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LibIPC: Prepend each message with its size

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This makes it much simpler to determine when we've read a complete message, and
will make it possible to integrate recvfd() in the future commit.
This commit is contained in:
Sergey Bugaev 2020-11-21 21:55:00 +03:00 • committed by Andreas Kling
parent d62346c0b1
commit fa2e3e2be4
3 changed files with 35 additions and 23 deletions
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47
Libraries/LibIPC/Connection.h
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@ -35,6 +35,7 @@
#include <LibCore/SyscallUtils.h>
#include <LibCore/Timer.h>
#include <LibIPC/Message.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/select.h>
@ -75,10 +76,13 @@ public:
return;
auto buffer = message.encode();
// Prepend the message size.
uint32_t message_size = buffer.size();
buffer.prepend(reinterpret_cast<const u8*>(&message_size), sizeof(message_size));
auto bytes_remaining = buffer.size();
while (bytes_remaining) {
auto nwritten = write(m_socket->fd(), buffer.data(), buffer.size());
size_t total_nwritten = 0;
while (total_nwritten < buffer.size()) {
auto nwritten = write(m_socket->fd(), buffer.data() + total_nwritten, buffer.size() - total_nwritten);
if (nwritten < 0) {
switch (errno) {
case EPIPE:
@ -95,7 +99,7 @@ public:
return;
}
}
bytes_remaining -= nwritten;
total_nwritten += nwritten;
}
m_responsiveness_timer->start();
@ -190,25 +194,34 @@ protected:
did_become_responsive();
}
size_t decoded_bytes = 0;
for (size_t index = 0; index < bytes.size(); index += decoded_bytes) {
size_t index = 0;
uint32_t message_size = 0;
for (; index + sizeof(message_size) < bytes.size(); index += message_size) {
message_size = *reinterpret_cast<uint32_t*>(bytes.data() + index);
if (message_size == 0 || bytes.size() - index - sizeof(uint32_t) < message_size)
break;
index += sizeof(message_size);
auto remaining_bytes = ByteBuffer::wrap(bytes.data() + index, bytes.size() - index);
if (auto message = LocalEndpoint::decode_message(remaining_bytes, decoded_bytes)) {
if (auto message = LocalEndpoint::decode_message(remaining_bytes)) {
m_unprocessed_messages.append(message.release_nonnull());
} else if (auto message = PeerEndpoint::decode_message(remaining_bytes, decoded_bytes)) {
} else if (auto message = PeerEndpoint::decode_message(remaining_bytes)) {
m_unprocessed_messages.append(message.release_nonnull());
} else {
// Sometimes we might receive a partial message. That's okay, just stash away
// the unprocessed bytes and we'll prepend them to the next incoming message
// in the next run of this function.
if (!m_unprocessed_bytes.is_empty()) {
dbg() << *this << "::drain_messages_from_peer: Already have unprocessed bytes";
shutdown();
}
m_unprocessed_bytes = remaining_bytes.isolated_copy();
dbgln("Failed to parse a message");
break;
}
ASSERT(decoded_bytes);
}
if (index < bytes.size()) {
// Sometimes we might receive a partial message. That's okay, just stash away
// the unprocessed bytes and we'll prepend them to the next incoming message
// in the next run of this function.
auto remaining_bytes = ByteBuffer::wrap(bytes.data() + index, bytes.size() - index);
if (!m_unprocessed_bytes.is_empty()) {
dbg() << *this << "::drain_messages_from_peer: Already have unprocessed bytes";
shutdown();
}
m_unprocessed_bytes = remaining_bytes.isolated_copy();
}
if (!m_unprocessed_messages.is_empty()) {