1 /*
2 * Copyright (C) 2014 Square, Inc.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 @file:JvmName("-InflaterSourceExtensions")
18 @file:Suppress("NOTHING_TO_INLINE") // Aliases to public API.
19
20 package okio
21
22 import java.io.IOException
23 import java.util.zip.DataFormatException
24 import java.util.zip.Inflater
25
26 /**
27 * A source that uses [DEFLATE](http://tools.ietf.org/html/rfc1951) to decompress data read from
28 * another source.
29 */
30 class InflaterSource
31 /**
32 * This internal constructor shares a buffer with its trusted caller. In general we can't share a
33 * `BufferedSource` because the inflater holds input bytes until they are inflated.
34 */
35 internal constructor(private val source: BufferedSource, private val inflater: Inflater) : Source {
36
37 /**
38 * When we call Inflater.setInput(), the inflater keeps our byte array until it needs input again.
39 * This tracks how many bytes the inflater is currently holding on to.
40 */
41 private var bufferBytesHeldByInflater = 0
42 private var closed = false
43
44 constructor(source: Source, inflater: Inflater) : this(source.buffer(), inflater)
45
46 @Throws(IOException::class)
readnull47 override fun read(sink: Buffer, byteCount: Long): Long {
48 while (true) {
49 val bytesInflated = readOrInflate(sink, byteCount)
50 if (bytesInflated > 0) return bytesInflated
51 if (inflater.finished() || inflater.needsDictionary()) return -1L
52 if (source.exhausted()) throw EOFException("source exhausted prematurely")
53 }
54 }
55
56 /**
57 * Consume deflated bytes from the underlying source, and write any inflated bytes to [sink].
58 * Returns the number of inflated bytes written to [sink]. This may return 0L, though it will
59 * always consume 1 or more bytes from the underlying source if it is not exhausted.
60 *
61 * Use this instead of [read] when it is useful to consume the deflated stream even when doing so
62 * doesn't yield inflated bytes.
63 */
64 @Throws(IOException::class)
readOrInflatenull65 fun readOrInflate(sink: Buffer, byteCount: Long): Long {
66 require(byteCount >= 0L) { "byteCount < 0: $byteCount" }
67 check(!closed) { "closed" }
68 if (byteCount == 0L) return 0L
69
70 try {
71 // Prepare the destination that we'll write into.
72 val tail = sink.writableSegment(1)
73 val toRead = minOf(byteCount, Segment.SIZE - tail.limit).toInt()
74
75 // Prepare the source that we'll read from.
76 refill()
77
78 // Decompress the inflater's compressed data into the sink.
79 val bytesInflated = inflater.inflate(tail.data, tail.limit, toRead)
80
81 // Release consumed bytes from the source.
82 releaseBytesAfterInflate()
83
84 // Track produced bytes in the destination.
85 if (bytesInflated > 0) {
86 tail.limit += bytesInflated
87 sink.size += bytesInflated
88 return bytesInflated.toLong()
89 }
90
91 // We allocated a tail segment, but didn't end up needing it. Recycle!
92 if (tail.pos == tail.limit) {
93 sink.head = tail.pop()
94 SegmentPool.recycle(tail)
95 }
96
97 return 0L
98 } catch (e: DataFormatException) {
99 throw IOException(e)
100 }
101 }
102
103 /**
104 * Refills the inflater with compressed data if it needs input. (And only if it needs input).
105 * Returns true if the inflater required input but the source was exhausted.
106 */
107 @Throws(IOException::class)
refillnull108 fun refill(): Boolean {
109 if (!inflater.needsInput()) return false
110
111 // If there are no further bytes in the source, we cannot refill.
112 if (source.exhausted()) return true
113
114 // Assign buffer bytes to the inflater.
115 val head = source.buffer.head!!
116 bufferBytesHeldByInflater = head.limit - head.pos
117 inflater.setInput(head.data, head.pos, bufferBytesHeldByInflater)
118 return false
119 }
120
121 /** When the inflater has processed compressed data, remove it from the buffer. */
releaseBytesAfterInflatenull122 private fun releaseBytesAfterInflate() {
123 if (bufferBytesHeldByInflater == 0) return
124 val toRelease = bufferBytesHeldByInflater - inflater.remaining
125 bufferBytesHeldByInflater -= toRelease
126 source.skip(toRelease.toLong())
127 }
128
timeoutnull129 override fun timeout(): Timeout = source.timeout()
130
131 @Throws(IOException::class)
132 override fun close() {
133 if (closed) return
134 inflater.end()
135 closed = true
136 source.close()
137 }
138 }
139
140 /**
141 * Returns an [InflaterSource] that DEFLATE-decompresses this [Source] while reading.
142 *
143 * @see InflaterSource
144 */
inflatenull145 inline fun Source.inflate(inflater: Inflater = Inflater()): InflaterSource =
146 InflaterSource(this, inflater)
147