github.com/blixtra/rkt@v0.8.1-0.20160204105720-ab0d1add1a43/pkg/fileutil/fileutil_linux.go (about)

     1  // Copyright 2014 Red Hat, Inc
     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  // +build linux
    16  
    17  package fileutil
    18  
    19  import (
    20  	"os"
    21  	"syscall"
    22  	"unsafe"
    23  )
    24  
    25  func hasHardLinks(fi os.FileInfo) bool {
    26  	// On directories, Nlink doesn't make sense when checking for hard links
    27  	return !fi.IsDir() && fi.Sys().(*syscall.Stat_t).Nlink > 1
    28  }
    29  
    30  func getInode(fi os.FileInfo) uint64 {
    31  	return fi.Sys().(*syscall.Stat_t).Ino
    32  }
    33  
    34  // These functions are from github.com/docker/docker/pkg/system
    35  
    36  // TODO(sgotti) waiting for a utimensat functions accepting flags and a
    37  // LUtimesNano using it in https://github.com/golang/sys/
    38  func LUtimesNano(path string, ts []syscall.Timespec) error {
    39  	// These are not currently available in syscall
    40  	AT_FDCWD := -100
    41  	AT_SYMLINK_NOFOLLOW := 0x100
    42  
    43  	var _path *byte
    44  	_path, err := syscall.BytePtrFromString(path)
    45  	if err != nil {
    46  		return err
    47  	}
    48  
    49  	if _, _, err := syscall.Syscall6(syscall.SYS_UTIMENSAT, uintptr(AT_FDCWD), uintptr(unsafe.Pointer(_path)), uintptr(unsafe.Pointer(&ts[0])), uintptr(AT_SYMLINK_NOFOLLOW), 0, 0); err != 0 && err != syscall.ENOSYS {
    50  		return err
    51  	}
    52  
    53  	return nil
    54  }
    55  
    56  // Returns a nil slice and nil error if the xattr is not set
    57  func Lgetxattr(path string, attr string) ([]byte, error) {
    58  	pathBytes, err := syscall.BytePtrFromString(path)
    59  	if err != nil {
    60  		return nil, err
    61  	}
    62  	attrBytes, err := syscall.BytePtrFromString(attr)
    63  	if err != nil {
    64  		return nil, err
    65  	}
    66  
    67  	dest := make([]byte, 128)
    68  	destBytes := unsafe.Pointer(&dest[0])
    69  	sz, _, errno := syscall.Syscall6(syscall.SYS_LGETXATTR, uintptr(unsafe.Pointer(pathBytes)), uintptr(unsafe.Pointer(attrBytes)), uintptr(destBytes), uintptr(len(dest)), 0, 0)
    70  	if errno == syscall.ENODATA {
    71  		return nil, nil
    72  	}
    73  	if errno == syscall.ERANGE {
    74  		dest = make([]byte, sz)
    75  		destBytes := unsafe.Pointer(&dest[0])
    76  		sz, _, errno = syscall.Syscall6(syscall.SYS_LGETXATTR, uintptr(unsafe.Pointer(pathBytes)), uintptr(unsafe.Pointer(attrBytes)), uintptr(destBytes), uintptr(len(dest)), 0, 0)
    77  	}
    78  	if errno != 0 {
    79  		return nil, errno
    80  	}
    81  
    82  	return dest[:sz], nil
    83  }
    84  
    85  var _zero uintptr
    86  
    87  func Lsetxattr(path string, attr string, data []byte, flags int) error {
    88  	pathBytes, err := syscall.BytePtrFromString(path)
    89  	if err != nil {
    90  		return err
    91  	}
    92  	attrBytes, err := syscall.BytePtrFromString(attr)
    93  	if err != nil {
    94  		return err
    95  	}
    96  	var dataBytes unsafe.Pointer
    97  	if len(data) > 0 {
    98  		dataBytes = unsafe.Pointer(&data[0])
    99  	} else {
   100  		dataBytes = unsafe.Pointer(&_zero)
   101  	}
   102  	_, _, errno := syscall.Syscall6(syscall.SYS_LSETXATTR, uintptr(unsafe.Pointer(pathBytes)), uintptr(unsafe.Pointer(attrBytes)), uintptr(dataBytes), uintptr(len(data)), uintptr(flags), 0)
   103  	if errno != 0 {
   104  		return errno
   105  	}
   106  	return nil
   107  }