Chunk size increased to QIODEVICE_BUFFERSIZE (currently 16k) where
chunking is still needed. Namely, on sequential devices and when
QByteArray is unable to allocate a large enough buffer. This is
necessary for backward compatibility
Improved validation and prevention of overflow in maxSize argument.
Updated autotest that relied on a null QByteArray when no data was
available and no errors were found. The only guarantee we should be
providing in this case is an empty result -- even though that behavior
is preserved for the time being.
Affected functions:
* QIODevice::read(qint64 maxSize)
Chunking will still happen for large maxSize (i.e., QByteArray
resize fails), where it could be used as a synonym for
QIODevice::readAll().
No stat'ing performed. Read from device continues for as long as it
is successful. Stops if an error occurs or if we get less data than
requested.
* QIODevice::readAll()
Chunking is performed for sequential devices where total size
wouldn't be known beforehand. For sequential devices, reading
continues as long as data is returned, even if less than requested.
Non-sequential devices will be stat'ed once. If QIODevice::size
returns 0, this is taken to mean unknown size and chunking is
performed.
Otherwise, a single read request is made for the specified size. On
failure to resize QByteArray, nothing is returned.
* QIODevice::readLine(qint64 maxSize)
Chunking is performed for maxSize == 0, or if we can't allocate a
large enough buffer.
No stat'ing performed at this level. Read from device continues
until EOL is found, as long as we get all requested data.
Task-number: QT-2347
Reviewed-by: Thiago Macieira
Reviewed-by: Miikka Heikkinen