package pgproto3 import ( "bytes" "encoding/binary" "encoding/json" "github.com/jackc/pgx/v5/internal/pgio" ) type ParameterDescription struct { ParameterOIDs []uint32 } // Backend identifies this message as sendable by the PostgreSQL backend. func (*ParameterDescription) Backend() {} // Decode decodes src into dst. src must contain the complete message with the exception of the initial 1 byte message // type identifier and 4 byte message length. func (dst *ParameterDescription) Decode(src []byte) error { buf := bytes.NewBuffer(src) if buf.Len() < 2 { return &invalidMessageFormatErr{messageType: "ParameterDescription"} } // Reported parameter count will be incorrect when number of args is greater than uint16 buf.Next(2) // Instead infer parameter count by remaining size of message parameterCount := buf.Len() / 4 *dst = ParameterDescription{ParameterOIDs: make([]uint32, parameterCount)} for i := 0; i < parameterCount; i++ { dst.ParameterOIDs[i] = binary.BigEndian.Uint32(buf.Next(4)) } return nil } // Encode encodes src into dst. dst will include the 1 byte message type identifier and the 4 byte message length. func (src *ParameterDescription) Encode(dst []byte) []byte { dst = append(dst, 't') sp := len(dst) dst = pgio.AppendInt32(dst, -1) dst = pgio.AppendUint16(dst, uint16(len(src.ParameterOIDs))) for _, oid := range src.ParameterOIDs { dst = pgio.AppendUint32(dst, oid) } pgio.SetInt32(dst[sp:], int32(len(dst[sp:]))) return dst } // MarshalJSON implements encoding/json.Marshaler. func (src ParameterDescription) MarshalJSON() ([]byte, error) { return json.Marshal(struct { Type string ParameterOIDs []uint32 }{ Type: "ParameterDescription", ParameterOIDs: src.ParameterOIDs, }) }