s3: fix pagination by collecting all versions when keyMarker is set

When paginating with keyMarker, we must collect all versions first because
filtering happens after sorting. Previously, we limited collection to maxKeys+1
which caused us to miss versions beyond the marker when there were many versions
before it.

weed/s3api/s3api_object_versioning.go

@@ -168,9 +168,14 @@ func (s3a *S3ApiServer) listObjectVersions(bucket, prefix, keyMarker, versionIdM
 	seenVersionIds := make(map[string]bool)
 
 	// Recursively find all .versions directories in the bucket
-	// Pass maxKeys+1 to collect one extra for truncation detection
+	// When keyMarker is set, we need to collect all versions since filtering happens after sorting
+	// Pass 0 (unlimited) when keyMarker is set, otherwise maxKeys+1 for truncation detection
 	bucketPath := path.Join(s3a.option.BucketsPath, bucket)
-	err := s3a.findVersionsRecursively(bucketPath, "", &allVersions, processedObjects, seenVersionIds, bucket, prefix, maxKeys+1)
+	maxCollect := maxKeys + 1
+	if keyMarker != "" {
+		maxCollect = 0 // Collect all versions when paginating, filter after sort
+	}
+	err := s3a.findVersionsRecursively(bucketPath, "", &allVersions, processedObjects, seenVersionIds, bucket, prefix, maxCollect)
 	if err != nil {
 		glog.Errorf("listObjectVersions: findVersionsRecursively failed: %v", err)
 		return nil, err
@@ -229,6 +234,10 @@ func (s3a *S3ApiServer) listObjectVersions(bucket, prefix, keyMarker, versionIdM
 	// Apply key-marker and version-id-marker filtering
 	// S3 pagination: skip versions at or before the marker, return versions AFTER the marker
 	// Versions are sorted: key ascending, then versionId descending (newest first for same key)
+	// 
+	// S3 behavior:
+	// - If key-marker is specified without version-id-marker: start after ALL versions of key-marker
+	// - If both are specified: start after the specific version of key-marker
 	if keyMarker != "" {
 		filteredVersions := make([]interface{}, 0, len(allVersions))
 		for _, version := range allVersions {
@@ -243,15 +252,15 @@ func (s3a *S3ApiServer) listObjectVersions(bucket, prefix, keyMarker, versionIdM
 			}
 
 			// Include this version if it's AFTER the marker
-			// For key > keyMarker: always include
-			// For key == keyMarker: include if versionId < versionIdMarker (since versionIds are descending)
-			// For key < keyMarker: skip (already returned in previous pages)
 			if key > keyMarker {
+				// Key is after marker key: always include
 				filteredVersions = append(filteredVersions, version)
 			} else if key == keyMarker && versionIdMarker != "" && versionId < versionIdMarker {
+				// Same key, but version is after the marker version (versionIds sorted descending)
 				filteredVersions = append(filteredVersions, version)
 			}
-			// else: skip this version (it was in a previous page)
+			// else: key < keyMarker OR (key == keyMarker with no versionIdMarker or version already seen)
+			// skip this version (it was in a previous page)
 		}
 		glog.V(1).Infof("listObjectVersions: after applying markers (key=%s, versionId=%s), %d -> %d versions",
 			keyMarker, versionIdMarker, len(allVersions), len(filteredVersions))