[libvirt] [PATCH v3] util: Block SIGPIPE until execve 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 block SIGPIPE in virFork, and unblock it before execve. Signed-off-by: Wang Yechao <wang.yechao255(a)zte.com.cn&gt; --- 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 --- src/util/vircommand.c | 17 +++++++++++++++++ 1 file changed, 17 insertions(+) diff --git a/src/util/vircommand.c b/src/util/vircommand.c index 79e1e87..bd3a582 100644 --- a/src/util/vircommand.c +++ b/src/util/vircommand.c @@ -321,6 +321,15 @@ virFork(void) virDispatchError(NULL); _exit(EXIT_CANCELED); } + + sigemptyset(&newmask); + sigaddset(&newmask, SIGPIPE); + if (pthread_sigmask(SIG_BLOCK, &newmask, NULL) != 0) { + virReportSystemError(errno, "%s", _("cannot block SIGPIPE")); + virDispatchError(NULL); + _exit(EXIT_CANCELED); + } + } return pid; } @@ -553,6 +562,7 @@ virExec(virCommandPtr cmd) struct sigaction waxon, waxoff; VIR_AUTOFREE(gid_t *) groups = NULL; int ngroups; + sigset_t set; if (cmd->args[0][0] != '/') { if (!(binary = binarystr = virFindFileInPath(cmd->args[0]))) { @@ -792,6 +802,13 @@ virExec(virCommandPtr cmd) /* Close logging again to ensure no FDs leak to child */ virLogReset(); + sigemptyset(&set); + sigaddset(&set, SIGPIPE); + if (pthread_sigmask(SIG_UNBLOCK, &set, NULL) != 0) { + virReportSystemError(errno, "%s", _("cannot unblock SIGPIPE")); + goto fork_error; + } + if (cmd->env) execve(binary, cmd->args, cmd->env); else -- 1.8.3.1