A safety improvement for random path generation...

A safety improvement for random path generation, and a small change to
Random for a more general interface. Review by community.

2 files changed, 19 insertions, 11 deletions

diff --git a/src/compiler/scala/tools/nsc/io/Path.scala b/src/compiler/scala/tools/nsc/io/Path.scala
index 6b88f3cfca..afef38be3c 100644
--- a/src/compiler/scala/tools/nsc/io/Path.scala
+++ b/src/compiler/scala/tools/nsc/io/Path.scala
@@ -9,9 +9,7 @@ import java.io.{
   FileInputStream, FileOutputStream, BufferedReader, BufferedWriter, InputStreamReader, OutputStreamWriter,
   BufferedInputStream, BufferedOutputStream, RandomAccessFile, File => JFile }
 import java.net.{ URI, URL }
-import collection.{ Seq, Traversable }
-import PartialFunction._
-import scala.util.Random.nextASCIIString
+import scala.util.Random.alphanumeric
 
 /** An abstraction for filesystem paths.  The differences between
  *  Path, File, and Directory are primarily to communicate intent.
@@ -71,7 +69,8 @@ object Path
     else if (jfile.isDirectory) new Directory(jfile)
     else new Path(jfile)
 
-  private[io] def randomPrefix = nextASCIIString(6)
+  /** Avoiding any shell/path issues by only using alphanumerics. */
+  private[io] def randomPrefix = alphanumeric take 6 mkString
   private[io] def fail(msg: String) = throw FileOperationException(msg)
 }
 import Path._
diff --git a/src/library/scala/util/Random.scala b/src/library/scala/util/Random.scala
index ffa248d638..cd9d5eed0e 100644
--- a/src/library/scala/util/Random.scala
+++ b/src/library/scala/util/Random.scala
@@ -89,14 +89,12 @@ class Random(val self: java.util.Random) {
     List.fill(length)(safeChar()).mkString
   }
 
-  /** Returns a pseudorandomly generated String drawing upon
-   *  only ASCII characters between 33 and 126.
+  /** Returns the next pseudorandom, uniformly distributed value
+   *  from the ASCII range 33-126.
    */
-  def nextASCIIString(length: Int) = {
-    val (min, max) = (33, 126)
-    def nextDigit = nextInt(max - min) + min
-
-    new String(Array.fill(length)(nextDigit.toByte), "ASCII")
+  def nextPrintableChar(): Char = {
+    val (low, high) = (33, 126)
+    (self.nextInt(high - low) + low).toChar
   }
 
   def setSeed(seed: Long) { self.setSeed(seed) }
@@ -111,6 +109,17 @@ object Random extends Random {
   import collection.mutable.ArrayBuffer
   import collection.generic.CanBuildFrom
 
+  /** Returns a Stream of pseudorandomly chosen alphanumeric characters,
+   *  equally chosen from A-Z, a-z, and 0-9.
+   *
+   *  @since 2.8
+   */
+  def alphanumeric: Stream[Char] = {
+    def isAlphaNum(c: Char) = (c >= 'A' && c <= 'Z') || (c >= 'a' && c <= 'z') || (c >= '0' && c <= '9')
+
+    Stream continually nextPrintableChar filter isAlphaNum
+  }
+
   /** Returns a new collection of the same type in a randomly chosen order.
    *
    *  @param  coll    the TraversableOnce to shuffle