reparse_windows.go

     1  // Copyright 2016 The Go Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package windows
     6  
     7  import (
     8  	"syscall"
     9  	"unsafe"
    10  )
    11  
    12  // Reparse tag values are taken from
    13  // https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-fscc/c8e77b37-3909-4fe6-a4ea-2b9d423b1ee4
    14  const (
    15  	FSCTL_SET_REPARSE_POINT    = 0x000900A4
    16  	IO_REPARSE_TAG_MOUNT_POINT = 0xA0000003
    17  	IO_REPARSE_TAG_DEDUP       = 0x80000013
    18  	IO_REPARSE_TAG_AF_UNIX     = 0x80000023
    19  
    20  	SYMLINK_FLAG_RELATIVE = 1
    21  )
    22  
    23  // These structures are described
    24  // in https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-fscc/ca069dad-ed16-42aa-b057-b6b207f447cc
    25  // and https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-fscc/b41f1cbf-10df-4a47-98d4-1c52a833d913.
    26  
    27  type REPARSE_DATA_BUFFER struct {
    28  	ReparseTag        uint32
    29  	ReparseDataLength uint16
    30  	Reserved          uint16
    31  	DUMMYUNIONNAME    byte
    32  }
    33  
    34  // REPARSE_DATA_BUFFER_HEADER is a common part of REPARSE_DATA_BUFFER structure.
    35  type REPARSE_DATA_BUFFER_HEADER struct {
    36  	ReparseTag uint32
    37  	// The size, in bytes, of the reparse data that follows
    38  	// the common portion of the REPARSE_DATA_BUFFER element.
    39  	// This value is the length of the data starting at the
    40  	// SubstituteNameOffset field.
    41  	ReparseDataLength uint16
    42  	Reserved          uint16
    43  }
    44  
    45  type SymbolicLinkReparseBuffer struct {
    46  	// The integer that contains the offset, in bytes,
    47  	// of the substitute name string in the PathBuffer array,
    48  	// computed as an offset from byte 0 of PathBuffer. Note that
    49  	// this offset must be divided by 2 to get the array index.
    50  	SubstituteNameOffset uint16
    51  	// The integer that contains the length, in bytes, of the
    52  	// substitute name string. If this string is null-terminated,
    53  	// SubstituteNameLength does not include the Unicode null character.
    54  	SubstituteNameLength uint16
    55  	// PrintNameOffset is similar to SubstituteNameOffset.
    56  	PrintNameOffset uint16
    57  	// PrintNameLength is similar to SubstituteNameLength.
    58  	PrintNameLength uint16
    59  	// Flags specifies whether the substitute name is a full path name or
    60  	// a path name relative to the directory containing the symbolic link.
    61  	Flags      uint32
    62  	PathBuffer [1]uint16
    63  }
    64  
    65  // Path returns path stored in rb.
    66  func (rb *SymbolicLinkReparseBuffer) Path() string {
    67  	n1 := rb.SubstituteNameOffset / 2
    68  	n2 := (rb.SubstituteNameOffset + rb.SubstituteNameLength) / 2
    69  	return syscall.UTF16ToString((*[0xffff]uint16)(unsafe.Pointer(&rb.PathBuffer[0]))[n1:n2:n2])
    70  }
    71  
    72  type MountPointReparseBuffer struct {
    73  	// The integer that contains the offset, in bytes,
    74  	// of the substitute name string in the PathBuffer array,
    75  	// computed as an offset from byte 0 of PathBuffer. Note that
    76  	// this offset must be divided by 2 to get the array index.
    77  	SubstituteNameOffset uint16
    78  	// The integer that contains the length, in bytes, of the
    79  	// substitute name string. If this string is null-terminated,
    80  	// SubstituteNameLength does not include the Unicode null character.
    81  	SubstituteNameLength uint16
    82  	// PrintNameOffset is similar to SubstituteNameOffset.
    83  	PrintNameOffset uint16
    84  	// PrintNameLength is similar to SubstituteNameLength.
    85  	PrintNameLength uint16
    86  	PathBuffer      [1]uint16
    87  }
    88  
    89  // Path returns path stored in rb.
    90  func (rb *MountPointReparseBuffer) Path() string {
    91  	n1 := rb.SubstituteNameOffset / 2
    92  	n2 := (rb.SubstituteNameOffset + rb.SubstituteNameLength) / 2
    93  	return syscall.UTF16ToString((*[0xffff]uint16)(unsafe.Pointer(&rb.PathBuffer[0]))[n1:n2:n2])
    94  }
    95
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