From b33eee5c34c75688c96d6cd874d82e55dab30491 Mon Sep 17 00:00:00 2001
From: euxane
Date: Wed, 18 Sep 2024 23:41:13 +0200
Subject: storage/provider: expose config and log dirs through
 DocumentsProvider

---
 app/src/main/AndroidManifest.xml                   |  14 ++
 .../storageprovider/FilesDocumentsProvider.kt      | 222 +++++++++++++++++++++
 app/src/main/res/xml/file_paths.xml                |  24 +++
 3 files changed, 260 insertions(+)
 create mode 100644 app/src/main/java/org/pacien/tincapp/storageprovider/FilesDocumentsProvider.kt
 create mode 100644 app/src/main/res/xml/file_paths.xml

diff --git a/app/src/main/AndroidManifest.xml b/app/src/main/AndroidManifest.xml
index e29bce6..e2ec0fc 100644
--- a/app/src/main/AndroidManifest.xml
+++ b/app/src/main/AndroidManifest.xml
@@ -85,6 +85,20 @@
             </intent-filter>
         </service>
 
+        <provider
+            android:name="org.pacien.tincapp.storageprovider.FilesDocumentsProvider"
+            android:authorities="org.pacien.tincapp.files"
+            android:exported="true"
+            android:grantUriPermissions="true"
+            android:permission="android.permission.MANAGE_DOCUMENTS">
+            <intent-filter>
+                <action android:name="android.content.action.DOCUMENTS_PROVIDER" />
+            </intent-filter>
+            <meta-data
+                android:name="android.support.FILE_PROVIDER_PATHS"
+                android:resource="@xml/file_paths" />
+        </provider>
+
     </application>
 
 </manifest>
diff --git a/app/src/main/java/org/pacien/tincapp/storageprovider/FilesDocumentsProvider.kt b/app/src/main/java/org/pacien/tincapp/storageprovider/FilesDocumentsProvider.kt
new file mode 100644
index 0000000..07ffaca
--- /dev/null
+++ b/app/src/main/java/org/pacien/tincapp/storageprovider/FilesDocumentsProvider.kt
@@ -0,0 +1,222 @@
+/*
+ * Tinc Mesh VPN: Android client and user interface
+ * Copyright (C) 2017-2024 Euxane P. TRAN-GIRARD
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package org.pacien.tincapp.storageprovider
+
+import android.os.CancellationSignal
+import android.os.ParcelFileDescriptor
+import android.database.Cursor
+import android.database.MatrixCursor
+import android.os.Build
+import android.provider.DocumentsContract
+import android.provider.DocumentsContract.Document
+import android.provider.DocumentsContract.Root
+import android.provider.DocumentsProvider
+import androidx.annotation.RequiresApi
+import org.pacien.tincapp.R
+import org.pacien.tincapp.context.AppPaths
+import java.io.File
+import java.io.FileNotFoundException
+import kotlin.io.path.Path
+import kotlin.io.path.name
+import kotlin.io.path.relativeTo
+
+class FilesDocumentsProvider : DocumentsProvider() {
+  companion object {
+    const val ROOT_ID = ""
+    const val ROOT_DOCUMENT_ID = "/"
+    const val VIRTUAL_ROOT_NETWORKS = "networks"
+    const val VIRTUAL_ROOT_LOG = "log"
+
+    private val DEFAULT_ROOT_PROJECTION = arrayOf(
+      Root.COLUMN_ROOT_ID,
+      Root.COLUMN_MIME_TYPES,
+      Root.COLUMN_FLAGS,
+      Root.COLUMN_ICON,
+      Root.COLUMN_TITLE,
+      Root.COLUMN_SUMMARY,
+      Root.COLUMN_DOCUMENT_ID,
+      Root.COLUMN_AVAILABLE_BYTES,
+    )
+
+    private val DEFAULT_DOCUMENT_PROJECTION = arrayOf(
+      Document.COLUMN_DOCUMENT_ID,
+      Document.COLUMN_MIME_TYPE,
+      Document.COLUMN_DISPLAY_NAME,
+      Document.COLUMN_LAST_MODIFIED,
+      Document.COLUMN_FLAGS,
+      Document.COLUMN_SIZE,
+    )
+  }
+
+  override fun onCreate(): Boolean = true
+
+  override fun queryRoots(projection: Array<out String>?): Cursor =
+    MatrixCursor(projection ?: DEFAULT_ROOT_PROJECTION).apply {
+      addRow(
+        Root.COLUMN_ROOT_ID to ROOT_ID,
+        Root.COLUMN_DOCUMENT_ID to ROOT_DOCUMENT_ID,
+        Root.COLUMN_FLAGS to (Root.FLAG_SUPPORTS_CREATE or Root.FLAG_SUPPORTS_IS_CHILD),
+        Root.COLUMN_MIME_TYPES to "*/*",
+        Root.COLUMN_TITLE to context!!.getString(R.string.app_name),
+        Root.COLUMN_ICON to R.mipmap.ic_launcher,
+      )
+    }
+
+  override fun queryDocument(documentId: String?, projection: Array<out String>?): Cursor =
+    MatrixCursor(projection ?: DEFAULT_DOCUMENT_PROJECTION).apply {
+      when (documentId) {
+        ROOT_DOCUMENT_ID -> addVirtualDirRow(ROOT_DOCUMENT_ID)
+        else -> addFileRow(documentId!!, fileForDocumentId(documentId))
+      }
+    }
+
+  override fun queryChildDocuments(
+    parentDocumentId: String?,
+    projection: Array<out String>?,
+    sortOrder: String?
+  ): Cursor =
+    MatrixCursor(projection ?: DEFAULT_DOCUMENT_PROJECTION).apply {
+      when (parentDocumentId) {
+        ROOT_DOCUMENT_ID -> {
+          addVirtualDirRow(VIRTUAL_ROOT_NETWORKS)
+          addVirtualDirRow(VIRTUAL_ROOT_LOG)
+        }
+
+        else -> fileForDocumentId(parentDocumentId!!).listFiles()?.forEach {
+          addFileRow(documentIdForFile(it), it)
+        }
+      }
+    }
+
+  @RequiresApi(Build.VERSION_CODES.O)
+  override fun findDocumentPath(
+    parentDocumentId: String?,
+    childDocumentId: String?
+  ): DocumentsContract.Path {
+    var childPath = Path(childDocumentId!!)
+    if (parentDocumentId != null)
+      childPath = childPath.relativeTo(Path(parentDocumentId))
+
+    val components = childPath.asSequence().map { it.name }.toList()
+    return DocumentsContract.Path(ROOT_ID, listOf(ROOT_DOCUMENT_ID) + components)
+  }
+
+  override fun isChildDocument(parentDocumentId: String?, documentId: String?): Boolean =
+    fileForDocumentId(parentDocumentId!!).isParentOf(fileForDocumentId(documentId!!))
+
+  override fun getDocumentType(documentId: String?): String =
+    fileForDocumentId(documentId!!).documentMimeType()
+
+  override fun deleteDocument(documentId: String?) {
+    fileForDocumentId(documentId!!).apply {
+      if (!deleteRecursively()) throw FileSystemException(this)
+    }
+  }
+
+  override fun openDocument(
+    documentId: String?,
+    mode: String?,
+    signal: CancellationSignal?
+  ): ParcelFileDescriptor =
+    ParcelFileDescriptor.open(
+      fileForDocumentId(documentId!!),
+      ParcelFileDescriptor.parseMode(mode),
+    )
+
+  override fun createDocument(
+    parentDocumentId: String?,
+    mimeType: String?,
+    displayName: String?
+  ): String =
+    File(fileForDocumentId(parentDocumentId!!), displayName!!).apply {
+      val success = when (mimeType) {
+        Document.MIME_TYPE_DIR -> mkdir()
+        else -> createNewFile()
+      }
+      if (!success) throw FileSystemException(this)
+    }.let {
+      documentIdForFile(it)
+    }
+
+  private fun fileForDocumentId(documentId: String): File =
+    documentId.split(File.separatorChar, limit = 2).let {
+      val root = it[0]
+      val under = if (it.size >= 2) it[1] else ""
+      when (root) {
+        VIRTUAL_ROOT_NETWORKS -> File(AppPaths.confDir(), under)
+        VIRTUAL_ROOT_LOG -> File(AppPaths.logDir(), under)
+        else -> throw FileNotFoundException()
+      }
+    }
+
+  private fun documentIdForFile(file: File): String =
+    if (AppPaths.confDir().isParentOf(file)) {
+      File(VIRTUAL_ROOT_NETWORKS, file.pathUnder(AppPaths.confDir())).path
+    } else if (AppPaths.logDir().isParentOf(file)) {
+      File(VIRTUAL_ROOT_LOG, file.pathUnder(AppPaths.logDir())).path
+    } else {
+      throw IllegalArgumentException()
+    }
+
+  private fun File.pathUnder(parent: File): String =
+    canonicalPath.removePrefix(parent.canonicalPath)
+
+  private fun File.isParentOf(childCandidate: File): Boolean {
+    var parentOfChild = childCandidate.canonicalFile.parentFile
+    while (parentOfChild != null) {
+      if (parentOfChild.equals(canonicalFile)) return true
+      parentOfChild = parentOfChild.parentFile
+    }
+    return false
+  }
+
+  private fun File.documentMimeType() =
+    if (isDirectory) Document.MIME_TYPE_DIR
+    else "text/plain"
+
+  private fun File.documentPermFlags() =
+    (if (isDirectory && canWrite()) Document.FLAG_DIR_SUPPORTS_CREATE else 0) or
+      (if (isFile && canWrite()) Document.FLAG_SUPPORTS_WRITE else 0) or
+      (if (parentFile?.canWrite() == true) Document.FLAG_SUPPORTS_DELETE else 0)
+
+  private fun MatrixCursor.addFileRow(documentId: String, file: File) {
+    addRow(
+      Document.COLUMN_DOCUMENT_ID to documentId,
+      Document.COLUMN_DISPLAY_NAME to file.name,
+      Document.COLUMN_SIZE to file.length(),
+      Document.COLUMN_LAST_MODIFIED to file.lastModified(),
+      Document.COLUMN_MIME_TYPE to file.documentMimeType(),
+      Document.COLUMN_FLAGS to file.documentPermFlags(),
+    )
+  }
+
+  private fun MatrixCursor.addVirtualDirRow(documentId: String) {
+    addRow(
+      Document.COLUMN_DOCUMENT_ID to documentId,
+      Document.COLUMN_DISPLAY_NAME to documentId,
+      Document.COLUMN_MIME_TYPE to Document.MIME_TYPE_DIR,
+      Document.COLUMN_FLAGS to Document.FLAG_DIR_SUPPORTS_CREATE,
+    )
+  }
+
+  private fun MatrixCursor.addRow(vararg pairs: Pair<String, Any?>) {
+    val row = newRow()
+    pairs.forEach { row.add(it.first, it.second) }
+  }
+}
\ No newline at end of file
diff --git a/app/src/main/res/xml/file_paths.xml b/app/src/main/res/xml/file_paths.xml
new file mode 100644
index 0000000..98a441b
--- /dev/null
+++ b/app/src/main/res/xml/file_paths.xml
@@ -0,0 +1,24 @@
+<?xml version="1.0" encoding="utf-8"?>
+
+<!--
+ * Tinc Mesh VPN: Android client and user interface
+ * Copyright (C) 2017-2024 Euxane P. TRAN-GIRARD
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+-->
+
+<paths>
+    <files-path name="networks" path="networks" />
+    <cache-path name="log" path="log" />
+</paths>
\ No newline at end of file
-- 
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