package msgpack import ( "fmt" "reflect" "github.com/vmihailenco/msgpack/v5/msgpcode" ) var sliceStringPtrType = reflect.TypeOf((*[]string)(nil)) // DecodeArrayLen decodes array length. Length is -1 when array is nil. func (d *Decoder) DecodeArrayLen() (int, error) { c, err := d.readCode() if err != nil { return 0, err } return d.arrayLen(c) } func (d *Decoder) arrayLen(c byte) (int, error) { if c == msgpcode.Nil { return -1, nil } else if c >= msgpcode.FixedArrayLow && c <= msgpcode.FixedArrayHigh { return int(c & msgpcode.FixedArrayMask), nil } switch c { case msgpcode.Array16: n, err := d.uint16() return int(n), err case msgpcode.Array32: n, err := d.uint32() return int(n), err } return 0, fmt.Errorf("msgpack: invalid code=%x decoding array length", c) } func decodeStringSliceValue(d *Decoder, v reflect.Value) error { ptr := v.Addr().Convert(sliceStringPtrType).Interface().(*[]string) return d.decodeStringSlicePtr(ptr) } func (d *Decoder) decodeStringSlicePtr(ptr *[]string) error { n, err := d.DecodeArrayLen() if err != nil { return err } if n == -1 { return nil } ss := makeStrings(*ptr, n) for i := 0; i < n; i++ { s, err := d.DecodeString() if err != nil { return err } ss = append(ss, s) } *ptr = ss return nil } func makeStrings(s []string, n int) []string { if n > sliceAllocLimit { n = sliceAllocLimit } if s == nil { return make([]string, 0, n) } if cap(s) >= n { return s[:0] } s = s[:cap(s)] s = append(s, make([]string, n-len(s))...) return s[:0] } func decodeSliceValue(d *Decoder, v reflect.Value) error { n, err := d.DecodeArrayLen() if err != nil { return err } if n == -1 { v.Set(reflect.Zero(v.Type())) return nil } if n == 0 && v.IsNil() { v.Set(reflect.MakeSlice(v.Type(), 0, 0)) return nil } if v.Cap() >= n { v.Set(v.Slice(0, n)) } else if v.Len() < v.Cap() { v.Set(v.Slice(0, v.Cap())) } for i := 0; i < n; i++ { if i >= v.Len() { v.Set(growSliceValue(v, n)) } elem := v.Index(i) if err := d.DecodeValue(elem); err != nil { return err } } return nil } func growSliceValue(v reflect.Value, n int) reflect.Value { diff := n - v.Len() if diff > sliceAllocLimit { diff = sliceAllocLimit } v = reflect.AppendSlice(v, reflect.MakeSlice(v.Type(), diff, diff)) return v } func decodeArrayValue(d *Decoder, v reflect.Value) error { n, err := d.DecodeArrayLen() if err != nil { return err } if n == -1 { return nil } if n > v.Len() { return fmt.Errorf("%s len is %d, but msgpack has %d elements", v.Type(), v.Len(), n) } for i := 0; i < n; i++ { sv := v.Index(i) if err := d.DecodeValue(sv); err != nil { return err } } return nil } func (d *Decoder) DecodeSlice() ([]interface{}, error) { c, err := d.readCode() if err != nil { return nil, err } return d.decodeSlice(c) } func (d *Decoder) decodeSlice(c byte) ([]interface{}, error) { n, err := d.arrayLen(c) if err != nil { return nil, err } if n == -1 { return nil, nil } s := make([]interface{}, 0, min(n, sliceAllocLimit)) for i := 0; i < n; i++ { v, err := d.decodeInterfaceCond() if err != nil { return nil, err } s = append(s, v) } return s, nil } func (d *Decoder) skipSlice(c byte) error { n, err := d.arrayLen(c) if err != nil { return err } for i := 0; i < n; i++ { if err := d.Skip(); err != nil { return err } } return nil }