From b3fbfcd3738a0ff864439499390513b95ca671aa Mon Sep 17 00:00:00 2001
From: Alex Trotsenko <alex1973tr@gmail.com>
Date: Wed, 23 Jun 2021 18:26:10 +0300
Subject: QLocalSocket: reimplement readLineData() function

The base implementation reads data using repeated calls to getChar(),
which is quite slow.

Change-Id: Ie46624df63791b2cdd3c8a28fe3327427d942505
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@gmx.de>
---
 src/corelib/io/qwindowspipereader.cpp | 24 ++++++++++++++++++++++++
 src/corelib/io/qwindowspipereader_p.h |  1 +
 2 files changed, 25 insertions(+)

(limited to 'src/corelib/io')

diff --git a/src/corelib/io/qwindowspipereader.cpp b/src/corelib/io/qwindowspipereader.cpp
index 539902c233..c3ac51df94 100644
--- a/src/corelib/io/qwindowspipereader.cpp
+++ b/src/corelib/io/qwindowspipereader.cpp
@@ -208,6 +208,30 @@ qint64 QWindowsPipeReader::read(char *data, qint64 maxlen)
     return readSoFar;
 }
 
+/*!
+    Reads a line from the internal buffer, but no more than \c{maxlen}
+    characters. A terminating '\0' byte is always appended to \c{data},
+    so \c{maxlen} must be larger than 1.
+ */
+qint64 QWindowsPipeReader::readLine(char *data, qint64 maxlen)
+{
+    QMutexLocker locker(&mutex);
+    qint64 readSoFar = 0;
+
+    if (actualReadBufferSize > 0) {
+        readSoFar = readBuffer.readLine(data, qMin(actualReadBufferSize + 1, maxlen));
+        actualReadBufferSize -= readSoFar;
+    }
+
+    if (!pipeBroken) {
+        startAsyncReadHelper(&locker);
+        if (readSoFar == 0)
+            return -2;      // signal EWOULDBLOCK
+    }
+
+    return readSoFar;
+}
+
 /*!
     Returns \c true if a complete line of data can be read from the buffer.
  */
diff --git a/src/corelib/io/qwindowspipereader_p.h b/src/corelib/io/qwindowspipereader_p.h
index 77c90645c6..e2190d67d9 100644
--- a/src/corelib/io/qwindowspipereader_p.h
+++ b/src/corelib/io/qwindowspipereader_p.h
@@ -78,6 +78,7 @@ public:
     bool isPipeClosed() const { return pipeBroken; }
     qint64 bytesAvailable() const;
     qint64 read(char *data, qint64 maxlen);
+    qint64 readLine(char *data, qint64 maxlen);
     bool canReadLine() const;
     DWORD checkPipeState();
     bool checkForReadyRead() { return consumePendingAndEmit(false); }
-- 
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