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Avoid zero-length memory copies with null array or string data #9200

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24 changes: 17 additions & 7 deletions src/common/classes/array.h
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Original file line number Diff line number Diff line change
Expand Up @@ -193,7 +193,8 @@ class Array : public Storage
void copyFrom(const Array<T, Storage>& source)
{
ensureCapacity(source.count, false);
memcpy(static_cast<void*>(data), source.data, sizeof(T) * source.count);
if (source.count)
memcpy(static_cast<void*>(data), source.data, sizeof(T) * source.count);
count = source.count;
}

Expand Down Expand Up @@ -260,17 +261,21 @@ class Array : public Storage
fb_assert(index <= count);
fb_assert(count < FB_MAX_SIZEOF);
ensureCapacity(count + 1);
memmove(static_cast<void*>(data + index + 1), data + index, sizeof(T) * (count++ - index));
if (count - index)
memmove(static_cast<void*>(data + index + 1), data + index, sizeof(T) * (count - index));
data[index] = item;
++count;
}

void insert(const size_type index, const Array<T, Storage>& items)
{
fb_assert(index <= count);
fb_assert(count <= FB_MAX_SIZEOF - items.count);
ensureCapacity(count + items.count);
memmove(static_cast<void*>(data + index + items.count), data + index, sizeof(T) * (count - index));
memcpy(static_cast<void*>(data + index), items.data, items.count);
if (count - index)
memmove(static_cast<void*>(data + index + items.count), data + index, sizeof(T) * (count - index));
if (items.count)
memcpy(static_cast<void*>(data + index), items.data, items.count);
count += items.count;
}

Expand All @@ -279,8 +284,10 @@ class Array : public Storage
fb_assert(index <= count);
fb_assert(count <= FB_MAX_SIZEOF - itemsCount);
ensureCapacity(count + itemsCount);
memmove(static_cast<void*>(data + index + itemsCount), data + index, sizeof(T) * (count - index));
memcpy(static_cast<void*>(data + index), items, sizeof(T) * itemsCount);
if (count - index)
memmove(static_cast<void*>(data + index + itemsCount), data + index, sizeof(T) * (count - index));
if (itemsCount)
memcpy(static_cast<void*>(data + index), items, sizeof(T) * itemsCount);
count += itemsCount;
}

Expand Down Expand Up @@ -574,8 +581,11 @@ class Array : public Storage

T* newdata = static_cast<T*>
(this->getPool().allocate(sizeof(T) * newcapacity));
if (preserve)
if (preserve && count != 0)
{
fb_assert(data != nullptr);
memcpy(static_cast<void*>(newdata), data, sizeof(T) * count);
}
freeData();
data = newdata;
capacity = newcapacity;
Expand Down
3 changes: 2 additions & 1 deletion src/common/classes/fb_string.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -100,7 +100,8 @@ namespace Firebird
: max_length(static_cast<internal_size_type>(limit))
{
initialize(sizeL);
memcpy(stringBuffer, dataL, sizeL);
if (sizeL)
memcpy(stringBuffer, dataL, sizeL);
}

AbstractString::AbstractString(const size_type limit, const_pointer p1, const size_type n1,
Expand Down
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