提交 61497d95 编写于 作者: L Laine Stump 提交者: Daniel Veillard

Use virFork() in __virExec(), virFileCreate() and virDirCreate()

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: use the generic virFork() in the 3 functions
上级 b4584612
......@@ -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;
......
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