summaryrefslogtreecommitdiff
path: root/vendor/github.com/godbus/dbus/v5/decoder.go
blob: 89bfed9d1a1c532aea1437cdbb00035bf05ffb2c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
package dbus

import (
	"encoding/binary"
	"io"
	"reflect"
)

type decoder struct {
	in    io.Reader
	order binary.ByteOrder
	pos   int
	fds   []int
}

// newDecoder returns a new decoder that reads values from in. The input is
// expected to be in the given byte order.
func newDecoder(in io.Reader, order binary.ByteOrder, fds []int) *decoder {
	dec := new(decoder)
	dec.in = in
	dec.order = order
	dec.fds = fds
	return dec
}

// align aligns the input to the given boundary and panics on error.
func (dec *decoder) align(n int) {
	if dec.pos%n != 0 {
		newpos := (dec.pos + n - 1) & ^(n - 1)
		empty := make([]byte, newpos-dec.pos)
		if _, err := io.ReadFull(dec.in, empty); err != nil {
			panic(err)
		}
		dec.pos = newpos
	}
}

// Calls binary.Read(dec.in, dec.order, v) and panics on read errors.
func (dec *decoder) binread(v interface{}) {
	if err := binary.Read(dec.in, dec.order, v); err != nil {
		panic(err)
	}
}

func (dec *decoder) Decode(sig Signature) (vs []interface{}, err error) {
	defer func() {
		var ok bool
		v := recover()
		if err, ok = v.(error); ok {
			if err == io.EOF || err == io.ErrUnexpectedEOF {
				err = FormatError("unexpected EOF")
			}
		}
	}()
	vs = make([]interface{}, 0)
	s := sig.str
	for s != "" {
		err, rem := validSingle(s, &depthCounter{})
		if err != nil {
			return nil, err
		}
		v := dec.decode(s[:len(s)-len(rem)], 0)
		vs = append(vs, v)
		s = rem
	}
	return vs, nil
}

func (dec *decoder) decode(s string, depth int) interface{} {
	dec.align(alignment(typeFor(s)))
	switch s[0] {
	case 'y':
		var b [1]byte
		if _, err := dec.in.Read(b[:]); err != nil {
			panic(err)
		}
		dec.pos++
		return b[0]
	case 'b':
		i := dec.decode("u", depth).(uint32)
		switch {
		case i == 0:
			return false
		case i == 1:
			return true
		default:
			panic(FormatError("invalid value for boolean"))
		}
	case 'n':
		var i int16
		dec.binread(&i)
		dec.pos += 2
		return i
	case 'i':
		var i int32
		dec.binread(&i)
		dec.pos += 4
		return i
	case 'x':
		var i int64
		dec.binread(&i)
		dec.pos += 8
		return i
	case 'q':
		var i uint16
		dec.binread(&i)
		dec.pos += 2
		return i
	case 'u':
		var i uint32
		dec.binread(&i)
		dec.pos += 4
		return i
	case 't':
		var i uint64
		dec.binread(&i)
		dec.pos += 8
		return i
	case 'd':
		var f float64
		dec.binread(&f)
		dec.pos += 8
		return f
	case 's':
		length := dec.decode("u", depth).(uint32)
		b := make([]byte, int(length)+1)
		if _, err := io.ReadFull(dec.in, b); err != nil {
			panic(err)
		}
		dec.pos += int(length) + 1
		return string(b[:len(b)-1])
	case 'o':
		return ObjectPath(dec.decode("s", depth).(string))
	case 'g':
		length := dec.decode("y", depth).(byte)
		b := make([]byte, int(length)+1)
		if _, err := io.ReadFull(dec.in, b); err != nil {
			panic(err)
		}
		dec.pos += int(length) + 1
		sig, err := ParseSignature(string(b[:len(b)-1]))
		if err != nil {
			panic(err)
		}
		return sig
	case 'v':
		if depth >= 64 {
			panic(FormatError("input exceeds container depth limit"))
		}
		var variant Variant
		sig := dec.decode("g", depth).(Signature)
		if len(sig.str) == 0 {
			panic(FormatError("variant signature is empty"))
		}
		err, rem := validSingle(sig.str, &depthCounter{})
		if err != nil {
			panic(err)
		}
		if rem != "" {
			panic(FormatError("variant signature has multiple types"))
		}
		variant.sig = sig
		variant.value = dec.decode(sig.str, depth+1)
		return variant
	case 'h':
		idx := dec.decode("u", depth).(uint32)
		if int(idx) < len(dec.fds) {
			return UnixFD(dec.fds[idx])
		}
		return UnixFDIndex(idx)
	case 'a':
		if len(s) > 1 && s[1] == '{' {
			ksig := s[2:3]
			vsig := s[3 : len(s)-1]
			v := reflect.MakeMap(reflect.MapOf(typeFor(ksig), typeFor(vsig)))
			if depth >= 63 {
				panic(FormatError("input exceeds container depth limit"))
			}
			length := dec.decode("u", depth).(uint32)
			// Even for empty maps, the correct padding must be included
			dec.align(8)
			spos := dec.pos
			for dec.pos < spos+int(length) {
				dec.align(8)
				if !isKeyType(v.Type().Key()) {
					panic(InvalidTypeError{v.Type()})
				}
				kv := dec.decode(ksig, depth+2)
				vv := dec.decode(vsig, depth+2)
				v.SetMapIndex(reflect.ValueOf(kv), reflect.ValueOf(vv))
			}
			return v.Interface()
		}
		if depth >= 64 {
			panic(FormatError("input exceeds container depth limit"))
		}
		sig := s[1:]
		length := dec.decode("u", depth).(uint32)
		// capacity can be determined only for fixed-size element types
		var capacity int
		if s := sigByteSize(sig); s != 0 {
			capacity = int(length) / s
		}
		v := reflect.MakeSlice(reflect.SliceOf(typeFor(sig)), 0, capacity)
		// Even for empty arrays, the correct padding must be included
		align := alignment(typeFor(s[1:]))
		if len(s) > 1 && s[1] == '(' {
			//Special case for arrays of structs
			//structs decode as a slice of interface{} values
			//but the dbus alignment does not match this
			align = 8
		}
		dec.align(align)
		spos := dec.pos
		for dec.pos < spos+int(length) {
			ev := dec.decode(s[1:], depth+1)
			v = reflect.Append(v, reflect.ValueOf(ev))
		}
		return v.Interface()
	case '(':
		if depth >= 64 {
			panic(FormatError("input exceeds container depth limit"))
		}
		dec.align(8)
		v := make([]interface{}, 0)
		s = s[1 : len(s)-1]
		for s != "" {
			err, rem := validSingle(s, &depthCounter{})
			if err != nil {
				panic(err)
			}
			ev := dec.decode(s[:len(s)-len(rem)], depth+1)
			v = append(v, ev)
			s = rem
		}
		return v
	default:
		panic(SignatureError{Sig: s})
	}
}

// sigByteSize tries to calculates size of the given signature in bytes.
//
// It returns zero when it can't, for example when it contains non-fixed size
// types such as strings, maps and arrays that require reading of the transmitted
// data, for that we would need to implement the unread method for Decoder first.
func sigByteSize(sig string) int {
	var total int
	for offset := 0; offset < len(sig); {
		switch sig[offset] {
		case 'y':
			total += 1
			offset += 1
		case 'n', 'q':
			total += 2
			offset += 1
		case 'b', 'i', 'u', 'h':
			total += 4
			offset += 1
		case 'x', 't', 'd':
			total += 8
			offset += 1
		case '(':
			i := 1
			depth := 1
			for i < len(sig[offset:]) && depth != 0 {
				if sig[offset+i] == '(' {
					depth++
				} else if sig[offset+i] == ')' {
					depth--
				}
				i++
			}
			s := sigByteSize(sig[offset+1 : offset+i-1])
			if s == 0 {
				return 0
			}
			total += s
			offset += i
		default:
			return 0
		}
	}
	return total
}

// A FormatError is an error in the wire format.
type FormatError string

func (e FormatError) Error() string {
	return "dbus: wire format error: " + string(e)
}