Found that TVar default constructor (the one with NO arguments) does NOT
initialise the `parent` member to a null pointer. Subsequently in the
auto load case (but not the normal profile loading case apparently) the
first time that (QStringList)VarUnit::shortVarName(TVar * var) is called
the call to:
var->getParent()
{noted above as the line before the crash was happening} was returning a
garbage (but not NULL) pointer that when used in p->getName() != "_G"
was the cause of the Segment Violation crash.
I am just writing code to initialise ALL the members of the TVar class for ALL
the constructors (some
members are not initialised in ANY of them). Will post the Pull Requests here
that apply the fix shortly.
** Changed in: mudlet
Assignee: (unassigned) => Stephen Lyons (slysven)
** Changed in: mudlet
Status: New => In Progress
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https://bugs.launchpad.net/bugs/1624720
Title:
Crash on first use of TVar::getName() during autologin
Status in Mudlet:
In Progress
Bug description:
Whilst working on the development branch I decided to enable the autologin
(check box on "connection preferences" dialog) and found that it seg. faults
consistently on the first use of TVar::getName()
whilst loading in the selected profile. I rechecked on the release_30
(post-"delta") preview and got precisely the same behaviour at the same point,
for the latter the top end of the stack trace was:
1 QString::QString qstring.h
898 0x467a1a
2 TVar::getName TVar.cpp 68
0x74784d
3 VarUnit::shortVarName VarUnit.cpp
153 0x74974a
4 VarUnit::addSavedVar VarUnit.cpp
189 0x749d1d
5 XMLimport::readVariableGroup XMLimport.cpp
240 0x7579a6
6 XMLimport::readVariablePackage XMLimport.cpp
293 0x757e3c
7 XMLimport::readPackage XMLimport.cpp
588 0x759b72
8 XMLimport::importPackage XMLimport.cpp
146 0x756f84
9 mudlet::doAutoLogin mudlet.cpp
2152 0x5fabd1
10 mudlet::startAutoLogin mudlet.cpp
2119 0x5fa57d
11 mudlet::qt_static_metacall moc_mudlet.cpp
300 0x76e4d3
... <More>
At 3 we have:
QStringList VarUnit::shortVarName(TVar * var){
QStringList names;
if (!var || var->getName() == "_G"){
names << "";
return names;
}
names << var->getName();
TVar * p = var->getParent();
==> while (p && p->getName() != "_G"){ <== Where crash is happening
names.insert(0,p->getName());
p = p->getParent();
}
return names;
}
and looking in the debugger p, although non-zero {and thus passing the first
test in the while(...)}
it is NOT a valid entity, i.e. the preceding var->getParent() is NOT
producing a valid value.
As this is a regression (it disables autologin) it must be rated at least a
"High" priority item only the fact that the ability to start a profile
automatically is a useful rather than an essential feature stops this being a
"Critical" - as well as indicating how many users (none at all)
seem to be using it for the latest code versions. I will investigate further
and try and triage what introduced it, but I expect some re-factoring has
eliminated some initialization step that is needed when auto-login is used but
is not encountered otherwise...!
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