gecko-dev/netwerk/test/unit/test_bug654926.js

"use strict";

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) {
  Assert.equal(status, Cr.NS_OK);
  var data = gen_1MiB();
  var os = entry.openOutputStream(0, data.length);

  // write 2MiB
  var i;
  for (i = 0; i < 2; i++) {
    write_and_check(os, data, data.length);
  }

  os.close();
  entry.close();

  // now change max_entry_size so that the existing entry is too big
  Services.prefs.setIntPref("browser.cache.disk.max_entry_size", 1024);

  // append to entry
  asyncOpenCacheEntry(
    "http://data/",
    "disk",
    Ci.nsICacheStorage.OPEN_NORMALLY,
    null,
    append_datafile
  );
}

function append_datafile(status, entry) {
  Assert.equal(status, Cr.NS_OK);
  var os = entry.openOutputStream(entry.dataSize, -1);
  var data = gen_1MiB();

  // append 1MiB
  try {
    write_and_check(os, data, data.length);
    do_throw();
  } catch (ex) {}

  // closing the ostream should fail in this case
  try {
    os.close();
    do_throw();
  } catch (ex) {}

  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();
}