swankjesse · February 7, 2021 16:27 · Feb 7, 2021
diff --git a/ZipFileSystemSketch.kt b/ZipFileSystemSketch.kt
@@ -0,0 +1,71 @@
+/*
+ * Copyright (C) 2021 Square, Inc.
+ *
+ * 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 okio
+
+import java.util.zip.InflaterInputStream
+import okio.Path.Companion.toPath
+
+@ExperimentalFileSystem
+class ZipFileSystemSketch private constructor(
+  private val fileSystem: FileSystem,
+  private val zipPath: Path,
+  private val entries: List<Entry>
+) : FileSystem() {
+
+  override fun canonicalize(path: Path): Path {
+    return "/".toPath() / path
+  }
+
+  override fun metadataOrNull(path: Path): FileMetadata? {
+    val canonicalPath = canonicalize(path)
+    return entries.firstOrNull { it.path == canonicalPath }?.metadata
+  }
+
+  override fun list(dir: Path): List<Path> {
+    val canonicalDir = canonicalize(dir)
+    return entries.mapNotNull { if (it.path.parent == canonicalDir) it.path else null }
+  }
+
+  override fun source(file: Path): Source {
+    val canonicalPath = canonicalize(file)
+    val entry = entries.firstOrNull { it.path == canonicalPath } 
+      ?: throw FileNotFoundException("no such file: $file")
+    val zipSource = fileSystem.source(zipPath)
+    val cursor = zipSource.cursor ?: throw IOException("zip file not random access")
+    cursor.seek(entry.offset)
+    // TODO(jwilson): there's some framing needed here.
+    return InflaterInputStream(zipSource.buffer().inputStream()).source()
+  }
+
+  override fun sink(file: Path): Sink = throw IOException("zip file systems are read-only")
+
+  override fun appendingSink(file: Path): Sink =
+    throw IOException("zip file systems are read-only")
+
+  override fun createDirectory(dir: Path): Unit =
+    throw IOException("zip file systems are read-only")
+
+  override fun atomicMove(source: Path, target: Path): Unit =
+    throw IOException("zip file systems are read-only")
+
+  override fun delete(path: Path): Unit = throw IOException("zip file systems are read-only")
+
+  private class Entry(
+    val path: Path,
+    val metadata: FileMetadata,
+    val offset: Long
+  )
+}