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[Qemu-devel] [PATCH 4/3] guest agent: ignore SIGPIPE signal
From: |
Denis V. Lunev |
Subject: |
[Qemu-devel] [PATCH 4/3] guest agent: ignore SIGPIPE signal |
Date: |
Thu, 25 Dec 2014 08:41:49 +0300 |
From: Simon Zolin <address@hidden>
If write operation fails on a pipe whose reading end is closed, qemu-ga
won't be terminated, but instead write() will fail with error EPIPE.
execve() inherits signals that are ignored, so reset SIGPIPE to its default
handler before calling execve() in a forked process.
Signed-off-by: Simon Zolin <address@hidden>
Signed-off-by: Denis V. Lunev <address@hidden>
CC: Michael Roth <address@hidden>
---
qga/commands-posix.c | 16 ++++++++++++++++
qga/main.c | 6 ++++++
2 files changed, 22 insertions(+)
diff --git a/qga/commands-posix.c b/qga/commands-posix.c
index 5872196..93aed2e 100644
--- a/qga/commands-posix.c
+++ b/qga/commands-posix.c
@@ -998,6 +998,20 @@ static int guest_exec_set_std(GuestFileHandle *gfh, int
std_fd, int fd_null)
return 0;
}
+/** Reset ignored signals back to default. */
+static void guest_exec_reset_child_sig(void)
+{
+ struct sigaction sigact;
+
+ memset(&sigact, 0, sizeof(struct sigaction));
+ sigact.sa_handler = SIG_DFL;
+
+ if (sigaction(SIGPIPE, &sigact, NULL) != 0) {
+ slog("sigaction() failed to reset child process's SIGPIPE: %s",
+ strerror(errno));
+ }
+}
+
int64_t qmp_guest_exec(const char *path,
bool has_params, strList *params,
bool has_env, strList *env,
@@ -1070,6 +1084,8 @@ int64_t qmp_guest_exec(const char *path,
/* exit(1); */
}
+ guest_exec_reset_child_sig();
+
execvpe(path, (char * const *)argv, (char * const *)envp);
slog("guest-exec child failed: %s", strerror(errno));
exit(1);
diff --git a/qga/main.c b/qga/main.c
index 9939a2b..bc6414c 100644
--- a/qga/main.c
+++ b/qga/main.c
@@ -160,6 +160,12 @@ static gboolean register_signal_handlers(void)
g_error("error configuring signal handler: %s", strerror(errno));
}
+ sigact.sa_handler = SIG_IGN;
+ if (sigaction(SIGPIPE, &sigact, NULL) != 0) {
+ g_error("error configuring SIGPIPE signal handler: %s",
+ strerror(errno));
+ }
+
return true;
}
--
1.9.1