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microbit: BUGFIX: Memory leak in ManagedType.h

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Corrected corner case memory leak. Instances of ManagedType<> created using the default
constructor would create a reference counter by default, with a value of 0. However, if
destructor or copy-assigned in this state, this reference count would not be destroyed,
resulting in a 4 byte leak on the heap for each occurence.
This commit is contained in:
Joe Finney 2015-09-17 23:16:40 +01:00
parent 78ad8a1646
commit a61bd49620
1 changed files with 18 additions and 2 deletions
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20
inc/ManagedType.h
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@ -136,7 +136,16 @@ ManagedType<T>::ManagedType(const ManagedType<T> &t)
template<typename T>
ManagedType<T>::~ManagedType()
{
if (--(*ref) == 0)
// Special case - we were created using a default constructor, and never assigned a value.
if (*ref == 0)
{
// Simply destroy our reference counter and we're done.
free(ref);
}
// Normal case - we have a valid piece of data.
// Decrement our reference counter and free all allocated memory if we're deleting the last reference.
else if (--(*ref) == 0)
{
delete object;
free(ref);
@ -152,7 +161,14 @@ ManagedType<T>& ManagedType<T>::operator = (const ManagedType<T>&t)
if (this == &t)
return *this;
if (--(*ref) == 0)
// Special case - we were created using a default constructor, and never assigned a value.
if (*ref == 0)
{
// Simply destroy our reference counter, as we're about to adopt another.
free(ref);
}
else if (--(*ref) == 0)
{
delete object;
free(ref);