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Merge remote-tracking branch 'upstream/avoid_prefs_heap_churn' into integration

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J. Nick Koston
2026-01-15 19:02:18 -10:00
parent 73eff47998 42b9863cd3
commit b3570a9bfd
1 changed files with 17 additions and 6 deletions
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23
esphome/core/helpers.h
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@@ -143,19 +143,29 @@ template<size_t InlineSize = 8> class SmallInlineBuffer {
delete[] this->heap_;
}
// Move constructor - memcpy is safe because union is zero-initialized
// Move constructor
SmallInlineBuffer(SmallInlineBuffer &&other) noexcept : len_(other.len_) {
memcpy(this->inline_, other.inline_, InlineSize);
other.len_ = 0; // Mark as empty so other's destructor is no-op
if (other.is_inline_()) {
memcpy(this->inline_, other.inline_, this->len_);
} else {
this->heap_ = other.heap_;
other.heap_ = nullptr;
}
other.len_ = 0;
}
// Move assignment - memcpy is safe because union is zero-initialized
// Move assignment
SmallInlineBuffer &operator=(SmallInlineBuffer &&other) noexcept {
if (this != &other) {
if (!this->is_inline_())
delete[] this->heap_;
this->len_ = other.len_;
memcpy(this->inline_, other.inline_, InlineSize);
if (other.is_inline_()) {
memcpy(this->inline_, other.inline_, this->len_);
} else {
this->heap_ = other.heap_;
other.heap_ = nullptr;
}
other.len_ = 0;
}
return *this;
@@ -170,6 +180,7 @@ template<size_t InlineSize = 8> class SmallInlineBuffer {
// Free existing heap allocation if switching from heap to inline or different heap size
if (!this->is_inline_() && (size <= InlineSize || size != this->len_)) {
delete[] this->heap_;
this->heap_ = nullptr; // Defensive: prevent use-after-free if logic changes
}
// Allocate new heap buffer if needed
if (size > InlineSize && (this->is_inline_() || size != this->len_)) {
@@ -188,7 +199,7 @@ template<size_t InlineSize = 8> class SmallInlineBuffer {
size_t len_{0};
union {
uint8_t inline_[InlineSize]{}; // Zero-init for safe memcpy in move ops
uint8_t inline_[InlineSize]{}; // Zero-init ensures clean initial state
uint8_t *heap_;
};
};