3 files changed, 36 insertions, 31 deletions

diff --git a/dalvik/src/main/java/dalvik/system/DexPathList.java b/dalvik/src/main/java/dalvik/system/DexPathList.java
index 1253223..048cc83 100644
--- a/dalvik/src/main/java/dalvik/system/DexPathList.java
+++ b/dalvik/src/main/java/dalvik/system/DexPathList.java
@@ -25,6 +25,11 @@ import java.util.Collections;
 import java.util.Enumeration;
 import java.util.regex.Pattern;
 import java.util.zip.ZipFile;
+import libcore.io.ErrnoException;
+import libcore.io.IoUtils;
+import libcore.io.Libcore;
+import libcore.io.StructStat;
+import static libcore.io.OsConstants.*;
 
 /**
  * A pair of lists of entries, associated with a {@code ClassLoader}.
@@ -154,36 +159,20 @@ import java.util.zip.ZipFile;
      * Helper for {@link #splitPaths}, which does the actual splitting
      * and filtering and adding to a result.
      */
-    private static void splitAndAdd(String path, boolean wantDirectories,
+    private static void splitAndAdd(String searchPath, boolean wantDirectories,
             ArrayList<File> resultList) {
-        if (path == null) {
+        if (searchPath == null) {
             return;
         }
-
-        String[] strings = path.split(Pattern.quote(File.pathSeparator));
-
-        for (String s : strings) {
-            File file = new File(s);
-
-            if (! (file.exists() && file.canRead())) {
-                continue;
-            }
-
-            /*
-             * Note: There are other entities in filesystems than
-             * regular files and directories.
-             */
-            if (wantDirectories) {
-                if (!file.isDirectory()) {
-                    continue;
-                }
-            } else {
-                if (!file.isFile()) {
-                    continue;
+        for (String path : searchPath.split(":")) {
+            try {
+                StructStat sb = Libcore.os.stat(path);
+                if ((wantDirectories && S_ISDIR(sb.st_mode)) ||
+                        (!wantDirectories && S_ISREG(sb.st_mode))) {
+                    resultList.add(new File(path));
                 }
+            } catch (ErrnoException ignored) {
             }
-
-            resultList.add(file);
         }
     }
 
@@ -370,14 +359,12 @@ import java.util.zip.ZipFile;
      */
     public String findLibrary(String libraryName) {
         String fileName = System.mapLibraryName(libraryName);
-
         for (File directory : nativeLibraryDirectories) {
-            File file = new File(directory, fileName);
-            if (file.exists() && file.isFile() && file.canRead()) {
-                return file.getPath();
+            String path = new File(directory, fileName).getPath();
+            if (IoUtils.canOpenReadOnly(path)) {
+                return path;
             }
         }
-
         return null;
     }
 
diff --git a/luni/src/main/java/java/lang/Runtime.java b/luni/src/main/java/java/lang/Runtime.java
index c4c12db..58142d3 100644
--- a/luni/src/main/java/java/lang/Runtime.java
+++ b/luni/src/main/java/java/lang/Runtime.java
@@ -44,6 +44,7 @@ import java.lang.ref.FinalizerReference;
 import java.util.ArrayList;
 import java.util.List;
 import java.util.StringTokenizer;
+import libcore.io.IoUtils;
 import libcore.io.Libcore;
 import static libcore.io.OsConstants._SC_NPROCESSORS_CONF;
 
@@ -372,7 +373,8 @@ public class Runtime {
         for (String directory : mLibPaths) {
             String candidate = directory + filename;
             candidates.add(candidate);
-            if (new File(candidate).exists()) {
+
+            if (IoUtils.canOpenReadOnly(candidate)) {
                 String error = nativeLoad(candidate, loader);
                 if (error == null) {
                     return; // We successfully loaded the library. Job done.
diff --git a/luni/src/main/java/libcore/io/IoUtils.java b/luni/src/main/java/libcore/io/IoUtils.java
index 7177f3f..0373ea9 100644
--- a/luni/src/main/java/libcore/io/IoUtils.java
+++ b/luni/src/main/java/libcore/io/IoUtils.java
@@ -147,6 +147,22 @@ public final class IoUtils {
         }
     }
 
+    /**
+     * Checks whether {@code path} can be opened read-only. Similar to File.exists, but doesn't
+     * require read permission on the parent, so it'll work in more cases, and allow you to
+     * remove read permission from more directories.
+     */
+    public static boolean canOpenReadOnly(String path) {
+        try {
+            // Use open(2) rather than stat(2) so we require fewer permissions. http://b/6485312.
+            FileDescriptor fd = Libcore.os.open(path, O_RDONLY, 0);
+            Libcore.os.close(fd);
+            return true;
+        } catch (ErrnoException errnoException) {
+            return false;
+        }
+    }
+
     public static void throwInterruptedIoException() throws InterruptedIOException {
         // This is typically thrown in response to an
         // InterruptedException which does not leave the thread in an