Extract util methods to separate classes

src/main/java/org/asamk/signal/util/IOUtils.java

@@ -0,0 +1,55 @@
+package org.asamk.signal.util;
+
+import java.io.File;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.StringWriter;
+import java.nio.charset.Charset;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.attribute.PosixFilePermission;
+import java.nio.file.attribute.PosixFilePermissions;
+import java.util.EnumSet;
+import java.util.Set;
+
+import static java.nio.file.attribute.PosixFilePermission.*;
+
+public class IOUtils {
+
+    private IOUtils() {
+    }
+
+    public static File createTempFile() throws IOException {
+        return File.createTempFile("signal_tmp_", ".tmp");
+    }
+
+    public static String readAll(InputStream in, Charset charset) throws IOException {
+        StringWriter output = new StringWriter();
+        byte[] buffer = new byte[4096];
+        int n;
+        while (-1 != (n = in.read(buffer))) {
+            output.write(new String(buffer, 0, n, charset));
+        }
+        return output.toString();
+    }
+
+    public static void createPrivateDirectories(String path) throws IOException {
+        final Path file = new File(path).toPath();
+        try {
+            Set<PosixFilePermission> perms = EnumSet.of(OWNER_READ, OWNER_WRITE, OWNER_EXECUTE);
+            Files.createDirectories(file, PosixFilePermissions.asFileAttribute(perms));
+        } catch (UnsupportedOperationException e) {
+            Files.createDirectories(file);
+        }
+    }
+
+    public static void createPrivateFile(String path) throws IOException {
+        final Path file = new File(path).toPath();
+        try {
+            Set<PosixFilePermission> perms = EnumSet.of(OWNER_READ, OWNER_WRITE);
+            Files.createFile(file, PosixFilePermissions.asFileAttribute(perms));
+        } catch (UnsupportedOperationException e) {
+            Files.createFile(file);
+        }
+    }
+}