaryPrefix + "*"
+)
+
+func IsInternal(name string) bool {
+	return name == PartFileName || name == JobFileName || strings.HasPrefix(name, temporaryPrefix)
+}
+
+func WriteAtomically(path string, data []byte) error {
+	temporary, err := os.CreateTemp(filepath.Dir(path), temporaryWildcard)
+	if err != nil {
+		return err
+	}
+	_, writeErr := temporary.Write(data)
+	closeErr := temporary.Close()
+	if writeErr != nil || closeErr != nil {
+		os.Remove(temporary.Name())
+		return errors.Join(writeErr, closeErr)
+	}
+	if err := os.Chmod(temporary.Name(), 0o644); err != nil {
+		os.Remove(temporary.Name())
+		return err
+	}
+	if err := os.Rename(temporary.Name(), path); err != nil {
+		os.Remove(temporary.Name())
+		return err
+	}
+	return nil
+}