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      1 // Copyright 2016 Google Inc. All rights reserved.
      2 //
      3 // Licensed under the Apache License, Version 2.0 (the "License");
      4 // you may not use this file except in compliance with the License.
      5 // You may obtain a copy of the License at
      6 //
      7 //     http://www.apache.org/licenses/LICENSE-2.0
      8 //
      9 // Unless required by applicable law or agreed to in writing, software
     10 // distributed under the License is distributed on an "AS IS" BASIS,
     11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     12 // See the License for the specific language governing permissions and
     13 // limitations under the License.
     14 
     15 package bootstrap
     16 
     17 import (
     18 	"fmt"
     19 	"path/filepath"
     20 	"strings"
     21 
     22 	"github.com/google/blueprint"
     23 	"github.com/google/blueprint/deptools"
     24 	"github.com/google/blueprint/pathtools"
     25 )
     26 
     27 // This file supports globbing source files in Blueprints files.
     28 //
     29 // The build.ninja file needs to be regenerated any time a file matching the glob is added
     30 // or removed.  The naive solution is to have the build.ninja file depend on all the
     31 // traversed directories, but this will cause the regeneration step to run every time a
     32 // non-matching file is added to a traversed directory, including backup files created by
     33 // editors.
     34 //
     35 // The solution implemented here optimizes out regenerations when the directory modifications
     36 // don't match the glob by having the build.ninja file depend on an intermedate file that
     37 // is only updated when a file matching the glob is added or removed.  The intermediate file
     38 // depends on the traversed directories via a depfile.  The depfile is used to avoid build
     39 // errors if a directory is deleted - a direct dependency on the deleted directory would result
     40 // in a build failure with a "missing and no known rule to make it" error.
     41 
     42 var (
     43 	globCmd = filepath.Join("$BinDir", "bpglob")
     44 
     45 	// globRule rule traverses directories to produce a list of files that match $glob
     46 	// and writes it to $out if it has changed, and writes the directories to $out.d
     47 	GlobRule = pctx.StaticRule("GlobRule",
     48 		blueprint.RuleParams{
     49 			Command:     fmt.Sprintf(`%s -o $out $excludes "$glob"`, globCmd),
     50 			CommandDeps: []string{globCmd},
     51 			Description: "glob $glob",
     52 
     53 			Restat:  true,
     54 			Deps:    blueprint.DepsGCC,
     55 			Depfile: "$out.d",
     56 		},
     57 		"glob", "excludes")
     58 )
     59 
     60 // GlobFileContext is the subset of ModuleContext and SingletonContext needed by GlobFile
     61 type GlobFileContext interface {
     62 	Build(pctx blueprint.PackageContext, params blueprint.BuildParams)
     63 }
     64 
     65 // GlobFile creates a rule to write to fileListFile a list of the files that match the specified
     66 // pattern but do not match any of the patterns specified in excludes.  The file will include
     67 // appropriate dependencies written to depFile to regenerate the file if and only if the list of
     68 // matching files has changed.
     69 func GlobFile(ctx GlobFileContext, pattern string, excludes []string,
     70 	fileListFile, depFile string) {
     71 
     72 	ctx.Build(pctx, blueprint.BuildParams{
     73 		Rule:    GlobRule,
     74 		Outputs: []string{fileListFile},
     75 		Args: map[string]string{
     76 			"glob":     pattern,
     77 			"excludes": joinWithPrefixAndQuote(excludes, "-e "),
     78 		},
     79 	})
     80 }
     81 
     82 func joinWithPrefixAndQuote(strs []string, prefix string) string {
     83 	if len(strs) == 0 {
     84 		return ""
     85 	}
     86 
     87 	if len(strs) == 1 {
     88 		return prefix + `"` + strs[0] + `"`
     89 	}
     90 
     91 	n := len(" ") * (len(strs) - 1)
     92 	for _, s := range strs {
     93 		n += len(prefix) + len(s) + len(`""`)
     94 	}
     95 
     96 	ret := make([]byte, 0, n)
     97 	for i, s := range strs {
     98 		if i != 0 {
     99 			ret = append(ret, ' ')
    100 		}
    101 		ret = append(ret, prefix...)
    102 		ret = append(ret, '"')
    103 		ret = append(ret, s...)
    104 		ret = append(ret, '"')
    105 	}
    106 	return string(ret)
    107 }
    108 
    109 // globSingleton collects any glob patterns that were seen by Context and writes out rules to
    110 // re-evaluate them whenever the contents of the searched directories change, and retrigger the
    111 // primary builder if the results change.
    112 type globSingleton struct {
    113 	globLister func() []blueprint.GlobPath
    114 }
    115 
    116 func globSingletonFactory(ctx *blueprint.Context) func() blueprint.Singleton {
    117 	return func() blueprint.Singleton {
    118 		return &globSingleton{
    119 			globLister: ctx.Globs,
    120 		}
    121 	}
    122 }
    123 
    124 func (s *globSingleton) GenerateBuildActions(ctx blueprint.SingletonContext) {
    125 	for _, g := range s.globLister() {
    126 		fileListFile := filepath.Join(BuildDir, ".glob", g.Name)
    127 		depFile := fileListFile + ".d"
    128 
    129 		fileList := strings.Join(g.Files, "\n") + "\n"
    130 		pathtools.WriteFileIfChanged(fileListFile, []byte(fileList), 0666)
    131 		deptools.WriteDepFile(depFile, fileListFile, g.Deps)
    132 
    133 		GlobFile(ctx, g.Pattern, g.Excludes, fileListFile, depFile)
    134 
    135 		// Make build.ninja depend on the fileListFile
    136 		ctx.AddNinjaFileDeps(fileListFile)
    137 	}
    138 }
    139