The Tor Browser / file revision

 function gen_1MiB()

 {

   var i;

   var data="x";

   for (i=0 ; i < 20 ; i++)

     data+=data;

   return data;

 }

 function write_and_check(str, data, len)

 {

   var written = str.write(data, len);

   if (written != len) {

     do_throw("str.write has not written all data!\n" +

              "  Expected: " + len  + "\n" +

              "  Actual: " + written + "\n");

   }

 }

 function write_datafile(status, entry)

 {

   do_check_eq(status, Cr.NS_OK);

   var os = entry.openOutputStream(0);

   var data = gen_1MiB();

   write_and_check(os, data, data.length);

   os.close();

   entry.close();

   // try to open the entry for appending

   asyncOpenCacheEntry("http://data/",

                       "disk", Ci.nsICacheStorage.OPEN_NORMALLY, null,

                       open_for_readwrite);

 }

 function open_for_readwrite(status, entry)

 {

   do_check_eq(status, Cr.NS_OK);

   var os = entry.openOutputStream(entry.dataSize);

   // Opening the entry for appending data calls nsDiskCacheStreamIO::Seek()

   // which initializes mFD. If no data is written then mBufDirty is false and

   // mFD won't be closed in nsDiskCacheStreamIO::Flush().

   os.close();

   entry.close();

   do_test_finished();

 }

 function run_test() {

   do_get_profile();

   // clear the cache

   evict_cache_entries();

   asyncOpenCacheEntry("http://data/",

                       "disk", Ci.nsICacheStorage.OPEN_NORMALLY, null,

                       write_datafile);

   do_test_pending();

 }