QIODevice: Fix readAll()

My patch from yesterday did not have any effect: Instead of
really using what was in the buffer, it used it but then read
it from the underlying device anyway.
Thanks Ritt Konstantin and Joao.

Reviewed-by: joao

2 files changed, 37 insertions, 2 deletions

diff --git a/src/corelib/io/qiodevice.cpp b/src/corelib/io/qiodevice.cpp
index 1e98473..4e14ba8 100644
--- a/src/corelib/io/qiodevice.cpp
+++ b/src/corelib/io/qiodevice.cpp
@@ -970,6 +970,7 @@ QByteArray QIODevice::readAll()
     if (!(d->openMode & Text) && !d->buffer.isEmpty()) {
         result = d->buffer.readAll();
         readBytes = result.size();
+        d->pos += readBytes;
     }
 
     qint64 theSize;
@@ -985,8 +986,8 @@ QByteArray QIODevice::readAll()
     } else {
         // Read it all in one go.
         // If resize fails, don't read anything.
-        result.resize(int(theSize - d->pos));
-        readBytes = read(result.data(), result.size());
+        result.resize(int(readBytes + theSize - d->pos));
+        readBytes += read(result.data() + readBytes, result.size() - readBytes);
     }
 
     if (readBytes <= 0)
diff --git a/tests/auto/qfile/tst_qfile.cpp b/tests/auto/qfile/tst_qfile.cpp
index d3a607d..453434d 100644
--- a/tests/auto/qfile/tst_qfile.cpp
+++ b/tests/auto/qfile/tst_qfile.cpp
@@ -131,6 +131,7 @@ private slots:
     void readLineNullInLine();
     void readAll_data();
     void readAll();
+    void readAllBuffer();
     void readAllStdin();
     void readLineStdin();
     void readLineStdin_lineByLine();
@@ -390,6 +391,7 @@ void tst_QFile::cleanupTestCase()
     QFile::remove("myLink2.lnk");
     QFile::remove("resources");
     QFile::remove("qfile_map_testfile");
+    QFile::remove("readAllBuffer.txt");
 }
 
 //------------------------------------------
@@ -793,6 +795,38 @@ void tst_QFile::readAll()
     QCOMPARE(a, b);
 }
 
+void tst_QFile::readAllBuffer()
+{
+    QString fileName = QLatin1String("readAllBuffer.txt");
+
+    QFile::remove(fileName);
+
+    QFile writer(fileName);
+    QFile reader(fileName);
+
+    QByteArray data1("This is arguably a very simple text.");
+    QByteArray data2("This is surely not as simple a test.");
+
+    QVERIFY( writer.open(QIODevice::ReadWrite | QIODevice::Unbuffered) );
+    QVERIFY( reader.open(QIODevice::ReadOnly) );
+
+    QCOMPARE( writer.write(data1), qint64(data1.size()) );
+    QVERIFY( writer.seek(0) );
+
+    QByteArray result;
+    result = reader.read(18);
+    QCOMPARE( result.size(), 18 );
+
+    QCOMPARE( writer.write(data2), qint64(data2.size()) ); // new data, old version buffered in reader
+    QCOMPARE( writer.write(data2), qint64(data2.size()) ); // new data, unbuffered in reader
+
+    result += reader.readAll();
+
+    QCOMPARE( result, data1 + data2 );
+
+    QFile::remove(fileName);
+}
+
 void tst_QFile::readAllStdin()
 {
 #if defined(Q_OS_WINCE) || defined(Q_OS_SYMBIAN)