more ios/macos targets implementation

src/jvmMain/kotlin/net.sergeych.bintools/FileDataProvider.kt

@@ -5,23 +5,23 @@ import java.io.OutputStream
 import java.nio.file.Path
 import kotlin.io.path.*
 
-class FileDataProvider(val folder: Path): DataProvider {
+class FileDataProvider(val folder: Path) : DataProvider {
 
-    class Source(private val input: InputStream): DataSource {
+    class Source(private val input: InputStream) : DataSource {
         override fun readByte(): Byte {
             val b = input.read()
-            if( b < 0) throw DataSource.EndOfData()
+            if (b < 0) throw DataSource.EndOfData()
             return b.toByte()
         }
 
         override fun readBytes(size: Int): ByteArray {
-            return input.readNBytes(size).also {
-                if( it.size < size ) throw DataSource.EndOfData()
+            return input.readNBytes2(size).also {
+                if (it.size < size) throw DataSource.EndOfData()
             }
         }
     }
 
-    class Sink(private val out: OutputStream): DataSink {
+    class Sink(private val out: OutputStream) : DataSink {
         override fun writeByte(data: Byte) {
             out.write(data.toInt())
         }
@@ -44,4 +44,16 @@ class FileDataProvider(val folder: Path): DataProvider {
         .listDirectoryEntries()
         .filter { it.isRegularFile() && it.isReadable() }
         .map { it.name }
+}
+
+/**
+ * Compatibility with Java8 and android. Read up to N bytes
+ */
+fun InputStream.readNBytes2(size: Int): ByteArray {
+    val result = ByteArray(size)
+    val len = read(result)
+    return if (len < size)
+        result.sliceArray(0..<len)
+    else
+        result
 }