QFile open question

[chenxuelian]

hi, everyone,
i have a question to ask you. it's about QFile. my code is:

QFile file("/proc/mounts");
if (!file.exists())
{
	qDebug() << "exist error" << file.error();
	file.close();
	return 0;		
}	
 
if (!file.open(QIODevice::ReadOnly | QIODevice::Text))
{
	qDebug() << "open error" << file.error();
	file.close();
	return 0;		
}
.......
file.close();

QFile file("/proc/mounts");
if (!file.exists())
{
	qDebug() << "exist error" << file.error();
	file.close();
	return 0;		
}	
	
if (!file.open(QIODevice::ReadOnly | QIODevice::Text))
{
	qDebug() << "open error" << file.error();
	file.close();
	return 0;		
}
.......
file.close();

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when i open the file some times, and then it printf "open error 4" ,4 means QFile::ResourceError,what's the problem.
thanks!