6763122: ZipFile ctor does not throw exception when file is not a zip file

Reviewed-by: bristor

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

@@ -273,8 +273,8 @@ static const jlong END_MAXLEN = 0xFFFF + ENDHDR;
 /*
  * Searches for end of central directory (END) header. The contents of
  * the END header will be read and placed in endbuf. Returns the file
- * position of the END header, otherwise returns 0 if the END header
+ * position of the END header, otherwise returns -1 if the END header
- * was not found or -1 if an error occurred.
+ * was not found or an error occurred.
  */
 static jlong
 findEND(jzfile *zip, void *endbuf)
@@ -314,7 +314,7 @@ findEND(jzfile *zip, void *endbuf)
             }
         }
     }
-    return 0; /* END header not found */
+    return -1; /* END header not found */
 }
 
 /*
@@ -460,9 +460,8 @@ if (1) { zip->msg = message; goto Catch; } else ((void)0)
 
 /*
  * Reads zip file central directory. Returns the file position of first
- * CEN header, otherwise returns 0 if central directory not found or -1
+ * CEN header, otherwise returns -1 if an error occured. If zip->msg != NULL
- * if an error occurred. If zip->msg != NULL then the error was a zip
+ * then the error was a zip format error and zip->msg has the error text.
- * format error and zip->msg has the error text.
  * Always pass in -1 for knownTotal; it's used for a recursive call.
  */
 static jlong
@@ -488,9 +487,9 @@ readCEN(jzfile *zip, jint knownTotal)
 
     /* Get position of END header */
     if ((endpos = findEND(zip, endbuf)) == -1)
-        return -1; /* system error */
+        return -1; /* no END header or system error */
 
-    if (endpos == 0) return 0;  /* END header not found */
+    if (endpos == 0) return 0;  /* only END header present */
 
     freeCEN(zip);
 

jdk/test/java/util/zip/TestEmptyZip.java

@@ -39,34 +39,23 @@ public class TestEmptyZip {
             throw new Exception("failed to delete " + zipName);
         }
 
-        // Verify 0-length file cannot be read
         f.createNewFile();
-        ZipFile zf = null;
         try {
-            zf = new ZipFile(f);
+            // Verify 0-length file cannot be read
-            fail();
+            checkCannotRead(f);
-        } catch (Exception ex) {
-            check(ex.getMessage().contains("zip file is empty"));
-        } finally {
-            if (zf != null) {
-                zf.close();
-            }
-        }
 
-        ZipInputStream zis = null;
+            // Verify non-zip file cannot be read
+            OutputStream out = new FileOutputStream(f);
             try {
-            zis = new ZipInputStream(new FileInputStream(f));
+                out.write("class Foo { }".getBytes());
-            ZipEntry ze = zis.getNextEntry();
-            check(ze == null);
-        } catch (Exception ex) {
-            unexpected(ex);
             } finally {
-            if (zis != null) {
+                out.close();
-                zis.close();
-            }
             }
+            checkCannotRead(f);
 
+        } finally {
             f.delete();
+        }
 
         // Verify 0-entries file can be written
         write(f);
@@ -78,6 +67,29 @@ public class TestEmptyZip {
         f.delete();
     }
 
+    static void checkCannotRead(File f) throws IOException {
+        try {
+            new ZipFile(f).close();
+            fail();
+        } catch (ZipException ze) {
+            if (f.length() == 0) {
+                check(ze.getMessage().contains("zip file is empty"));
+            } else {
+                pass();
+            }
+        }
+        ZipInputStream zis = null;
+        try {
+            zis = new ZipInputStream(new FileInputStream(f));
+            ZipEntry ze = zis.getNextEntry();
+            check(ze == null);
+        } catch (IOException ex) {
+            unexpected(ex);
+        } finally {
+            if (zis != null) zis.close();
+        }
+    }
+
     static void write(File f) throws Exception {
         ZipOutputStream zos = null;
         try {