blob: efc47478fe4b518867a0a4a3124bebd0fed7a5df [file] [log] [blame]
// Copyright (c) 2010 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.
#ifndef CHROMEOS_PLATFORM_UPDATE_ENGINE_DELTA_DIFF_GENERATOR_H__
#define CHROMEOS_PLATFORM_UPDATE_ENGINE_DELTA_DIFF_GENERATOR_H__
#include <string>
#include <vector>
#include "base/basictypes.h"
#include "update_engine/graph_types.h"
#include "update_engine/update_metadata.pb.h"
// There is one function in DeltaDiffGenerator of importance to users
// of the class: GenerateDeltaUpdateFile(). Before calling it,
// the old and new images must be mounted. Call GenerateDeltaUpdateFile()
// with both the mount-points of the images in addition to the paths of
// the images (both old and new). A delta from old to new will be
// generated and stored in output_path.
namespace chromeos_update_engine {
class DeltaDiffGenerator {
public:
// Represents a disk block on the install partition.
struct Block {
// During install, each block on the install partition will be written
// and some may be read (in all likelihood, many will be read).
// The reading and writing will be performed by InstallOperations,
// each of which has a corresponding vertex in a graph.
// A Block object tells which vertex will read or write this block
// at install time.
// Generally, there will be a vector of Block objects whose length
// is the number of blocks on the install partition.
Block() : reader(Vertex::kInvalidIndex), writer(Vertex::kInvalidIndex) {}
Vertex::Index reader;
Vertex::Index writer;
};
// This is the only function that external users of the class should call.
// old_image and new_image are paths to two image files. They should be
// mounted read-only at paths old_root and new_root respectively.
// {old,new}_kernel_part are paths to the old and new kernel partition
// images, respectively.
// output_path is the filename where the delta update should be written.
// Returns true on success.
static bool GenerateDeltaUpdateFile(const std::string& old_root,
const std::string& old_image,
const std::string& new_root,
const std::string& new_image,
const std::string& old_kernel_part,
const std::string& new_kernel_part,
const std::string& output_path);
// These functions are public so that the unit tests can access them:
// Reads old_filename (if it exists) and a new_filename and determines
// the smallest way to encode this file for the diff. It stores
// necessary data in out_data and fills in out_op.
// If there's no change in old and new files, it creates a MOVE
// operation. If there is a change, or the old file doesn't exist,
// the smallest of REPLACE, REPLACE_BZ, or BSDIFF wins.
// new_filename must contain at least one byte.
// Returns true on success.
static bool ReadFileToDiff(const std::string& old_filename,
const std::string& new_filename,
std::vector<char>* out_data,
DeltaArchiveManifest_InstallOperation* out_op);
// Modifies blocks read by 'op' so that any blocks referred to by
// 'remove_extents' are replaced with blocks from 'replace_extents'.
// 'remove_extents' and 'replace_extents' must be the same number of blocks.
// Blocks will be substituted in the order listed in the vectors.
// E.g. if 'op' reads blocks 1, 2, 3, 4, 5, 6, 7, 8, remove_extents
// contains blocks 6, 2, 3, 5, and replace blocks contains
// 12, 13, 14, 15, then op will be changed to read from:
// 1, 13, 14, 4, 15, 12, 7, 8
static void SubstituteBlocks(DeltaArchiveManifest_InstallOperation* op,
const std::vector<Extent>& remove_extents,
const std::vector<Extent>& replace_extents);
// Cuts 'edges' from 'graph' according to the AU algorithm. This means
// for each edge A->B, remove the dependency that B occur before A.
// Do this by creating a new operation X that copies from the blocks
// specified by the edge's properties to temp space T. Modify B to read
// from T rather than the blocks in the edge. Modify A to depend on X,
// but not on B. Free space is found by looking in 'blocks'.
// Returns true on success.
static bool CutEdges(Graph* graph,
const std::vector<Block>& blocks,
const std::set<Edge>& edges);
// Stores all Extents in 'extents' into 'out'.
static void StoreExtents(std::vector<Extent>& extents,
google::protobuf::RepeatedPtrField<Extent>* out);
// Creates all the edges for the graph. Writers of a block point to
// readers of the same block. This is because for an edge A->B, B
// must complete before A executes.
static void CreateEdges(Graph* graph, const std::vector<Block>& blocks);
// Install operations in the manifest may reference data blobs, which
// are in data_blobs_path. This function creates a new data blobs file
// with the data blobs in the same order as the referencing install
// operations in the manifest. E.g. if manifest[0] has a data blob
// "X" at offset 1, manifest[1] has a data blob "Y" at offset 0,
// and data_blobs_path's file contains "YX", new_data_blobs_path
// will set to be a file that contains "XY".
static bool ReorderDataBlobs(DeltaArchiveManifest* manifest,
const std::string& data_blobs_path,
const std::string& new_data_blobs_path);
private:
// This should never be constructed
DISALLOW_IMPLICIT_CONSTRUCTORS(DeltaDiffGenerator);
};
extern const char* const kBsdiffPath;
extern const char* const kBspatchPath;
extern const char* const kDeltaMagic;
}; // namespace chromeos_update_engine
#endif // CHROMEOS_PLATFORM_UPDATE_ENGINE_DELTA_DIFF_GENERATOR_H__