| 1 | /** $Id: VBoxGuestR3LibDaemonize.cpp 96407 2022-08-22 17:43:14Z vboxsync $ */
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| 2 | /** @file
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| 3 | * VBoxGuestR3Lib - Ring-3 Support Library for VirtualBox guest additions, daemonize a process.
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| 4 | */
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| 5 |
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| 6 | /*
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| 7 | * Copyright (C) 2007-2022 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 | #if defined(RT_OS_OS2)
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| 42 | # define INCL_BASE
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| 43 | # define INCL_ERRORS
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| 44 | # include <os2.h>
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| 45 |
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| 46 | # include <iprt/alloca.h>
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| 47 | # include <iprt/string.h>
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| 48 |
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| 49 | #elif defined(RT_OS_WINDOWS)
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| 50 | # error "PORTME"
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| 51 |
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| 52 | #else /* the unices */
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| 53 | # include <sys/types.h>
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| 54 | # include <sys/stat.h>
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| 55 | # include <sys/wait.h>
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| 56 | # include <stdio.h>
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| 57 | # include <fcntl.h>
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| 58 | # include <stdlib.h>
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| 59 | # include <unistd.h>
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| 60 | # include <signal.h>
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| 61 | # include <errno.h>
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| 62 | #endif
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| 63 |
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| 64 | #include <iprt/process.h>
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| 65 | #include <iprt/string.h>
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| 66 | #include "VBoxGuestR3LibInternal.h"
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| 67 |
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| 68 |
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| 69 | /**
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| 70 | * Daemonize the process for running in the background.
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| 71 | *
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| 72 | * This is supposed to do the same job as the BSD daemon() call.
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| 73 | *
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| 74 | * @returns 0 on success
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| 75 | *
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| 76 | * @param fNoChDir Pass false to change working directory to root.
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| 77 | * @param fNoClose Pass false to redirect standard file streams to /dev/null.
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| 78 | * @param fRespawn Restart the daemonised process after five seconds if it
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| 79 | * terminates abnormally.
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| 80 | * @param pcRespawn Where to store a count of how often we have respawned,
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| 81 | * intended for avoiding error spamming. Optional.
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| 82 | *
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| 83 | * @todo Use RTProcDaemonize instead of this.
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| 84 | * @todo Implement fRespawn on OS/2.
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| 85 | * @todo Make the respawn interval configurable. But not until someone
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| 86 | * actually needs that.
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| 87 | */
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| 88 | VBGLR3DECL(int) VbglR3Daemonize(bool fNoChDir, bool fNoClose, bool fRespawn, unsigned *pcRespawn)
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| 89 | {
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| 90 | #if defined(RT_OS_OS2)
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| 91 | PPIB pPib;
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| 92 | PTIB pTib;
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| 93 | DosGetInfoBlocks(&pTib, &pPib);
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| 94 |
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| 95 | AssertRelease(!fRespawn);
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| 96 | /* Get the full path to the executable. */
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| 97 | char szExe[CCHMAXPATH];
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| 98 | APIRET rc = DosQueryModuleName(pPib->pib_hmte, sizeof(szExe), szExe);
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| 99 | if (rc)
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| 100 | return RTErrConvertFromOS2(rc);
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| 101 |
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| 102 | /* calc the length of the command line. */
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| 103 | char *pch = pPib->pib_pchcmd;
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| 104 | size_t cch0 = strlen(pch);
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| 105 | pch += cch0 + 1;
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| 106 | size_t cch1 = strlen(pch);
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| 107 | pch += cch1 + 1;
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| 108 | char *pchArgs;
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| 109 | if (cch1 && *pch)
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| 110 | {
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| 111 | do pch = strchr(pch, '\0') + 1;
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| 112 | while (*pch);
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| 113 |
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| 114 | size_t cchTotal = pch - pPib->pib_pchcmd;
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| 115 | pchArgs = (char *)alloca(cchTotal + sizeof("--daemonized\0\0"));
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| 116 | memcpy(pchArgs, pPib->pib_pchcmd, cchTotal - 1);
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| 117 | memcpy(pchArgs + cchTotal - 1, "--daemonized\0\0", sizeof("--daemonized\0\0"));
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| 118 | }
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| 119 | else
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| 120 | {
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| 121 | size_t cchTotal = pch - pPib->pib_pchcmd + 1;
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| 122 | pchArgs = (char *)alloca(cchTotal + sizeof(" --daemonized "));
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| 123 | memcpy(pchArgs, pPib->pib_pchcmd, cch0 + 1);
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| 124 | pch = pchArgs + cch0 + 1;
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| 125 | memcpy(pch, " --daemonized ", sizeof(" --daemonized ") - 1);
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| 126 | pch += sizeof(" --daemonized ") - 1;
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| 127 | if (cch1)
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| 128 | memcpy(pch, pPib->pib_pchcmd + cch0 + 1, cch1 + 2);
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| 129 | else
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| 130 | pch[0] = pch[1] = '\0';
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| 131 | }
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| 132 |
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| 133 | /* spawn a detach process */
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| 134 | char szObj[128];
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| 135 | RESULTCODES ResCodes = { 0, 0 };
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| 136 | szObj[0] = '\0';
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| 137 | rc = DosExecPgm(szObj, sizeof(szObj), EXEC_BACKGROUND, (PCSZ)pchArgs, NULL, &ResCodes, (PCSZ)szExe);
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| 138 | if (rc)
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| 139 | {
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| 140 | /** @todo Change this to some standard log/print error?? */
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| 141 | /* VBoxServiceError("DosExecPgm failed with rc=%d and szObj='%s'\n", rc, szObj); */
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| 142 | return RTErrConvertFromOS2(rc);
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| 143 | }
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| 144 | DosExit(EXIT_PROCESS, 0);
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| 145 | return VERR_GENERAL_FAILURE;
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| 146 |
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| 147 | #elif defined(RT_OS_WINDOWS)
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| 148 | # error "PORTME"
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| 149 |
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| 150 | #else /* the unices */
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| 151 | /*
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| 152 | * Fork the child process in a new session and quit the parent.
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| 153 | *
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| 154 | * - fork once and create a new session (setsid). This will detach us
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| 155 | * from the controlling tty meaning that we won't receive the SIGHUP
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| 156 | * (or any other signal) sent to that session.
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| 157 | * - The SIGHUP signal is ignored because the session/parent may throw
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| 158 | * us one before we get to the setsid.
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| 159 | * - When the parent exit(0) we will become an orphan and re-parented to
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| 160 | * the init process.
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| 161 | * - Because of the Linux / System V semantics of assigning the controlling
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| 162 | * tty automagically when a session leader first opens a tty, we will
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| 163 | * fork() once more on Linux to get rid of the session leadership role.
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| 164 | */
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| 165 |
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| 166 | struct sigaction OldSigAct;
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| 167 | struct sigaction SigAct;
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| 168 | RT_ZERO(SigAct);
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| 169 | SigAct.sa_handler = SIG_IGN;
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| 170 | int rcSigAct = sigaction(SIGHUP, &SigAct, &OldSigAct);
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| 171 |
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| 172 | pid_t pid = fork();
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| 173 | if (pid == -1)
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| 174 | return RTErrConvertFromErrno(errno);
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| 175 | if (pid != 0)
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| 176 | exit(0);
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| 177 |
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| 178 | /*
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| 179 | * The orphaned child becomes is reparented to the init process.
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| 180 | * We create a new session for it (setsid), point the standard
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| 181 | * file descriptors to /dev/null, and change to the root directory.
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| 182 | */
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| 183 | pid_t newpgid = setsid();
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| 184 | int SavedErrno = errno;
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| 185 | if (rcSigAct != -1)
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| 186 | sigaction(SIGHUP, &OldSigAct, NULL);
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| 187 | if (newpgid == -1)
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| 188 | return RTErrConvertFromErrno(SavedErrno);
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| 189 |
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| 190 | if (!fNoClose)
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| 191 | {
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| 192 | /* Open stdin(0), stdout(1) and stderr(2) as /dev/null. */
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| 193 | int fd = open("/dev/null", O_RDWR);
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| 194 | if (fd == -1) /* paranoia */
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| 195 | {
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| 196 | close(STDIN_FILENO);
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| 197 | close(STDOUT_FILENO);
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| 198 | close(STDERR_FILENO);
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| 199 | fd = open("/dev/null", O_RDWR);
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| 200 | }
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| 201 | if (fd != -1)
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| 202 | {
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| 203 | dup2(fd, STDIN_FILENO);
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| 204 | dup2(fd, STDOUT_FILENO);
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| 205 | dup2(fd, STDERR_FILENO);
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| 206 | if (fd > 2)
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| 207 | close(fd);
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| 208 | }
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| 209 | }
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| 210 |
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| 211 | if (!fNoChDir)
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| 212 | {
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| 213 | int rcShutUpGcc = chdir("/");
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| 214 | RT_NOREF_PV(rcShutUpGcc);
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| 215 | }
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| 216 |
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| 217 | /*
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| 218 | * Change the umask - this is non-standard daemon() behavior.
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| 219 | */
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| 220 | umask(027);
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| 221 |
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| 222 | # ifdef RT_OS_LINUX
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| 223 | /*
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| 224 | * And fork again to lose session leader status (non-standard daemon()
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| 225 | * behaviour).
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| 226 | */
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| 227 | pid = fork();
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| 228 | if (pid == -1)
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| 229 | return RTErrConvertFromErrno(errno);
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| 230 | if (pid != 0)
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| 231 | exit(0);
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| 232 | # endif /* RT_OS_LINUX */
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| 233 |
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| 234 | if (fRespawn)
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| 235 | {
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| 236 | /* We implement re-spawning as a third fork(), with the parent process
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| 237 | * monitoring the child and re-starting it after a delay if it exits
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| 238 | * abnormally. */
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| 239 | unsigned cRespawn = 0;
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| 240 | for (;;)
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| 241 | {
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| 242 | int iStatus, rcWait;
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| 243 |
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| 244 | if (pcRespawn != NULL)
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| 245 | *pcRespawn = cRespawn;
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| 246 | pid = fork();
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| 247 | if (pid == -1)
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| 248 | return RTErrConvertFromErrno(errno);
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| 249 | if (pid == 0)
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| 250 | return VINF_SUCCESS;
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| 251 | do
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| 252 | rcWait = waitpid(pid, &iStatus, 0);
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| 253 | while (rcWait == -1 && errno == EINTR);
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| 254 | if (rcWait == -1)
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| 255 | exit(1);
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| 256 | if (WIFEXITED(iStatus) && WEXITSTATUS(iStatus) == 0)
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| 257 | exit(0);
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| 258 | sleep(5);
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| 259 | ++cRespawn;
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| 260 | }
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| 261 | }
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| 262 | return VINF_SUCCESS;
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| 263 | #endif
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| 264 | }
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