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// Copyright 2020 Google Inc. All rights reserved.
//
// 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
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package bazel
import (
"encoding/json"
"fmt"
"path/filepath"
"strings"
"github.com/google/blueprint/proptools"
)
// artifact contains relevant portions of Bazel's aquery proto, Artifact.
// Represents a single artifact, whether it's a source file or a derived output file.
type artifact struct {
Id int
PathFragmentId int
}
type pathFragment struct {
Id int
Label string
ParentId int
}
// KeyValuePair represents Bazel's aquery proto, KeyValuePair.
type KeyValuePair struct {
Key string
Value string
}
// depSetOfFiles contains relevant portions of Bazel's aquery proto, DepSetOfFiles.
// Represents a data structure containing one or more files. Depsets in Bazel are an efficient
// data structure for storing large numbers of file paths.
type depSetOfFiles struct {
Id int
DirectArtifactIds []int
TransitiveDepSetIds []int
}
// action contains relevant portions of Bazel's aquery proto, Action.
// Represents a single command line invocation in the Bazel build graph.
type action struct {
Arguments []string
EnvironmentVariables []KeyValuePair
InputDepSetIds []int
Mnemonic string
OutputIds []int
}
// actionGraphContainer contains relevant portions of Bazel's aquery proto, ActionGraphContainer.
// An aquery response from Bazel contains a single ActionGraphContainer proto.
type actionGraphContainer struct {
Artifacts []artifact
Actions []action
DepSetOfFiles []depSetOfFiles
PathFragments []pathFragment
}
// BuildStatement contains information to register a build statement corresponding (one to one)
// with a Bazel action from Bazel's action graph.
type BuildStatement struct {
Command string
Depfile *string
OutputPaths []string
InputPaths []string
SymlinkPaths []string
Env []KeyValuePair
Mnemonic string
}
// A helper type for aquery processing which facilitates retrieval of path IDs from their
// less readable Bazel structures (depset and path fragment).
type aqueryArtifactHandler struct {
// Maps middleman artifact Id to input artifact depset ID.
// Middleman artifacts are treated as "substitute" artifacts for mixed builds. For example,
// if we find a middleman action which has outputs [foo, bar], and output [baz_middleman], then,
// for each other action which has input [baz_middleman], we add [foo, bar] to the inputs for
// that action instead.
middlemanIdToDepsetIds map[int][]int
// Maps depset Id to depset struct.
depsetIdToDepset map[int]depSetOfFiles
// depsetIdToArtifactIdsCache is a memoization of depset flattening, because flattening
// may be an expensive operation.
depsetIdToArtifactIdsCache map[int][]int
// Maps artifact Id to fully expanded path.
artifactIdToPath map[int]string
}
func newAqueryHandler(aqueryResult actionGraphContainer) (*aqueryArtifactHandler, error) {
pathFragments := map[int]pathFragment{}
for _, pathFragment := range aqueryResult.PathFragments {
pathFragments[pathFragment.Id] = pathFragment
}
artifactIdToPath := map[int]string{}
for _, artifact := range aqueryResult.Artifacts {
artifactPath, err := expandPathFragment(artifact.PathFragmentId, pathFragments)
if err != nil {
return nil, err
}
artifactIdToPath[artifact.Id] = artifactPath
}
depsetIdToDepset := map[int]depSetOfFiles{}
for _, depset := range aqueryResult.DepSetOfFiles {
depsetIdToDepset[depset.Id] = depset
}
// Do a pass through all actions to identify which artifacts are middleman artifacts.
middlemanIdToDepsetIds := map[int][]int{}
for _, actionEntry := range aqueryResult.Actions {
if actionEntry.Mnemonic == "Middleman" {
for _, outputId := range actionEntry.OutputIds {
middlemanIdToDepsetIds[outputId] = actionEntry.InputDepSetIds
}
}
}
return &aqueryArtifactHandler{
middlemanIdToDepsetIds: middlemanIdToDepsetIds,
depsetIdToDepset: depsetIdToDepset,
depsetIdToArtifactIdsCache: map[int][]int{},
artifactIdToPath: artifactIdToPath,
}, nil
}
func (a *aqueryArtifactHandler) getInputPaths(depsetIds []int) ([]string, error) {
inputPaths := []string{}
for _, inputDepSetId := range depsetIds {
inputArtifacts, err := a.artifactIdsFromDepsetId(inputDepSetId)
if err != nil {
return nil, err
}
for _, inputId := range inputArtifacts {
if middlemanInputDepsetIds, isMiddlemanArtifact := a.middlemanIdToDepsetIds[inputId]; isMiddlemanArtifact {
// Add all inputs from middleman actions which created middleman artifacts which are
// in the inputs for this action.
swappedInputPaths, err := a.getInputPaths(middlemanInputDepsetIds)
if err != nil {
return nil, err
}
inputPaths = append(inputPaths, swappedInputPaths...)
} else {
inputPath, exists := a.artifactIdToPath[inputId]
if !exists {
return nil, fmt.Errorf("undefined input artifactId %d", inputId)
}
inputPaths = append(inputPaths, inputPath)
}
}
}
return inputPaths, nil
}
func (a *aqueryArtifactHandler) artifactIdsFromDepsetId(depsetId int) ([]int, error) {
if result, exists := a.depsetIdToArtifactIdsCache[depsetId]; exists {
return result, nil
}
if depset, exists := a.depsetIdToDepset[depsetId]; exists {
result := depset.DirectArtifactIds
for _, childId := range depset.TransitiveDepSetIds {
childArtifactIds, err := a.artifactIdsFromDepsetId(childId)
if err != nil {
return nil, err
}
result = append(result, childArtifactIds...)
}
a.depsetIdToArtifactIdsCache[depsetId] = result
return result, nil
} else {
return nil, fmt.Errorf("undefined input depsetId %d", depsetId)
}
}
// AqueryBuildStatements returns an array of BuildStatements which should be registered (and output
// to a ninja file) to correspond one-to-one with the given action graph json proto (from a bazel
// aquery invocation).
func AqueryBuildStatements(aqueryJsonProto []byte) ([]BuildStatement, error) {
buildStatements := []BuildStatement{}
var aqueryResult actionGraphContainer
err := json.Unmarshal(aqueryJsonProto, &aqueryResult)
if err != nil {
return nil, err
}
aqueryHandler, err := newAqueryHandler(aqueryResult)
if err != nil {
return nil, err
}
for _, actionEntry := range aqueryResult.Actions {
if shouldSkipAction(actionEntry) {
continue
}
outputPaths := []string{}
var depfile *string
for _, outputId := range actionEntry.OutputIds {
outputPath, exists := aqueryHandler.artifactIdToPath[outputId]
if !exists {
return nil, fmt.Errorf("undefined outputId %d", outputId)
}
ext := filepath.Ext(outputPath)
if ext == ".d" {
if depfile != nil {
return nil, fmt.Errorf("found multiple potential depfiles %q, %q", *depfile, outputPath)
} else {
depfile = &outputPath
}
} else {
outputPaths = append(outputPaths, outputPath)
}
}
inputPaths, err := aqueryHandler.getInputPaths(actionEntry.InputDepSetIds)
if err != nil {
return nil, err
}
buildStatement := BuildStatement{
Command: strings.Join(proptools.ShellEscapeList(actionEntry.Arguments), " "),
Depfile: depfile,
OutputPaths: outputPaths,
InputPaths: inputPaths,
Env: actionEntry.EnvironmentVariables,
Mnemonic: actionEntry.Mnemonic,
}
if isSymlinkAction(actionEntry) {
if len(inputPaths) != 1 || len(outputPaths) != 1 {
return nil, fmt.Errorf("Expect 1 input and 1 output to symlink action, got: input %q, output %q", inputPaths, outputPaths)
}
out := outputPaths[0]
outDir := proptools.ShellEscapeIncludingSpaces(filepath.Dir(out))
out = proptools.ShellEscapeIncludingSpaces(out)
in := proptools.ShellEscapeIncludingSpaces(inputPaths[0])
buildStatement.Command = fmt.Sprintf("mkdir -p %[1]s && rm -f %[2]s && ln -rsf %[3]s %[2]s", outDir, out, in)
buildStatement.SymlinkPaths = outputPaths[:]
} else if len(actionEntry.Arguments) < 1 {
return nil, fmt.Errorf("received action with no command: [%v]", buildStatement)
}
buildStatements = append(buildStatements, buildStatement)
}
return buildStatements, nil
}
func isSymlinkAction(a action) bool {
return a.Mnemonic == "Symlink" || a.Mnemonic == "SolibSymlink"
}
func shouldSkipAction(a action) bool {
// TODO(b/180945121): Handle complex symlink actions.
if a.Mnemonic == "SymlinkTree" || a.Mnemonic == "SourceSymlinkManifest" {
return true
}
// Middleman actions are not handled like other actions; they are handled separately as a
// preparatory step so that their inputs may be relayed to actions depending on middleman
// artifacts.
if a.Mnemonic == "Middleman" {
return true
}
// Skip "Fail" actions, which are placeholder actions designed to always fail.
if a.Mnemonic == "Fail" {
return true
}
// TODO(b/180946980): Handle FileWrite. The aquery proto currently contains no information
// about the contents that are written.
if a.Mnemonic == "FileWrite" {
return true
}
return false
}
func expandPathFragment(id int, pathFragmentsMap map[int]pathFragment) (string, error) {
labels := []string{}
currId := id
// Only positive IDs are valid for path fragments. An ID of zero indicates a terminal node.
for currId > 0 {
currFragment, ok := pathFragmentsMap[currId]
if !ok {
return "", fmt.Errorf("undefined path fragment id %d", currId)
}
labels = append([]string{currFragment.Label}, labels...)
if currId == currFragment.ParentId {
return "", fmt.Errorf("Fragment cannot refer to itself as parent %#v", currFragment)
}
currId = currFragment.ParentId
}
return filepath.Join(labels...), nil
}