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Kernel: Report EAGAIN from read() on a non-blocking socket if the buffer is empty

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This is not EOF, and never should have been so -- can trip up other code
when porting.

Also updates LibGUI and WindowServer which both relied on the old
behaviour (and didn't work without changes). There may be others, but I
didn't run into them with a quick inspection.
This commit is contained in:
Robin Burchell 2019-05-20 01:18:33 +02:00 • committed by Andreas Kling
parent 40a5eb4e6e
commit a8864dc590
3 changed files with 20 additions and 11 deletions
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14
Kernel/Net/LocalSocket.cpp
View file

@ -153,10 +153,20 @@ bool LocalSocket::can_read(FileDescriptor& descriptor) const
ssize_t LocalSocket::read(FileDescriptor& descriptor, byte* buffer, ssize_t size) ssize_t LocalSocket::read(FileDescriptor& descriptor, byte* buffer, ssize_t size)
{ {
auto role = descriptor.socket_role(); auto role = descriptor.socket_role();
if (role == SocketRole::Accepted) if (role == SocketRole::Accepted) {
if (!descriptor.is_blocking()) {
if (m_for_server.is_empty())
return -EAGAIN;
}
return m_for_server.read(buffer, size); return m_for_server.read(buffer, size);
if (role == SocketRole::Connected) }
if (role == SocketRole::Connected) {
if (!descriptor.is_blocking()) {
if (m_for_client.is_empty())
return -EAGAIN;
}
return m_for_client.read(buffer, size); return m_for_client.read(buffer, size);
}
ASSERT_NOT_REACHED(); ASSERT_NOT_REACHED();
} }

15
LibGUI/GEventLoop.cpp
View file

@ -324,22 +324,22 @@ void GEventLoop::process_unprocessed_bundles()
bool GEventLoop::drain_messages_from_server() bool GEventLoop::drain_messages_from_server()
{ {
bool is_first_pass = true;
for (;;) { for (;;) {
WSAPI_ServerMessage message; WSAPI_ServerMessage message;
ssize_t nread = read(s_windowserver_fd, &message, sizeof(WSAPI_ServerMessage)); ssize_t nread = read(s_windowserver_fd, &message, sizeof(WSAPI_ServerMessage));
if (nread < 0) { if (nread < 0) {
if (errno == EAGAIN) {
return true;
}
perror("read"); perror("read");
quit(1); quit(1);
return false; return false;
} }
if (nread == 0) { if (nread == 0) {
if (is_first_pass) { fprintf(stderr, "EOF on WindowServer fd\n");
fprintf(stderr, "EOF on WindowServer fd\n"); quit(1);
quit(1); exit(-1);
return false; return false;
}
return true;
} }
assert(nread == sizeof(message)); assert(nread == sizeof(message));
ByteBuffer extra_data; ByteBuffer extra_data;
@ -355,7 +355,6 @@ bool GEventLoop::drain_messages_from_server()
ASSERT(extra_nread == message.extra_size); ASSERT(extra_nread == message.extra_size);
} }
m_unprocessed_bundles.append({ move(message), move(extra_data) }); m_unprocessed_bundles.append({ move(message), move(extra_data) });
is_first_pass = false;
} }
} }

2
Servers/WindowServer/WSEventLoop.cpp
View file

@ -301,7 +301,7 @@ void WSEventLoop::drain_client(WSClientConnection& client)
WSAPI_ClientMessage message; WSAPI_ClientMessage message;
// FIXME: Don't go one message at a time, that's so much context switching, oof. // FIXME: Don't go one message at a time, that's so much context switching, oof.
ssize_t nread = read(client.fd(), &message, sizeof(WSAPI_ClientMessage)); ssize_t nread = read(client.fd(), &message, sizeof(WSAPI_ClientMessage));
if (nread == 0) { if (nread == 0 || (nread == -1 && errno == EAGAIN)) {
if (!messages_received) if (!messages_received)
post_event(client, make<WSClientDisconnectedNotification>(client.client_id())); post_event(client, make<WSClientDisconnectedNotification>(client.client_id()));
break; break;