89 lines
2.0 KiB
Go
89 lines
2.0 KiB
Go
package pgproto3
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import (
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"bytes"
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"encoding/json"
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"errors"
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"github.com/jackc/pgio"
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)
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type Describe struct {
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ObjectType byte // 'S' = prepared statement, 'P' = portal
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Name string
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}
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// Frontend identifies this message as sendable by a PostgreSQL frontend.
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func (*Describe) Frontend() {}
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// Decode decodes src into dst. src must contain the complete message with the exception of the initial 1 byte message
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// type identifier and 4 byte message length.
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func (dst *Describe) Decode(src []byte) error {
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if len(src) < 2 {
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return &invalidMessageFormatErr{messageType: "Describe"}
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}
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dst.ObjectType = src[0]
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rp := 1
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idx := bytes.IndexByte(src[rp:], 0)
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if idx != len(src[rp:])-1 {
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return &invalidMessageFormatErr{messageType: "Describe"}
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}
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dst.Name = string(src[rp : len(src)-1])
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return nil
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}
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// Encode encodes src into dst. dst will include the 1 byte message type identifier and the 4 byte message length.
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func (src *Describe) Encode(dst []byte) []byte {
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dst = append(dst, 'D')
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sp := len(dst)
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dst = pgio.AppendInt32(dst, -1)
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dst = append(dst, src.ObjectType)
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dst = append(dst, src.Name...)
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dst = append(dst, 0)
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pgio.SetInt32(dst[sp:], int32(len(dst[sp:])))
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return dst
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}
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// MarshalJSON implements encoding/json.Marshaler.
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func (src Describe) MarshalJSON() ([]byte, error) {
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return json.Marshal(struct {
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Type string
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ObjectType string
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Name string
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}{
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Type: "Describe",
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ObjectType: string(src.ObjectType),
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Name: src.Name,
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})
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}
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// UnmarshalJSON implements encoding/json.Unmarshaler.
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func (dst *Describe) UnmarshalJSON(data []byte) error {
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// Ignore null, like in the main JSON package.
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if string(data) == "null" {
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return nil
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}
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var msg struct {
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ObjectType string
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Name string
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}
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if err := json.Unmarshal(data, &msg); err != nil {
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return err
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}
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if len(msg.ObjectType) != 1 {
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return errors.New("invalid length for Describe.ObjectType")
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}
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dst.ObjectType = byte(msg.ObjectType[0])
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dst.Name = msg.Name
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return nil
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}
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