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llvm-project/lldb/source/Core/DataBufferMemoryMap.cpp

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//===-- DataBufferMemoryMap.cpp ---------------------------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
// C Includes
#include <fcntl.h>
#include <sys/stat.h>
#ifdef _WIN32
#include "lldb/Host/windows/windows.h"
#else
#include <sys/mman.h>
#define MAP_EXTRA_HOST_READ_FLAGS 0
#if defined(__APPLE__)
//----------------------------------------------------------------------
// Newer versions of MacOSX have a flag that will allow us to read from
// binaries whose code signature is invalid without crashing by using
// the MAP_RESILIENT_CODESIGN flag. Also if a file from removable media
// is mapped we can avoid crashing and return zeroes to any pages we try
// to read if the media becomes unavailable by using the
// MAP_RESILIENT_MEDIA flag.
//----------------------------------------------------------------------
#if defined(MAP_RESILIENT_CODESIGN)
#undef MAP_EXTRA_HOST_READ_FLAGS
#if defined(MAP_RESILIENT_MEDIA)
#define MAP_EXTRA_HOST_READ_FLAGS MAP_RESILIENT_CODESIGN | MAP_RESILIENT_MEDIA
#else
#define MAP_EXTRA_HOST_READ_FLAGS MAP_RESILIENT_CODESIGN
#endif
#endif // #if defined(MAP_RESILIENT_CODESIGN)
#endif // #if defined (__APPLE__)
#endif // #else #ifdef _WIN32
// C++ Includes
#include <cerrno>
#include <climits>
// Other libraries and framework includes
#include "llvm/Support/MathExtras.h"
// Project includes
#include "lldb/Core/DataBufferMemoryMap.h"
#include "lldb/Core/Error.h"
#include "lldb/Core/Log.h"
#include "lldb/Host/File.h"
#include "lldb/Host/FileSpec.h"
#include "lldb/Host/HostInfo.h"
using namespace lldb;
using namespace lldb_private;
//----------------------------------------------------------------------
// Default Constructor
//----------------------------------------------------------------------
DataBufferMemoryMap::DataBufferMemoryMap()
: m_mmap_addr(nullptr), m_mmap_size(0), m_data(nullptr), m_size(0) {}
//----------------------------------------------------------------------
// Virtual destructor since this class inherits from a pure virtual
// base class.
//----------------------------------------------------------------------
DataBufferMemoryMap::~DataBufferMemoryMap() { Clear(); }
//----------------------------------------------------------------------
// Return a pointer to the bytes owned by this object, or nullptr if
// the object contains no bytes.
//----------------------------------------------------------------------
uint8_t *DataBufferMemoryMap::GetBytes() { return m_data; }
//----------------------------------------------------------------------
// Return a const pointer to the bytes owned by this object, or nullptr
// if the object contains no bytes.
//----------------------------------------------------------------------
const uint8_t *DataBufferMemoryMap::GetBytes() const { return m_data; }
//----------------------------------------------------------------------
// Return the number of bytes this object currently contains.
//----------------------------------------------------------------------
uint64_t DataBufferMemoryMap::GetByteSize() const { return m_size; }
//----------------------------------------------------------------------
// Reverts this object to an empty state by unmapping any memory
// that is currently owned.
//----------------------------------------------------------------------
void DataBufferMemoryMap::Clear() {
if (m_mmap_addr != nullptr) {
Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_MMAP));
if (log)
log->Printf("DataBufferMemoryMap::Clear() m_mmap_addr = %p, m_mmap_size "
"= %" PRIu64 "",
(void *)m_mmap_addr, (uint64_t)m_mmap_size);
#ifdef _WIN32
UnmapViewOfFile(m_mmap_addr);
#else
::munmap((void *)m_mmap_addr, m_mmap_size);
#endif
m_mmap_addr = nullptr;
m_mmap_size = 0;
m_data = nullptr;
m_size = 0;
}
}
//----------------------------------------------------------------------
// Memory map "length" bytes from "file" starting "offset"
// bytes into the file. If "length" is set to SIZE_MAX, then
// map as many bytes as possible.
//
// Returns the number of bytes mapped starting from the requested
// offset.
//----------------------------------------------------------------------
size_t DataBufferMemoryMap::MemoryMapFromFileSpec(const FileSpec *filespec,
lldb::offset_t offset,
size_t length,
bool writeable) {
if (filespec != nullptr) {
Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_MMAP));
if (log) {
log->Printf("DataBufferMemoryMap::MemoryMapFromFileSpec(file=\"%s\", "
"offset=0x%" PRIx64 ", length=0x%" PRIx64 ", writeable=%i",
filespec->GetPath().c_str(), offset, (uint64_t)length,
writeable);
}
char path[PATH_MAX];
if (filespec->GetPath(path, sizeof(path))) {
uint32_t options = File::eOpenOptionRead;
if (writeable)
options |= File::eOpenOptionWrite;
File file;
Error error(file.Open(path, options));
if (error.Success()) {
const bool fd_is_file = true;
return MemoryMapFromFileDescriptor(file.GetDescriptor(), offset, length,
writeable, fd_is_file);
}
}
}
// We should only get here if there was an error
Clear();
return 0;
}
#ifdef _WIN32
static size_t win32memmapalignment = 0;
void LoadWin32MemMapAlignment() {
SYSTEM_INFO data;
GetSystemInfo(&data);
win32memmapalignment = data.dwAllocationGranularity;
}
#endif
//----------------------------------------------------------------------
// The file descriptor FD is assumed to already be opened as read only
// and the STAT structure is assumed to a valid pointer and already
// containing valid data from a call to stat().
//
// Memory map FILE_LENGTH bytes in FILE starting FILE_OFFSET bytes into
// the file. If FILE_LENGTH is set to SIZE_MAX, then map as many bytes
// as possible.
//
// RETURNS
// Number of bytes mapped starting from the requested offset.
//----------------------------------------------------------------------
size_t DataBufferMemoryMap::MemoryMapFromFileDescriptor(int fd,
lldb::offset_t offset,
size_t length,
bool writeable,
bool fd_is_file) {
Clear();
if (fd >= 0) {
Log *log(lldb_private::GetLogIfAllCategoriesSet(LIBLLDB_LOG_MMAP |
LIBLLDB_LOG_VERBOSE));
if (log) {
log->Printf("DataBufferMemoryMap::MemoryMapFromFileDescriptor(fd=%i, "
"offset=0x%" PRIx64 ", length=0x%" PRIx64
", writeable=%i, fd_is_file=%i)",
fd, offset, (uint64_t)length, writeable, fd_is_file);
}
#ifdef _WIN32
HANDLE handle = (HANDLE)_get_osfhandle(fd);
DWORD file_size_low, file_size_high;
file_size_low = GetFileSize(handle, &file_size_high);
const lldb::offset_t file_size =
llvm::Make_64(file_size_high, file_size_low);
const lldb::offset_t max_bytes_available = file_size - offset;
const size_t max_bytes_mappable =
(size_t)std::min<lldb::offset_t>(SIZE_MAX, max_bytes_available);
if (length == SIZE_MAX || length > max_bytes_mappable) {
// Cap the length if too much data was requested
length = max_bytes_mappable;
}
if (length > 0) {
HANDLE fileMapping = CreateFileMapping(
handle, nullptr, writeable ? PAGE_READWRITE : PAGE_READONLY,
file_size_high, file_size_low, nullptr);
if (fileMapping != nullptr) {
if (win32memmapalignment == 0)
LoadWin32MemMapAlignment();
lldb::offset_t realoffset = offset;
lldb::offset_t delta = 0;
if (realoffset % win32memmapalignment != 0) {
realoffset = realoffset / win32memmapalignment * win32memmapalignment;
delta = offset - realoffset;
}
LPVOID data = MapViewOfFile(fileMapping,
writeable ? FILE_MAP_WRITE : FILE_MAP_READ,
0, realoffset, length + delta);
m_mmap_addr = (uint8_t *)data;
if (!data) {
Error error;
error.SetErrorToErrno();
} else {
m_data = m_mmap_addr + delta;
m_size = length;
}
CloseHandle(fileMapping);
}
}
#else
struct stat stat;
if (::fstat(fd, &stat) == 0) {
if (S_ISREG(stat.st_mode) &&
(stat.st_size > static_cast<off_t>(offset))) {
const size_t max_bytes_available = stat.st_size - offset;
if (length == SIZE_MAX) {
length = max_bytes_available;
} else if (length > max_bytes_available) {
// Cap the length if too much data was requested
length = max_bytes_available;
}
if (length > 0) {
int prot = PROT_READ;
int flags = MAP_PRIVATE;
if (writeable)
prot |= PROT_WRITE;
else
flags |= MAP_EXTRA_HOST_READ_FLAGS;
if (fd_is_file)
flags |= MAP_FILE;
m_mmap_addr =
(uint8_t *)::mmap(nullptr, length, prot, flags, fd, offset);
Error error;
if (m_mmap_addr == (void *)-1) {
error.SetErrorToErrno();
if (error.GetError() == EINVAL) {
// We may still have a shot at memory mapping if we align things
// correctly
size_t page_offset = offset % HostInfo::GetPageSize();
if (page_offset != 0) {
m_mmap_addr =
(uint8_t *)::mmap(nullptr, length + page_offset, prot,
flags, fd, offset - page_offset);
if (m_mmap_addr == (void *)-1) {
// Failed to map file
m_mmap_addr = nullptr;
} else if (m_mmap_addr != nullptr) {
// We recovered and were able to memory map
// after we aligned things to page boundaries
// Save the actual mmap'ed size
m_mmap_size = length + page_offset;
// Our data is at an offset into the mapped data
m_data = m_mmap_addr + page_offset;
// Our pretend size is the size that was requested
m_size = length;
}
}
}
if (error.GetError() == ENOMEM) {
error.SetErrorStringWithFormat("could not allocate %" PRId64
" bytes of memory to mmap in file",
(uint64_t)length);
}
} else {
// We were able to map the requested data in one chunk
// where our mmap and actual data are the same.
m_mmap_size = length;
m_data = m_mmap_addr;
m_size = length;
}
if (log) {
log->Printf(
"DataBufferMemoryMap::MemoryMapFromFileSpec() m_mmap_addr = "
"%p, m_mmap_size = %" PRIu64 ", error = %s",
(void *)m_mmap_addr, (uint64_t)m_mmap_size, error.AsCString());
}
}
}
}
#endif
}
return GetByteSize();
}
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