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/** $Id: VBoxGuestR3LibDaemonize.cpp $ */
/** @file
* VBoxGuestR3Lib - Ring-3 Support Library for VirtualBox guest additions, daemonize a process.
*/
/*
* Copyright (C) 2007-2019 Oracle Corporation
*
* This file is part of VirtualBox Open Source Edition (OSE), as
* available from http://www.virtualbox.org. This file is free software;
* you can redistribute it and/or modify it under the terms of the GNU
* General Public License (GPL) as published by the Free Software
* Foundation, in version 2 as it comes in the "COPYING" file of the
* VirtualBox OSE distribution. VirtualBox OSE is distributed in the
* hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
*
* The contents of this file may alternatively be used under the terms
* of the Common Development and Distribution License Version 1.0
* (CDDL) only, as it comes in the "COPYING.CDDL" file of the
* VirtualBox OSE 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.
*/
/*********************************************************************************************************************************
* Header Files *
*********************************************************************************************************************************/
#if defined(RT_OS_OS2)
# define INCL_BASE
# define INCL_ERRORS
# include <os2.h>
# include <iprt/alloca.h>
# include <iprt/string.h>
#elif defined(RT_OS_WINDOWS)
# error "PORTME"
#else /* the unices */
# include <sys/types.h>
# include <sys/stat.h>
# include <sys/wait.h>
# include <stdio.h>
# include <fcntl.h>
# include <stdlib.h>
# include <unistd.h>
# include <signal.h>
# include <errno.h>
#endif
#include <iprt/process.h>
#include <iprt/string.h>
#include "VBoxGuestR3LibInternal.h"
/**
* Daemonize the process for running in the background.
*
* This is supposed to do the same job as the BSD daemon() call.
*
* @returns 0 on success
*
* @param fNoChDir Pass false to change working directory to root.
* @param fNoClose Pass false to redirect standard file streams to /dev/null.
* @param fRespawn Restart the daemonised process after five seconds if it
* terminates abnormally.
* @param pcRespawn Where to store a count of how often we have respawned,
* intended for avoiding error spamming. Optional.
*
* @todo Use RTProcDaemonize instead of this.
* @todo Implement fRespawn on OS/2.
* @todo Make the respawn interval configurable. But not until someone
* actually needs that.
*/
VBGLR3DECL(int) VbglR3Daemonize(bool fNoChDir, bool fNoClose, bool fRespawn, unsigned *pcRespawn)
{
#if defined(RT_OS_OS2)
PPIB pPib;
PTIB pTib;
DosGetInfoBlocks(&pTib, &pPib);
AssertRelease(!fRespawn);
/* Get the full path to the executable. */
char szExe[CCHMAXPATH];
APIRET rc = DosQueryModuleName(pPib->pib_hmte, sizeof(szExe), szExe);
if (rc)
return RTErrConvertFromOS2(rc);
/* calc the length of the command line. */
char *pch = pPib->pib_pchcmd;
size_t cch0 = strlen(pch);
pch += cch0 + 1;
size_t cch1 = strlen(pch);
pch += cch1 + 1;
char *pchArgs;
if (cch1 && *pch)
{
do pch = strchr(pch, '\0') + 1;
while (*pch);
size_t cchTotal = pch - pPib->pib_pchcmd;
pchArgs = (char *)alloca(cchTotal + sizeof("--daemonized\0\0"));
memcpy(pchArgs, pPib->pib_pchcmd, cchTotal - 1);
memcpy(pchArgs + cchTotal - 1, "--daemonized\0\0", sizeof("--daemonized\0\0"));
}
else
{
size_t cchTotal = pch - pPib->pib_pchcmd + 1;
pchArgs = (char *)alloca(cchTotal + sizeof(" --daemonized "));
memcpy(pchArgs, pPib->pib_pchcmd, cch0 + 1);
pch = pchArgs + cch0 + 1;
memcpy(pch, " --daemonized ", sizeof(" --daemonized ") - 1);
pch += sizeof(" --daemonized ") - 1;
if (cch1)
memcpy(pch, pPib->pib_pchcmd + cch0 + 1, cch1 + 2);
else
pch[0] = pch[1] = '\0';
}
/* spawn a detach process */
char szObj[128];
RESULTCODES ResCodes = { 0, 0 };
szObj[0] = '\0';
rc = DosExecPgm(szObj, sizeof(szObj), EXEC_BACKGROUND, (PCSZ)pchArgs, NULL, &ResCodes, (PCSZ)szExe);
if (rc)
{
/** @todo Change this to some standard log/print error?? */
/* VBoxServiceError("DosExecPgm failed with rc=%d and szObj='%s'\n", rc, szObj); */
return RTErrConvertFromOS2(rc);
}
DosExit(EXIT_PROCESS, 0);
return VERR_GENERAL_FAILURE;
#elif defined(RT_OS_WINDOWS)
# error "PORTME"
#else /* the unices */
/*
* Fork the child process in a new session and quit the parent.
*
* - fork once and create a new session (setsid). This will detach us
* from the controlling tty meaning that we won't receive the SIGHUP
* (or any other signal) sent to that session.
* - The SIGHUP signal is ignored because the session/parent may throw
* us one before we get to the setsid.
* - When the parent exit(0) we will become an orphan and re-parented to
* the init process.
* - Because of the Linux / System V semantics of assigning the controlling
* tty automagically when a session leader first opens a tty, we will
* fork() once more on Linux to get rid of the session leadership role.
*/
struct sigaction OldSigAct;
struct sigaction SigAct;
RT_ZERO(SigAct);
SigAct.sa_handler = SIG_IGN;
int rcSigAct = sigaction(SIGHUP, &SigAct, &OldSigAct);
pid_t pid = fork();
if (pid == -1)
return RTErrConvertFromErrno(errno);
if (pid != 0)
exit(0);
/*
* The orphaned child becomes is reparented to the init process.
* We create a new session for it (setsid), point the standard
* file descriptors to /dev/null, and change to the root directory.
*/
pid_t newpgid = setsid();
int SavedErrno = errno;
if (rcSigAct != -1)
sigaction(SIGHUP, &OldSigAct, NULL);
if (newpgid == -1)
return RTErrConvertFromErrno(SavedErrno);
if (!fNoClose)
{
/* Open stdin(0), stdout(1) and stderr(2) as /dev/null. */
int fd = open("/dev/null", O_RDWR);
if (fd == -1) /* paranoia */
{
close(STDIN_FILENO);
close(STDOUT_FILENO);
close(STDERR_FILENO);
fd = open("/dev/null", O_RDWR);
}
if (fd != -1)
{
dup2(fd, STDIN_FILENO);
dup2(fd, STDOUT_FILENO);
dup2(fd, STDERR_FILENO);
if (fd > 2)
close(fd);
}
}
if (!fNoChDir)
{
int rcShutUpGcc = chdir("/");
RT_NOREF_PV(rcShutUpGcc);
}
/*
* Change the umask - this is non-standard daemon() behavior.
*/
umask(027);
# ifdef RT_OS_LINUX
/*
* And fork again to lose session leader status (non-standard daemon()
* behaviour).
*/
pid = fork();
if (pid == -1)
return RTErrConvertFromErrno(errno);
if (pid != 0)
exit(0);
# endif /* RT_OS_LINUX */
if (fRespawn)
{
/* We implement re-spawning as a third fork(), with the parent process
* monitoring the child and re-starting it after a delay if it exits
* abnormally. */
unsigned cRespawn = 0;
for (;;)
{
int iStatus, rcWait;
if (pcRespawn != NULL)
*pcRespawn = cRespawn;
pid = fork();
if (pid == -1)
return RTErrConvertFromErrno(errno);
if (pid == 0)
return VINF_SUCCESS;
do
rcWait = waitpid(pid, &iStatus, 0);
while (rcWait == -1 && errno == EINTR);
if (rcWait == -1)
exit(1);
if (WIFEXITED(iStatus) && WEXITSTATUS(iStatus) == 0)
exit(0);
sleep(5);
++cRespawn;
}
}
return VINF_SUCCESS;
#endif
}
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