Add support for bsdiff of file system metadata blocks

test_utils.cc

 // Copyright (c) 2009 The Chromium OS 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 "update_engine/test_utils.h"
 
 #include <sys/stat.h>
 #include <sys/types.h>
 #include <errno.h>
 #include <stdio.h>
@@ skipping 160 matching lines @@
 
 void FillWithData(vector<char>* buffer) {
   size_t input_counter = 0;
   for (vector<char>::iterator it = buffer->begin(); it != buffer->end(); ++it) {
     *it = kRandomString[input_counter];
     input_counter++;
     input_counter %= sizeof(kRandomString);
   }
 }
 
+void CreateEmptyExtImageAtPath(const string& path,
+                               size_t size,
+                               int block_size) {
+  EXPECT_EQ(0, System(StringPrintf("dd if=/dev/zero of=%s"
+                                   " seek=%zu bs=1 count=1",
+                                   path.c_str(), size)));
+  EXPECT_EQ(0, System(StringPrintf("mkfs.ext3 -b %d -F %s",
+                                   block_size, path.c_str())));
+}
+
 void CreateExtImageAtPath(const string& path, vector<string>* out_paths) {
   // create 10MiB sparse file
   EXPECT_EQ(0, System(StringPrintf("dd if=/dev/zero of=%s"
                                    " seek=10485759 bs=1 count=1",
                                    path.c_str())));
   EXPECT_EQ(0, System(StringPrintf("mkfs.ext3 -b 4096 -F %s", path.c_str())));
   EXPECT_EQ(0, System(StringPrintf("mkdir -p %s", kMountPath)));
   EXPECT_EQ(0, System(StringPrintf("mount -o loop %s %s", path.c_str(),
                                    kMountPath)));
   EXPECT_EQ(0, System(StringPrintf("echo hi > %s/hi", kMountPath)));
   EXPECT_EQ(0, System(StringPrintf("echo hello > %s/hello", kMountPath)));
   EXPECT_EQ(0, System(StringPrintf("mkdir %s/some_dir", kMountPath)));
   EXPECT_EQ(0, System(StringPrintf("mkdir %s/some_dir/empty_dir", kMountPath)));
   EXPECT_EQ(0, System(StringPrintf("mkdir %s/some_dir/mnt", kMountPath)));
   EXPECT_EQ(0, System(StringPrintf("echo T > %s/some_dir/test", kMountPath)));
   EXPECT_EQ(0, System(StringPrintf("mkfifo %s/some_dir/fifo", kMountPath)));
   EXPECT_EQ(0, System(StringPrintf("mknod %s/cdev c 2 3", kMountPath)));
   EXPECT_EQ(0, System(StringPrintf("ln -s /some/target %s/sym", kMountPath)));
   EXPECT_EQ(0, System(StringPrintf("ln %s/some_dir/test %s/testlink",
                                    kMountPath, kMountPath)));
   EXPECT_EQ(0, System(StringPrintf("umount -d %s", kMountPath)));
-  
+
   if (out_paths) {
     out_paths->clear();
     out_paths->push_back("");
     out_paths->push_back("/hi");
     out_paths->push_back("/hello");
     out_paths->push_back("/some_dir");
     out_paths->push_back("/some_dir/empty_dir");
     out_paths->push_back("/some_dir/mnt");
     out_paths->push_back("/some_dir/test");
     out_paths->push_back("/some_dir/fifo");
@@ skipping 43 matching lines @@
   EXPECT_FALSE(iter.IsErr());
   EXPECT_TRUE(expected_paths.empty());
   if (!expected_paths.empty()) {
     for (set<string>::const_iterator it = expected_paths.begin();
          it != expected_paths.end(); ++it) {
       LOG(INFO) << "extra path: " << *it;
     }
   }
 }
 
+ScopedLoopMounter::ScopedLoopMounter(const std::string& file_path,
+                                     std::string* mnt_path,
+                                     unsigned long flags) {
+  EXPECT_TRUE(utils::MakeTempDirectory("/tmp/mnt.XXXXXX", mnt_path));
+  dir_remover_.reset(new ScopedDirRemover(*mnt_path));
+
+  std::string loop_dev = GetUnusedLoopDevice();
+  EXPECT_EQ(0, system(StringPrintf("losetup %s %s", loop_dev.c_str(),
+                                   file_path.c_str()).c_str()));
+  loop_releaser_.reset(new ScopedLoopbackDeviceReleaser(loop_dev));
+
+  EXPECT_TRUE(utils::MountFilesystem(loop_dev, *mnt_path, flags));
+  unmounter_.reset(new ScopedFilesystemUnmounter(*mnt_path));
+}
+
 }  // namespace chromeos_update_engine