commonMain.okio.-Base64.kt Maven / Gradle / Ivy
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You 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.
*/
package okio
import okio.ByteString.Companion.encodeUtf8
import kotlin.native.concurrent.SharedImmutable
/** @author Alexander Y. Kleymenov */
@SharedImmutable
internal val BASE64 =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/".encodeUtf8().data
@SharedImmutable
internal val BASE64_URL_SAFE =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_".encodeUtf8().data
internal fun String.decodeBase64ToArray(): ByteArray? {
// Ignore trailing '=' padding and whitespace from the input.
var limit = length
while (limit > 0) {
val c = this[limit - 1]
if (c != '=' && c != '\n' && c != '\r' && c != ' ' && c != '\t') {
break
}
limit--
}
// If the input includes whitespace, this output array will be longer than necessary.
val out = ByteArray((limit * 6L / 8L).toInt())
var outCount = 0
var inCount = 0
var word = 0
for (pos in 0 until limit) {
val c = this[pos]
val bits: Int
if (c in 'A'..'Z') {
// char ASCII value
// A 65 0
// Z 90 25 (ASCII - 65)
bits = c.code - 65
} else if (c in 'a'..'z') {
// char ASCII value
// a 97 26
// z 122 51 (ASCII - 71)
bits = c.code - 71
} else if (c in '0'..'9') {
// char ASCII value
// 0 48 52
// 9 57 61 (ASCII + 4)
bits = c.code + 4
} else if (c == '+' || c == '-') {
bits = 62
} else if (c == '/' || c == '_') {
bits = 63
} else if (c == '\n' || c == '\r' || c == ' ' || c == '\t') {
continue
} else {
return null
}
// Append this char's 6 bits to the word.
word = word shl 6 or bits
// For every 4 chars of input, we accumulate 24 bits of output. Emit 3 bytes.
inCount++
if (inCount % 4 == 0) {
out[outCount++] = (word shr 16).toByte()
out[outCount++] = (word shr 8).toByte()
out[outCount++] = word.toByte()
}
}
val lastWordChars = inCount % 4
when (lastWordChars) {
1 -> {
// We read 1 char followed by "===". But 6 bits is a truncated byte! Fail.
return null
}
2 -> {
// We read 2 chars followed by "==". Emit 1 byte with 8 of those 12 bits.
word = word shl 12
out[outCount++] = (word shr 16).toByte()
}
3 -> {
// We read 3 chars, followed by "=". Emit 2 bytes for 16 of those 18 bits.
word = word shl 6
out[outCount++] = (word shr 16).toByte()
out[outCount++] = (word shr 8).toByte()
}
}
// If we sized our out array perfectly, we're done.
if (outCount == out.size) return out
// Copy the decoded bytes to a new, right-sized array.
return out.copyOf(outCount)
}
internal fun ByteArray.encodeBase64(map: ByteArray = BASE64): String {
val length = (size + 2) / 3 * 4
val out = ByteArray(length)
var index = 0
val end = size - size % 3
var i = 0
while (i < end) {
val b0 = this[i++].toInt()
val b1 = this[i++].toInt()
val b2 = this[i++].toInt()
out[index++] = map[(b0 and 0xff shr 2)]
out[index++] = map[(b0 and 0x03 shl 4) or (b1 and 0xff shr 4)]
out[index++] = map[(b1 and 0x0f shl 2) or (b2 and 0xff shr 6)]
out[index++] = map[(b2 and 0x3f)]
}
when (size - end) {
1 -> {
val b0 = this[i].toInt()
out[index++] = map[b0 and 0xff shr 2]
out[index++] = map[b0 and 0x03 shl 4]
out[index++] = '='.code.toByte()
out[index] = '='.code.toByte()
}
2 -> {
val b0 = this[i++].toInt()
val b1 = this[i].toInt()
out[index++] = map[(b0 and 0xff shr 2)]
out[index++] = map[(b0 and 0x03 shl 4) or (b1 and 0xff shr 4)]
out[index++] = map[(b1 and 0x0f shl 2)]
out[index] = '='.code.toByte()
}
}
return out.toUtf8String()
}