FontProviderHelper.kt
/*
* Copyright 2022 The Android Open Source Project
*
* 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.
*/
package androidx.compose.ui.text.googlefonts
import android.annotation.SuppressLint
import android.content.pm.PackageInfo
import android.content.pm.PackageManager
import android.content.pm.Signature
import android.content.res.Resources
import androidx.annotation.WorkerThread
import androidx.compose.ui.text.ExperimentalTextApi
import androidx.core.content.res.FontResourcesParserCompat
import java.util.Arrays
@SuppressLint("ListIterator") // this is not a hot code path, nor is it optimized
@OptIn(ExperimentalTextApi::class)
@WorkerThread
internal fun GoogleFont.Provider.checkAvailable(
packageManager: PackageManager,
resources: Resources
): Boolean {
// check package is available (false return paths)
@Suppress("DEPRECATION")
val providerInfo = packageManager.resolveContentProvider(providerAuthority, 0) ?: return false
if (providerInfo.packageName != providerPackage) return false
// now check signatures (true or except after this)
val signatures = packageManager.getSignatures(providerInfo.packageName)
val sortedSignatures = signatures.sortedWith(ByteArrayComparator)
val allExpectedCerts = loadCertsIfNeeded(resources)
val certsMatched = allExpectedCerts.any { certList ->
val expected = certList?.sortedWith(ByteArrayComparator)
if (expected?.size != sortedSignatures.size) return@any false
for (i in expected.indices) {
if (!Arrays.equals(expected[i], sortedSignatures[i])) return@any false
}
true
}
return if (certsMatched) {
true
} else {
throwFormattedCertsMissError(signatures)
}
}
@SuppressLint("ListIterator") // not a hot code path, not optimized
private fun throwFormattedCertsMissError(signatures: List<ByteArray>): Nothing {
val fullDescription = signatures.joinToString(
",",
prefix = "listOf(listOf(",
postfix = "))"
) { repr(it) }
throw IllegalStateException(
"Provided signatures did not match. Actual signatures of package are:\n\n$fullDescription"
)
}
private fun repr(b: ByteArray): String {
return b.joinToString(",", prefix = "byteArrayOf(", postfix = ")")
}
@OptIn(ExperimentalTextApi::class)
private fun GoogleFont.Provider.loadCertsIfNeeded(resources: Resources): List<List<ByteArray?>?> {
if (certificates != null) {
return certificates
}
return FontResourcesParserCompat.readCerts(resources, certificatesRes)
}
private fun PackageManager.getSignatures(packageName: String): List<ByteArray> {
@Suppress("DEPRECATION")
@SuppressLint("PackageManagerGetSignatures")
val packageInfo: PackageInfo = getPackageInfo(packageName, PackageManager.GET_SIGNATURES)
@Suppress("DEPRECATION")
return convertToByteArrayList(packageInfo.signatures)
}
private val ByteArrayComparator = Comparator { l: ByteArray, r: ByteArray ->
if (l.size != r.size) {
return@Comparator l.size - r.size
}
var i = 0
while (i < l.size) {
if (l[i] != r[i]) {
return@Comparator l[i] - r[i]
}
++i
}
0
}
private fun convertToByteArrayList(signatures: Array<Signature>): List<ByteArray> {
val shaList: MutableList<ByteArray> = ArrayList()
for (signature in signatures) {
shaList.add(signature.toByteArray())
}
return shaList
}