For __virExec() this is a semantic NOP except for when fork() fails. __virExec() would previously forget to restore the signal mask in this case; virFork() corrects this behavior. virFileCreate() and virDirCreate() gain the code to reset the logging and properly deal with the signal handling race condition. This also removes a log message that had a typo ("cannot fork o create file '%s'") - this error is now logged in a more generic manner in virFork() (more generic, but really just as informative, since the fact that it's forking to create a file is immaterial to the fact that it simply can't fork) --- src/util/util.c | 100 ++++++++++++++---------------------------------------- 1 files changed, 26 insertions(+), 74 deletions(-) diff --git a/src/util/util.c b/src/util/util.c index d9beddf..c3b4084 100644 --- a/src/util/util.c +++ b/src/util/util.c @@ -451,20 +451,6 @@ __virExec(const char *const*argv, int pipeerr[2] = {-1,-1}; int childout = -1; int childerr = -1; - int logprio; - sigset_t oldmask, newmask; - struct sigaction sig_action; - - /* - * Need to block signals now, so that child process can safely - * kill off caller's signal handlers without a race. - */ - sigfillset(&newmask); - if (pthread_sigmask(SIG_SETMASK, &newmask, &oldmask) != 0) { - virReportSystemError(errno, - "%s", _("cannot block signals")); - return -1; - } if ((null = open("/dev/null", O_RDONLY)) < 0) { virReportSystemError(errno, @@ -531,17 +517,9 @@ __virExec(const char *const*argv, childerr = null; } - /* Ensure we hold the logging lock, to protect child processes - * from deadlocking on another threads inheirited mutex state */ - virLogLock(); - pid = fork(); - - /* Unlock for both parent and child process */ - virLogUnlock(); + int forkRet = virFork(&pid); if (pid < 0) { - virReportSystemError(errno, - "%s", _("cannot fork child process")); goto cleanup; } @@ -556,12 +534,8 @@ __virExec(const char *const*argv, *errfd = pipeerr[0]; } - /* Restore our original signal mask now child is safely - running */ - if (pthread_sigmask(SIG_SETMASK, &oldmask, NULL) != 0) { - virReportSystemError(errno, - "%s", _("cannot unblock signals")); - return -1; + if (forkRet < 0) { + goto cleanup; } *retpid = pid; @@ -570,38 +544,10 @@ __virExec(const char *const*argv, /* child */ - /* Remove any error callback too, so errors in child now - get sent to stderr where they stand a fighting chance - of being seen / logged */ - virSetErrorFunc(NULL, NULL); - - /* Make sure any hook logging is sent to stderr, since virExec will - * close any unknown FDs (including logging handlers) before launching - * the new process */ - logprio = virLogGetDefaultPriority(); - virLogReset(); - virLogSetDefaultPriority(logprio); - - /* Clear out all signal handlers from parent so nothing - unexpected can happen in our child once we unblock - signals */ - sig_action.sa_handler = SIG_DFL; - sig_action.sa_flags = 0; - sigemptyset(&sig_action.sa_mask); - - for (i = 1 ; i < NSIG ; i++) - /* Only possible errors are EFAULT or EINVAL - The former wont happen, the latter we - expect, so no need to check return value */ - sigaction(i, &sig_action, NULL); - - /* Unmask all signals in child, since we've no idea - what the caller's done with their signal mask - and don't want to propagate that to children */ - sigemptyset(&newmask); - if (pthread_sigmask(SIG_SETMASK, &newmask, NULL) != 0) { - virReportSystemError(errno, - "%s", _("cannot unblock signals")); + if (forkRet < 0) { + /* The fork was sucessful, but after that there was an error + * in the child (which was already logged). + */ _exit(1); } @@ -1370,14 +1316,10 @@ int virFileCreate(const char *path, mode_t mode, * following dance avoids problems caused by root-squashing * NFS servers. */ - virLogLock(); - pid = fork(); - virLogUnlock(); + int forkRet = virFork(&pid); if (pid < 0) { ret = errno; - virReportSystemError(errno, - _("cannot fork o create file '%s'"), path); return ret; } @@ -1429,7 +1371,15 @@ parenterror: return ret; } - /* child - set desired uid/gid, then attempt to create the file */ + + /* child */ + + if (forkRet < 0) { + /* error encountered and logged in virFork() after the fork. */ + goto childerror; + } + + /* set desired uid/gid, then attempt to create the file */ if ((gid != 0) && (setgid(gid) != 0)) { ret = errno; @@ -1480,15 +1430,10 @@ int virDirCreate(const char *path, mode_t mode, return virDirCreateSimple(path, mode, uid, gid, flags); } - virLogLock(); - pid = fork(); - virLogUnlock(); + int forkRet = virFork(&pid); if (pid < 0) { ret = errno; - virReportSystemError(errno, - _("cannot fork to create directory '%s'"), - path); return ret; } @@ -1538,7 +1483,14 @@ parenterror: return ret; } - /* child - set desired uid/gid, then attempt to create the directory */ + /* child */ + + if (forkRet < 0) { + /* error encountered and logged in virFork() after the fork. */ + goto childerror; + } + + /* set desired uid/gid, then attempt to create the directory */ if ((gid != 0) && (setgid(gid) != 0)) { ret = errno; -- 1.6.6.1 -- libvir-list mailing list libvir-list@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/libvir-list