[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`.

1 files changed, 0 insertions, 193 deletions

diff --git a/view/sharedcache/core/MappedFile.cpp b/view/sharedcache/core/MappedFile.cpp
deleted file mode 100644
index 21bda4f8..00000000
--- a/view/sharedcache/core/MappedFile.cpp
+++ /dev/null
@@ -1,193 +0,0 @@
-#ifdef _MSC_VER
-	#include <windows.h>
-#else
-	#include <sys/mman.h>
-	#include <fcntl.h>
-	#include <cstdlib>
-	#include <sys/resource.h>
-#endif
-
-#include "MappedFile.h"
-#include "binaryninjaapi.h"
-
-#ifndef _MSC_VER
-uint64_t AdjustFileDescriptorLimit()
-{
-	// The soft file descriptor limit on Linux and Mac is a lot lower than
-	// on Windows (1024 for Linux, 256 for Mac). Recent iOS shared caches
-	// have 60+ files which may not leave much headroom if a user opens
-	// more than one at a time. Attempt to increase the file descriptor
-	// limit to 1024, and limit ourselves to caching half of them as a
-	// memory vs performance trade-off (closing and re-opening a file
-	// requires parsing and applying the slide information again).
-	uint64_t maxFPLimit = 1024;
-
-	// check for BN_SHAREDCACHE_FP_MAX
-	//  if it exists, set maxFPLimit to that value
-	if (auto env = getenv("BN_SHAREDCACHE_FP_MAX"); env)
-	{
-		// FIXME behav on 0 here is unintuitive, '0123' will interpret as octal and be 83 according to manpage. meh.
-		maxFPLimit = strtoull(env, nullptr, 0);
-		if (maxFPLimit < 10)
-		{
-			BinaryNinja::LogWarn(
-				"BN_SHAREDCACHE_FP_MAX set to below 10. A value of at least 10 is recommended for performant analysis "
-			    "on SharedCache Binaries.");
-		}
-		if (maxFPLimit == 0)
-		{
-			BinaryNinja::LogError("BN_SHAREDCACHE_FP_MAX set to 0. Adjusting to 1");
-			maxFPLimit = 1;
-		}
-	}
-
-	rlimit rlim {};
-	getrlimit(RLIMIT_NOFILE, &rlim);
-	uint64_t previousLimit = rlim.rlim_cur;
-	uint64_t targetLimit = std::min(maxFPLimit, rlim.rlim_max);
-	if (rlim.rlim_cur < targetLimit)
-	{
-		rlim.rlim_cur = targetLimit;
-		if (setrlimit(RLIMIT_NOFILE, &rlim) < 0)
-		{
-			perror("setrlimit(RLIMIT_NOFILE)");
-			rlim.rlim_cur = previousLimit;
-		}
-	}
-
-	maxFPLimit = rlim.rlim_cur / 2;
-	return maxFPLimit;
-}
-
-MappedFile::~MappedFile()
-{
-	Unmap();
-	if (fd)
-		fclose(fd);
-}
-
-std::optional<MappedFile> MappedFile::OpenFile(const std::string& path)
-{
-	MappedFile file;
-	file._mmap = nullptr;
-	file.fd = fopen(path.c_str(), "r");
-	if (file.fd == nullptr)
-		return std::nullopt;
-
-	fseek(file.fd, 0L, SEEK_END);
-	file.len = ftell(file.fd);
-	fseek(file.fd, 0L, SEEK_SET);
-
-	return file;
-}
-
-MapStatus MappedFile::Map()
-{
-	if (_mmap)
-		return MapStatus::Success;
-
-	void* result = mmap(nullptr, len, PROT_READ | PROT_WRITE, MAP_PRIVATE, fileno(fd), 0u);
-	if (result == MAP_FAILED)
-	{
-		BinaryNinja::LogErrorF("mmap failed: {}", strerror(errno));  // Use errno to log the reason
-		return MapStatus::Error;
-	}
-	_mmap = static_cast<uint8_t*>(result);
-
-	return MapStatus::Success;
-}
-
-MapStatus MappedFile::Unmap()
-{
-	if (_mmap)
-	{
-		munmap(_mmap, len);
-		_mmap = nullptr;
-	}
-	return MapStatus::Success;
-}
-#else
-uint64_t AdjustFileDescriptorLimit()
-{
-	return 0x1000000;
-}
-
-MappedFile::~MappedFile()
-{
-	Unmap();
-	if (hFile)
-		CloseHandle(hFile);
-}
-
-std::optional<MappedFile> MappedFile::OpenFile(const std::string& path)
-{
-	MappedFile file;
-	file._mmap = nullptr;
-	file.hFile = CreateFile(path.c_str(),  // file name
-		GENERIC_READ,                      // desired access (read-only)
-		FILE_SHARE_READ,                   // share mode
-		NULL,                              // security attributes
-		OPEN_EXISTING,                     // creation disposition
-		FILE_ATTRIBUTE_NORMAL,             // flags and attributes
-		NULL);                             // template file
-
-	if (file.hFile == INVALID_HANDLE_VALUE)
-		return std::nullopt;
-
-	LARGE_INTEGER fileSize;
-	if (!GetFileSizeEx(file.hFile, &fileSize))
-	{
-		CloseHandle(file.hFile);
-		return std::nullopt;
-	}
-	file.len = static_cast<size_t>(fileSize.QuadPart);
-
-	return file;
-}
-
-MapStatus MappedFile::Map()
-{
-	if (_mmap)
-		return MapStatus::Success;
-
-	HANDLE hMapping = CreateFileMapping(hFile,  // file handle
-		NULL,                                   // security attributes
-		PAGE_WRITECOPY,                         // protection
-		0,                                      // maximum size (high-order DWORD)
-		0,                                      // maximum size (low-order DWORD)
-		NULL);                                  // name of the mapping object
-
-	if (hMapping == NULL)
-	{
-		CloseHandle(hFile);
-		return MapStatus::Error;
-	}
-
-	_mmap = static_cast<uint8_t*>(MapViewOfFile(hMapping,  // handle to the file mapping object
-		FILE_MAP_COPY,                                     // desired access
-		0,                                                 // file offset (high-order DWORD)
-		0,                                                 // file offset (low-order DWORD)
-		0));                                               // number of bytes to map (0 = entire file)
-
-	if (_mmap == nullptr)
-	{
-		CloseHandle(hMapping);
-		CloseHandle(hFile);
-		return MapStatus::Error;
-	}
-
-	CloseHandle(hMapping);
-	CloseHandle(hFile);
-
-	return MapStatus::Success;
-}
-
-MapStatus MappedFile::Unmap()
-{
-	if (_mmap)
-	{
-		UnmapViewOfFile(_mmap);
-	}
-	return MapStatus::Success;
-}
-#endif