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/* $Id: RTTimeZoneGetCurrent-posix.cpp $ */
/** @file
* IPRT - RTTimeZoneGetCurrent, POSIX.
*/
/*
* Copyright (C) 2020-2023 Oracle and/or its affiliates.
*
* This file is part of VirtualBox base platform packages, as
* available from https://www.virtualbox.org.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation, in version 3 of the
* License.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see <https://www.gnu.org/licenses>.
*
* The contents of this file may alternatively be used under the terms
* of the Common Development and Distribution License Version 1.0
* (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
* in the VirtualBox distribution, in which case the provisions of the
* CDDL are applicable instead of those of the GPL.
*
* You may elect to license modified versions of this file under the
* terms and conditions of either the GPL or the CDDL or both.
*
* SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
*/
/*********************************************************************************************************************************
* Header Files *
*********************************************************************************************************************************/
#include <iprt/time.h>
#include "internal/iprt.h"
#include <iprt/env.h>
#include <iprt/file.h>
#include <iprt/path.h>
#include <iprt/string.h>
#include <iprt/err.h>
#include <iprt/errcore.h>
#include <iprt/types.h>
#include <iprt/symlink.h>
#include <iprt/stream.h>
#if defined(RT_OS_DARWIN) || defined(RT_OS_SOLARIS)
# include <tzfile.h>
#else
# define TZDIR "/usr/share/zoneinfo"
# define TZ_MAGIC "TZif"
#endif
/*********************************************************************************************************************************
* Defined Constants And Macros *
*********************************************************************************************************************************/
#define PATH_LOCALTIME "/etc/localtime"
#if defined(RT_OS_FREEBSD)
# define PATH_TIMEZONE "/var/db/zoneinfo"
#else
# define PATH_TIMEZONE "/etc/timezone"
#endif
#define PATH_SYSCONFIG_CLOCK "/etc/sysconfig/clock"
/**
* Checks if a time zone database file is valid by verifying it begins with
* TZ_MAGIC.
*
* @returns IPRT status code.
* @param pszTimezone The time zone database file relative to
* <tzfile.h>:TZDIR (normally /usr/share/zoneinfo),
* e.g. Europe/London, or Etc/UTC, or UTC, or etc.
*
* @note File format is documented in RFC-8536.
*/
static int rtIsValidTimeZoneFile(const char *pszTimeZone)
{
if (pszTimeZone == NULL || *pszTimeZone == '\0' || *pszTimeZone == '/')
return VERR_INVALID_PARAMETER;
int rc = RTStrValidateEncoding(pszTimeZone);
if (RT_SUCCESS(rc))
{
/* construct full pathname of the time zone file */
char szTZPath[RTPATH_MAX];
rc = RTPathJoin(szTZPath, sizeof(szTZPath), TZDIR, pszTimeZone);
if (RT_SUCCESS(rc))
{
/* open the time zone file and check that it begins with the correct magic number */
RTFILE hFile = NIL_RTFILE;
rc = RTFileOpen(&hFile, szTZPath, RTFILE_O_READ | RTFILE_O_OPEN | RTFILE_O_DENY_WRITE);
if (RT_SUCCESS(rc))
{
char achTZBuf[sizeof(TZ_MAGIC)];
rc = RTFileRead(hFile, achTZBuf, sizeof(achTZBuf), NULL);
RTFileClose(hFile);
if (RT_SUCCESS(rc))
{
if (memcmp(achTZBuf, RT_STR_TUPLE(TZ_MAGIC)) == 0)
rc = VINF_SUCCESS;
else
rc = VERR_INVALID_MAGIC;
}
}
}
}
return rc;
}
/**
* Return the system time zone.
*
* @returns IPRT status code.
* @param pszName The buffer to return the time zone in.
* @param cbName The size of the pszName buffer.
*/
RTDECL(int) RTTimeZoneGetCurrent(char *pszName, size_t cbName)
{
int rc = RTEnvGetEx(RTENV_DEFAULT, "TZ", pszName, cbName, NULL);
if (RT_SUCCESS(rc))
{
/*
* $TZ can have two different formats and one of them doesn't specify
* a time zone database file under <tzfile.h>:TZDIR but since all
* current callers of this routine expect a time zone filename we do
* the validation check here so that if it is invalid then we fall back
* to the other mechanisms to return the system's current time zone.
*/
if (*pszName == ':') /* POSIX allows $TZ to begin with a colon (:) so we allow for that here */
memmove(pszName, pszName + 1, strlen(pszName));
/** @todo this isn't perfect for absolute paths... Should probably try treat
* it like /etc/localtime. */
rc = rtIsValidTimeZoneFile(pszName);
if (RT_SUCCESS(rc))
return rc;
}
else if (rc != VERR_ENV_VAR_NOT_FOUND)
return rc;
/*
* /etc/localtime is a symbolic link to the system time zone on many OSes
* including Solaris, macOS, Ubuntu, RH/OEL 6 and later, Arch Linux, NetBSD,
* and etc. We extract the time zone pathname relative to TZDIR defined in
* <tzfile.h> which is normally /usr/share/zoneinfo.
*
* N.B. Some OSes have /etc/localtime as a regular file instead of a
* symlink and while we could trawl through all the files under TZDIR
* looking for a match we instead fallback to other popular mechanisms of
* specifying the system-wide time zone for the sake of simplicity.
*/
char szBuf[RTPATH_MAX];
const char *pszPath = PATH_LOCALTIME;
if (RTSymlinkExists(pszPath))
{
/* the contents of the symink may contain '..' or other links */
char szLinkPathReal[RTPATH_MAX];
rc = RTPathReal(pszPath, szLinkPathReal, sizeof(szLinkPathReal));
if (RT_SUCCESS(rc))
{
rc = RTPathReal(TZDIR, szBuf, sizeof(szBuf));
AssertRC(rc);
if (RT_SUCCESS(rc))
{
Assert(RTPathStartsWith(szLinkPathReal, szBuf));
if (RTPathStartsWith(szLinkPathReal, szBuf))
{
/* <tzfile.h>:TZDIR doesn't include a trailing slash */
const char *pszTimeZone = &szLinkPathReal[strlen(szBuf) + 1];
rc = rtIsValidTimeZoneFile(pszTimeZone);
if (RT_SUCCESS(rc))
return RTStrCopy(pszName, cbName, pszTimeZone);
}
}
}
}
/*
* /etc/timezone is a regular file consisting of a single line containing
* the time zone (e.g. Europe/London or Etc/UTC or etc.) and is used by a
* variety of Linux distros such as Ubuntu, Gentoo, Debian, and etc.
* The equivalent on FreeBSD is /var/db/zoneinfo.
*/
pszPath = PATH_TIMEZONE;
if (RTFileExists(pszPath))
{
RTFILE hFile = NIL_RTFILE;
rc = RTFileOpen(&hFile, PATH_TIMEZONE, RTFILE_O_READ | RTFILE_O_OPEN | RTFILE_O_DENY_WRITE);
if (RT_SUCCESS(rc))
{
size_t cbRead = 0;
rc = RTFileRead(hFile, szBuf, sizeof(szBuf), &cbRead);
RTFileClose(hFile);
if (RT_SUCCESS(rc) && cbRead > 0)
{
/* Get the first line and strip it. */
szBuf[RT_MIN(sizeof(szBuf) - 1, cbRead)] = '\0';
size_t const offNewLine = RTStrOffCharOrTerm(szBuf, '\n');
szBuf[offNewLine] = '\0';
const char *pszTimeZone = RTStrStrip(szBuf);
rc = rtIsValidTimeZoneFile(pszTimeZone);
if (RT_SUCCESS(rc))
return RTStrCopy(pszName, cbName, pszTimeZone);
}
}
}
/*
* Older versions of RedHat / OEL don't have /etc/localtime as a symlink or
* /etc/timezone but instead have /etc/sysconfig/clock which contains a line
* of the syntax ZONE=Europe/London or ZONE="Europe/London" amongst other entries.
*/
pszPath = PATH_SYSCONFIG_CLOCK;
if (RTFileExists(pszPath))
{
PRTSTREAM pStrm;
rc = RTStrmOpen(pszPath, "r", &pStrm);
if (RT_SUCCESS(rc))
{
while (RT_SUCCESS(rc = RTStrmGetLine(pStrm, szBuf, sizeof(szBuf))))
{
static char const s_szVarEq[] = "ZONE=";
char *pszStart = RTStrStrip(szBuf);
if (memcmp(pszStart, RT_STR_TUPLE(s_szVarEq)) == 0)
{
char *pszTimeZone = &pszStart[sizeof(s_szVarEq) - 1];
/* Drop any quoting before using the value, assuming it is plain stuff: */
if (*pszTimeZone == '\"' || *pszTimeZone == '\'')
{
pszTimeZone++;
size_t const cchTimeZone = strlen(pszTimeZone);
if (cchTimeZone && (pszTimeZone[cchTimeZone - 1] == '"' || pszTimeZone[cchTimeZone - 1] == '\''))
pszTimeZone[cchTimeZone - 1] = '\0';
}
rc = rtIsValidTimeZoneFile(pszTimeZone);
if (RT_SUCCESS(rc))
{
RTStrmClose(pStrm);
return RTStrCopy(pszName, cbName, pszTimeZone);
}
}
}
RTStrmClose(pStrm);
}
}
return rc;
}
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