6440786: Cannot create a ZIP file containing zero entries

Summary: Allow reading and writing of ZIP files with zero entries.
Reviewed-by: alanb

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

 /*
- * Copyright 1996-2006 Sun Microsystems, Inc.  All Rights Reserved.
+ * Copyright 1996-2008 Sun Microsystems, Inc.  All Rights Reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -317,9 +317,6 @@ class ZipOutputStream extends DeflaterOutputStream implements ZipConstants {
         if (current != null) {
             closeEntry();
         }
-        if (xentries.size() < 1) {
-            throw new ZipException("ZIP file must have at least one entry");
-        }
         // write central directory
         long off = written;
         for (XEntry xentry : xentries)

src/share/native/java/util/zip/zip_util.c

 /*
- * Copyright 1995-2006 Sun Microsystems, Inc.  All Rights Reserved.
+ * Copyright 1995-2008 Sun Microsystems, Inc.  All Rights Reserved.
  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  *
  * This code is free software; you can redistribute it and/or modify it
@@ -722,16 +722,22 @@ ZIP_Put_In_Cache(const char *name, ZFILE zfd, char **pmsg, jlong lastModified)
     }
 
     len = zip->len = ZFILE_Lseek(zfd, 0, SEEK_END);
-    if (len == -1) {
-        if (pmsg && JVM_GetLastErrorString(errbuf, sizeof(errbuf)) > 0)
-            *pmsg = errbuf;
+    if (len <= 0) {
+        if (len == 0) { /* zip file is empty */
+            if (pmsg) {
+                *pmsg = "zip file is empty";
+            }
+        } else { /* error */
+            if (pmsg && JVM_GetLastErrorString(errbuf, sizeof(errbuf)) > 0)
+                *pmsg = errbuf;
+        }
         ZFILE_Close(zfd);
         freeZip(zip);
         return NULL;
     }
 
     zip->zfd = zfd;
-    if (readCEN(zip, -1) <= 0) {
+    if (readCEN(zip, -1) < 0) {
         /* An error occurred while trying to read the zip file */
         if (pmsg != 0) {
             /* Set the zip error message */
@@ -947,10 +953,15 @@ jzentry *
 ZIP_GetEntry(jzfile *zip, char *name, jint ulen)
 {
     unsigned int hsh = hash(name);
-    jint idx = zip->table[hsh % zip->tablelen];
-    jzentry *ze;
+    jint idx;
+    jzentry *ze = 0;
 
     ZIP_Lock(zip);
+    if (zip->total == 0) {
+        goto Finally;
+    }
+
+    idx = zip->table[hsh % zip->tablelen];
 
     /*
      * This while loop is an optimization where a double lookup
@@ -1025,6 +1036,7 @@ ZIP_GetEntry(jzfile *zip, char *name, jint ulen)
         ulen = 0;
     }
 
+Finally:
     ZIP_Unlock(zip);
     return ze;
 }

test/java/util/zip/TestEmptyZip.java

+/*
+ * Copyright 2008 Sun Microsystems, Inc.  All Rights Reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
+ * CA 95054 USA or visit www.sun.com if you need additional information or
+ * have any questions.
+ */
+
+/* @test
+ * @bug 6334003 6440786
+ * @summary Test ability to write and read zip files that have no entries.
+ * @author Dave Bristor
+ */
+
+import java.io.*;
+import java.util.*;
+import java.util.zip.*;
+
+public class TestEmptyZip {
+    public static void realMain(String[] args) throws Throwable {
+        String zipName = "foo.zip";
+        File f = new File(System.getProperty("test.scratch", "."), zipName);
+        if (f.exists() && !f.delete()) {
+            throw new Exception("failed to delete " + zipName);
+        }
+
+        // Verify 0-length file cannot be read
+        f.createNewFile();
+        ZipFile zf = null;
+        try {
+            zf = new ZipFile(f);
+            fail();
+        } catch (Exception ex) {
+            check(ex.getMessage().contains("zip file is empty"));
+        } finally {
+            if (zf != null) {
+                zf.close();
+            }
+        }
+
+        ZipInputStream zis = null;
+        try {
+            zis = new ZipInputStream(new FileInputStream(f));
+            ZipEntry ze = zis.getNextEntry();
+            check(ze == null);
+        } catch (Exception ex) {
+            unexpected(ex);
+        } finally {
+            if (zis != null) {
+                zis.close();
+            }
+        }
+
+        f.delete();
+
+        // Verify 0-entries file can be written
+        write(f);
+
+        // Verify 0-entries file can be read
+        readFile(f);
+        readStream(f);
+
+        f.delete();
+    }
+
+    static void write(File f) throws Exception {
+        ZipOutputStream zos = null;
+        try {
+            zos = new ZipOutputStream(new FileOutputStream(f));
+            zos.finish();
+            zos.close();
+            pass();
+        } catch (Exception ex) {
+            unexpected(ex);
+        } finally {
+            if (zos != null) {
+                zos.close();
+            }
+        }
+    }
+
+    static void readFile(File f) throws Exception {
+        ZipFile zf = null;
+        try {
+            zf = new ZipFile(f);
+
+            Enumeration e = zf.entries();
+            while (e.hasMoreElements()) {
+                ZipEntry entry = (ZipEntry) e.nextElement();
+                fail();
+            }
+            zf.close();
+            pass();
+        } catch (Exception ex) {
+            unexpected(ex);
+        } finally {
+            if (zf != null) {
+                zf.close();
+            }
+        }
+    }
+
+    static void readStream(File f) throws Exception {
+        ZipInputStream zis = null;
+        try {
+            zis = new ZipInputStream(new FileInputStream(f));
+            ZipEntry ze = zis.getNextEntry();
+            check(ze == null);
+            byte[] buf = new byte[1024];
+            check(zis.read(buf, 0, 1024) == -1);
+        } finally {
+            if (zis != null) {
+                zis.close();
+            }
+        }
+    }
+
+    //--------------------- Infrastructure ---------------------------
+    static volatile int passed = 0, failed = 0;
+    static boolean pass() {passed++; return true;}
+    static boolean fail() {failed++; Thread.dumpStack(); return false;}
+    static boolean fail(String msg) {System.out.println(msg); return fail();}
+    static void unexpected(Throwable t) {failed++; t.printStackTrace();}
+    static boolean check(boolean cond) {if (cond) pass(); else fail(); return cond;}
+    static boolean equal(Object x, Object y) {
+        if (x == null ? y == null : x.equals(y)) return pass();
+        else return fail(x + " not equal to " + y);}
+    public static void main(String[] args) throws Throwable {
+        try {realMain(args);} catch (Throwable t) {unexpected(t);}
+        System.out.println("\nPassed = " + passed + " failed = " + failed);
+        if (failed > 0) throw new AssertionError("Some tests failed");}
+}