all: retry incomplete socket reads

Fixes greetd and hyprland ipc sockets reads being incomplete and
breaking said integrations on slow machines.

src/core/CMakeLists.txt

@@ -40,6 +40,7 @@ qt_add_library(quickshell-core STATIC
 	scriptmodel.cpp
 	colorquantizer.cpp
 	toolsupport.cpp
+	streamreader.cpp
 )
 
 qt_add_qml_module(quickshell-core

src/core/streamreader.cpp

@@ -0,0 +1,98 @@
+#include "streamreader.hpp"
+#include <cstring>
+
+#include <qbytearray.h>
+#include <qiodevice.h>
+#include <qtypes.h>
+
+void StreamReader::setDevice(QIODevice* device) {
+	this->reset();
+	this->device = device;
+}
+
+void StreamReader::startTransaction() {
+	this->cursor = 0;
+	this->failed = false;
+}
+
+bool StreamReader::fill() {
+	auto available = this->device->bytesAvailable();
+	if (available <= 0) return false;
+	auto oldSize = this->buffer.size();
+	this->buffer.resize(oldSize + available);
+	auto bytesRead = this->device->read(this->buffer.data() + oldSize, available); // NOLINT
+
+	if (bytesRead <= 0) {
+		this->buffer.resize(oldSize);
+		return false;
+	}
+
+	this->buffer.resize(oldSize + bytesRead);
+	return true;
+}
+
+QByteArray StreamReader::readBytes(qsizetype count) {
+	if (this->failed) return {};
+
+	auto needed = this->cursor + count;
+
+	while (this->buffer.size() < needed) {
+		if (!this->fill()) {
+			this->failed = true;
+			return {};
+		}
+	}
+
+	auto result = this->buffer.mid(this->cursor, count);
+	this->cursor += count;
+	return result;
+}
+
+QByteArray StreamReader::readUntil(char terminator) {
+	if (this->failed) return {};
+
+	auto searchFrom = this->cursor;
+	auto idx = this->buffer.indexOf(terminator, searchFrom);
+
+	while (idx == -1) {
+		searchFrom = this->buffer.size();
+		if (!this->fill()) {
+			this->failed = true;
+			return {};
+		}
+
+		idx = this->buffer.indexOf(terminator, searchFrom);
+	}
+
+	auto length = idx - this->cursor + 1;
+	auto result = this->buffer.mid(this->cursor, length);
+	this->cursor += length;
+	return result;
+}
+
+void StreamReader::readInto(char* ptr, qsizetype count) {
+	auto data = this->readBytes(count);
+	if (!data.isEmpty()) memcpy(ptr, data.data(), count);
+}
+
+qint32 StreamReader::readI32() {
+	qint32 value = 0;
+	this->readInto(reinterpret_cast<char*>(&value), sizeof(qint32));
+	return value;
+}
+
+bool StreamReader::commitTransaction() {
+	if (this->failed) {
+		this->cursor = 0;
+		return false;
+	}
+
+	this->buffer.remove(0, this->cursor);
+	this->cursor = 0;
+	return true;
+}
+
+void StreamReader::reset() {
+	this->buffer.clear();
+	this->cursor = 0;
+}

src/core/streamreader.hpp

@@ -0,0 +1,26 @@
+#pragma once
+
+#include <qbytearray.h>
+#include <qiodevice.h>
+#include <qtypes.h>
+
+class StreamReader {
+public:
+	void setDevice(QIODevice* device);
+
+	void startTransaction();
+	QByteArray readBytes(qsizetype count);
+	QByteArray readUntil(char terminator);
+	void readInto(char* ptr, qsizetype count);
+	qint32 readI32();
+	bool commitTransaction();
+	void reset();
+
+private:
+	bool fill();
+
+	QIODevice* device = nullptr;
+	QByteArray buffer;
+	qsizetype cursor = 0;
+	bool failed = false;
+};