copy_linux.go

Documentation: github.com/containerd/continuity/fs

     1  /*
     2     Copyright The containerd Authors.
     3  
     4     Licensed under the Apache License, Version 2.0 (the "License");
     5     you may not use this file except in compliance with the License.
     6     You may obtain a copy of the License at
     7  
     8         http://www.apache.org/licenses/LICENSE-2.0
     9  
    10     Unless required by applicable law or agreed to in writing, software
    11     distributed under the License is distributed on an "AS IS" BASIS,
    12     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13     See the License for the specific language governing permissions and
    14     limitations under the License.
    15  */
    16  
    17  package fs
    18  
    19  import (
    20  	"fmt"
    21  	"os"
    22  	"syscall"
    23  
    24  	"github.com/containerd/continuity/sysx"
    25  	"golang.org/x/sys/unix"
    26  )
    27  
    28  func copyFileInfo(fi os.FileInfo, src, name string) error {
    29  	st := fi.Sys().(*syscall.Stat_t)
    30  	if err := os.Lchown(name, int(st.Uid), int(st.Gid)); err != nil {
    31  		if os.IsPermission(err) {
    32  			// Normally if uid/gid are the same this would be a no-op, but some
    33  			// filesystems may still return EPERM... for instance NFS does this.
    34  			// In such a case, this is not an error.
    35  			if dstStat, err2 := os.Lstat(name); err2 == nil {
    36  				st2 := dstStat.Sys().(*syscall.Stat_t)
    37  				if st.Uid == st2.Uid && st.Gid == st2.Gid {
    38  					err = nil
    39  				}
    40  			}
    41  		}
    42  		if err != nil {
    43  			return fmt.Errorf("failed to chown %s: %w", name, err)
    44  		}
    45  	}
    46  
    47  	if (fi.Mode() & os.ModeSymlink) != os.ModeSymlink {
    48  		if err := os.Chmod(name, fi.Mode()); err != nil {
    49  			return fmt.Errorf("failed to chmod %s: %w", name, err)
    50  		}
    51  	}
    52  
    53  	timespec := []unix.Timespec{
    54  		unix.NsecToTimespec(syscall.TimespecToNsec(StatAtime(st))),
    55  		unix.NsecToTimespec(syscall.TimespecToNsec(StatMtime(st))),
    56  	}
    57  	if err := unix.UtimesNanoAt(unix.AT_FDCWD, name, timespec, unix.AT_SYMLINK_NOFOLLOW); err != nil {
    58  		return fmt.Errorf("failed to utime %s: %w", name, err)
    59  	}
    60  
    61  	return nil
    62  }
    63  
    64  func copyXAttrs(dst, src string, excludes map[string]struct{}, errorHandler XAttrErrorHandler) error {
    65  	xattrKeys, err := sysx.LListxattr(src)
    66  	if err != nil {
    67  		e := fmt.Errorf("failed to list xattrs on %s: %w", src, err)
    68  		if errorHandler != nil {
    69  			e = errorHandler(dst, src, "", e)
    70  		}
    71  		return e
    72  	}
    73  	for _, xattr := range xattrKeys {
    74  		if _, exclude := excludes[xattr]; exclude {
    75  			continue
    76  		}
    77  		data, err := sysx.LGetxattr(src, xattr)
    78  		if err != nil {
    79  			e := fmt.Errorf("failed to get xattr %q on %s: %w", xattr, src, err)
    80  			if errorHandler != nil {
    81  				if e = errorHandler(dst, src, xattr, e); e == nil {
    82  					continue
    83  				}
    84  			}
    85  			return e
    86  		}
    87  		if err := sysx.LSetxattr(dst, xattr, data, 0); err != nil {
    88  			e := fmt.Errorf("failed to set xattr %q on %s: %w", xattr, dst, err)
    89  			if errorHandler != nil {
    90  				if e = errorHandler(dst, src, xattr, e); e == nil {
    91  					continue
    92  				}
    93  			}
    94  			return e
    95  		}
    96  	}
    97  
    98  	return nil
    99  }
   100
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