path: root/src/VBox/Additions/common/VBoxGuest/lib/VBoxGuestR3LibDaemonize.cpp

/** $Id: VBoxGuestR3LibDaemonize.cpp $ */
/** @file
 * VBoxGuestR3Lib - Ring-3 Support Library for VirtualBox guest additions, daemonize a process.
 */

/*
 * Copyright (C) 2007-2023 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                                                                                                                 *
*********************************************************************************************************************************/
#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 <VBox/err.h>
#include <VBox/log.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.
 * @param   fReturnOnUpdate If True, this function will return control to caller when
 *                          child process will terminate with exit code of VBGLR3EXITCODERELOAD,
 *                          indicating that Guest Additions update has been started and this running
 *                          process will be asked to be restarted by arrival of the next SIGUSR1
 *                          signal (caller should wait for SIGUSR1). If False, this functions will
 *                          never return, but rather exit() when child process terminates with
 *                          exit code 0.
 * @param   pfUpdateStarted A flag which passed to caller if fReturnOnUpdate is True (can be NULL).
 * @param   szPidfile       Optional path to parent process' pidfile (can be NULL).
 * @param   phPidfile       Optional path to parent process' pidfile handle (can not be NULL if
 *                          szPidfile was specified).
 *
 * @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) VbglR3DaemonizeEx(bool fNoChDir, bool fNoClose, bool fRespawn, unsigned *pcRespawn,
                                  bool fReturnOnUpdate, bool *pfUpdateStarted, const char *szPidfile,
                                  RTFILE *phPidfile)
{
#if defined(RT_OS_OS2)
    PPIB pPib;
    PTIB pTib;
    DosGetInfoBlocks(&pTib, &pPib);

    RT_NOREF(fReturnOnUpdate);
    RT_NOREF(pfUpdateStarted);
    RT_NOREF(szPidfile);
    RT_NOREF(phPidfile);

    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 */

    /* Check if another instance is already running. */
    if (szPidfile != NULL)
    {
        if (phPidfile != NULL)
        {
            int rc = VbglR3PidfileWait(szPidfile, phPidfile, 5000);

             /* Another instance of process is already running. */
            if (rc == VERR_FILE_LOCK_VIOLATION)
            {
                LogRel(("cannot aquire pidfile %s, exitting\n", szPidfile));
                exit(1);
            }

            /* Unable to lock on pidfile. */
            if (RT_FAILURE(rc))
                exit(1);
        }
        else
            return VERR_INVALID_PARAMETER;
    }

    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))
            {
                if (WEXITSTATUS(iStatus) == 0)
                    exit(0);
                else if (fReturnOnUpdate && WEXITSTATUS(iStatus) == VBGLR3EXITCODERELOAD)
                {
                    /* Tell caller that update has been started. */
                    if (pfUpdateStarted != NULL)
                        *pfUpdateStarted = true;

                    return VINF_SUCCESS;
                }
            }
            sleep(5);
            ++cRespawn;
        }
    }
    return VINF_SUCCESS;
#endif
}

/**
 * A wrapper function for VbglR3DaemonizeEx.
 */
VBGLR3DECL(int) VbglR3Daemonize(bool fNoChDir, bool fNoClose, bool fRespawn, unsigned *pcRespawn)
{
    return VbglR3DaemonizeEx(fNoChDir, fNoClose, fRespawn, pcRespawn, false, NULL, NULL, NULL);
}