Fix lookup of a root directory that doesn't exist to always throw NoSuchFileException.

This prevents creation of a new root directory (or file!) using Files.createDirectory
etc. in file systems that support multiple roots.

3 files changed, 80 insertions, 9 deletions

diff --git a/jimfs/src/main/java/com/google/jimfs/internal/FileTree.java b/jimfs/src/main/java/com/google/jimfs/internal/FileTree.java
index 044cbcf..d3eaa55 100644
--- a/jimfs/src/main/java/com/google/jimfs/internal/FileTree.java
+++ b/jimfs/src/main/java/com/google/jimfs/internal/FileTree.java
@@ -98,10 +98,9 @@ final class FileTree {
       // lookup the root directory
       DirectoryEntry entry = superRoot.asDirectoryTable().get(path.root());
       if (entry == null) {
-        // root not found
-        return !names.isEmpty()
-            ? null
-            : new DirectoryEntry(superRoot, path.root(), null);
+        // root not found; always return null as no real parent directory exists
+        // this prevents new roots from being created in file systems supporting multiple roots
+        return null;
       } else if (names.isEmpty()) {
         // root found, no more names to look up
         return entry;
diff --git a/jimfs/src/test/java/com/google/jimfs/JimfsWindowsLikeIntegrationTest.java b/jimfs/src/test/java/com/google/jimfs/JimfsWindowsLikeIntegrationTest.java
index e09e641..362e873 100644
--- a/jimfs/src/test/java/com/google/jimfs/JimfsWindowsLikeIntegrationTest.java
+++ b/jimfs/src/test/java/com/google/jimfs/JimfsWindowsLikeIntegrationTest.java
@@ -274,4 +274,61 @@ public class JimfsWindowsLikeIntegrationTest extends AbstractJimfsIntegrationTes
     } catch (UnsupportedOperationException expected) {
     }
   }
+
+  @Test
+  public void testCreateFileOrDirectory_forRootPath_fails() throws IOException {
+    try {
+      Files.createDirectory(path("Z:\\"));
+      fail();
+    } catch (IOException expected) {
+    }
+
+    try {
+      Files.createFile(path("Z:\\"));
+      fail();
+    } catch (IOException expected) {
+    }
+
+    try {
+      Files.createSymbolicLink(path("Z:\\"), path("foo"));
+      fail();
+    } catch (IOException expected) {
+    }
+  }
+
+  @Test
+  public void testCopyFile_toRootPath_fails() throws IOException {
+    Files.createFile(path("foo"));
+    Files.createDirectory(path("bar"));
+
+    try {
+      Files.copy(path("foo"), path("Z:\\"));
+      fail();
+    } catch (IOException expected) {
+    }
+
+    try {
+      Files.copy(path("bar"), path("Z:\\"));
+      fail();
+    } catch (IOException expected) {
+    }
+  }
+
+  @Test
+  public void testMoveFile_toRootPath_fails() throws IOException {
+    Files.createFile(path("foo"));
+    Files.createDirectory(path("bar"));
+
+    try {
+      Files.move(path("foo"), path("Z:\\"));
+      fail();
+    } catch (IOException expected) {
+    }
+
+    try {
+      Files.move(path("bar"), path("Z:\\"));
+      fail();
+    } catch (IOException expected) {
+    }
+  }
 }
diff --git a/jimfs/src/test/java/com/google/jimfs/internal/FileTreeTest.java b/jimfs/src/test/java/com/google/jimfs/internal/FileTreeTest.java
index e390021..4e66e7d 100644
--- a/jimfs/src/test/java/com/google/jimfs/internal/FileTreeTest.java
+++ b/jimfs/src/test/java/com/google/jimfs/internal/FileTreeTest.java
@@ -69,8 +69,8 @@ public class FileTreeTest {
    */
 
   /**
-   * This path service is for unix-like paths, with the exception that it recognizes $ as a root in
-   * addition to /, allowing for two roots.
+   * This path service is for unix-like paths, with the exception that it recognizes $ and ! as
+   * roots in addition to /, allowing for up to three roots.
    */
   private final PathService pathService = fakePathService(
       new PathType(CaseSensitivity.CASE_SENSITIVE, true, '/') {
@@ -82,7 +82,7 @@ public class FileTreeTest {
         @Override
         public ParseResult parsePath(String path) {
           String root = null;
-          if (path.startsWith("/") || path.startsWith("$")) {
+          if (path.matches("^[/$!].*")) {
             root = path.substring(0, 1);
             path = path.substring(1);
           }
@@ -103,8 +103,8 @@ public class FileTreeTest {
 
         @Override
         public ParseResult parseUriPath(String uriPath) {
-          checkArgument(uriPath.startsWith("//") || uriPath.startsWith("/$"),
-              "uriPath (%s) must start with // or /$");
+          checkArgument(uriPath.matches("^/[/$!].*"),
+              "uriPath (%s) must start with // or /$ or /!");
           return parsePath(uriPath.substring(1)); // skip leading /
         }
       });
@@ -163,6 +163,21 @@ public class FileTreeTest {
   }
 
   @Test
+  public void testLookup_nonExistentRoot() throws IOException {
+    try {
+      lookup("!");
+      fail();
+    } catch (NoSuchFileException expected) {
+    }
+
+    try {
+      lookup("!a");
+      fail();
+    } catch (NoSuchFileException expected) {
+    }
+  }
+
+  @Test
   public void testLookup_absolute() throws IOException {
     assertExists(lookup("/work"), "/", "work");
     assertExists(lookup("/work/one/two/three"), "two", "three");