From d56013fb245dc2878ee91bbb937a91850050ada3 Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Mon, 21 Nov 2022 17:42:04 +0100
Subject: [PATCH] sd-bus: handle -EINTR return from bus_poll()

In sd_bus_wait(), let's convert EINTR to a return code of 0, thus asking
the caller do loop again and enter sd_bus_process() again (which will
not find any queued events). This way we'll not return an error on
something that isn't really an error. This should typically make sure
things are properly handled by the caller, magically, without eating up
the event entirely, and still giving the caller time to run some code if
they want.

(cherry picked from commit 3022916b4d2483452c3ddbbac9ee7c4372b1cb46)

Resolves: #2137584
---
 src/libsystemd/sd-bus/bus-socket.c |  5 ++++-
 src/libsystemd/sd-bus/sd-bus.c     | 18 +++++++++++++++---
 2 files changed, 19 insertions(+), 4 deletions(-)

diff --git a/src/libsystemd/sd-bus/bus-socket.c b/src/libsystemd/sd-bus/bus-socket.c
index c94befef73..253f41c636 100644
--- a/src/libsystemd/sd-bus/bus-socket.c
+++ b/src/libsystemd/sd-bus/bus-socket.c
@@ -1308,8 +1308,11 @@ int bus_socket_process_opening(sd_bus *b) {
         assert(b->state == BUS_OPENING);
 
         events = fd_wait_for_event(b->output_fd, POLLOUT, 0);
-        if (events < 0)
+        if (events < 0) {
+                if (ERRNO_IS_TRANSIENT(events))
+                        return 0;
                 return events;
+        }
         if (!(events & (POLLOUT|POLLERR|POLLHUP)))
                 return 0;
 
diff --git a/src/libsystemd/sd-bus/sd-bus.c b/src/libsystemd/sd-bus/sd-bus.c
index bc716afabf..c3a1bae295 100644
--- a/src/libsystemd/sd-bus/sd-bus.c
+++ b/src/libsystemd/sd-bus/sd-bus.c
@@ -2465,8 +2465,11 @@ _public_ int sd_bus_call(
                         left = UINT64_MAX;
 
                 r = bus_poll(bus, true, left);
-                if (r < 0)
+                if (r < 0) {
+                        if (ERRNO_IS_TRANSIENT(r))
+                                continue;
                         goto fail;
+                }
                 if (r == 0) {
                         r = -ETIMEDOUT;
                         goto fail;
@@ -3321,6 +3324,7 @@ static int bus_poll(sd_bus *bus, bool need_more, uint64_t timeout_usec) {
 }
 
 _public_ int sd_bus_wait(sd_bus *bus, uint64_t timeout_usec) {
+        int r;
 
         assert_return(bus, -EINVAL);
         assert_return(bus = bus_resolve(bus), -ENOPKG);
@@ -3335,7 +3339,11 @@ _public_ int sd_bus_wait(sd_bus *bus, uint64_t timeout_usec) {
         if (bus->rqueue_size > 0)
                 return 0;
 
-        return bus_poll(bus, false, timeout_usec);
+        r = bus_poll(bus, false, timeout_usec);
+        if (r < 0 && ERRNO_IS_TRANSIENT(r))
+                return 1; /* treat EINTR as success, but let's exit, so that the caller will call back into us soon. */
+
+        return r;
 }
 
 _public_ int sd_bus_flush(sd_bus *bus) {
@@ -3377,8 +3385,12 @@ _public_ int sd_bus_flush(sd_bus *bus) {
                         return 0;
 
                 r = bus_poll(bus, false, UINT64_MAX);
-                if (r < 0)
+                if (r < 0) {
+                        if (ERRNO_IS_TRANSIENT(r))
+                                continue;
+
                         return r;
+                }
         }
 }