1 | /* $Id: symlink-win.cpp 76553 2019-01-01 01:45:53Z vboxsync $ */
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2 | /** @file
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3 | * IPRT - Symbolic Links, Windows.
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4 | */
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5 |
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6 | /*
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7 | * Copyright (C) 2010-2019 Oracle Corporation
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8 | *
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9 | * This file is part of VirtualBox Open Source Edition (OSE), as
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10 | * available from http://www.virtualbox.org. This file is free software;
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11 | * you can redistribute it and/or modify it under the terms of the GNU
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12 | * General Public License (GPL) as published by the Free Software
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13 | * Foundation, in version 2 as it comes in the "COPYING" file of the
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14 | * VirtualBox OSE distribution. VirtualBox OSE is distributed in the
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15 | * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
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16 | *
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17 | * The contents of this file may alternatively be used under the terms
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18 | * of the Common Development and Distribution License Version 1.0
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19 | * (CDDL) only, as it comes in the "COPYING.CDDL" file of the
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20 | * VirtualBox OSE distribution, in which case the provisions of the
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21 | * CDDL are applicable instead of those of the GPL.
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22 | *
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23 | * You may elect to license modified versions of this file under the
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24 | * terms and conditions of either the GPL or the CDDL or both.
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25 | */
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26 |
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27 |
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28 | /*********************************************************************************************************************************
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29 | * Header Files *
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30 | *********************************************************************************************************************************/
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31 | #define LOG_GROUP RTLOGGROUP_SYMLINK
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32 | #include <iprt/win/windows.h>
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33 |
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34 | #include <iprt/symlink.h>
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35 | #include "internal-r3-win.h"
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36 |
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37 | #include <iprt/assert.h>
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38 | #include <iprt/err.h>
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39 | #include <iprt/log.h>
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40 | #include <iprt/path.h>
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41 | #include <iprt/mem.h>
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42 | #include <iprt/string.h>
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43 | #include <iprt/utf16.h>
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44 | #include "internal/path.h"
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45 |
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46 |
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47 |
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48 | /*********************************************************************************************************************************
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49 | * Structures and Typedefs *
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50 | *********************************************************************************************************************************/
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51 | typedef struct MY_REPARSE_DATA_BUFFER
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52 | {
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53 | ULONG ReparseTag;
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54 | #define MY_IO_REPARSE_TAG_SYMLINK 0xa000000c
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55 | #define MY_IO_REPARSE_TAG_MOUNT_POINT 0xa0000003
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56 |
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57 | USHORT ReparseDataLength;
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58 | USHORT Reserved;
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59 | union
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60 | {
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61 | struct
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62 | {
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63 | USHORT SubstituteNameOffset;
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64 | USHORT SubstituteNameLength;
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65 | USHORT PrintNameOffset;
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66 | USHORT PrintNameLength;
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67 | ULONG Flags;
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68 | #define MY_SYMLINK_FLAG_RELATIVE 1
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69 | WCHAR PathBuffer[1];
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70 | } SymbolicLinkReparseBuffer;
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71 | struct
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72 | {
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73 | USHORT SubstituteNameOffset;
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74 | USHORT SubstituteNameLength;
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75 | USHORT PrintNameOffset;
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76 | USHORT PrintNameLength;
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77 | WCHAR PathBuffer[1];
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78 | } MountPointReparseBuffer;
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79 | struct
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80 | {
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81 | UCHAR DataBuffer[1];
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82 | } GenericReparseBuffer;
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83 | };
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84 | } MY_REPARSE_DATA_BUFFER;
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85 | #define MY_FSCTL_GET_REPARSE_POINT CTL_CODE(FILE_DEVICE_FILE_SYSTEM, 42, METHOD_BUFFERED, FILE_ANY_ACCESS)
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86 |
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87 |
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88 | RTDECL(bool) RTSymlinkExists(const char *pszSymlink)
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89 | {
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90 | bool fRc = false;
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91 | RTFSOBJINFO ObjInfo;
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92 | int rc = RTPathQueryInfoEx(pszSymlink, &ObjInfo, RTFSOBJATTRADD_NOTHING, RTPATH_F_ON_LINK);
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93 | if (RT_SUCCESS(rc))
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94 | fRc = RTFS_IS_SYMLINK(ObjInfo.Attr.fMode);
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95 |
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96 | LogFlow(("RTSymlinkExists(%p={%s}): returns %RTbool\n", pszSymlink, pszSymlink, fRc));
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97 | return fRc;
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98 | }
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99 |
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100 |
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101 | RTDECL(bool) RTSymlinkIsDangling(const char *pszSymlink)
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102 | {
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103 | bool fRc = false;
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104 | RTFSOBJINFO ObjInfo;
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105 | int rc = RTPathQueryInfoEx(pszSymlink, &ObjInfo, RTFSOBJATTRADD_NOTHING, RTPATH_F_ON_LINK);
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106 | if (RT_SUCCESS(rc))
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107 | {
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108 | fRc = RTFS_IS_SYMLINK(ObjInfo.Attr.fMode);
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109 | if (fRc)
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110 | {
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111 | rc = RTPathQueryInfoEx(pszSymlink, &ObjInfo, RTFSOBJATTRADD_NOTHING, RTPATH_F_FOLLOW_LINK);
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112 | fRc = !RT_SUCCESS_NP(rc);
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113 | }
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114 | }
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115 |
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116 | LogFlow(("RTSymlinkIsDangling(%p={%s}): returns %RTbool\n", pszSymlink, pszSymlink, fRc));
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117 | return fRc;
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118 | }
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119 |
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120 |
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121 | RTDECL(int) RTSymlinkCreate(const char *pszSymlink, const char *pszTarget, RTSYMLINKTYPE enmType, uint32_t fCreate)
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122 | {
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123 | /*
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124 | * Validate the input.
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125 | */
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126 | AssertReturn(enmType > RTSYMLINKTYPE_INVALID && enmType < RTSYMLINKTYPE_END, VERR_INVALID_PARAMETER);
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127 | AssertPtrReturn(pszSymlink, VERR_INVALID_POINTER);
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128 | AssertPtrReturn(pszTarget, VERR_INVALID_POINTER);
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129 | RT_NOREF_PV(fCreate);
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130 |
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131 | /*
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132 | * Resolve the API.
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133 | */
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134 | typedef BOOLEAN (WINAPI *PFNCREATESYMBOLICLINKW)(LPCWSTR, LPCWSTR, DWORD);
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135 | static PFNCREATESYMBOLICLINKW s_pfnCreateSymbolicLinkW = NULL;
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136 | static bool s_fTried = FALSE;
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137 | if (!s_fTried)
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138 | {
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139 | PFNCREATESYMBOLICLINKW pfn = (PFNCREATESYMBOLICLINKW)GetProcAddress(g_hModKernel32, "CreateSymbolicLinkW");
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140 | if (pfn)
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141 | s_pfnCreateSymbolicLinkW = pfn;
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142 | s_fTried = true;
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143 | }
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144 | if (!s_pfnCreateSymbolicLinkW)
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145 | {
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146 | LogFlow(("RTSymlinkCreate(%p={%s}, %p={%s}, %d, %#x): returns VERR_NOT_SUPPORTED - Windows API not found\n",
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147 | pszSymlink, pszSymlink, pszTarget, pszTarget, enmType, fCreate));
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148 | return VERR_NOT_SUPPORTED;
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149 | }
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150 |
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151 | /*
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152 | * Convert the paths.
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153 | */
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154 | PRTUTF16 pwszNativeSymlink;
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155 | int rc = RTPathWinFromUtf8(&pwszNativeSymlink, pszSymlink, 0 /*fFlags*/);
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156 | if (RT_SUCCESS(rc))
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157 | {
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158 | PRTUTF16 pwszNativeTarget;
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159 | rc = RTPathWinFromUtf8(&pwszNativeTarget, pszTarget, 0 /*fFlags*/);
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160 | if (RT_SUCCESS(rc))
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161 | {
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162 | /* The link target path must use backslashes to work reliably. */
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163 | RTUTF16 wc;
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164 | PRTUTF16 pwsz = pwszNativeTarget;
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165 | while ((wc = *pwsz) != '\0')
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166 | {
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167 | if (wc == '/')
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168 | *pwsz = '\\';
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169 | pwsz++;
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170 | }
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171 |
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172 | /*
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173 | * Massage the target path, determin the link type.
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174 | */
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175 | size_t cchTarget = strlen(pszTarget);
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176 | size_t cchVolSpecTarget = rtPathVolumeSpecLen(pszTarget);
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177 | #if 0 /* looks like this isn't needed after all. That makes everything much simper :-) */
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178 | if ( cchTarget > RT_MIN(cchVolSpecTarget, 1)
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179 | && RTPATH_IS_SLASH(pszTarget[cchTarget - 1]))
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180 | {
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181 | size_t cwcNativeTarget = RTUtf16Len(pwszNativeTarget);
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182 | size_t offFromEnd = 1;
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183 | while ( offFromEnd < cchTarget
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184 | && cchTarget - offFromEnd >= cchVolSpecTarget
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185 | && RTPATH_IS_SLASH(pszTarget[cchTarget - offFromEnd]))
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186 | {
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187 | Assert(offFromEnd < cwcNativeTarget);
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188 | pwszNativeTarget[cwcNativeTarget - offFromEnd] = 0;
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189 | offFromEnd++;
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190 | }
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191 | }
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192 | #endif
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193 |
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194 | if (enmType == RTSYMLINKTYPE_UNKNOWN)
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195 | {
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196 | if ( cchTarget > cchVolSpecTarget
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197 | && RTPATH_IS_SLASH(pszTarget[cchTarget - 1]))
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198 | enmType = RTSYMLINKTYPE_DIR;
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199 | else if (cchVolSpecTarget)
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200 | {
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201 | /** @todo this is subject to sharing violations. */
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202 | DWORD dwAttr = GetFileAttributesW(pwszNativeTarget);
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203 | if ( dwAttr != INVALID_FILE_ATTRIBUTES
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204 | && (dwAttr & FILE_ATTRIBUTE_DIRECTORY))
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205 | enmType = RTSYMLINKTYPE_DIR;
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206 | }
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207 | else
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208 | {
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209 | /** @todo Join the symlink directory with the target and
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210 | * look up the attributes on that. -lazy bird. */
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211 | }
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212 | }
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213 |
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214 | /*
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215 | * Create the link.
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216 | */
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217 | if (s_pfnCreateSymbolicLinkW(pwszNativeSymlink, pwszNativeTarget, enmType == RTSYMLINKTYPE_DIR))
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218 | rc = VINF_SUCCESS;
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219 | else
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220 | rc = RTErrConvertFromWin32(GetLastError());
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221 |
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222 | RTPathWinFree(pwszNativeTarget);
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223 | }
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224 | RTPathWinFree(pwszNativeSymlink);
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225 | }
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226 |
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227 | LogFlow(("RTSymlinkCreate(%p={%s}, %p={%s}, %d, %#x): returns %Rrc\n", pszSymlink, pszSymlink, pszTarget, pszTarget, enmType, fCreate, rc));
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228 | return rc;
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229 | }
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230 |
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231 |
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232 | RTDECL(int) RTSymlinkDelete(const char *pszSymlink, uint32_t fDelete)
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233 | {
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234 | RT_NOREF_PV(fDelete);
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235 |
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236 | /*
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237 | * Convert the path.
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238 | */
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239 | PRTUTF16 pwszNativeSymlink;
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240 | int rc = RTPathWinFromUtf8(&pwszNativeSymlink, pszSymlink, 0 /*fFlags*/);
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241 | if (RT_SUCCESS(rc))
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242 | {
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243 | /*
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244 | * We have to use different APIs depending on whether this is a
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245 | * directory or file link. This means we're subject to one more race
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246 | * than on posix at the moment. We could probably avoid this though,
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247 | * if we wanted to go talk with the native API layer below Win32...
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248 | */
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249 | DWORD dwAttr = GetFileAttributesW(pwszNativeSymlink);
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250 | if (dwAttr != INVALID_FILE_ATTRIBUTES)
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251 | {
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252 | if (dwAttr & FILE_ATTRIBUTE_REPARSE_POINT)
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253 | {
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254 | BOOL fRc;
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255 | if (dwAttr & FILE_ATTRIBUTE_DIRECTORY)
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256 | fRc = RemoveDirectoryW(pwszNativeSymlink);
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257 | else
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258 | fRc = DeleteFileW(pwszNativeSymlink);
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259 | if (fRc)
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260 | rc = VINF_SUCCESS;
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261 | else
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262 | rc = RTErrConvertFromWin32(GetLastError());
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263 | }
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264 | else
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265 | rc = VERR_NOT_SYMLINK;
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266 | }
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267 | else
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268 | rc = RTErrConvertFromWin32(GetLastError());
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269 | RTPathWinFree(pwszNativeSymlink);
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270 | }
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271 |
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272 | LogFlow(("RTSymlinkDelete(%p={%s}, %#x): returns %Rrc\n", pszSymlink, pszSymlink, fDelete, rc));
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273 | return rc;
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274 | }
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275 |
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276 |
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277 | RTDECL(int) RTSymlinkRead(const char *pszSymlink, char *pszTarget, size_t cbTarget, uint32_t fRead)
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278 | {
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279 | RT_NOREF_PV(fRead);
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280 |
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281 | char *pszMyTarget;
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282 | int rc = RTSymlinkReadA(pszSymlink, &pszMyTarget);
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283 | if (RT_SUCCESS(rc))
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284 | {
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285 | rc = RTStrCopy(pszTarget, cbTarget, pszMyTarget);
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286 | RTStrFree(pszMyTarget);
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287 | }
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288 | LogFlow(("RTSymlinkRead(%p={%s}): returns %Rrc\n", pszSymlink, pszSymlink, rc));
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289 | return rc;
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290 | }
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291 |
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292 |
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293 | RTDECL(int) RTSymlinkReadA(const char *pszSymlink, char **ppszTarget)
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294 | {
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295 | AssertPtr(ppszTarget);
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296 | PRTUTF16 pwszNativeSymlink;
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297 | int rc = RTPathWinFromUtf8(&pwszNativeSymlink, pszSymlink, 0 /*fFlags*/);
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298 | if (RT_SUCCESS(rc))
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299 | {
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300 | HANDLE hSymlink = CreateFileW(pwszNativeSymlink,
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301 | GENERIC_READ,
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302 | FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE,
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303 | NULL,
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304 | OPEN_EXISTING,
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305 | FILE_FLAG_OPEN_REPARSE_POINT | FILE_FLAG_BACKUP_SEMANTICS,
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306 | NULL);
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307 | if (hSymlink != INVALID_HANDLE_VALUE)
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308 | {
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309 | DWORD cbReturned = 0;
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310 | union
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311 | {
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312 | MY_REPARSE_DATA_BUFFER Buf;
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313 | uint8_t abBuf[16*_1K + sizeof(WCHAR)];
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314 | } u;
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315 | if (DeviceIoControl(hSymlink,
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316 | MY_FSCTL_GET_REPARSE_POINT,
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317 | NULL /*pInBuffer */,
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318 | 0 /*cbInBuffer */,
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319 | &u.Buf,
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320 | sizeof(u) - sizeof(WCHAR),
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321 | &cbReturned,
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322 | NULL /*pOverlapped*/))
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323 | {
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324 | if (u.Buf.ReparseTag == MY_IO_REPARSE_TAG_SYMLINK)
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325 | {
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326 | PWCHAR pwszTarget = &u.Buf.SymbolicLinkReparseBuffer.PathBuffer[0];
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327 | pwszTarget += u.Buf.SymbolicLinkReparseBuffer.SubstituteNameOffset / 2;
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328 | pwszTarget[u.Buf.SymbolicLinkReparseBuffer.SubstituteNameLength / 2] = 0;
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329 | if ( !(u.Buf.SymbolicLinkReparseBuffer.Flags & MY_SYMLINK_FLAG_RELATIVE)
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330 | && pwszTarget[0] == '\\'
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331 | && pwszTarget[1] == '?'
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332 | && pwszTarget[2] == '?'
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333 | && pwszTarget[3] == '\\'
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334 | && pwszTarget[4] != 0
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335 | )
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336 | pwszTarget += 4;
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337 | rc = RTUtf16ToUtf8(pwszTarget, ppszTarget);
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338 | }
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339 | else
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340 | rc = VERR_NOT_SYMLINK;
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341 | }
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342 | else
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343 | rc = RTErrConvertFromWin32(GetLastError());
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344 | CloseHandle(hSymlink);
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345 | }
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346 | else
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347 | rc = RTErrConvertFromWin32(GetLastError());
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348 | RTPathWinFree(pwszNativeSymlink);
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349 | }
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350 |
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351 | if (RT_SUCCESS(rc))
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352 | LogFlow(("RTSymlinkReadA(%p={%s},%p): returns %Rrc *ppszTarget=%p:{%s}\n", pszSymlink, pszSymlink, ppszTarget, rc, *ppszTarget, *ppszTarget));
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353 | else
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354 | LogFlow(("RTSymlinkReadA(%p={%s},%p): returns %Rrc\n", pszSymlink, pszSymlink, ppszTarget, rc));
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355 | return rc;
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356 | }
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357 |
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