feat(backend): user + library admin API, atomic sanitized upload

backend/internal/bookfile/bookfile.go

@@ -0,0 +1,42 @@
+package bookfile
+
+import (
+	"path/filepath"
+	"strings"
+	"unicode"
+)
+
+func FormatFromExt(name string) string {
+	switch strings.ToLower(filepath.Ext(name)) {
+	case ".cbz", ".zip":
+		return "cbz"
+	case ".pdf":
+		return "pdf"
+	case ".epub":
+		return "epub"
+	case ".txt":
+		return "txt"
+	case ".md":
+		return "md"
+	}
+	return ""
+}
+
+func SafeName(s string) string {
+	s = strings.Map(func(r rune) rune {
+		if unicode.IsControl(r) {
+			return -1
+		}
+		return r
+	}, s)
+	s = strings.ReplaceAll(s, "\\", "/")
+	s = filepath.Base(filepath.ToSlash(s))
+	if s == "." || s == "/" {
+		return ""
+	}
+	s = strings.TrimSpace(s)
+	if len(s) > 200 {
+		s = strings.TrimSpace(s[:200])
+	}
+	return s
+}