1 | /* $Id: symlink-posix.cpp 98103 2023-01-17 14:15:46Z vboxsync $ */
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2 | /** @file
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3 | * IPRT - Symbolic Links, POSIX.
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4 | */
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5 |
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6 | /*
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7 | * Copyright (C) 2010-2023 Oracle and/or its affiliates.
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8 | *
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9 | * This file is part of VirtualBox base platform packages, as
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10 | * available from https://www.virtualbox.org.
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11 | *
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12 | * This program is free software; you can redistribute it and/or
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13 | * modify it under the terms of the GNU General Public License
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14 | * as published by the Free Software Foundation, in version 3 of the
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15 | * License.
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16 | *
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17 | * This program is distributed in the hope that it will be useful, but
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18 | * WITHOUT ANY WARRANTY; without even the implied warranty of
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19 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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20 | * General Public License for more details.
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21 | *
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22 | * You should have received a copy of the GNU General Public License
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23 | * along with this program; if not, see <https://www.gnu.org/licenses>.
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24 | *
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25 | * The contents of this file may alternatively be used under the terms
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26 | * of the Common Development and Distribution License Version 1.0
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27 | * (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
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28 | * in the VirtualBox distribution, in which case the provisions of the
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29 | * CDDL are applicable instead of those of the GPL.
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30 | *
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31 | * You may elect to license modified versions of this file under the
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32 | * terms and conditions of either the GPL or the CDDL or both.
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33 | *
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34 | * SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
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35 | */
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36 |
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37 |
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38 | /*********************************************************************************************************************************
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39 | * Header Files *
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40 | *********************************************************************************************************************************/
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41 | #define LOG_GROUP RTLOGGROUP_SYMLINK
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42 |
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43 | #include <errno.h>
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44 | #include <sys/stat.h>
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45 | #include <unistd.h>
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46 |
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47 | #include <iprt/symlink.h>
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48 |
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49 | #include <iprt/assert.h>
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50 | #include <iprt/err.h>
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51 | #include <iprt/log.h>
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52 | #include <iprt/mem.h>
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53 | #include <iprt/string.h>
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54 | #include "internal/path.h"
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55 |
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56 |
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57 |
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58 | RTDECL(bool) RTSymlinkExists(const char *pszSymlink)
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59 | {
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60 | bool fRc = false;
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61 | char const *pszNativeSymlink;
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62 | int rc = rtPathToNative(&pszNativeSymlink, pszSymlink, NULL);
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63 | if (RT_SUCCESS(rc))
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64 | {
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65 | struct stat s;
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66 | fRc = !lstat(pszNativeSymlink, &s)
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67 | && S_ISLNK(s.st_mode);
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68 |
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69 | rtPathFreeNative(pszNativeSymlink, pszSymlink);
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70 | }
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71 |
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72 | LogFlow(("RTSymlinkExists(%p={%s}): returns %RTbool\n", pszSymlink, pszSymlink, fRc));
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73 | return fRc;
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74 | }
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75 |
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76 |
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77 | RTDECL(bool) RTSymlinkIsDangling(const char *pszSymlink)
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78 | {
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79 | bool fRc = false;
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80 | char const *pszNativeSymlink;
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81 | int rc = rtPathToNative(&pszNativeSymlink, pszSymlink, NULL);
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82 | if (RT_SUCCESS(rc))
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83 | {
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84 | struct stat s;
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85 | fRc = !lstat(pszNativeSymlink, &s)
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86 | && S_ISLNK(s.st_mode);
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87 | if (fRc)
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88 | {
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89 | errno = 0;
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90 | fRc = stat(pszNativeSymlink, &s) != 0
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91 | && ( errno == ENOENT
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92 | || errno == ENOTDIR
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93 | || errno == ELOOP);
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94 | }
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95 |
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96 | rtPathFreeNative(pszNativeSymlink, pszSymlink);
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97 | }
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98 |
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99 | LogFlow(("RTSymlinkIsDangling(%p={%s}): returns %RTbool\n", pszSymlink, pszSymlink, fRc));
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100 | return fRc;
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101 | }
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102 |
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103 |
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104 | RTDECL(int) RTSymlinkCreate(const char *pszSymlink, const char *pszTarget, RTSYMLINKTYPE enmType, uint32_t fCreate)
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105 | {
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106 | RT_NOREF_PV(fCreate);
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107 |
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108 | /*
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109 | * Validate the input.
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110 | */
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111 | AssertReturn(enmType > RTSYMLINKTYPE_INVALID && enmType < RTSYMLINKTYPE_END, VERR_INVALID_PARAMETER);
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112 | AssertPtrReturn(pszSymlink, VERR_INVALID_POINTER);
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113 | AssertPtrReturn(pszTarget, VERR_INVALID_POINTER);
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114 |
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115 | /*
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116 | * Convert the paths.
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117 | */
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118 | char const *pszNativeSymlink;
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119 | int rc = rtPathToNative(&pszNativeSymlink, pszSymlink, NULL);
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120 | if (RT_SUCCESS(rc))
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121 | {
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122 | const char *pszNativeTarget;
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123 | rc = rtPathToNative(&pszNativeTarget, pszTarget, NULL);
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124 | if (RT_SUCCESS(rc))
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125 | {
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126 | /*
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127 | * Create the link.
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128 | */
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129 | if (symlink(pszNativeTarget, pszNativeSymlink) == 0)
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130 | rc = VINF_SUCCESS;
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131 | else
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132 | rc = RTErrConvertFromErrno(errno);
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133 |
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134 | rtPathFreeNative(pszNativeTarget, pszTarget);
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135 | }
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136 | rtPathFreeNative(pszNativeSymlink, pszSymlink);
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137 | }
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138 |
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139 | LogFlow(("RTSymlinkCreate(%p={%s}, %p={%s}, %d, %#x): returns %Rrc\n", pszSymlink, pszSymlink, pszTarget, pszTarget, enmType, fCreate, rc));
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140 | return rc;
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141 | }
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142 |
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143 |
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144 | RTDECL(int) RTSymlinkDelete(const char *pszSymlink, uint32_t fDelete)
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145 | {
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146 | RT_NOREF_PV(fDelete);
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147 |
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148 | char const *pszNativeSymlink;
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149 | int rc = rtPathToNative(&pszNativeSymlink, pszSymlink, NULL);
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150 | if (RT_SUCCESS(rc))
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151 | {
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152 | struct stat s;
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153 | if (!lstat(pszNativeSymlink, &s))
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154 | {
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155 | if (S_ISLNK(s.st_mode))
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156 | {
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157 | if (unlink(pszNativeSymlink) == 0)
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158 | rc = VINF_SUCCESS;
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159 | else
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160 | rc = RTErrConvertFromErrno(errno);
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161 | }
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162 | else
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163 | rc = VERR_NOT_SYMLINK;
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164 | }
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165 | else
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166 | rc = RTErrConvertFromErrno(errno);
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167 | rtPathFreeNative(pszNativeSymlink, pszSymlink);
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168 | }
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169 |
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170 | LogFlow(("RTSymlinkDelete(%p={%s}, #%x): returns %Rrc\n", pszSymlink, pszSymlink, fDelete, rc));
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171 | return rc;
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172 | }
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173 |
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174 |
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175 | RTDECL(int) RTSymlinkRead(const char *pszSymlink, char *pszTarget, size_t cbTarget, uint32_t fRead)
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176 | {
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177 | RT_NOREF_PV(fRead);
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178 |
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179 | char *pszMyTarget;
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180 | int rc = RTSymlinkReadA(pszSymlink, &pszMyTarget);
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181 | if (RT_SUCCESS(rc))
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182 | {
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183 | rc = RTStrCopy(pszTarget, cbTarget, pszMyTarget);
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184 | RTStrFree(pszMyTarget);
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185 | }
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186 | LogFlow(("RTSymlinkRead(%p={%s}): returns %Rrc\n", pszSymlink, pszSymlink, rc));
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187 | return rc;
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188 | }
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189 |
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190 |
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191 | RTDECL(int) RTSymlinkReadA(const char *pszSymlink, char **ppszTarget)
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192 | {
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193 | AssertPtr(ppszTarget);
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194 | char const *pszNativeSymlink;
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195 | int rc = rtPathToNative(&pszNativeSymlink, pszSymlink, NULL);
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196 | if (RT_SUCCESS(rc))
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197 | {
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198 | /* Guess the initial buffer size. */
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199 | ssize_t cbBuf;
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200 | struct stat s;
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201 | if (!lstat(pszNativeSymlink, &s))
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202 | cbBuf = RT_MAX(RT_ALIGN_Z(s.st_size, 64), 64);
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203 | else
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204 | cbBuf = 1024;
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205 |
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206 | /* Read loop that grows the buffer. */
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207 | char *pszBuf = NULL;
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208 | for (;;)
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209 | {
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210 | RTMemTmpFree(pszBuf);
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211 | pszBuf = (char *)RTMemTmpAlloc(cbBuf);
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212 | if (pszBuf)
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213 | {
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214 | ssize_t cbReturned = readlink(pszNativeSymlink, pszBuf, cbBuf);
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215 | if (cbReturned >= cbBuf)
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216 | {
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217 | /* Increase the buffer size and try again */
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218 | cbBuf *= 2;
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219 | continue;
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220 | }
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221 |
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222 | if (cbReturned > 0)
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223 | {
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224 | pszBuf[cbReturned] = '\0';
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225 | rc = rtPathFromNativeDup(ppszTarget, pszBuf, pszSymlink);
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226 | }
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227 | else if (errno == EINVAL)
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228 | rc = VERR_NOT_SYMLINK;
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229 | else
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230 | rc = RTErrConvertFromErrno(errno);
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231 | }
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232 | else
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233 | rc = VERR_NO_TMP_MEMORY;
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234 | break;
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235 | } /* for loop */
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236 |
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237 | RTMemTmpFree(pszBuf);
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238 | rtPathFreeNative(pszNativeSymlink, pszSymlink);
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239 | }
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240 |
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241 | if (RT_SUCCESS(rc))
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242 | LogFlow(("RTSymlinkReadA(%p={%s},%p): returns %Rrc *ppszTarget=%p:{%s}\n", pszSymlink, pszSymlink, ppszTarget, rc, *ppszTarget, *ppszTarget));
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243 | else
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244 | LogFlow(("RTSymlinkReadA(%p={%s},%p): returns %Rrc\n", pszSymlink, pszSymlink, ppszTarget, rc));
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245 | return rc;
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246 | }
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247 |
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