refactor and cleanup [skip ci]

submodules/Postbox/Sources/ManagedFile.swift

@@ -0,0 +1,115 @@
+import Foundation
+import SwiftSignalKit
+
+public enum ManagedFileMode {
+    case read
+    case readwrite
+    case append
+}
+
+private func wrappedWrite(_ fd: Int32, _ data: UnsafeRawPointer, _ count: Int) -> Int {
+    return write(fd, data, count)
+}
+
+private func wrappedRead(_ fd: Int32, _ data: UnsafeMutableRawPointer, _ count: Int) -> Int {
+    return read(fd, data, count)
+}
+
+public final class ManagedFile {
+    private let queue: Queue?
+    private let fd: Int32
+    private let mode: ManagedFileMode
+    
+    public init?(queue: Queue?, path: String, mode: ManagedFileMode) {
+        if let queue = queue {
+            assert(queue.isCurrent())
+        }
+        self.queue = queue
+        self.mode = mode
+        let fileMode: Int32
+        let accessMode: UInt16
+        switch mode {
+            case .read:
+                fileMode = O_RDONLY
+                accessMode = S_IRUSR
+            case .readwrite:
+                fileMode = O_RDWR | O_CREAT
+                accessMode = S_IRUSR | S_IWUSR
+            case .append:
+                fileMode = O_WRONLY | O_CREAT | O_APPEND
+                accessMode = S_IRUSR | S_IWUSR
+        }
+        let fd = open(path, fileMode, accessMode)
+        if fd >= 0 {
+            self.fd = fd
+        } else {
+            return nil
+        }
+    }
+    
+    deinit {
+        if let queue = self.queue {
+            assert(queue.isCurrent())
+        }
+        close(self.fd)
+    }
+    
+    public func write(_ data: UnsafeRawPointer, count: Int) -> Int {
+        if let queue = self.queue {
+            assert(queue.isCurrent())
+        }
+        return wrappedWrite(self.fd, data, count)
+    }
+    
+    public func read(_ data: UnsafeMutableRawPointer, _ count: Int) -> Int {
+        if let queue = self.queue {
+            assert(queue.isCurrent())
+        }
+        return wrappedRead(self.fd, data, count)
+    }
+    
+    public func readData(count: Int) -> Data {
+        if let queue = self.queue {
+            assert(queue.isCurrent())
+        }
+        var result = Data(count: count)
+        result.withUnsafeMutableBytes { (bytes: UnsafeMutablePointer<Int8>) -> Void in
+            let readCount = self.read(bytes, count)
+            assert(readCount == count)
+        }
+        return result
+    }
+    
+    public func seek(position: Int64) {
+        if let queue = self.queue {
+            assert(queue.isCurrent())
+        }
+        lseek(self.fd, position, SEEK_SET)
+    }
+    
+    public func truncate(count: Int64) {
+        if let queue = self.queue {
+            assert(queue.isCurrent())
+        }
+        ftruncate(self.fd, count)
+    }
+    
+    public func getSize() -> Int? {
+        if let queue = self.queue {
+            assert(queue.isCurrent())
+        }
+        var value = stat()
+        if fstat(self.fd, &value) == 0 {
+            return Int(value.st_size)
+        } else {
+            return nil
+        }
+    }
+    
+    public func sync() {
+        if let queue = self.queue {
+            assert(queue.isCurrent())
+        }
+        fsync(self.fd)
+    }
+}