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LibIPC: Fix waiting for specific message

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When waiting for a specific message, only consider messages
from the peer endpoint. Otherwise a message with the same id
for the local endpoint may be misinterpreted.

This fixes the Terminal sometimes hanging after bootup because
a local endpoint message is mistaken for the CreateMenuResponse
message.
This commit is contained in:
Tom 2020-08-02 19:34:09 -06:00 committed by Andreas Kling
parent c813bb7355
commit 8b0b653471
Notes: sideshowbarker 2024-07-19 04:21:26 +09:00 
Author: https://github.com/tomuta
Commit: https://github.com/SerenityOS/serenity/commit/8b0b6534719
Pull-request: https://github.com/SerenityOS/serenity/pull/2973
Reviewed-by: https://github.com/awesomekling
1 changed files with 30 additions and 24 deletions
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54
Libraries/LibIPC/ServerConnection.h
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@ -83,29 +83,7 @@ public:
template<typename MessageType>
OwnPtr<MessageType> wait_for_specific_message()
{
// Double check we don't already have the event waiting for us.
// Otherwise we might end up blocked for a while for no reason.
for (size_t i = 0; i < m_unprocessed_messages.size(); ++i) {
if (m_unprocessed_messages[i].message_id() == MessageType::static_message_id())
return m_unprocessed_messages.take(i).template release_nonnull<MessageType>();
}
for (;;) {
fd_set rfds;
FD_ZERO(&rfds);
FD_SET(m_connection->fd(), &rfds);
int rc = Core::safe_syscall(select, m_connection->fd() + 1, &rfds, nullptr, nullptr, nullptr);
if (rc < 0) {
perror("select");
}
ASSERT(rc > 0);
ASSERT(FD_ISSET(m_connection->fd(), &rfds));
if (!drain_messages_from_server())
return nullptr;
for (size_t i = 0; i < m_unprocessed_messages.size(); ++i) {
if (m_unprocessed_messages[i].message_id() == MessageType::static_message_id())
return m_unprocessed_messages.take(i).template release_nonnull<MessageType>();
}
}
return wait_for_specific_endpoint_message<MessageType, LocalEndpoint>();
}
bool post_message(const Message& message)
@ -126,12 +104,40 @@ public:
{
bool success = post_message(RequestType(forward<Args>(args)...));
ASSERT(success);
auto response = wait_for_specific_message<typename RequestType::ResponseType>();
auto response = wait_for_specific_endpoint_message<typename RequestType::ResponseType, PeerEndpoint>();
ASSERT(response);
return response;
}
private:
template<typename MessageType, typename Endpoint>
OwnPtr<MessageType> wait_for_specific_endpoint_message()
{
for (;;) {
// Double check we don't already have the event waiting for us.
// Otherwise we might end up blocked for a while for no reason.
for (size_t i = 0; i < m_unprocessed_messages.size(); ++i) {
auto& message = m_unprocessed_messages[i];
if (message.endpoint_magic() != Endpoint::static_magic())
continue;
if (message.message_id() == MessageType::static_message_id())
return m_unprocessed_messages.take(i).template release_nonnull<MessageType>();
}
fd_set rfds;
FD_ZERO(&rfds);
FD_SET(m_connection->fd(), &rfds);
int rc = Core::safe_syscall(select, m_connection->fd() + 1, &rfds, nullptr, nullptr, nullptr);
if (rc < 0) {
perror("select");
}
ASSERT(rc > 0);
ASSERT(FD_ISSET(m_connection->fd(), &rfds));
if (!drain_messages_from_server())
return nullptr;
}
}
bool drain_messages_from_server()
{
Vector<u8> bytes;