Workaround JDK bug 8034057

This causes a FileSystemException when trying to retrieve FileStore for a path,
and falsely returns false for Files.isWritable

Squashed commit of the following:

commit d2cc0d966f3bc94aa836b316a42b3c5724bc01ef
Author: Robert Muir <rmuir@apache.org>
Date:   Tue Aug 18 15:49:48 2015 -0400

    fixes for the non-bogus comments

commit 6e0a272f5f8ef7358654ded8ff4ffc31831fa5c7
Author: Robert Muir <rmuir@apache.org>
Date:   Tue Aug 18 15:30:43 2015 -0400

    Fix isWritable too

commit 2a8764ca118fc4c950bfc60d0b97de873e0e82ad
Author: Robert Muir <rmuir@apache.org>
Date:   Tue Aug 18 14:49:50 2015 -0400

    try to workaround filestore bug

core/src/main/java/org/elasticsearch/common/cli/CheckFileCommand.java

@@ -76,7 +76,7 @@ public abstract class CheckFileCommand extends CliTool.Command {
         if (paths != null && paths.length > 0) {
             for (Path path : paths) {
                 try {
-                    boolean supportsPosixPermissions = Files.getFileStore(path).supportsFileAttributeView(PosixFileAttributeView.class);
+                    boolean supportsPosixPermissions = Environment.getFileStore(path).supportsFileAttributeView(PosixFileAttributeView.class);
                     if (supportsPosixPermissions) {
                         PosixFileAttributes attributes = Files.readAttributes(path, PosixFileAttributes.class);
                         permissions.put(path, attributes.permissions());

core/src/main/java/org/elasticsearch/env/ESFileStore.java

@@ -26,10 +26,12 @@ import org.elasticsearch.common.io.PathUtils;
 
 import java.io.IOException;
 import java.nio.file.FileStore;
+import java.nio.file.FileSystemException;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.attribute.FileAttributeView;
 import java.nio.file.attribute.FileStoreAttributeView;
+import java.util.Arrays;
 
 /** 
  * Implementation of FileStore that supports
@@ -73,13 +75,16 @@ class ESFileStore extends FileStore {
         }
     }
     
-    /** Files.getFileStore(Path) useless here!  Don't complain, just try it yourself. */
+    /** 
-    static FileStore getMatchingFileStore(Path path, FileStore fileStores[]) throws IOException {
+     * Files.getFileStore(Path) useless here!  Don't complain, just try it yourself. 
-        FileStore store = Files.getFileStore(path);
+     */
-        
+    @SuppressForbidden(reason = "works around the bugs")
+    static FileStore getMatchingFileStore(Path path, FileStore fileStores[]) throws IOException {       
         if (Constants.WINDOWS) {
-            return store; // be defensive, don't even try to do anything fancy.
+            return getFileStoreWindows(path, fileStores);
         }
+        
+        FileStore store = Files.getFileStore(path);
 
         try {
             String mount = getMountPointLinux(store);
@@ -110,6 +115,57 @@ class ESFileStore extends FileStore {
         // fall back to crappy one we got from Files.getFileStore
         return store;    
     }
+    
+    /** 
+     * remove this code and just use getFileStore for windows on java 9
+     * works around https://bugs.openjdk.java.net/browse/JDK-8034057
+     */
+    @SuppressForbidden(reason = "works around https://bugs.openjdk.java.net/browse/JDK-8034057")
+    static FileStore getFileStoreWindows(Path path, FileStore fileStores[]) throws IOException {
+        assert Constants.WINDOWS;
+        
+        try {
+            return Files.getFileStore(path);
+        } catch (FileSystemException possibleBug) {
+            final char driveLetter;
+            // look for a drive letter to see if its the SUBST bug,
+            // it might be some other type of path, like a windows share
+            // if something goes wrong, we just deliver the original exception
+            try {
+                String root = path.toRealPath().getRoot().toString();
+                if (root.length() < 2) {
+                    throw new RuntimeException("root isn't a drive letter: " + root);
+                }
+                driveLetter = Character.toLowerCase(root.charAt(0));
+                if (Character.isAlphabetic(driveLetter) == false || root.charAt(1) != ':') {
+                    throw new RuntimeException("root isn't a drive letter: " + root);
+                }
+            } catch (Throwable checkFailed) {
+                // something went wrong, 
+                possibleBug.addSuppressed(checkFailed);
+                throw possibleBug;
+            }
+            
+            // we have a drive letter: the hack begins!!!!!!!!
+            try {
+                // we have no choice but to parse toString of all stores and find the matching drive letter
+                for (FileStore store : fileStores) {
+                    String toString = store.toString();
+                    int length = toString.length();
+                    if (length > 3 && toString.endsWith(":)") && toString.charAt(length - 4) == '(') {
+                        if (Character.toLowerCase(toString.charAt(length - 3)) == driveLetter) {
+                            return store;
+                        }
+                    }
+                }
+                throw new RuntimeException("no filestores matched");
+            } catch (Throwable weTried) {
+                IOException newException = new IOException("Unable to retrieve filestore for '" + path + "', tried matching against " + Arrays.toString(fileStores), weTried);
+                newException.addSuppressed(possibleBug);
+                throw newException;
+            }
+        }
+    }
 
     @Override
     public String name() {

core/src/main/java/org/elasticsearch/env/Environment.java

@@ -19,6 +19,7 @@
 
 package org.elasticsearch.env;
 
+import org.apache.lucene.util.Constants;
 import org.elasticsearch.cluster.ClusterName;
 import org.elasticsearch.common.SuppressForbidden;
 import org.elasticsearch.common.io.PathUtils;
@@ -302,9 +303,37 @@ public class Environment {
      *   <li>Only requires the security permissions of {@link Files#getFileStore(Path)},
      *       no permissions to the actual mount point are required.
      *   <li>Exception handling has the same semantics as {@link Files#getFileStore(Path)}.
+     *   <li>Works around https://bugs.openjdk.java.net/browse/JDK-8034057.
      * </ul>
      */
-    public FileStore getFileStore(Path path) throws IOException {
+    public static FileStore getFileStore(Path path) throws IOException {
         return ESFileStore.getMatchingFileStore(path, fileStores);
     }
+    
+    /**
+     * Returns true if the path is writable.
+     * Acts just like {@link Files#isWritable(Path)}, except won't
+     * falsely return false for paths on SUBST'd drive letters
+     * See https://bugs.openjdk.java.net/browse/JDK-8034057
+     * Note this will set the file modification time (to its already-set value)
+     * to test access.
+     */
+    @SuppressForbidden(reason = "works around https://bugs.openjdk.java.net/browse/JDK-8034057")
+    public static boolean isWritable(Path path) throws IOException {
+        boolean v = Files.isWritable(path);
+        if (v || Constants.WINDOWS == false) {
+            return v;
+        }
+
+        // isWritable returned false on windows, the hack begins!!!!!!
+        // resetting the modification time is the least destructive/simplest
+        // way to check for both files and directories, and fails early just
+        // in getting the current value if file doesn't exist, etc
+        try {
+            Files.setLastModifiedTime(path, Files.getLastModifiedTime(path));
+            return true;
+        } catch (Throwable e) {
+            return false;
+        }
+    }
 }

core/src/main/java/org/elasticsearch/plugins/PluginManager.java

@@ -112,7 +112,7 @@ public class PluginManager {
             Files.createDirectory(environment.pluginsFile());
         }
 
-        if (!Files.isWritable(environment.pluginsFile())) {
+        if (!Environment.isWritable(environment.pluginsFile())) {
             throw new IOException("plugin directory " + environment.pluginsFile() + " is read only");
         }
 
@@ -246,7 +246,7 @@ public class PluginManager {
             } catch (IOException e) {
                 throw new IOException("Could not move [" + binFile + "] to [" + toLocation + "]", e);
             }
-            if (Files.getFileStore(toLocation).supportsFileAttributeView(PosixFileAttributeView.class)) {
+            if (Environment.getFileStore(toLocation).supportsFileAttributeView(PosixFileAttributeView.class)) {
                 // add read and execute permissions to existing perms, so execution will work.
                 // read should generally be set already, but set it anyway: don't rely on umask...
                 final Set<PosixFilePermission> executePerms = new HashSet<>();

dev-tools/src/main/resources/forbidden/all-signatures.txt

@@ -56,3 +56,6 @@ java.io.ObjectInputStream
 java.io.ObjectInput
 
 java.nio.file.Files#isHidden(java.nio.file.Path) @ Dependent on the operating system, use FileSystemUtils.isHidden instead
+
+java.nio.file.Files#getFileStore(java.nio.file.Path) @ Use Environment.getFileStore() instead, impacted by JDK-8034057
+java.nio.file.Files#isWritable(java.nio.file.Path) @ Use Environment.isWritable() instead, impacted by JDK-8034057