github.com/zhuohuang-hust/src-cbuild@v0.0.0-20230105071821-c7aab3e7c840/builder/tarsum.go (about)

     1  package builder
     2  
     3  import (
     4  	"fmt"
     5  	"io"
     6  	"os"
     7  	"path/filepath"
     8  
     9  	"github.com/docker/docker/pkg/archive"
    10  	"github.com/docker/docker/pkg/chrootarchive"
    11  	"github.com/docker/docker/pkg/ioutils"
    12  	"github.com/docker/docker/pkg/symlink"
    13  	"github.com/docker/docker/pkg/tarsum"
    14  )
    15  
    16  type tarSumContext struct {
    17  	root string
    18  	sums tarsum.FileInfoSums
    19  }
    20  
    21  func (c *tarSumContext) Close() error {
    22  	return os.RemoveAll(c.root)
    23  }
    24  
    25  func convertPathError(err error, cleanpath string) error {
    26  	if err, ok := err.(*os.PathError); ok {
    27  		err.Path = cleanpath
    28  		return err
    29  	}
    30  	return err
    31  }
    32  
    33  func (c *tarSumContext) Open(path string) (io.ReadCloser, error) {
    34  	cleanpath, fullpath, err := c.normalize(path)
    35  	if err != nil {
    36  		return nil, err
    37  	}
    38  	r, err := os.Open(fullpath)
    39  	if err != nil {
    40  		return nil, convertPathError(err, cleanpath)
    41  	}
    42  	return r, nil
    43  }
    44  
    45  func (c *tarSumContext) Stat(path string) (string, FileInfo, error) {
    46  	cleanpath, fullpath, err := c.normalize(path)
    47  	if err != nil {
    48  		return "", nil, err
    49  	}
    50  
    51  	st, err := os.Lstat(fullpath)
    52  	if err != nil {
    53  		return "", nil, convertPathError(err, cleanpath)
    54  	}
    55  
    56  	rel, err := filepath.Rel(c.root, fullpath)
    57  	if err != nil {
    58  		return "", nil, convertPathError(err, cleanpath)
    59  	}
    60  
    61  	// We set sum to path by default for the case where GetFile returns nil.
    62  	// The usual case is if relative path is empty.
    63  	sum := path
    64  	// Use the checksum of the followed path(not the possible symlink) because
    65  	// this is the file that is actually copied.
    66  	if tsInfo := c.sums.GetFile(filepath.ToSlash(rel)); tsInfo != nil {
    67  		sum = tsInfo.Sum()
    68  	}
    69  	fi := &HashedFileInfo{PathFileInfo{st, fullpath, filepath.Base(cleanpath)}, sum}
    70  	return rel, fi, nil
    71  }
    72  
    73  // MakeTarSumContext returns a build Context from a tar stream.
    74  //
    75  // It extracts the tar stream to a temporary folder that is deleted as soon as
    76  // the Context is closed.
    77  // As the extraction happens, a tarsum is calculated for every file, and the set of
    78  // all those sums then becomes the source of truth for all operations on this Context.
    79  //
    80  // Closing tarStream has to be done by the caller.
    81  func MakeTarSumContext(tarStream io.Reader) (ModifiableContext, error) {
    82  	root, err := ioutils.TempDir("", "docker-builder")
    83  	if err != nil {
    84  		return nil, err
    85  	}
    86  
    87  	tsc := &tarSumContext{root: root}
    88  
    89  	// Make sure we clean-up upon error.  In the happy case the caller
    90  	// is expected to manage the clean-up
    91  	defer func() {
    92  		if err != nil {
    93  			tsc.Close()
    94  		}
    95  	}()
    96  
    97  	decompressedStream, err := archive.DecompressStream(tarStream)
    98  	if err != nil {
    99  		return nil, err
   100  	}
   101  
   102  	sum, err := tarsum.NewTarSum(decompressedStream, true, tarsum.Version1)
   103  	if err != nil {
   104  		return nil, err
   105  	}
   106  
   107  	if err := chrootarchive.Untar(sum, root, nil); err != nil {
   108  		return nil, err
   109  	}
   110  
   111  	tsc.sums = sum.GetSums()
   112  
   113  	return tsc, nil
   114  }
   115  
   116  func (c *tarSumContext) normalize(path string) (cleanpath, fullpath string, err error) {
   117  	cleanpath = filepath.Clean(string(os.PathSeparator) + path)[1:]
   118  	fullpath, err = symlink.FollowSymlinkInScope(filepath.Join(c.root, path), c.root)
   119  	if err != nil {
   120  		return "", "", fmt.Errorf("Forbidden path outside the build context: %s (%s)", path, fullpath)
   121  	}
   122  	_, err = os.Lstat(fullpath)
   123  	if err != nil {
   124  		return "", "", convertPathError(err, path)
   125  	}
   126  	return
   127  }
   128  
   129  func (c *tarSumContext) Walk(root string, walkFn WalkFunc) error {
   130  	root = filepath.Join(c.root, filepath.Join(string(filepath.Separator), root))
   131  	return filepath.Walk(root, func(fullpath string, info os.FileInfo, err error) error {
   132  		rel, err := filepath.Rel(c.root, fullpath)
   133  		if err != nil {
   134  			return err
   135  		}
   136  		if rel == "." {
   137  			return nil
   138  		}
   139  
   140  		sum := rel
   141  		if tsInfo := c.sums.GetFile(filepath.ToSlash(rel)); tsInfo != nil {
   142  			sum = tsInfo.Sum()
   143  		}
   144  		fi := &HashedFileInfo{PathFileInfo{FileInfo: info, FilePath: fullpath}, sum}
   145  		if err := walkFn(rel, fi, nil); err != nil {
   146  			return err
   147  		}
   148  		return nil
   149  	})
   150  }
   151  
   152  func (c *tarSumContext) Remove(path string) error {
   153  	_, fullpath, err := c.normalize(path)
   154  	if err != nil {
   155  		return err
   156  	}
   157  	return os.RemoveAll(fullpath)
   158  }