CODEWITHSUNDEEP
c++qtqt4ros
thegermanpole
thegermanpole

Reputation: 133

Getting segmentation faults on QFile::setFileName

For a logging feature using ROS rqt+Qt4 I am trying to write to multiple files in a hardcoded folder hierarchy.

I have a parent class inheriting from QtWidget holding multiple QFile* members. I then assign them storage with *filehandle = new QFile(this).

Writing to the files works fine, but if I try to even set the Filename on the filehandles for reading the logfiles, I get an immediate Segmentation fault. However, not for all of the files I can see no consistent pattern in what file paths are affected.

Upvotes: 0

Views: 736

Answers (2)

javi
javi

Reputation: 1

I got the same error i was declaring QFile as a private variable inside my class.

QFile  archivo_pattern_bin;

then using it to open an hex file in the indicated absolute path

archivo_pattern_bin.setFileName(pattern_file_path);
archivo_pattern_bin.open(QIODevice::ReadWrite);
archivo_pattern_bin.flush();

this returned the windows segmentation error when debugging exactly at setFileName()

But now im just declaring a pointer

QFile * archivo_pattern_bin;

and creating the Qfile object dynamically

archivo_pattern_bin = new QFile(this);
archivo_pattern_bin->setFileName(pattern_file_path);
archivo_pattern_bin->open(QIODevice::ReadWrite);
archivo_pattern_bin->flush();

Also i was writting an array outside its defined size thus corrupting everything.......

and everything is alright now :D thanks pablo

Upvotes: 0

Pablo Gutiérrez
Pablo Gutiérrez

Reputation: 31

Some code would help.

From what I can see, the result of the new is a *QFile that should be assigned to another *QFile

QFile * filehandle;

*filehandle = new QFile(this)     //is wrong

filehandle = new QFile(this)      //is right

Remember that segmentation faults come from access to memory that has not been correctly reserved or that have been fred early with a delete statement.

If you stuck to much in a segmentation fault problem a quick way to know where is the problem is to run your program with a debugger (gdb). If you use QT Creator the process is really easy.

Upvotes: 1

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