feat: s3 server support (#6088 close #5186)

Currently tested: List, Get, Remove

server/s3/pager.go

@@ -0,0 +1,67 @@
+// Credits: https://pkg.go.dev/github.com/rclone/rclone@v1.65.2/cmd/serve/s3
+// Package s3 implements a fake s3 server for alist
+package s3
+
+import (
+	"sort"
+
+	"github.com/Mikubill/gofakes3"
+)
+
+// pager splits the object list into smulitply pages.
+func (db *s3Backend) pager(list *gofakes3.ObjectList, page gofakes3.ListBucketPage) (*gofakes3.ObjectList, error) {
+	// sort by alphabet
+	sort.Slice(list.CommonPrefixes, func(i, j int) bool {
+		return list.CommonPrefixes[i].Prefix < list.CommonPrefixes[j].Prefix
+	})
+	// sort by modtime
+	sort.Slice(list.Contents, func(i, j int) bool {
+		return list.Contents[i].LastModified.Before(list.Contents[j].LastModified.Time)
+	})
+	tokens := page.MaxKeys
+	if tokens == 0 {
+		tokens = 1000
+	}
+	if page.HasMarker {
+		for i, obj := range list.Contents {
+			if obj.Key == page.Marker {
+				list.Contents = list.Contents[i+1:]
+				break
+			}
+		}
+		for i, obj := range list.CommonPrefixes {
+			if obj.Prefix == page.Marker {
+				list.CommonPrefixes = list.CommonPrefixes[i+1:]
+				break
+			}
+		}
+	}
+
+	response := gofakes3.NewObjectList()
+	for _, obj := range list.CommonPrefixes {
+		if tokens <= 0 {
+			break
+		}
+		response.AddPrefix(obj.Prefix)
+		tokens--
+	}
+
+	for _, obj := range list.Contents {
+		if tokens <= 0 {
+			break
+		}
+		response.Add(obj)
+		tokens--
+	}
+
+	if len(list.CommonPrefixes)+len(list.Contents) > int(page.MaxKeys) {
+		response.IsTruncated = true
+		if len(response.Contents) > 0 {
+			response.NextMarker = response.Contents[len(response.Contents)-1].Key
+		} else {
+			response.NextMarker = response.CommonPrefixes[len(response.CommonPrefixes)-1].Prefix
+		}
+	}
+
+	return response, nil
+}