| 1 | /* $Id: RTTimeZoneGetCurrent-posix.cpp 98103 2023-01-17 14:15:46Z 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 | static int rtIsValidTimeZoneFile(const char *pszTimeZone)
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| 84 | {
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| 85 | if (pszTimeZone == NULL || *pszTimeZone == '\0' || *pszTimeZone == '/')
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| 86 | return VERR_INVALID_PARAMETER;
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| 87 |
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| 88 | int rc = RTStrValidateEncoding(pszTimeZone);
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| 89 | if (RT_SUCCESS(rc))
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| 90 | {
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| 91 | /* construct full pathname of the time zone file */
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| 92 | char szTZPath[RTPATH_MAX];
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| 93 | rc = RTPathJoin(szTZPath, sizeof(szTZPath), TZDIR, pszTimeZone);
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| 94 | if (RT_SUCCESS(rc))
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| 95 | {
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| 96 | /* open the time zone file and check that it begins with the correct magic number */
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| 97 | RTFILE hFile = NIL_RTFILE;
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| 98 | rc = RTFileOpen(&hFile, szTZPath, RTFILE_O_READ | RTFILE_O_OPEN | RTFILE_O_DENY_WRITE);
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| 99 | if (RT_SUCCESS(rc))
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| 100 | {
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| 101 | char achTZBuf[sizeof(TZ_MAGIC)];
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| 102 | rc = RTFileRead(hFile, achTZBuf, sizeof(achTZBuf), NULL);
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| 103 | RTFileClose(hFile);
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| 104 | if (RT_SUCCESS(rc))
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| 105 | {
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| 106 | if (memcmp(achTZBuf, RT_STR_TUPLE(TZ_MAGIC)) == 0)
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| 107 | rc = VINF_SUCCESS;
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| 108 | else
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| 109 | rc = VERR_INVALID_MAGIC;
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| 110 | }
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| 111 | }
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| 112 | }
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| 113 | }
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| 114 |
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| 115 | return rc;
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| 116 | }
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| 117 |
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| 118 |
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| 119 | /**
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| 120 | * Return the system time zone.
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| 121 | *
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| 122 | * @returns IPRT status code.
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| 123 | * @param pszName The buffer to return the time zone in.
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| 124 | * @param cbName The size of the pszName buffer.
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| 125 | */
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| 126 | RTDECL(int) RTTimeZoneGetCurrent(char *pszName, size_t cbName)
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| 127 | {
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| 128 | int rc = RTEnvGetEx(RTENV_DEFAULT, "TZ", pszName, cbName, NULL);
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| 129 | if (RT_SUCCESS(rc))
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| 130 | {
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| 131 | /*
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| 132 | * $TZ can have two different formats and one of them doesn't specify
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| 133 | * a time zone database file under <tzfile.h>:TZDIR but since all
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| 134 | * current callers of this routine expect a time zone filename we do
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| 135 | * the validation check here so that if it is invalid then we fall back
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| 136 | * to the other mechanisms to return the system's current time zone.
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| 137 | */
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| 138 | if (*pszName == ':') /* POSIX allows $TZ to begin with a colon (:) so we allow for that here */
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| 139 | memmove(pszName, pszName + 1, strlen(pszName));
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| 140 | /** @todo this isn't perfect for absolute paths... Should probably try treat
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| 141 | * it like /etc/localtime. */
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| 142 | rc = rtIsValidTimeZoneFile(pszName);
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| 143 | if (RT_SUCCESS(rc))
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| 144 | return rc;
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| 145 | }
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| 146 | else if (rc != VERR_ENV_VAR_NOT_FOUND)
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| 147 | return rc;
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| 148 |
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| 149 | /*
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| 150 | * /etc/localtime is a symbolic link to the system time zone on many OSes
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| 151 | * including Solaris, macOS, Ubuntu, RH/OEL 6 and later, Arch Linux, NetBSD,
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| 152 | * and etc. We extract the time zone pathname relative to TZDIR defined in
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| 153 | * <tzfile.h> which is normally /usr/share/zoneinfo.
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| 154 | *
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| 155 | * N.B. Some OSes have /etc/localtime as a regular file instead of a
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| 156 | * symlink and while we could trawl through all the files under TZDIR
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| 157 | * looking for a match we instead fallback to other popular mechanisms of
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| 158 | * specifying the system-wide time zone for the sake of simplicity.
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| 159 | */
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| 160 | char szBuf[RTPATH_MAX];
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| 161 | const char *pszPath = PATH_LOCALTIME;
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| 162 | if (RTSymlinkExists(pszPath))
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| 163 | {
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| 164 | /* the contents of the symink may contain '..' or other links */
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| 165 | char szLinkPathReal[RTPATH_MAX];
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| 166 | rc = RTPathReal(pszPath, szLinkPathReal, sizeof(szLinkPathReal));
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| 167 | if (RT_SUCCESS(rc))
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| 168 | {
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| 169 | rc = RTPathReal(TZDIR, szBuf, sizeof(szBuf));
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| 170 | AssertRC(rc);
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| 171 | if (RT_SUCCESS(rc))
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| 172 | {
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| 173 | Assert(RTPathStartsWith(szLinkPathReal, szBuf));
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| 174 | if (RTPathStartsWith(szLinkPathReal, szBuf))
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| 175 | {
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| 176 | /* <tzfile.h>:TZDIR doesn't include a trailing slash */
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| 177 | const char *pszTimeZone = &szLinkPathReal[strlen(szBuf) + 1];
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| 178 | rc = rtIsValidTimeZoneFile(pszTimeZone);
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| 179 | if (RT_SUCCESS(rc))
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| 180 | return RTStrCopy(pszName, cbName, pszTimeZone);
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| 181 | }
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| 182 | }
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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 | * /etc/timezone is a regular file consisting of a single line containing
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| 188 | * the time zone (e.g. Europe/London or Etc/UTC or etc.) and is used by a
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| 189 | * variety of Linux distros such as Ubuntu, Gentoo, Debian, and etc.
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| 190 | * The equivalent on FreeBSD is /var/db/zoneinfo.
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| 191 | */
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| 192 | pszPath = PATH_TIMEZONE;
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| 193 | if (RTFileExists(pszPath))
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| 194 | {
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| 195 | RTFILE hFile = NIL_RTFILE;
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| 196 | rc = RTFileOpen(&hFile, PATH_TIMEZONE, RTFILE_O_READ | RTFILE_O_OPEN | RTFILE_O_DENY_WRITE);
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| 197 | if (RT_SUCCESS(rc))
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| 198 | {
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| 199 | size_t cbRead = 0;
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| 200 | rc = RTFileRead(hFile, szBuf, sizeof(szBuf), &cbRead);
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| 201 | RTFileClose(hFile);
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| 202 | if (RT_SUCCESS(rc) && cbRead > 0)
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| 203 | {
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| 204 | /* Get the first line and strip it. */
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| 205 | szBuf[RT_MIN(sizeof(szBuf) - 1, cbRead)] = '\0';
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| 206 | size_t const offNewLine = RTStrOffCharOrTerm(szBuf, '\n');
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| 207 | szBuf[offNewLine] = '\0';
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| 208 | const char *pszTimeZone = RTStrStrip(szBuf);
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| 209 |
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| 210 | rc = rtIsValidTimeZoneFile(pszTimeZone);
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| 211 | if (RT_SUCCESS(rc))
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| 212 | return RTStrCopy(pszName, cbName, pszTimeZone);
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| 213 | }
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| 214 | }
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| 215 | }
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| 216 |
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| 217 | /*
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| 218 | * Older versions of RedHat / OEL don't have /etc/localtime as a symlink or
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| 219 | * /etc/timezone but instead have /etc/sysconfig/clock which contains a line
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| 220 | * of the syntax ZONE=Europe/London amongst other entries.
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| 221 | */
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| 222 | pszPath = PATH_SYSCONFIG_CLOCK;
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| 223 | if (RTFileExists(pszPath))
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| 224 | {
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| 225 | PRTSTREAM pStrm;
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| 226 | rc = RTStrmOpen(pszPath, "r", &pStrm);
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| 227 | if (RT_SUCCESS(rc))
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| 228 | {
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| 229 | while (RT_SUCCESS(rc = RTStrmGetLine(pStrm, szBuf, sizeof(szBuf))))
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| 230 | {
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| 231 | static char const s_szVarEq[] = "ZONE=";
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| 232 | if (memcmp(szBuf, RT_STR_TUPLE(s_szVarEq)) == 0)
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| 233 | {
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| 234 | const char *pszTimeZone = &szBuf[sizeof(s_szVarEq) - 1];
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| 235 | rc = rtIsValidTimeZoneFile(pszTimeZone);
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| 236 | if (RT_SUCCESS(rc))
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| 237 | {
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| 238 | RTStrmClose(pStrm);
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| 239 | return RTStrCopy(pszName, cbName, pszTimeZone);
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| 240 | }
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| 241 | }
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| 242 | }
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| 243 | RTStrmClose(pStrm);
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| 244 | }
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| 245 | }
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| 246 |
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| 247 | return rc;
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| 248 | }
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| 249 |
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