--- a/jdk/src/share/classes/java/util/zip/ZipFile.java	Thu Mar 11 17:50:30 2010 +0000
+++ b/jdk/src/share/classes/java/util/zip/ZipFile.java	Thu Mar 11 14:06:09 2010 -0800
@@ -36,6 +36,8 @@
 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.*;
 
 /**
@@ -78,6 +80,17 @@
 
     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.
      *
@@ -196,7 +209,7 @@
             throw new NullPointerException("charset is null");
         this.zc = ZipCoder.get(charset);
         long t0 = System.nanoTime();
-        jzfile = open(name, mode, file.lastModified());
+        jzfile = open(name, mode, file.lastModified(), usemmap);
         sun.misc.PerfCounter.getZipFileOpenTime().addElapsedTimeFrom(t0);
         sun.misc.PerfCounter.getZipFileCount().increment();
         this.name = name;
@@ -673,8 +686,8 @@
     }
 
 
-    private static native long open(String name, int mode, long lastModified)
-        throws IOException;
+    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);

--- a/jdk/src/share/native/java/util/zip/ZipFile.c	Thu Mar 11 17:50:30 2010 +0000
+++ b/jdk/src/share/native/java/util/zip/ZipFile.c	Thu Mar 11 14:06:09 2010 -0800
@@ -81,7 +81,8 @@
 
 JNIEXPORT jlong JNICALL
 Java_java_util_zip_ZipFile_open(JNIEnv *env, jclass cls, jstring name,
-                                        jint mode, jlong lastModified)
+                                        jint mode, jlong lastModified,
+                                        jboolean usemmap)
 {
     const char *path = JNU_GetStringPlatformChars(env, name, 0);
     char *msg = 0;
@@ -109,7 +110,7 @@
                 goto finally;
             }
 #endif
-            zip = ZIP_Put_In_Cache(path, zfd, &msg, lastModified);
+            zip = ZIP_Put_In_Cache0(path, zfd, &msg, lastModified, usemmap);
         }
 
         if (zip != 0) {

--- a/jdk/src/share/native/java/util/zip/zip_util.c	Thu Mar 11 17:50:30 2010 +0000
+++ b/jdk/src/share/native/java/util/zip/zip_util.c	Thu Mar 11 14:06:09 2010 -0800
@@ -251,11 +251,16 @@
     if (zip->lock != NULL) MDESTROY(zip->lock);
     free(zip->name);
     freeCEN(zip);
+
 #ifdef USE_MMAP
-    if (zip->maddr != NULL) munmap((char *)zip->maddr, zip->mlen);
-#else
-    free(zip->cencache.data);
+    if (zip->usemmap) {
+        if (zip->maddr != NULL)
+            munmap((char *)zip->maddr, zip->mlen);
+    } else
 #endif
+    {
+        free(zip->cencache.data);
+    }
     if (zip->comment != NULL)
         free(zip->comment);
     if (zip->zfd != -1) ZFILE_Close(zip->zfd);
@@ -585,49 +590,53 @@
         ZIP_FORMAT_ERROR("invalid END header (bad central directory offset)");
 
 #ifdef USE_MMAP
-     /* On Solaris & Linux prior to JDK 6, we used to mmap the whole jar file to
-      * read the jar file contents. However, this greatly increased the perceived
-      * footprint numbers because the mmap'ed pages were adding into the totals shown
-      * by 'ps' and 'top'. We switched to mmaping only the central directory of jar
-      * file while calling 'read' to read the rest of jar file. Here are a list of
-      * reasons apart from above of why we are doing so:
-      * 1. Greatly reduces mmap overhead after startup complete;
-      * 2. Avoids dual path code maintainance;
-      * 3. Greatly reduces risk of address space (not virtual memory) exhaustion.
-      */
-    if (pagesize == 0) {
-        pagesize = (jlong)sysconf(_SC_PAGESIZE);
-        if (pagesize == 0) goto Catch;
-    }
-    if (cenpos > pagesize) {
-        offset = cenpos & ~(pagesize - 1);
-    } else {
-        offset = 0;
+    if (zip->usemmap) {
+      /* On Solaris & Linux prior to JDK 6, we used to mmap the whole jar file to
+       * read the jar file contents. However, this greatly increased the perceived
+       * footprint numbers because the mmap'ed pages were adding into the totals shown
+       * by 'ps' and 'top'. We switched to mmaping only the central directory of jar
+       * file while calling 'read' to read the rest of jar file. Here are a list of
+       * reasons apart from above of why we are doing so:
+       * 1. Greatly reduces mmap overhead after startup complete;
+       * 2. Avoids dual path code maintainance;
+       * 3. Greatly reduces risk of address space (not virtual memory) exhaustion.
+       */
+        if (pagesize == 0) {
+            pagesize = (jlong)sysconf(_SC_PAGESIZE);
+            if (pagesize == 0) goto Catch;
+        }
+        if (cenpos > pagesize) {
+            offset = cenpos & ~(pagesize - 1);
+        } else {
+            offset = 0;
+        }
+        /* When we are not calling recursively, knownTotal is -1. */
+        if (knownTotal == -1) {
+            void* mappedAddr;
+            /* Mmap the CEN and END part only. We have to figure
+               out the page size in order to make offset to be multiples of
+               page size.
+            */
+            zip->mlen = cenpos - offset + cenlen + endhdrlen;
+            zip->offset = offset;
+            mappedAddr = mmap64(0, zip->mlen, PROT_READ, MAP_SHARED, zip->zfd, (off64_t) offset);
+            zip->maddr = (mappedAddr == (void*) MAP_FAILED) ? NULL :
+                (unsigned char*)mappedAddr;
+
+            if (zip->maddr == NULL) {
+                jio_fprintf(stderr, "mmap failed for CEN and END part of zip file\n");
+                goto Catch;
+            }
+        }
+        cenbuf = zip->maddr + cenpos - offset;
+    } else
+#endif
+    {
+        if ((cenbuf = malloc((size_t) cenlen)) == NULL ||
+            (readFullyAt(zip->zfd, cenbuf, cenlen, cenpos) == -1))
+        goto Catch;
     }
-    /* When we are not calling recursively, knownTotal is -1. */
-    if (knownTotal == -1) {
-        void* mappedAddr;
-        /* Mmap the CEN and END part only. We have to figure
-           out the page size in order to make offset to be multiples of
-           page size.
-        */
-        zip->mlen = cenpos - offset + cenlen + endhdrlen;
-        zip->offset = offset;
-        mappedAddr = mmap64(0, zip->mlen, PROT_READ, MAP_SHARED, zip->zfd, (off64_t) offset);
-        zip->maddr = (mappedAddr == (void*) MAP_FAILED) ? NULL :
-            (unsigned char*)mappedAddr;
 
-        if (zip->maddr == NULL) {
-            jio_fprintf(stderr, "mmap failed for CEN and END part of zip file\n");
-            goto Catch;
-        }
-    }
-    cenbuf = zip->maddr + cenpos - offset;
-#else
-    if ((cenbuf = malloc((size_t) cenlen)) == NULL ||
-        (readFullyAt(zip->zfd, cenbuf, cenlen, cenpos) == -1))
-        goto Catch;
-#endif
     cenend = cenbuf + cenlen;
 
     /* Initialize zip file data structures based on the total number
@@ -700,9 +709,11 @@
     cenpos = -1;
 
  Finally:
-#ifndef USE_MMAP
-    free(cenbuf);
+#ifdef USE_MMAP
+    if (!zip->usemmap)
 #endif
+        free(cenbuf);
+
     return cenpos;
 }
 
@@ -782,9 +793,17 @@
  * If a zip error occurs, then *pmsg will be set to the error message text if
  * pmsg != 0. Otherwise, *pmsg will be set to NULL.
  */
+
 jzfile *
 ZIP_Put_In_Cache(const char *name, ZFILE zfd, char **pmsg, jlong lastModified)
 {
+    return ZIP_Put_In_Cache0(name, zfd, pmsg, lastModified, JNI_TRUE);
+}
+
+jzfile *
+ZIP_Put_In_Cache0(const char *name, ZFILE zfd, char **pmsg, jlong lastModified,
+                 jboolean usemmap)
+{
     static char errbuf[256];
     jlong len;
     jzfile *zip;
@@ -793,6 +812,9 @@
         return NULL;
     }
 
+#ifdef USE_MMAP
+    zip->usemmap = usemmap;
+#endif
     zip->refs = 1;
     zip->lastModified = lastModified;
 
@@ -877,8 +899,6 @@
     return;
 }
 
-#ifndef USE_MMAP
-
 /* Empirically, most CEN headers are smaller than this. */
 #define AMPLE_CEN_HEADER_SIZE 160
 
@@ -928,7 +948,6 @@
     cache->pos  = cenpos;
     return cen;
 }
-#endif /* not USE_MMAP */
 
 typedef enum { ACCESS_RANDOM, ACCESS_SEQUENTIAL } AccessHint;
 
@@ -953,14 +972,17 @@
     ze->comment = NULL;
 
 #ifdef USE_MMAP
-    cen = (char*) zip->maddr + zc->cenpos - zip->offset;
-#else
-    if (accessHint == ACCESS_RANDOM)
-        cen = readCENHeader(zip, zc->cenpos, AMPLE_CEN_HEADER_SIZE);
-    else
-        cen = sequentialAccessReadCENHeader(zip, zc->cenpos);
-    if (cen == NULL) goto Catch;
+    if (zip->usemmap) {
+        cen = (char*) zip->maddr + zc->cenpos - zip->offset;
+    } else
 #endif
+    {
+        if (accessHint == ACCESS_RANDOM)
+            cen = readCENHeader(zip, zc->cenpos, AMPLE_CEN_HEADER_SIZE);
+        else
+            cen = sequentialAccessReadCENHeader(zip, zc->cenpos);
+        if (cen == NULL) goto Catch;
+    }
 
     nlen      = CENNAM(cen);
     elen      = CENEXT(cen);
@@ -976,7 +998,6 @@
     if ((ze->name = malloc(nlen + 1)) == NULL) goto Catch;
     memcpy(ze->name, cen + CENHDR, nlen);
     ze->name[nlen] = '\0';
-
     if (elen > 0) {
         char *extra = cen + CENHDR + nlen;
 
@@ -1037,9 +1058,10 @@
     ze = NULL;
 
  Finally:
-#ifndef USE_MMAP
-    if (cen != NULL && accessHint == ACCESS_RANDOM) free(cen);
+#ifdef USE_MMAP
+    if (!zip->usemmap)
 #endif
+        if (cen != NULL && accessHint == ACCESS_RANDOM) free(cen);
     return ze;
 }
 

--- a/jdk/src/share/native/java/util/zip/zip_util.h	Thu Mar 11 17:50:30 2010 +0000
+++ b/jdk/src/share/native/java/util/zip/zip_util.h	Thu Mar 11 14:06:09 2010 -0800
@@ -45,9 +45,6 @@
  * Header sizes including signatures
  */
 
-#ifdef USE_MMAP
-#define SIGSIZ  4
-#endif
 #define LOCHDR 30
 #define EXTHDR 16
 #define CENHDR 46
@@ -211,9 +208,9 @@
     jlong mlen;           /* length (in bytes) mmaped */
     jlong offset;         /* offset of the mmapped region from the
                              start of the file. */
-#else
+    jboolean usemmap;     /* if mmap is used. */
+#endif
     cencache cencache;    /* CEN header cache */
-#endif
     ZFILE zfd;            /* open file descriptor */
     void *lock;           /* read lock */
     char *comment;        /* zip file comment */
@@ -259,6 +256,9 @@
 jzfile *
 ZIP_Put_In_Cache(const char *name, ZFILE zfd, char **pmsg, jlong lastModified);
 
+jzfile *
+ZIP_Put_In_Cache0(const char *name, ZFILE zfd, char **pmsg, jlong lastModified, jboolean usemmap);
+
 void JNICALL
 ZIP_Close(jzfile *zip);