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Thu, 18 Jul 2024 09:48:52 -0700 (PDT) From: Andrew Cooper To: Xen-devel Cc: Andrew Cooper , Anthony PERARD , Juergen Gross Subject: [PATCH 6/6] tools/libxs: Stop playing with SIGPIPE Date: Thu, 18 Jul 2024 17:48:42 +0100 Message-Id: <20240718164842.3650702-7-andrew.cooper3@citrix.com> X-Mailer: git-send-email 2.39.2 In-Reply-To: <20240718164842.3650702-1-andrew.cooper3@citrix.com> References: <20240718164842.3650702-1-andrew.cooper3@citrix.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-ZohoMail-DKIM: pass (identity @citrix.com) X-ZM-MESSAGEID: 1721321353441116600 Content-Type: text/plain; charset="utf-8" It's very rude for a library to play with signals behind the back of the application, no matter ones views on the default behaviour of SIGPIPE under POSIX. Even if the application doesn't care about the xenstored socket, it= my care about others. This logic has existed since xenstore/xenstored was originally added in com= mit 29c9e570b1ed ("Add xenstore daemon and library") in 2005. It's also unnecessary. Pass MSG_NOSIGNAL when talking to xenstored over a pipe (to avoid sucumbing to SIGPIPE if xenstored has crashed), and forgo any playing with the signal disposition. This has a side benefit of saving 2 syscalls per xenstore request. Signed-off-by: Andrew Cooper Reviewed-by: Jason Andryuk Reviewed-by: Juergen Gross --- CC: Anthony PERARD CC: Juergen Gross --- tools/libs/store/xs.c | 10 +--------- 1 file changed, 1 insertion(+), 9 deletions(-) diff --git a/tools/libs/store/xs.c b/tools/libs/store/xs.c index 9db5c02661f5..63d754e17014 100644 --- a/tools/libs/store/xs.c +++ b/tools/libs/store/xs.c @@ -579,7 +579,7 @@ static bool sendmsg_exact(int fd, struct iovec *iov, un= signed int nr) assert(iov->iov_len =3D=3D sizeof(struct xsd_sockmsg)); =20 while (hdr.msg_iovlen) { - ssize_t res =3D sendmsg(fd, &hdr, 0); + ssize_t res =3D sendmsg(fd, &hdr, MSG_NOSIGNAL); =20 if (res < 0 && errno =3D=3D EINTR) continue; @@ -680,7 +680,6 @@ static void *xs_talkv(struct xs_handle *h, void *ret =3D NULL; int saved_errno; unsigned int i, msg_len; - struct sigaction ignorepipe, oldact; =20 /* Element 0 must be xsd_sockmsg */ assert(num_vecs >=3D 1); @@ -697,11 +696,6 @@ static void *xs_talkv(struct xs_handle *h, =20 msg->len =3D msg_len; =20 - ignorepipe.sa_handler =3D SIG_IGN; - sigemptyset(&ignorepipe.sa_mask); - ignorepipe.sa_flags =3D 0; - sigaction(SIGPIPE, &ignorepipe, &oldact); - mutex_lock(&h->request_mutex); =20 if (!write_request(h, iovec, num_vecs)) @@ -713,7 +707,6 @@ static void *xs_talkv(struct xs_handle *h, =20 mutex_unlock(&h->request_mutex); =20 - sigaction(SIGPIPE, &oldact, NULL); if (reply_type =3D=3D XS_ERROR) { saved_errno =3D get_error(ret); free(ret); @@ -732,7 +725,6 @@ static void *xs_talkv(struct xs_handle *h, /* We're in a bad state, so close fd. */ saved_errno =3D errno; mutex_unlock(&h->request_mutex); - sigaction(SIGPIPE, &oldact, NULL); close_fd: close(h->fd); h->fd =3D -1; --=20 2.39.2