1 | /* $Id: RTTimeZoneGetCurrent-posix.cpp 98104 2023-01-17 14:47:49Z vboxsync $ */
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2 | /** @file
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3 | * IPRT - RTTimeZoneGetCurrent, POSIX.
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4 | */
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5 |
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6 | /*
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7 | * Copyright (C) 2020-2023 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 | #include <iprt/time.h>
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42 | #include "internal/iprt.h"
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43 |
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44 | #include <iprt/env.h>
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45 | #include <iprt/file.h>
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46 | #include <iprt/path.h>
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47 | #include <iprt/string.h>
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48 | #include <iprt/err.h>
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49 | #include <iprt/errcore.h>
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50 | #include <iprt/types.h>
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51 | #include <iprt/symlink.h>
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52 | #include <iprt/stream.h>
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53 |
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54 | #if defined(RT_OS_DARWIN) || defined(RT_OS_SOLARIS)
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55 | # include <tzfile.h>
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56 | #else
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57 | # define TZDIR "/usr/share/zoneinfo"
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58 | # define TZ_MAGIC "TZif"
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59 | #endif
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60 |
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61 |
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62 | /*********************************************************************************************************************************
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63 | * Defined Constants And Macros *
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64 | *********************************************************************************************************************************/
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65 | #define PATH_LOCALTIME "/etc/localtime"
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66 | #if defined(RT_OS_FREEBSD)
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67 | # define PATH_TIMEZONE "/var/db/zoneinfo"
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68 | #else
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69 | # define PATH_TIMEZONE "/etc/timezone"
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70 | #endif
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71 | #define PATH_SYSCONFIG_CLOCK "/etc/sysconfig/clock"
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72 |
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73 |
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74 | /**
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75 | * Checks if a time zone database file is valid by verifying it begins with
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76 | * TZ_MAGIC.
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77 | *
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78 | * @returns IPRT status code.
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79 | * @param pszTimezone The time zone database file relative to
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80 | * <tzfile.h>:TZDIR (normally /usr/share/zoneinfo),
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81 | * e.g. Europe/London, or Etc/UTC, or UTC, or etc.
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82 | *
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83 | * @note File format is documented in RFC-8536.
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84 | */
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85 | static int rtIsValidTimeZoneFile(const char *pszTimeZone)
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86 | {
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87 | if (pszTimeZone == NULL || *pszTimeZone == '\0' || *pszTimeZone == '/')
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88 | return VERR_INVALID_PARAMETER;
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89 |
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90 | int rc = RTStrValidateEncoding(pszTimeZone);
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91 | if (RT_SUCCESS(rc))
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92 | {
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93 | /* construct full pathname of the time zone file */
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94 | char szTZPath[RTPATH_MAX];
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95 | rc = RTPathJoin(szTZPath, sizeof(szTZPath), TZDIR, pszTimeZone);
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96 | if (RT_SUCCESS(rc))
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97 | {
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98 | /* open the time zone file and check that it begins with the correct magic number */
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99 | RTFILE hFile = NIL_RTFILE;
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100 | rc = RTFileOpen(&hFile, szTZPath, RTFILE_O_READ | RTFILE_O_OPEN | RTFILE_O_DENY_WRITE);
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101 | if (RT_SUCCESS(rc))
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102 | {
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103 | char achTZBuf[sizeof(TZ_MAGIC)];
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104 | rc = RTFileRead(hFile, achTZBuf, sizeof(achTZBuf), NULL);
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105 | RTFileClose(hFile);
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106 | if (RT_SUCCESS(rc))
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107 | {
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108 | if (memcmp(achTZBuf, RT_STR_TUPLE(TZ_MAGIC)) == 0)
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109 | rc = VINF_SUCCESS;
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110 | else
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111 | rc = VERR_INVALID_MAGIC;
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112 | }
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113 | }
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114 | }
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115 | }
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116 |
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117 | return rc;
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118 | }
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119 |
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120 |
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121 | /**
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122 | * Return the system time zone.
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123 | *
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124 | * @returns IPRT status code.
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125 | * @param pszName The buffer to return the time zone in.
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126 | * @param cbName The size of the pszName buffer.
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127 | */
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128 | RTDECL(int) RTTimeZoneGetCurrent(char *pszName, size_t cbName)
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129 | {
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130 | int rc = RTEnvGetEx(RTENV_DEFAULT, "TZ", pszName, cbName, NULL);
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131 | if (RT_SUCCESS(rc))
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132 | {
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133 | /*
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134 | * $TZ can have two different formats and one of them doesn't specify
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135 | * a time zone database file under <tzfile.h>:TZDIR but since all
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136 | * current callers of this routine expect a time zone filename we do
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137 | * the validation check here so that if it is invalid then we fall back
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138 | * to the other mechanisms to return the system's current time zone.
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139 | */
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140 | if (*pszName == ':') /* POSIX allows $TZ to begin with a colon (:) so we allow for that here */
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141 | memmove(pszName, pszName + 1, strlen(pszName));
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142 | /** @todo this isn't perfect for absolute paths... Should probably try treat
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143 | * it like /etc/localtime. */
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144 | rc = rtIsValidTimeZoneFile(pszName);
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145 | if (RT_SUCCESS(rc))
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146 | return rc;
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147 | }
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148 | else if (rc != VERR_ENV_VAR_NOT_FOUND)
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149 | return rc;
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150 |
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151 | /*
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152 | * /etc/localtime is a symbolic link to the system time zone on many OSes
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153 | * including Solaris, macOS, Ubuntu, RH/OEL 6 and later, Arch Linux, NetBSD,
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154 | * and etc. We extract the time zone pathname relative to TZDIR defined in
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155 | * <tzfile.h> which is normally /usr/share/zoneinfo.
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156 | *
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157 | * N.B. Some OSes have /etc/localtime as a regular file instead of a
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158 | * symlink and while we could trawl through all the files under TZDIR
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159 | * looking for a match we instead fallback to other popular mechanisms of
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160 | * specifying the system-wide time zone for the sake of simplicity.
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161 | */
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162 | char szBuf[RTPATH_MAX];
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163 | const char *pszPath = PATH_LOCALTIME;
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164 | if (RTSymlinkExists(pszPath))
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165 | {
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166 | /* the contents of the symink may contain '..' or other links */
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167 | char szLinkPathReal[RTPATH_MAX];
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168 | rc = RTPathReal(pszPath, szLinkPathReal, sizeof(szLinkPathReal));
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169 | if (RT_SUCCESS(rc))
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170 | {
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171 | rc = RTPathReal(TZDIR, szBuf, sizeof(szBuf));
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172 | AssertRC(rc);
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173 | if (RT_SUCCESS(rc))
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174 | {
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175 | Assert(RTPathStartsWith(szLinkPathReal, szBuf));
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176 | if (RTPathStartsWith(szLinkPathReal, szBuf))
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177 | {
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178 | /* <tzfile.h>:TZDIR doesn't include a trailing slash */
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179 | const char *pszTimeZone = &szLinkPathReal[strlen(szBuf) + 1];
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180 | rc = rtIsValidTimeZoneFile(pszTimeZone);
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181 | if (RT_SUCCESS(rc))
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182 | return RTStrCopy(pszName, cbName, pszTimeZone);
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183 | }
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184 | }
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185 | }
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186 | }
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187 |
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188 | /*
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189 | * /etc/timezone is a regular file consisting of a single line containing
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190 | * the time zone (e.g. Europe/London or Etc/UTC or etc.) and is used by a
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191 | * variety of Linux distros such as Ubuntu, Gentoo, Debian, and etc.
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192 | * The equivalent on FreeBSD is /var/db/zoneinfo.
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193 | */
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194 | pszPath = PATH_TIMEZONE;
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195 | if (RTFileExists(pszPath))
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196 | {
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197 | RTFILE hFile = NIL_RTFILE;
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198 | rc = RTFileOpen(&hFile, PATH_TIMEZONE, RTFILE_O_READ | RTFILE_O_OPEN | RTFILE_O_DENY_WRITE);
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199 | if (RT_SUCCESS(rc))
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200 | {
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201 | size_t cbRead = 0;
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202 | rc = RTFileRead(hFile, szBuf, sizeof(szBuf), &cbRead);
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203 | RTFileClose(hFile);
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204 | if (RT_SUCCESS(rc) && cbRead > 0)
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205 | {
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206 | /* Get the first line and strip it. */
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207 | szBuf[RT_MIN(sizeof(szBuf) - 1, cbRead)] = '\0';
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208 | size_t const offNewLine = RTStrOffCharOrTerm(szBuf, '\n');
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209 | szBuf[offNewLine] = '\0';
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210 | const char *pszTimeZone = RTStrStrip(szBuf);
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211 |
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212 | rc = rtIsValidTimeZoneFile(pszTimeZone);
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213 | if (RT_SUCCESS(rc))
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214 | return RTStrCopy(pszName, cbName, pszTimeZone);
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215 | }
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216 | }
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217 | }
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218 |
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219 | /*
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220 | * Older versions of RedHat / OEL don't have /etc/localtime as a symlink or
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221 | * /etc/timezone but instead have /etc/sysconfig/clock which contains a line
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222 | * of the syntax ZONE=Europe/London or ZONE="Europe/London" amongst other entries.
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223 | */
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224 | pszPath = PATH_SYSCONFIG_CLOCK;
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225 | if (RTFileExists(pszPath))
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226 | {
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227 | PRTSTREAM pStrm;
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228 | rc = RTStrmOpen(pszPath, "r", &pStrm);
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229 | if (RT_SUCCESS(rc))
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230 | {
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231 | while (RT_SUCCESS(rc = RTStrmGetLine(pStrm, szBuf, sizeof(szBuf))))
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232 | {
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233 | static char const s_szVarEq[] = "ZONE=";
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234 | char *pszStart = RTStrStrip(szBuf);
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235 | if (memcmp(pszStart, RT_STR_TUPLE(s_szVarEq)) == 0)
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236 | {
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237 | char *pszTimeZone = &pszStart[sizeof(s_szVarEq) - 1];
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238 |
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239 | /* Drop any quoting before using the value, assuming it is plain stuff: */
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240 | if (*pszTimeZone == '\"' || *pszTimeZone == '\'')
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241 | {
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242 | pszTimeZone++;
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243 | size_t const cchTimeZone = strlen(pszTimeZone);
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244 | if (cchTimeZone && (pszTimeZone[cchTimeZone - 1] == '"' || pszTimeZone[cchTimeZone - 1] == '\''))
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245 | pszTimeZone[cchTimeZone - 1] = '\0';
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246 | }
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247 |
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248 | rc = rtIsValidTimeZoneFile(pszTimeZone);
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249 | if (RT_SUCCESS(rc))
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250 | {
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251 | RTStrmClose(pStrm);
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252 | return RTStrCopy(pszName, cbName, pszTimeZone);
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253 | }
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254 | }
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255 | }
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256 | RTStrmClose(pStrm);
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257 | }
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258 | }
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259 |
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260 | return rc;
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261 | }
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262 |
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