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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.
//
//===----------------------------------------------------------------------===//
#include <errno.h>
#include <fcntl.h>
#include <limits.h>
#include <sys/stat.h>
#ifdef _WIN32
#include "lldb/Host/windows/windows.h"
#else
#include <sys/mman.h>
#endif
#include "llvm/Support/MathExtras.h"
#include "lldb/Core/DataBufferMemoryMap.h"
#include "lldb/Core/Error.h"
#include "lldb/Host/File.h"
#include "lldb/Host/FileSpec.h"
#include "lldb/Host/Host.h"
#include "lldb/Core/Log.h"
#include "lldb/lldb-private-log.h"
using namespace lldb;
using namespace lldb_private;
//----------------------------------------------------------------------
// Default Constructor
//----------------------------------------------------------------------
DataBufferMemoryMap::DataBufferMemoryMap() :
m_mmap_addr(NULL),
m_mmap_size(0),
m_data(NULL),
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 NULL 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 NULL
// 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 != NULL)
{
Log *log(lldb_private::GetLogIfAllCategoriesSet (LIBLLDB_LOG_MMAP));
if (log)
log->Printf("DataBufferMemoryMap::Clear() m_mmap_addr = %p, m_mmap_size = %" PRIu64 "", 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 = NULL;
m_mmap_size = 0;
m_data = NULL;
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 != NULL)
{
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, NULL, writeable ? PAGE_READWRITE : PAGE_READONLY, file_size_high, file_size_low, NULL);
if (fileMapping != NULL)
{
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;
if (writeable)
prot |= PROT_WRITE;
int flags = MAP_PRIVATE;
if (fd_is_file)
flags |= MAP_FILE;
m_mmap_addr = (uint8_t *)::mmap(NULL, 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 % Host::GetPageSize();
if (page_offset != 0)
{
m_mmap_addr = (uint8_t *)::mmap(NULL, length + page_offset, prot, flags, fd, offset - page_offset);
if (m_mmap_addr == (void*)-1)
{
// Failed to map file
m_mmap_addr = NULL;
}
else if (m_mmap_addr != NULL)
{
// 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 the mapped data
m_data = m_mmap_addr + page_offset;
// Our pretend size is the size that was requestd
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",
m_mmap_addr, (uint64_t)m_mmap_size, error.AsCString());
}
}
}
}
#endif
}
return GetByteSize ();
}
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