[libvirt] [PATCH v4] util: Ignore SIGPIPE before write logs to stderr in child process
Libvirtd has set SIGPIPE to ignored, and virFork resets all signal
handlers to the defaults. But child process may write logs to
stderr/stdout, that may generate SIGPIPE if journald has stopped.
So in virExec(), set SIGPIPE to ignored before invoke
virCommandMassClose, and revert it back to SIG_DFL after that.
In virProcessRunInFork(), just set SIGPIPE to ignored.
Signed-off-by: Wang Yechao <wang.yechao255(a)zte.com.cn>
---
v1 patch:
https://www.redhat.com/archives/libvir-list/2019-October/msg00720.html
Changes in v2:
- use pthread_sigmask to block SIGPIPE
Changes in v3:
- pass SIG_UNBLOCK(not SIG_SETMASK) to pthread_sigmask when unlock SIGPIPE
Changes in v4:
- don't block SIGPIPE, ignore it when invoke VIR_FORCE_CLOSE and
virCommandMassClose
---
src/util/vircommand.c | 16 ++++++++++++++++
src/util/virprocess.c | 10 ++++++++++
2 files changed, 26 insertions(+)
diff --git a/src/util/vircommand.c b/src/util/vircommand.c
index 763bcb6..bb6e73b 100644
--- a/src/util/vircommand.c
+++ b/src/util/vircommand.c
@@ -653,9 +653,25 @@ virExec(virCommandPtr cmd)
umask(cmd->mask);
ret = EXIT_CANCELED;
+ memset(&waxoff, 0, sizeof(waxoff));
+ waxoff.sa_handler = SIG_IGN;
+ sigemptyset(&waxoff.sa_mask);
+ memset(&waxon, 0, sizeof(waxon));
+ if (sigaction(SIGPIPE, &waxoff, &waxon) < 0) {
+ virReportSystemError(errno, "%s",
+ _("Could not disable SIGPIPE"));
+ goto fork_error;
+ }
+
if (virCommandMassClose(cmd, childin, childout, childerr) < 0)
goto fork_error;
+ if (sigaction(SIGPIPE, &waxon, NULL) < 0) {
+ virReportSystemError(errno, "%s",
+ _("Could not re-enable SIGPIPE"));
+ goto fork_error;
+ }
+
if (prepareStdFd(childin, STDIN_FILENO) < 0) {
virReportSystemError(errno,
"%s", _("failed to setup stdin file
handle"));
diff --git a/src/util/virprocess.c b/src/util/virprocess.c
index e8d4ba0..da66dcf 100644
--- a/src/util/virprocess.c
+++ b/src/util/virprocess.c
@@ -1151,6 +1151,16 @@ virProcessRunInFork(virProcessForkCallback cb,
goto cleanup;
if (child == 0) {
+ struct sigaction waxoff;
+
+ memset(&waxoff, 0, sizeof(waxoff));
+ waxoff.sa_handler = SIG_IGN;
+ sigemptyset(&waxoff.sa_mask);
+ if (sigaction(SIGPIPE, &waxoff, NULL) < 0) {
+ virReportSystemError(errno, "%s",
+ _("Could not disable SIGPIPE"));
+ }
+
VIR_FORCE_CLOSE(errfd[0]);
ret = virProcessRunInForkHelper(errfd[1], parent, cb, opaque);
VIR_FORCE_CLOSE(errfd[1]);
--
1.8.3.1