src/share/classes/java/util/zip/ZipFile.java

*** 34,43 ****
--- 34,45 ----
  import java.util.Vector;
  import java.util.Enumeration;
  import java.util.Set;
  import java.util.HashSet;
  import java.util.NoSuchElementException;
+ import java.security.AccessController;
+ import sun.security.action.GetPropertyAction;
  import static java.util.zip.ZipConstants64.*;
  
  /**
   * This class is used to read entries from a zip file.
   *
*** 76,85 ****
--- 78,98 ----
          initIDs();
      }
  
      private static native void initIDs();
  
+     private static final boolean usemmap;
+ 
+     static {
+         // A system prpperty to disable mmap use to avoid vm crash when
+         // in-use zip file is accidently overwritten by others.
+         String prop = AccessController.doPrivileged(
+             new GetPropertyAction("sun.zip.disableMemoryMapping"));
+         usemmap = (prop == null ||
+                    !(prop.length() == 0 || prop.equalsIgnoreCase("true"))); 
+     }
+ 
      /**
       * Opens a zip file for reading.
       *
       * <p>First, if there is a security manager, its <code>checkRead</code>
       * method is called with the <code>name</code> argument as its argument
*** 194,204 ****
          }
          if (charset == null)
              throw new NullPointerException("charset is null");
          this.zc = ZipCoder.get(charset);
          long t0 = System.nanoTime();
!         jzfile = open(name, mode, file.lastModified());
          sun.misc.PerfCounter.getZipFileOpenTime().addElapsedTimeFrom(t0);
          sun.misc.PerfCounter.getZipFileCount().increment();
          this.name = name;
          this.total = getTotal(jzfile);
      }
--- 207,217 ----
          }
          if (charset == null)
              throw new NullPointerException("charset is null");
          this.zc = ZipCoder.get(charset);
          long t0 = System.nanoTime();
!         jzfile = open(name, mode, file.lastModified(), usemmap);
          sun.misc.PerfCounter.getZipFileOpenTime().addElapsedTimeFrom(t0);
          sun.misc.PerfCounter.getZipFileCount().increment();
          this.name = name;
          this.total = getTotal(jzfile);
      }
*** 671,682 ****
              }
          }
      }
  
  
!     private static native long open(String name, int mode, long lastModified)
!         throws IOException;
      private static native int getTotal(long jzfile);
      private static native int read(long jzfile, long jzentry,
                                     long pos, byte[] b, int off, int len);
  
      // access to the native zentry object
--- 684,695 ----
              }
          }
      }
  
  
!     private static native long open(String name, int mode, long lastModified,
!                                     boolean usemmap) throws IOException;
      private static native int getTotal(long jzfile);
      private static native int read(long jzfile, long jzentry,
                                     long pos, byte[] b, int off, int len);
  
      // access to the native zentry object