forked from cilium/cilium
/
binary.go
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/
binary.go
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// Copyright 2019 Authors of Cilium
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// Copyright (c) 2009 The Go Authors. All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are
// met:
//
// * Redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer.
// * Redistributions in binary form must reproduce the above
// copyright notice, this list of conditions and the following disclaimer
// in the documentation and/or other materials provided with the
// distribution.
// * Neither the name of Google Inc. nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
package binary
import (
"encoding/binary"
"math"
"reflect"
)
type coder struct {
order binary.ByteOrder
buf []byte
offset int
}
type decoder coder
func (d *decoder) bool() bool {
x := d.buf[d.offset]
d.offset++
return x != 0
}
func (d *decoder) uint8() uint8 {
x := d.buf[d.offset]
d.offset++
return x
}
func (d *decoder) uint16() uint16 {
x := d.order.Uint16(d.buf[d.offset : d.offset+2])
d.offset += 2
return x
}
func (d *decoder) uint32() uint32 {
x := d.order.Uint32(d.buf[d.offset : d.offset+4])
d.offset += 4
return x
}
func (d *decoder) uint64() uint64 {
x := d.order.Uint64(d.buf[d.offset : d.offset+8])
d.offset += 8
return x
}
func (d *decoder) skip(v reflect.Value) {
d.offset += dataSize(v)
}
// sizeof returns the size >= 0 of variables for the given type or -1 if the type is not acceptable.
func sizeof(t reflect.Type) int {
switch t.Kind() {
case reflect.Array:
if s := sizeof(t.Elem()); s >= 0 {
return s * t.Len()
}
case reflect.Struct:
sum := 0
for i, n := 0, t.NumField(); i < n; i++ {
s := sizeof(t.Field(i).Type)
if s < 0 {
return -1
}
sum += s
}
return sum
case reflect.Bool,
reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64,
reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64,
reflect.Float32, reflect.Float64, reflect.Complex64, reflect.Complex128:
return int(t.Size())
}
return -1
}
// dataSize returns the number of bytes the actual data represented by v occupies in memory.
// For compound structures, it sums the sizes of the elements. Thus, for instance, for a slice
// it returns the length of the slice times the element size and does not count the memory
// occupied by the header. If the type of v is not acceptable, dataSize returns -1.
func dataSize(v reflect.Value) int {
if v.Kind() == reflect.Slice {
if s := sizeof(v.Type().Elem()); s >= 0 {
return s * v.Len()
}
return -1
}
return sizeof(v.Type())
}
func (d *decoder) int8() int8 { return int8(d.uint8()) }
func (d *decoder) int16() int16 { return int16(d.uint16()) }
func (d *decoder) int32() int32 { return int32(d.uint32()) }
func (d *decoder) int64() int64 { return int64(d.uint64()) }
func (d *decoder) value(v reflect.Value) {
switch v.Kind() {
case reflect.Array:
l := v.Len()
for i := 0; i < l; i++ {
d.value(v.Index(i))
}
case reflect.Struct:
t := v.Type()
l := v.NumField()
for i := 0; i < l; i++ {
// Note: Calling v.CanSet() below is an optimization.
// It would be sufficient to check the field name,
// but creating the StructField info for each field is
// costly (run "go test -bench=ReadStruct" and compare
// results when making changes to this code).
if v := v.Field(i); v.CanSet() || t.Field(i).Name != "_" {
d.value(v)
} else {
d.skip(v)
}
}
case reflect.Slice:
l := v.Len()
for i := 0; i < l; i++ {
d.value(v.Index(i))
}
case reflect.Bool:
v.SetBool(d.bool())
case reflect.Int8:
v.SetInt(int64(d.int8()))
case reflect.Int16:
v.SetInt(int64(d.int16()))
case reflect.Int32:
v.SetInt(int64(d.int32()))
case reflect.Int64:
v.SetInt(d.int64())
case reflect.Uint8:
v.SetUint(uint64(d.uint8()))
case reflect.Uint16:
v.SetUint(uint64(d.uint16()))
case reflect.Uint32:
v.SetUint(uint64(d.uint32()))
case reflect.Uint64:
v.SetUint(d.uint64())
case reflect.Float32:
v.SetFloat(float64(math.Float32frombits(d.uint32())))
case reflect.Float64:
v.SetFloat(math.Float64frombits(d.uint64()))
case reflect.Complex64:
v.SetComplex(complex(
float64(math.Float32frombits(d.uint32())),
float64(math.Float32frombits(d.uint32())),
))
case reflect.Complex128:
v.SetComplex(complex(
math.Float64frombits(d.uint64()),
math.Float64frombits(d.uint64()),
))
}
}
// Read reads structured binary data from r into data.
// Data must be a pointer to a fixed-size value or a slice
// of fixed-size values.
// Bytes read from r are decoded using the specified byte order
// and written to successive fields of the data.
// When decoding boolean values, a zero byte is decoded as false, and
// any other non-zero byte is decoded as true.
// When reading into structs, the field data for fields with
// blank (_) field names is skipped; i.e., blank field names
// may be used for padding.
// When reading into a struct, all non-blank fields must be exported
// or Read may panic.
//
// The error is EOF only if no bytes were read.
// If an EOF happens after reading some but not all the bytes,
// Read returns ErrUnexpectedEOF.
// This Read function differs from the upstream encoding/binary.Read as it does
// not requires the caller to setup a reader as well as this function does
// not allocate any memory to read from the given slice of bytes.
func Read(r []byte, order binary.ByteOrder, data interface{}) error {
// Fallback to reflect-based decoding.
v := reflect.ValueOf(data)
switch v.Kind() {
case reflect.Ptr:
v = v.Elem()
}
d := &decoder{order: order, buf: r}
d.value(v)
return nil
}