Details
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Bug
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Resolution: Done
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P1: Critical
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6.1.0
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None
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Linux/X11
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4f730fc5f13b906d7bb2461f803ecedb4937c16d (qt/qtbase/dev) f00efd82334d16197ebe4f5a9c01f54ba8ba925e (qt/qtbase/6.1) 4b39f612615a63d421975a1869175a0c685c9293 (qt/qtbase/6.2) 7adcec5b8feeefdaffa4ee72d0b9c8e282e10f6a (qt/tqtc-qtbase/5.15)
Description
When checking our application for memory leaks, I encountered a problem with the memory handling in QFontDatabase that can already be seen with the following test case:
#include <QApplication> #include <QFontDatabase> #include <QTimer> int main(int argc, char **argv) { QApplication app(argc, argv); const auto id = QFontDatabase::addApplicationFont(QStringLiteral("anyexistingfont.ttf")); if (id == -1) qWarning("Adding font failed"); QTimer::singleShot(1000, qApp, &QApplication::quit); const int status = app.exec(); QFontDatabase::removeAllApplicationFonts(); return status; }
I used valgrind with the --leak-check=full --show-leak-kinds=all options and encountered the following problem:
==44736== 30,720 bytes in 1 blocks are still reachable in loss record 291 of 291 ==44736== at 0x4840D7B: realloc (vg_replace_malloc.c:834) ==44736== by 0x81C6854: FcFontSetAdd (in /usr/lib/libfontconfig.so.1.12.0) ==44736== by 0x81BB5F4: ??? (in /usr/lib/libfontconfig.so.1.12.0) ==44736== by 0x81BB80C: ??? (in /usr/lib/libfontconfig.so.1.12.0) ==44736== by 0x81BB8C9: FcConfigBuildFonts (in /usr/lib/libfontconfig.so.1.12.0) ==44736== by 0x81C7568: FcInitLoadConfigAndFonts (in /usr/lib/libfontconfig.so.1.12.0) ==44736== by 0x81B7D96: ??? (in /usr/lib/libfontconfig.so.1.12.0) ==44736== by 0x81B8B9C: FcConfigGetFonts (in /usr/lib/libfontconfig.so.1.12.0) ==44736== by 0x5851DF5: QFontconfigDatabase::addApplicationFont(QByteArray const&, QString const&, QFontDatabasePrivate::ApplicationFont*) (in /local/ssd/mlangen/build/a3gui.default/usr/lib/libQt6Gui.so.6.1.0) ==44736== by 0x56C6A8F: QFontDatabasePrivate::addAppFont(QByteArray const&, QString const&) (in /local/ssd/mlangen/build/a3gui.default/usr/lib/libQt6Gui.so.6.1.0) ==44736== by 0x56C6F93: QFontDatabase::addApplicationFont(QString const&) (in /local/ssd/mlangen/build/a3gui.default/usr/lib/libQt6Gui.so.6.1.0) ==44736== by 0x201F04: main (fontdatabase.cpp:9)
I wonder if this memory could be freed somehow?