Fix getting duplicate serial ports with null characters

The function toStringAndTrimNullCharacter() deletes only trailing zeroes
from right to left direction up to the first non-zero character were meet.
This can return the wrong string in case there are the zero characters to
the left of the non-zero characters.

We should look for the first zero-character from left to right direction,
and discard all right part of a string, including the zero-character.

(cherry-picked from 84de1b10d242551a51b6c4ce5eda657c4743bc63)
Task-number: QTBUG-47127
Change-Id: I4d101b49bbb153bddbe535a920d616b5fef130e9
Reviewed-by: Denis Shienkov <denis.shienkov@gmail.com>

1 files changed, 4 insertions, 5 deletions

diff --git a/src/serialport/qserialportinfo_win.cpp b/src/serialport/qserialportinfo_win.cpp
index caf70f4..d5e991b 100644
--- a/src/serialport/qserialportinfo_win.cpp
+++ b/src/serialport/qserialportinfo_win.cpp
@@ -73,11 +73,10 @@ static inline const QList<GuidFlagsPair>& guidFlagsPairs()
 
 static QString toStringAndTrimNullCharacter(const QByteArray &buffer)
 {
-    QString result = QString::fromWCharArray(reinterpret_cast<const wchar_t *>(buffer.constData()),
-                                             buffer.size() / sizeof(wchar_t));
-    while (!result.isEmpty() && (result.at(result.size() - 1).unicode() == 0))
-        result.chop(1);
-    return result;
+    const QString result = QString::fromWCharArray(reinterpret_cast<const wchar_t *>(buffer.constData()),
+                                                   buffer.size() / sizeof(wchar_t));
+    const int index = result.indexOf(QChar(0));
+    return index == -1 ? result : result.mid(0, index);
 }
 
 static QStringList portNamesFromHardwareDeviceMap()