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// Copyright (C) 2015 The Android Open Source Project
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.
#include <map>
#include <set>
#include <string>
#include <vector>
#include "update_engine/payload_generator/blob_file_writer.h"
#include "update_engine/payload_generator/delta_diff_generator.h"
#include "update_engine/payload_generator/graph_types.h"
#include "update_engine/payload_generator/operations_generator.h"
// InplaceGenerator contains all functionality related to the inplace algorithm
// for generating update payloads. These are the functions used when delta minor
// version is 1.
namespace chromeos_update_engine {
// This struct stores all relevant info for an edge that is cut between
// nodes old_src -> old_dst by creating new vertex new_vertex. The new
// relationship is:
// old_src -(read before)-> new_vertex <-(write before)- old_dst
// new_vertex is a MOVE operation that moves some existing blocks into
// temp space. The temp extents are, by necessity, stored in new_vertex
// (as dst extents) and old_dst (as src extents), but they are also broken
// out into tmp_extents, as the nodes themselves may contain many more
// extents.
struct CutEdgeVertexes {
Vertex::Index new_vertex;
Vertex::Index old_src;
Vertex::Index old_dst;
std::vector<Extent> tmp_extents;
class InplaceGenerator : public OperationsGenerator {
// 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;
InplaceGenerator() = default;
// Checks all the operations in the graph have a type assigned.
static void CheckGraph(const Graph& graph);
// 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(Vertex* vertex,
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::set<Edge>& edges,
std::vector<CutEdgeVertexes>* out_cuts);
// 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);
// Takes |op_indexes|, which is effectively a mapping from order in
// which the op is performed -> graph vertex index, and produces the
// reverse: a mapping from graph vertex index -> op_indexes index.
static void GenerateReverseTopoOrderMap(
const std::vector<Vertex::Index>& op_indexes,
std::vector<std::vector<Vertex::Index>::size_type>* reverse_op_indexes);
// Sorts the vector |cuts| by its |cuts[].old_dest| member. Order is
// determined by the order of elements in op_indexes.
static void SortCutsByTopoOrder(const std::vector<Vertex::Index>& op_indexes,
std::vector<CutEdgeVertexes>* cuts);
// Given a topologically sorted graph |op_indexes| and |graph|, alters
// |op_indexes| to move all the full operations to the end of the vector.
// Full operations should not be depended on, so this is safe.
static void MoveAndSortFullOpsToBack(Graph* graph,
std::vector<Vertex::Index>* op_indexes);
// Returns true iff there are no extents in the graph that refer to temp
// blocks. Temp blocks are in the range [kTempBlockStart, kSparseHole).
static bool NoTempBlocksRemain(const Graph& graph);
// Takes a |graph|, which has edges that must be cut, as listed in
// |cuts|. Cuts the edges. Maintains a list in which the operations
// will be performed (in |op_indexes|) and the reverse (in
// |reverse_op_indexes|). Cutting edges requires scratch space, and
// if insufficient scratch is found, the file is reread and will be
// send down (either as REPLACE or REPLACE_BZ). Returns true on
// success.
static bool AssignTempBlocks(
Graph* graph,
const std::string& new_part,
BlobFileWriter* blob_file,
std::vector<Vertex::Index>* op_indexes,
std::vector<std::vector<Vertex::Index>::size_type>* reverse_op_indexes,
const std::vector<CutEdgeVertexes>& cuts);
// Handles allocation of temp blocks to a cut edge by converting the
// dest node to a full op. This removes the need for temp blocks, but
// comes at the cost of a worse compression ratio.
// For example, say we have A->B->A. It would first be cut to form:
// A->B->N<-A, where N copies blocks to temp space. If there are no
// temp blocks, this function can be called to convert it to the form:
// A->B. Now, A is a full operation.
static bool ConvertCutToFullOp(Graph* graph,
const CutEdgeVertexes& cut,
const std::string& new_part,
BlobFileWriter* blob_file);
// Takes a graph, which is not a DAG, which represents the files just
// read from disk, and converts it into a DAG by breaking all cycles
// and finding temp space to resolve broken edges.
// The final order of the nodes is given in |final_order|
// Some files may need to be reread from disk, thus |fd| and
// |data_file_size| are be passed.
// If |scratch_vertex| is not kInvalidIndex, removes it from
// |final_order| before returning.
// Returns true on success.
static bool ConvertGraphToDag(Graph* graph,
const std::string& new_part,
BlobFileWriter* blob_file,
std::vector<Vertex::Index>* final_order,
Vertex::Index scratch_vertex);
// Creates a dummy REPLACE_BZ node in the given |vertex|. This can be used
// to provide scratch space. The node writes |num_blocks| blocks starting at
// |start_block|The node should be marked invalid before writing all nodes to
// the output file.
static void CreateScratchNode(uint64_t start_block,
uint64_t num_blocks,
Vertex* vertex);
// The |blocks| vector contains a reader and writer for each block on the
// filesystem that's being in-place updated. We populate the reader/writer
// fields of |blocks| by calling this function.
// For each block in |operation| that is read or written, find that block
// in |blocks| and set the reader/writer field to the vertex passed.
// |graph| is not strictly necessary, but useful for printing out
// error messages.
static bool AddInstallOpToBlocksVector(const InstallOperation& operation,
const Graph& graph,
Vertex::Index vertex,
std::vector<Block>* blocks);
// Add a vertex (if |existing_vertex| is kInvalidVertex) or update an
// |existing_vertex| with the passed |operation|.
// This method will also register the vertex as the reader or writer of the
// blocks involved in the operation updating the |blocks| vector. The
// |op_name| associated with the Vertex is used for logging purposes.
static bool AddInstallOpToGraph(Graph* graph,
Vertex::Index existing_vertex,
std::vector<Block>* blocks,
const InstallOperation& operation,
const std::string& op_name);
// Apply the transformation stored in |the_map| to the |collection| vector
// replacing the map keys found in |collection| with its associated value in
// |the_map|.
static void ApplyMap(std::vector<uint64_t>* collection,
const std::map<uint64_t, uint64_t>& the_map);
// Resolve all read-after-write dependencies in the operation list |aops|. The
// operations in |aops| are such that they generate the desired |new_part| if
// applied reading always from the original image. This function reorders the
// operations and generates new operations when needed to make these
// operations produce the same |new_part| result when applied in-place.
// The new operations will create blobs in |data_file_fd| and update
// the file size pointed by |data_file_size| if needed.
// On success, stores the new operations in |aops| in the right order and
// returns true.
static bool ResolveReadAfterWriteDependencies(
const PartitionConfig& old_part,
const PartitionConfig& new_part,
uint64_t partition_size,
size_t block_size,
BlobFileWriter* blob_file,
std::vector<AnnotatedOperation>* aops);
// Generate the update payload operations for the given partition using
// only operations that read from the target and/or write to the target,
// hence, applying the payload "in-place" in the target partition. This method
// assumes that the contents of the source image are pre-copied to the target
// partition, up to the size of the source image. Use this method to generate
// a delta update with the minor version kInPlaceMinorPayloadVersion.
// The operations are stored in |aops|. All the offsets in the operations
// reference the data written to |blob_file|.
bool GenerateOperations(const PayloadGenerationConfig& config,
const PartitionConfig& old_part,
const PartitionConfig& new_part,
BlobFileWriter* blob_file,
std::vector<AnnotatedOperation>* aops) override;
}; // namespace chromeos_update_engine