go.chromium.org/luci@v0.0.0-20240309015107-7cdc2e660f33/cipkg/base/generators/fs.go (about)

     1  // Copyright 2023 The LUCI Authors.
     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 generators
    16  
    17  import (
    18  	"archive/tar"
    19  	"fmt"
    20  	"hash"
    21  	"io"
    22  	"io/fs"
    23  )
    24  
    25  func getHashFromFile(name string, src fs.File, h hash.Hash) error {
    26  	// Tar is used for calculating hash from files - including metadata - in a
    27  	// simple way.
    28  	tw := tar.NewWriter(h)
    29  	defer tw.Close()
    30  	return hashFile(name, src, tw)
    31  }
    32  
    33  func getHashFromFS(src fs.FS, h hash.Hash) error {
    34  	// Tar is used for calculating hash from files - including metadata - in a
    35  	// simple way.
    36  	tw := tar.NewWriter(h)
    37  	defer tw.Close()
    38  
    39  	return fs.WalkDir(src, ".", func(name string, d fs.DirEntry, err error) error {
    40  		if err != nil {
    41  			return err
    42  		}
    43  
    44  		var info fs.FileInfo
    45  		// Resolve symlink
    46  		if d.Type() == fs.ModeSymlink {
    47  			f, err := src.Open(name)
    48  			if err != nil {
    49  				return fmt.Errorf("failed to open file: %s: %w", name, err)
    50  			}
    51  			defer f.Close()
    52  			if info, err = f.Stat(); err != nil {
    53  				return fmt.Errorf("failed to stat file: %s: %w", name, err)
    54  			}
    55  		} else {
    56  			if info, err = fs.Stat(src, name); err != nil {
    57  				return fmt.Errorf("failed to stat file: %s: %w", name, err)
    58  			}
    59  		}
    60  
    61  		switch info.Mode().Type() {
    62  		case fs.ModeSymlink:
    63  			return fmt.Errorf("unexpected symlink: %s", name)
    64  		case fs.ModeDir:
    65  			if err := tw.WriteHeader(&tar.Header{
    66  				Typeflag: tar.TypeDir,
    67  				Name:     name,
    68  				Mode:     int64(info.Mode()),
    69  			}); err != nil {
    70  				return fmt.Errorf("failed to write header: %s: %w", name, err)
    71  			}
    72  		default: // Regular File
    73  			f, err := src.Open(name)
    74  			if err != nil {
    75  				return fmt.Errorf("failed to open file: %s: %w", name, err)
    76  			}
    77  			defer f.Close()
    78  			if err := hashFile(name, f, tw); err != nil {
    79  				return err
    80  			}
    81  		}
    82  		return nil
    83  	})
    84  }
    85  
    86  func hashFile(name string, src fs.File, tw *tar.Writer) error {
    87  	info, err := src.Stat()
    88  	if err != nil {
    89  		return fmt.Errorf("failed to stat file: %s: %w", name, err)
    90  	}
    91  	if err := tw.WriteHeader(&tar.Header{
    92  		Typeflag: tar.TypeReg,
    93  		Name:     name,
    94  		Mode:     int64(info.Mode()),
    95  		Size:     info.Size(),
    96  	}); err != nil {
    97  		return fmt.Errorf("failed to write header: %s: %w", name, err)
    98  	}
    99  	if _, err := io.Copy(tw, src); err != nil {
   100  		return fmt.Errorf("failed to write file: %s: %w", name, err)
   101  	}
   102  	return nil
   103  }