net: Ignore the magic number sniffer if it determines an application/octet-st...

net/base/mime_sniffer_unittest.cc

 // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "base/basictypes.h"
 #include "googleurl/src/gurl.h"
 #include "net/base/mime_sniffer.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace {
@@ skipping 70 matching lines @@
       "text/plain", "text/plain" },
     { "\x89" "PNG\x0D\x0A\x1A\x0A", sizeof("\x89" "PNG\x0D\x0A\x1A\x0A")-1,
       "http://www.example.com/foo",
       "application/octet-stream", "image/png" },
     { "\xFF\xD8\xFF\x23\x49\xAF", sizeof("\xFF\xD8\xFF\x23\x49\xAF")-1,
       "http://www.example.com/foo",
       "", "image/jpeg" },
   };
 
   TestArray(tests, arraysize(tests));
+
+  // Don't sniff Linux installers with embedded shell scripts as text/plain.
+  std::string content = "#!/bin/bash\necho hi\n";
+  content.resize(5000, '\n');
+  content.resize(20000, '\xFD');
+  EXPECT_EQ("application/octet-stream",
+            SniffMimeType(content, "http://www.example.com/foo.bin",
+                          "application/octet-stream"));
 }
 
 TEST(MimeSnifferTest, ChromeExtensionsTest) {
   SnifferTest tests[] = {
     // schemes
     { "Cr24\x02\x00\x00\x00", sizeof("Cr24\x02\x00\x00\x00")-1,
       "http://www.example.com/foo.crx",
       "", "application/x-chrome-extension" },
     { "Cr24\x02\x00\x00\x00", sizeof("Cr24\x02\x00\x00\x00")-1,
       "https://www.example.com/foo.crx",
@@ skipping 264 matching lines @@
   // Make a large input, with 600 bytes of "x".
   std::string content;
   content.resize(600);
   std::fill(content.begin(), content.end(), 'x');
 
   // content.size() >= kMaxBytesToSniff (512) so the sniff is unambiguous.
   std::string mime_type;
   EXPECT_TRUE(net::SniffMimeType(content.data(), content.size(), GURL(),
                                  "text/xml", &mime_type));
 }