Lazy-initialise rootPath in FileSystem.

Path construction entails calling isFileSystemCaseSensitive at a time when subclasses have not been initialised. This can cause a crash. Solve by deferring init of the path.

PiperOrigin-RevId: 172914501

2 files changed, 28 insertions, 16 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/vfs/FileSystem.java b/src/main/java/com/google/devtools/build/lib/vfs/FileSystem.java
index ee4bff1785..75851faa91 100644
--- a/src/main/java/com/google/devtools/build/lib/vfs/FileSystem.java
+++ b/src/main/java/com/google/devtools/build/lib/vfs/FileSystem.java
@@ -119,11 +119,8 @@ public abstract class FileSystem {
     }
   }
 
-  protected final Path rootPath;
-
-  protected FileSystem() {
-    this.rootPath = getPathFactory().createRootPath(this);
-  }
+  /** Lazy-initialized on first access, always use {@link FileSystem#getRootDirectory} */
+  private Path rootPath;
 
   /** Returns filesystem-specific path factory. */
   protected PathFactory getPathFactory() {
@@ -152,13 +149,20 @@ public abstract class FileSystem {
     if (!pathName.isAbsolute()) {
       throw new IllegalArgumentException(pathName.getPathString()  + " (not an absolute path)");
     }
-    return rootPath.getRelative(pathName);
+    return getRootDirectory().getRelative(pathName);
   }
 
   /**
    * Returns a path representing the root directory of the current file system.
    */
   public final Path getRootDirectory() {
+    if (rootPath == null) {
+      synchronized (this) {
+        if (rootPath == null) {
+          rootPath = getPathFactory().createRootPath(this);
+        }
+      }
+    }
     return rootPath;
   }
 
@@ -395,7 +399,9 @@ public abstract class FileSystem {
     if (maxLinks-- == 0) {
       throw new IOException(naive + " (Too many levels of symbolic links)");
     }
-    if (linkTarget.isAbsolute()) { dir = rootPath; }
+    if (linkTarget.isAbsolute()) {
+      dir = getRootDirectory();
+    }
     for (String name : linkTarget.segments()) {
       if (name.equals(".") || name.isEmpty()) {
         // no-op
diff --git a/src/main/java/com/google/devtools/build/lib/vfs/inmemoryfs/InMemoryFileSystem.java b/src/main/java/com/google/devtools/build/lib/vfs/inmemoryfs/InMemoryFileSystem.java
index d2db9967a1..7a91db7eed 100644
--- a/src/main/java/com/google/devtools/build/lib/vfs/inmemoryfs/InMemoryFileSystem.java
+++ b/src/main/java/com/google/devtools/build/lib/vfs/inmemoryfs/InMemoryFileSystem.java
@@ -332,7 +332,7 @@ public class InMemoryFileSystem extends FileSystem {
     // and it may only appear as part of a contiguous prefix sequence.
 
     Stack<String> stack = new Stack<>();
-    PathFragment rootPathFragment = rootPath.asFragment();
+    PathFragment rootPathFragment = getRootDirectory().asFragment();
     for (Path p = path; !p.asFragment().equals(rootPathFragment); p = p.getParentDirectory()) {
       stack.push(p.getBaseName());
     }
@@ -408,7 +408,7 @@ public class InMemoryFileSystem extends FileSystem {
     if (followSymlinks) {
       return scopeLimitedStat(path, true);
     } else {
-      if (path.equals(rootPath)) {
+      if (path.equals(getRootDirectory())) {
         return rootInode;
       } else {
         return getNoFollowStatOrOutOfScopeParent(path);
@@ -441,7 +441,7 @@ public class InMemoryFileSystem extends FileSystem {
     if (followSymlinks) {
       return pathWalk(path, false);
     } else {
-      if (path.equals(rootPath)) {
+      if (path.equals(getRootDirectory())) {
         return rootInode;
       } else {
         return getNoFollowStatOrOutOfScopeParent(path);
@@ -582,7 +582,9 @@ public class InMemoryFileSystem extends FileSystem {
 
   @Override
   protected boolean createDirectory(Path path) throws IOException {
-    if (path.equals(rootPath)) { throw Error.EACCES.exception(path); }
+    if (path.equals(getRootDirectory())) {
+      throw Error.EACCES.exception(path);
+    }
 
     InMemoryDirectoryInfo parent;
     synchronized (this) {
@@ -608,7 +610,9 @@ public class InMemoryFileSystem extends FileSystem {
   @Override
   protected void createSymbolicLink(Path path, PathFragment targetFragment)
       throws IOException {
-    if (path.equals(rootPath)) { throw Error.EACCES.exception(path); }
+    if (path.equals(getRootDirectory())) {
+      throw Error.EACCES.exception(path);
+    }
 
     synchronized (this) {
       InMemoryDirectoryInfo parent = getDirectory(path.getParentDirectory());
@@ -659,7 +663,9 @@ public class InMemoryFileSystem extends FileSystem {
 
   @Override
   protected boolean delete(Path path) throws IOException {
-    if (path.equals(rootPath)) { throw Error.EBUSY.exception(path); }
+    if (path.equals(getRootDirectory())) {
+      throw Error.EBUSY.exception(path);
+    }
     if (!exists(path, false)) { return false; }
 
     synchronized (this) {
@@ -731,10 +737,10 @@ public class InMemoryFileSystem extends FileSystem {
   @Override
   protected void renameTo(Path sourcePath, Path targetPath)
       throws IOException {
-    if (sourcePath.equals(rootPath)) {
+    if (sourcePath.equals(getRootDirectory())) {
       throw Error.EACCES.exception(sourcePath);
     }
-    if (targetPath.equals(rootPath)) {
+    if (targetPath.equals(getRootDirectory())) {
       throw Error.EACCES.exception(targetPath);
     }
     synchronized (this) {
@@ -782,7 +788,7 @@ public class InMemoryFileSystem extends FileSystem {
       throws IOException {
 
     // Same check used when creating a symbolic link
-    if (originalPath.equals(rootPath)) {
+    if (originalPath.equals(getRootDirectory())) {
       throw Error.EACCES.exception(originalPath);
     }