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/** $Id: VBoxGuestR3LibPidFile.cpp $ */
/** @file
* VBoxGuestR3Lib - Ring-3 Support Library for VirtualBox guest additions,
* Create a PID file.
*/
/*
* Copyright (C) 2015-2023 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/file.h>
#include <iprt/string.h>
#include <iprt/process.h>
#include <iprt/thread.h>
#include <iprt/err.h>
#include "VBoxGuestR3LibInternal.h"
/* A time to wait before starting the next attempt to check a pidfile. */
#define VBGL_PIDFILE_WAIT_RELAX_TIME_MS (250)
/**
* Creates a PID File and returns the open file descriptor.
*
* On DOS based system, file sharing (deny write) is used for locking the PID
* file.
*
* On Unix-y systems, an exclusive advisory lock is used for locking the PID
* file since the file sharing support is usually missing there.
*
* This API will overwrite any existing PID Files without a lock on them, on the
* assumption that they are stale files which an old process did not properly
* clean up.
*
* @returns IPRT status code.
* @param pszPath The path and filename to create the PID File under
* @param phFile Where to store the file descriptor of the open (and locked
* on Unix-y systems) PID File. On failure, or if another
* process owns the PID File, this will be set to NIL_RTFILE.
*/
VBGLR3DECL(int) VbglR3PidFile(const char *pszPath, PRTFILE phFile)
{
AssertPtrReturn(pszPath, VERR_INVALID_PARAMETER);
AssertPtrReturn(phFile, VERR_INVALID_PARAMETER);
*phFile = NIL_RTFILE;
RTFILE hPidFile;
int rc = RTFileOpen(&hPidFile, pszPath,
RTFILE_O_READWRITE | RTFILE_O_OPEN_CREATE | RTFILE_O_DENY_WRITE
| (0644 << RTFILE_O_CREATE_MODE_SHIFT));
if (RT_SUCCESS(rc))
{
#if !defined(RT_OS_WINDOWS) && !defined(RT_OS_OS2)
/** @todo using size 0 for locking means lock all on Posix.
* We should adopt this as our convention too, or something
* similar. */
rc = RTFileLock(hPidFile, RTFILE_LOCK_WRITE, 0, 0);
if (RT_FAILURE(rc))
RTFileClose(hPidFile);
else
#endif
{
char szBuf[256];
size_t cbPid = RTStrPrintf(szBuf, sizeof(szBuf), "%d\n",
RTProcSelf());
RTFileWrite(hPidFile, szBuf, cbPid, NULL);
*phFile = hPidFile;
}
}
return rc;
}
/**
* Close and remove an open PID File.
*
* @param pszPath The path to the PID File,
* @param hFile The handle for the file. NIL_RTFILE is ignored as usual.
*/
VBGLR3DECL(void) VbglR3ClosePidFile(const char *pszPath, RTFILE hFile)
{
AssertPtrReturnVoid(pszPath);
if (hFile != NIL_RTFILE)
{
#if defined(RT_OS_WINDOWS) || defined(RT_OS_OS2)
RTFileWriteAt(hFile, 0, "-1", 2, NULL);
#else
RTFileDelete(pszPath);
#endif
RTFileClose(hFile);
}
}
/**
* Wait for other process to release pidfile.
*
* This function is a wrapper to VbglR3PidFile().
*
* @returns IPRT status code.
* @param szPidfile Path to pidfile.
* @param phPidfile Handle to pidfile.
* @param u64TimeoutMs A timeout value in milliseconds to wait for
* other process to release pidfile.
*/
VBGLR3DECL(int) VbglR3PidfileWait(const char *szPidfile, RTFILE *phPidfile, uint64_t u64TimeoutMs)
{
int rc = VERR_FILE_LOCK_VIOLATION;
uint64_t u64Start = RTTimeSystemMilliTS();
AssertPtrReturn(szPidfile, VERR_INVALID_PARAMETER);
AssertPtrReturn(phPidfile, VERR_INVALID_PARAMETER);
while ( !RT_SUCCESS((rc = VbglR3PidFile(szPidfile, phPidfile)))
&& (RTTimeSystemMilliTS() - u64Start < u64TimeoutMs))
{
RTThreadSleep(VBGL_PIDFILE_WAIT_RELAX_TIME_MS);
}
return rc;
}
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