mirror of
https://github.com/OffchainLabs/prysm.git
synced 2026-01-10 07:58:22 -05:00
cd429dc253
* Add basic parsing feature for accessing by index * Add more tests for 2d byte vector * Add List case for access indexing * Handle 2D bytes List example * Fix misleading cases for CalculateOffsetAndLength * Use elementSizes[index] if it is the last path element * Add variable_container_list field for mocking attester_slashings in BeaconBlockBody * Remove redundant protobuf message * Better documentation * Changelog * Fix `expectedSize` of `VariableTestContainer`: as we added `variable_container_list` here * Apply reviews from Radek
84 lines
2.6 KiB
Go
84 lines
2.6 KiB
Go
package query
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import (
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"errors"
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"fmt"
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)
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// CalculateOffsetAndLength calculates the offset and length of a given path within the SSZ object.
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// By walking the given path, it accumulates the offsets based on sszInfo.
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func CalculateOffsetAndLength(sszInfo *sszInfo, path []PathElement) (*sszInfo, uint64, uint64, error) {
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if sszInfo == nil {
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return nil, 0, 0, errors.New("sszInfo is nil")
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}
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if len(path) == 0 {
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return nil, 0, 0, errors.New("path is empty")
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}
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walk := sszInfo
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offset := uint64(0)
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for pathIndex, elem := range path {
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containerInfo, err := walk.ContainerInfo()
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if err != nil {
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return nil, 0, 0, fmt.Errorf("could not get field infos: %w", err)
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}
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fieldInfo, exists := containerInfo.fields[elem.Name]
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if !exists {
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return nil, 0, 0, fmt.Errorf("field %s not found in containerInfo", elem.Name)
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}
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offset += fieldInfo.offset
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walk = fieldInfo.sszInfo
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// Check for accessing List/Vector elements by index
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if elem.Index != nil {
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switch walk.sszType {
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case List:
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index := *elem.Index
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listInfo := walk.listInfo
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if index >= listInfo.length {
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return nil, 0, 0, fmt.Errorf("index %d out of bounds for field %s with size %d", index, elem.Name, listInfo.length)
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}
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walk = listInfo.element
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if walk.isVariable {
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// Cumulative sum of sizes of previous elements to get the offset.
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for i := range index {
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offset += listInfo.elementSizes[i]
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}
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// NOTE: When populating recursively, the shared element template is updated for each
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// list item, causing it to retain the size information of the last processed element.
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// This wouldn't be an issue if this is in the middle of the path, as the walk would be updated
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// to the next field's sszInfo, which would have the correct size information.
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// However, if this is the last element in the path, we need to ensure we return the correct size
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// for the indexed element. Hence, we return the size from elementSizes.
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if pathIndex == len(path)-1 {
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return walk, offset, listInfo.elementSizes[index], nil
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}
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} else {
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offset += index * listInfo.element.Size()
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}
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case Vector:
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index := *elem.Index
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vectorInfo := walk.vectorInfo
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if index >= vectorInfo.length {
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return nil, 0, 0, fmt.Errorf("index %d out of bounds for field %s with size %d", index, elem.Name, vectorInfo.length)
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}
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offset += index * vectorInfo.element.Size()
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walk = vectorInfo.element
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default:
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return nil, 0, 0, fmt.Errorf("field %s of type %s does not support index access", elem.Name, walk.sszType)
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}
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}
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}
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return walk, offset, walk.Size(), nil
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}
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