10:22 a.m.
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