28fac4d700
This introduces a new `address_t` type and two new casts: `pointer_cast` and `address_cast` for casting between an `address_t` and a pointer. These should make it easier to audit the codebase for casts between pointers and integers. In particular, the remaining `reinterpret_cast`s and `pointer_cast`s should be the only places where we could perform invalid pointer arithmetic. Also adds a `pointer_offset` helper that adds an offset (in bytes) to a pointer, preserving its original type. This is a sufficiently common pattern that it seemed worthwhile to centralise it.
43 lines
1.1 KiB
C++
43 lines
1.1 KiB
C++
#pragma once
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#include <cstdint>
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namespace snmalloc
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{
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/**
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* The type used for an address. Currently, all addresses are assumed to be
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* provenance-carrying values and so it is possible to cast back from the
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* result of arithmetic on an address_t. Eventually, this will want to be
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* separated into two types, one for raw addresses and one for addresses that
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* can be cast back to pointers.
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*/
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typedef uintptr_t address_t;
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/**
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* Perform pointer arithmetic and return the adjusted pointer.
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*/
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template<typename T>
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inline T* pointer_offset(T* base, size_t diff)
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{
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return reinterpret_cast<T*>(reinterpret_cast<char*>(base) + diff);
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}
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/**
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* Cast from a pointer type to an address.
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*/
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template<typename T>
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inline address_t address_cast(T* ptr)
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{
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return reinterpret_cast<address_t>(ptr);
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}
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/**
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* Cast from an address back to a pointer of the specified type. All uses of
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* this will eventually need auditing for CHERI compatibility.
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*/
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template<typename T>
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inline T* pointer_cast(address_t address)
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{
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return reinterpret_cast<T*>(address);
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}
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}
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