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// Copyright 2016 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 bootstrap
import (
"bytes"
"fmt"
"path/filepath"
"strings"
"github.com/google/blueprint"
"github.com/google/blueprint/deptools"
"github.com/google/blueprint/pathtools"
)
// This file supports globbing source files in Blueprints files.
//
// The build.ninja file needs to be regenerated any time a file matching the glob is added
// or removed. The naive solution is to have the build.ninja file depend on all the
// traversed directories, but this will cause the regeneration step to run every time a
// non-matching file is added to a traversed directory, including backup files created by
// editors.
//
// The solution implemented here optimizes out regenerations when the directory modifications
// don't match the glob by having the build.ninja file depend on an intermedate file that
// is only updated when a file matching the glob is added or removed. The intermediate file
// depends on the traversed directories via a depfile. The depfile is used to avoid build
// errors if a directory is deleted - a direct dependency on the deleted directory would result
// in a build failure with a "missing and no known rule to make it" error.
var (
globCmd = filepath.Join(miniBootstrapDir, "bpglob")
// globRule rule traverses directories to produce a list of files that match $glob
// and writes it to $out if it has changed, and writes the directories to $out.d
GlobRule = pctx.StaticRule("GlobRule",
blueprint.RuleParams{
Command: fmt.Sprintf(`%s -o $out $excludes "$glob"`, globCmd),
CommandDeps: []string{globCmd},
Description: "glob $glob",
Restat: true,
Deps: blueprint.DepsGCC,
Depfile: "$out.d",
},
"glob", "excludes")
)
// GlobFileContext is the subset of ModuleContext and SingletonContext needed by GlobFile
type GlobFileContext interface {
Build(pctx blueprint.PackageContext, params blueprint.BuildParams)
}
// GlobFile creates a rule to write to fileListFile a list of the files that match the specified
// pattern but do not match any of the patterns specified in excludes. The file will include
// appropriate dependencies written to depFile to regenerate the file if and only if the list of
// matching files has changed.
func GlobFile(ctx GlobFileContext, pattern string, excludes []string,
fileListFile, depFile string) {
ctx.Build(pctx, blueprint.BuildParams{
Rule: GlobRule,
Outputs: []string{fileListFile},
Args: map[string]string{
"glob": pattern,
"excludes": joinWithPrefixAndQuote(excludes, "-e "),
},
})
}
func joinWithPrefixAndQuote(strs []string, prefix string) string {
if len(strs) == 0 {
return ""
}
if len(strs) == 1 {
return prefix + `"` + strs[0] + `"`
}
n := len(" ") * (len(strs) - 1)
for _, s := range strs {
n += len(prefix) + len(s) + len(`""`)
}
ret := make([]byte, 0, n)
for i, s := range strs {
if i != 0 {
ret = append(ret, ' ')
}
ret = append(ret, prefix...)
ret = append(ret, '"')
ret = append(ret, s...)
ret = append(ret, '"')
}
return string(ret)
}
// globSingleton collects any glob patterns that were seen by Context and writes out rules to
// re-evaluate them whenever the contents of the searched directories change, and retrigger the
// primary builder if the results change.
type globSingleton struct {
globLister func() []blueprint.GlobPath
writeRule bool
}
func globSingletonFactory(ctx *blueprint.Context) func() blueprint.Singleton {
return func() blueprint.Singleton {
return &globSingleton{
globLister: ctx.Globs,
}
}
}
func (s *globSingleton) GenerateBuildActions(ctx blueprint.SingletonContext) {
for _, g := range s.globLister() {
fileListFile := filepath.Join(BuildDir, ".glob", g.Name)
if s.writeRule {
depFile := fileListFile + ".d"
fileList := strings.Join(g.Files, "\n") + "\n"
pathtools.WriteFileIfChanged(fileListFile, []byte(fileList), 0666)
deptools.WriteDepFile(depFile, fileListFile, g.Deps)
GlobFile(ctx, g.Pattern, g.Excludes, fileListFile, depFile)
} else {
// Make build.ninja depend on the fileListFile
ctx.AddNinjaFileDeps(fileListFile)
}
}
}
func generateGlobNinjaFile(globLister func() []blueprint.GlobPath) ([]byte, []error) {
ctx := blueprint.NewContext()
ctx.RegisterSingletonType("glob", func() blueprint.Singleton {
return &globSingleton{
globLister: globLister,
writeRule: true,
}
})
extraDeps, errs := ctx.ResolveDependencies(nil)
if len(extraDeps) > 0 {
return nil, []error{fmt.Errorf("shouldn't have extra deps")}
}
if len(errs) > 0 {
return nil, errs
}
extraDeps, errs = ctx.PrepareBuildActions(nil)
if len(extraDeps) > 0 {
return nil, []error{fmt.Errorf("shouldn't have extra deps")}
}
if len(errs) > 0 {
return nil, errs
}
buf := bytes.NewBuffer(nil)
err := ctx.WriteBuildFile(buf)
if err != nil {
return nil, []error{err}
}
return buf.Bytes(), nil
}
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