1 files changed, 26 insertions, 33 deletions

diff --git a/guava/src/com/google/common/io/Files.java b/guava/src/com/google/common/io/Files.java
index ba5528ff8..499ea6a20 100644
--- a/guava/src/com/google/common/io/Files.java
+++ b/guava/src/com/google/common/io/Files.java
@@ -20,6 +20,7 @@ import static com.google.common.io.FileWriteMode.APPEND;
 
 import com.google.common.annotations.Beta;
 import com.google.common.annotations.GwtIncompatible;
+import com.google.common.annotations.J2ktIncompatible;
 import com.google.common.base.Joiner;
 import com.google.common.base.Optional;
 import com.google.common.base.Predicate;
@@ -33,6 +34,7 @@ import com.google.common.hash.HashCode;
 import com.google.common.hash.HashFunction;
 import com.google.errorprone.annotations.CanIgnoreReturnValue;
 import com.google.errorprone.annotations.InlineMe;
+import com.google.j2objc.annotations.J2ObjCIncompatible;
 import java.io.BufferedReader;
 import java.io.BufferedWriter;
 import java.io.File;
@@ -66,13 +68,11 @@ import org.checkerframework.checker.nullness.qual.Nullable;
  * @author Colin Decker
  * @since 1.0
  */
+@J2ktIncompatible
 @GwtIncompatible
 @ElementTypesAreNonnullByDefault
 public final class Files {
 
-  /** Maximum loop count when creating temp directories. */
-  private static final int TEMP_DIR_ATTEMPTS = 10000;
-
   private Files() {}
 
   /**
@@ -119,7 +119,9 @@ public final class Files {
     return new FileByteSource(file);
   }
 
-  private static final class FileByteSource extends ByteSource {
+  private static final class FileByteSource extends
+      ByteSource
+  {
 
     private final File file;
 
@@ -394,17 +396,19 @@ public final class Files {
    * Atomically creates a new directory somewhere beneath the system's temporary directory (as
    * defined by the {@code java.io.tmpdir} system property), and returns its name.
    *
+   * <p>The temporary directory is created with permissions restricted to the current user or, in
+   * the case of Android, the current app. If that is not possible (as is the case under the very
+   * old Android Ice Cream Sandwich release), then this method throws an exception instead of
+   * creating a directory that would be more accessible. (This behavior is new in Guava 32.0.0.
+   * Previous versions would create a directory that is more accessible, as discussed in <a
+   * href="https://github.com/google/guava/issues/4011">CVE-2020-8908</a>.)
+   *
    * <p>Use this method instead of {@link File#createTempFile(String, String)} when you wish to
    * create a directory, not a regular file. A common pitfall is to call {@code createTempFile},
    * delete the file and create a directory in its place, but this leads a race condition which can
    * be exploited to create security vulnerabilities, especially when executable files are to be
    * written into the directory.
    *
-   * <p>Depending on the environmment that this code is run in, the system temporary directory (and
-   * thus the directory this method creates) may be more visible that a program would like - files
-   * written to this directory may be read or overwritten by hostile programs running on the same
-   * machine.
-   *
    * <p>This method assumes that the temporary volume is writable, has free inodes and free blocks,
    * and that it will not be called thousands of times per second.
    *
@@ -412,36 +416,26 @@ public final class Files {
    * java.nio.file.Files#createTempDirectory}.
    *
    * @return the newly-created directory
-   * @throws IllegalStateException if the directory could not be created
+   * @throws IllegalStateException if the directory could not be created, such as if the system does
+   *     not support creating temporary directories securely
    * @deprecated For Android users, see the <a
    *     href="https://developer.android.com/training/data-storage" target="_blank">Data and File
    *     Storage overview</a> to select an appropriate temporary directory (perhaps {@code
-   *     context.getCacheDir()}). For developers on Java 7 or later, use {@link
-   *     java.nio.file.Files#createTempDirectory}, transforming it to a {@link File} using {@link
-   *     java.nio.file.Path#toFile() toFile()} if needed.
+   *     context.getCacheDir()}), and create your own directory under that. (For example, you might
+   *     use {@code new File(context.getCacheDir(), "directoryname").mkdir()}, or, if you need an
+   *     arbitrary number of temporary directories, you might have to generate multiple directory
+   *     names in a loop until {@code mkdir()} returns {@code true}.) For developers on Java 7 or
+   *     later, use {@link java.nio.file.Files#createTempDirectory}, transforming it to a {@link
+   *     File} using {@link java.nio.file.Path#toFile() toFile()} if needed. To restrict permissions
+   *     as this method does, pass {@code
+   *     PosixFilePermissions.asFileAttribute(PosixFilePermissions.fromString("rwx------"))} to your
+   *     call to {@code createTempDirectory}.
    */
   @Beta
   @Deprecated
+  @J2ObjCIncompatible
   public static File createTempDir() {
-    File baseDir = new File(System.getProperty("java.io.tmpdir"));
-    @SuppressWarnings("GoodTime") // reading system time without TimeSource
-    String baseName = System.currentTimeMillis() + "-";
-
-    for (int counter = 0; counter < TEMP_DIR_ATTEMPTS; counter++) {
-      File tempDir = new File(baseDir, baseName + counter);
-      if (tempDir.mkdir()) {
-        return tempDir;
-      }
-    }
-    throw new IllegalStateException(
-        "Failed to create directory within "
-            + TEMP_DIR_ATTEMPTS
-            + " attempts (tried "
-            + baseName
-            + "0 to "
-            + baseName
-            + (TEMP_DIR_ATTEMPTS - 1)
-            + ')');
+    return TempFileCreator.INSTANCE.createTempDir();
   }
 
   /**
@@ -847,7 +841,6 @@ public final class Files {
    *
    * @since 23.5
    */
-  @Beta
   public static Traverser<File> fileTraverser() {
     return Traverser.forTree(FILE_TREE);
   }