go_path.go

Documentation: github.com/bazelbuild/rules_go/go/tools/builders

     1  // Copyright 2018 The Bazel Authors. 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 main
    16  
    17  import (
    18  	"archive/zip"
    19  	"encoding/json"
    20  	"errors"
    21  	"flag"
    22  	"fmt"
    23  	"io"
    24  	"io/ioutil"
    25  	"log"
    26  	"os"
    27  	"path/filepath"
    28  )
    29  
    30  type mode int
    31  
    32  const (
    33  	invalidMode mode = iota
    34  	archiveMode
    35  	copyMode
    36  	linkMode
    37  )
    38  
    39  func modeFromString(s string) (mode, error) {
    40  	switch s {
    41  	case "archive":
    42  		return archiveMode, nil
    43  	case "copy":
    44  		return copyMode, nil
    45  	case "link":
    46  		return linkMode, nil
    47  	default:
    48  		return invalidMode, fmt.Errorf("invalid mode: %s", s)
    49  	}
    50  }
    51  
    52  type manifestEntry struct {
    53  	Src, Dst string
    54  }
    55  
    56  func main() {
    57  	log.SetPrefix("GoPath: ")
    58  	log.SetFlags(0)
    59  	if err := run(os.Args[1:]); err != nil {
    60  		log.Fatal(err)
    61  	}
    62  }
    63  
    64  func run(args []string) error {
    65  	var manifest, out string
    66  	flags := flag.NewFlagSet("go_path", flag.ContinueOnError)
    67  	flags.StringVar(&manifest, "manifest", "", "name of json file listing files to include")
    68  	flags.StringVar(&out, "out", "", "output file or directory")
    69  	modeFlag := flags.String("mode", "", "copy, link, or archive")
    70  	if err := flags.Parse(args); err != nil {
    71  		return err
    72  	}
    73  	if manifest == "" {
    74  		return errors.New("-manifest not set")
    75  	}
    76  	if out == "" {
    77  		return errors.New("-out not set")
    78  	}
    79  	if *modeFlag == "" {
    80  		return errors.New("-mode not set")
    81  	}
    82  	mode, err := modeFromString(*modeFlag)
    83  	if err != nil {
    84  		return err
    85  	}
    86  
    87  	entries, err := readManifest(manifest)
    88  	if err != nil {
    89  		return err
    90  	}
    91  
    92  	switch mode {
    93  	case archiveMode:
    94  		err = archivePath(out, entries)
    95  	case copyMode:
    96  		err = copyPath(out, entries)
    97  	case linkMode:
    98  		err = linkPath(out, entries)
    99  	}
   100  	return err
   101  }
   102  
   103  func readManifest(path string) ([]manifestEntry, error) {
   104  	data, err := ioutil.ReadFile(path)
   105  	if err != nil {
   106  		return nil, fmt.Errorf("error reading manifest: %v", err)
   107  	}
   108  	var entries []manifestEntry
   109  	if err := json.Unmarshal(data, &entries); err != nil {
   110  		return nil, fmt.Errorf("error unmarshalling manifest %s: %v", path, err)
   111  	}
   112  	return entries, nil
   113  }
   114  
   115  func archivePath(out string, manifest []manifestEntry) (err error) {
   116  	outFile, err := os.Create(out)
   117  	if err != nil {
   118  		return err
   119  	}
   120  	defer func() {
   121  		if e := outFile.Close(); err == nil && e != nil {
   122  			err = fmt.Errorf("error closing archive %s: %v", out, e)
   123  		}
   124  	}()
   125  	outZip := zip.NewWriter(outFile)
   126  
   127  	for _, entry := range manifest {
   128  		srcFile, err := os.Open(abs(filepath.FromSlash(entry.Src)))
   129  		if err != nil {
   130  			return err
   131  		}
   132  		w, err := outZip.Create(entry.Dst)
   133  		if err != nil {
   134  			srcFile.Close()
   135  			return err
   136  		}
   137  		if _, err := io.Copy(w, srcFile); err != nil {
   138  			srcFile.Close()
   139  			return err
   140  		}
   141  		if err := srcFile.Close(); err != nil {
   142  			return err
   143  		}
   144  	}
   145  
   146  	if err := outZip.Close(); err != nil {
   147  		return fmt.Errorf("error constructing archive %s: %v", out, err)
   148  	}
   149  	return nil
   150  }
   151  
   152  func copyPath(out string, manifest []manifestEntry) error {
   153  	if err := os.MkdirAll(out, 0777); err != nil {
   154  		return err
   155  	}
   156  	for _, entry := range manifest {
   157  		dst := abs(filepath.Join(out, filepath.FromSlash(entry.Dst)))
   158  		if err := os.MkdirAll(filepath.Dir(dst), 0777); err != nil {
   159  			return err
   160  		}
   161  		srcFile, err := os.Open(abs(filepath.FromSlash(entry.Src)))
   162  		if err != nil {
   163  			return err
   164  		}
   165  		dstFile, err := os.Create(dst)
   166  		if err != nil {
   167  			srcFile.Close()
   168  			return err
   169  		}
   170  		if _, err := io.Copy(dstFile, srcFile); err != nil {
   171  			dstFile.Close()
   172  			srcFile.Close()
   173  			return err
   174  		}
   175  		srcFile.Close()
   176  		if err := dstFile.Close(); err != nil {
   177  			return err
   178  		}
   179  	}
   180  	return nil
   181  }
   182  
   183  func linkPath(out string, manifest []manifestEntry) error {
   184  	// out directory may already exist and may contain old symlinks. Delete.
   185  	if err := os.RemoveAll(out); err != nil {
   186  		return err
   187  	}
   188  	if err := os.MkdirAll(out, 0777); err != nil {
   189  		return err
   190  	}
   191  	for _, entry := range manifest {
   192  		dst := filepath.Join(out, filepath.FromSlash(entry.Dst))
   193  		dstDir := filepath.Dir(dst)
   194  		src, _ := filepath.Rel(dstDir, entry.Src)
   195  		if err := os.MkdirAll(dstDir, 0777); err != nil {
   196  			return err
   197  		}
   198  		if err := os.Symlink(src, dst); err != nil {
   199  			return err
   200  		}
   201  	}
   202  	return nil
   203  }
   204
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