/** $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 # include # include #elif defined(RT_OS_WINDOWS) # error "PORTME" #else /* the unices */ # include # include # include # include # include # include # include # include # include #endif #include #include #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 }