From a72b98ed5a357bb380d81f07f3f36946aa729bb2 Mon Sep 17 00:00:00 2001
From: Mark Rowe <mark@vector35.com>
Date: Mon, 23 Feb 2026 23:26:27 -0800
Subject: [DSC] Simplify file mapping to fix intermittent unrelocated pointers

The `FileAccessorCache`'s LRU eviction could discard a file's mapped
data after slide info had already been applied to it. Future accesses to
the file produced a fresh mapping, but failed to reapply the slide info.
This could result in pointers not correctly being slid, such as in
https://github.com/Vector35/binaryninja-api/issues/7689.

The LRU cache existed to stay within OS file descriptor limits, since
the old `MappedFile` held its fd open for the lifetime of the mapping.
There's no real reason for it to hold the file descriptor open like
this. Closing it after `mmap` is sufficient to avoid the file descriptor
limits.

`MappedFileRegion` replaces the combination of `FileAccessorCache`,
`WeakFileAccessor`, and `MappedFileAccessor`. It closes the fd
immediately after mmap, so all files can stay mapped without consuming
descriptors, making the cache unnecessary.

`MappedFileRegion` is owned directly by the `CacheEntry` for its full
lifetime. Slide info is applied exactly once to each `MappedFileRegion`.
---
 view/sharedcache/core/FileAccessorCache.h | 76 -------------------------------
 1 file changed, 76 deletions(-)
 delete mode 100644 view/sharedcache/core/FileAccessorCache.h

(limited to 'view/sharedcache/core/FileAccessorCache.h')

diff --git a/view/sharedcache/core/FileAccessorCache.h b/view/sharedcache/core/FileAccessorCache.h
deleted file mode 100644
index 46de6fcc..00000000
--- a/view/sharedcache/core/FileAccessorCache.h
+++ /dev/null
@@ -1,76 +0,0 @@
-#pragma once
-
-#include <shared_mutex>
-
-#include "MappedFileAccessor.h"
-
-typedef uint32_t CacheAccessorID;
-
-// TODO: We might want to make this more than just the path, for example
-// TODO: We might want to make it unique to a view session (session id).
-// Get a unique entry id for the given file path.
-CacheAccessorID GetCacheAccessorID(const std::string& filePath);
-
-class WeakFileAccessor;
-
-class FileAccessorCache
-{
-	size_t m_cacheSize;
-	std::mutex m_mutex;
-	// NOTE: If we end up wanting to handle 1000's of files we should consider std::list.
-	std::deque<CacheAccessorID> m_cache;
-	std::unordered_map<CacheAccessorID, std::shared_ptr<MappedFileAccessor>> m_accessors;
-
-	explicit FileAccessorCache(size_t cacheSize = 8);
-
-	void EvictLastUsed();
-
-public:
-	static FileAccessorCache& Global();
-
-	// Get a weak reference to a file accessor, the reference at this point is alive.
-	// The reference is always alive at this point either because it is in the cache or it has been inserted in.
-	// Subsequent calls to this might kill the backing file accessor resulting in the weak ref recreating the file
-	// accessor and inserting itself back into its related cache.
-	WeakFileAccessor Open(const std::string& filePath);
-
-	void RemoveAccessor(CacheAccessorID id);
-
-	// Adjust the cache size limit.
-	// This will NOT evict current cache entries, as they are already available.
-	// Any subsequent call to `Open` will assume this cache size, evicting until the size is equal to the cache size.
-	void SetCacheSize(const uint64_t size) { m_cacheSize = size; };
-
-	size_t GetCacheSize() const { return m_cacheSize; }
-
-	size_t GetCacheCount() const { return m_accessors.size(); }
-};
-
-class WeakFileAccessor
-{
-	using ReviveCallback = std::function<void(MappedFileAccessor&)>;
-
-	// Weak pointer to the mapped file accessor, once this is expired we will re-open.
-	std::weak_ptr<MappedFileAccessor> m_weakPtr;
-	// File path for re-opening if needed
-	std::string m_filePath;
-
-	// Used to re-add writes once the file accessor is "revived".
-	std::optional<ReviveCallback> m_reviveCallback;
-
-	// TODO: Store a weak_ptr/shared_ptr to FileAccessorCache? That way we dont access Global()
-	// TODO: Only need to do the above if we want multiple caches.
-
-public:
-	explicit WeakFileAccessor(std::weak_ptr<MappedFileAccessor> weakPtr, std::string filePath) :
-		m_weakPtr(std::move(weakPtr)), m_filePath(std::move(filePath))
-	{}
-
-	// Register the function to be called once the file accessor is revived, this is typically
-	// used to re-apply writes such as from slide info.
-	void RegisterReviveCallback(const ReviveCallback& callback) {
-		m_reviveCallback = callback;
-	}
-
-	std::shared_ptr<MappedFileAccessor> lock();
-};
-- 
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