old-cross-binutils/gold/fileread.h
2007-08-21 23:37:56 +00:00

263 lines
6.3 KiB
C++

// fileread.h -- read files for gold -*- C++ -*-
// Classes used to read data from binary input files.
#ifndef GOLD_FILEREAD_H
#define GOLD_FILEREAD_H
#include <list>
#include <map>
#include <string>
#include "options.h"
namespace gold
{
class Dirsearch;
class File_view;
// File_read manages a file descriptor for a file we are reading. We
// close file descriptors if we run out of them, so this class reopens
// the file as needed.
class File_read
{
public:
File_read()
: name_(), descriptor_(-1), lock_count_(0), views_(),
saved_views_(), contents_(NULL), contents_size_(0)
{ }
~File_read();
// Open a file.
bool
open(const std::string& name);
// Pretend to open the file, but provide the file contents. No
// actual file system activity will occur. This is used for
// testing.
bool
open(const std::string& name, const unsigned char* contents, off_t size);
// Return the file name.
const std::string&
filename() const
{ return this->name_; }
// Lock the file for access within a particular Task::run execution.
// This means that the descriptor can not be closed. This routine
// may only be called from the main thread.
void
lock();
// Unlock the descriptor, permitting it to be closed if necessary.
void
unlock();
// Test whether the object is locked.
bool
is_locked();
// Return a view into the file. The pointer will remain valid until
// the File_read is unlocked. If PBYTES is NULL, it is an error if
// we can not read enough data. Otherwise *PBYTES is set to the
// number of bytes read.
const unsigned char*
get_view(off_t start, off_t size, off_t* pbytes = NULL);
// Read data from the file into the buffer P. PBYTES is as in
// get_view.
void
read(off_t start, off_t size, void* p, off_t* pbytes = NULL);
// Return a lasting view into the file. This is allocated with new,
// and the caller is responsible for deleting it when done. The
// data associated with this view will remain valid until the view
// is deleted. PBYTES is handled as with get_view.
File_view*
get_lasting_view(off_t start, off_t size, off_t *pbytes = NULL);
private:
// This class may not be copied.
File_read(const File_read&);
File_read& operator=(const File_read&);
// A view into the file when not using mmap.
class View
{
public:
View(off_t start, off_t size, unsigned char* data)
: start_(start), size_(size), data_(data), lock_count_(0)
{ }
~View();
off_t
start() const
{ return this->start_; }
off_t
size() const
{ return this->size_; }
unsigned char*
data() const
{ return this->data_; }
void
lock();
void
unlock();
bool
is_locked();
private:
View(const View&);
View& operator=(const View&);
off_t start_;
off_t size_;
unsigned char* data_;
int lock_count_;
};
friend class File_view;
// Find a view into the file.
View*
find_view(off_t start, off_t size);
// Read data from the file into a buffer.
off_t
do_read(off_t start, off_t size, void* p, off_t* pbytes);
// Find or make a view into the file.
View*
find_or_make_view(off_t start, off_t size, off_t* pbytes);
// Clear the file views.
void
clear_views(bool);
// The size of a file page for buffering data.
static const off_t page_size = 8192;
// Given a file offset, return the page offset.
static off_t
page_offset(off_t file_offset)
{ return file_offset & ~ (page_size - 1); }
// Given a file size, return the size to read integral pages.
static off_t
pages(off_t file_size)
{ return (file_size + (page_size - 1)) & ~ (page_size - 1); }
// The type of a mapping from page start to views.
typedef std::map<off_t, View*> Views;
// A simple list of Views.
typedef std::list<View*> Saved_views;
// File name.
std::string name_;
// File descriptor.
int descriptor_;
// Number of locks on the file.
int lock_count_;
// Buffered views into the file.
Views views_;
// List of views which were locked but had to be removed from views_
// because they were not large enough.
Saved_views saved_views_;
// Specified file contents. Used only for testing purposes.
const unsigned char* contents_;
// Specified file size. Used only for testing purposes.
off_t contents_size_;
};
// A view of file data that persists even when the file is unlocked.
// Callers should destroy these when no longer required. These are
// obtained form File_read::get_lasting_view. They may only be
// destroyed when the underlying File_read is locked.
class File_view
{
public:
// This may only be called when the underlying File_read is locked.
~File_view();
// Return a pointer to the data associated with this view.
const unsigned char*
data() const
{ return this->data_; }
private:
File_view(const File_view&);
File_view& operator=(const File_view&);
friend class File_read;
// Callers have to get these via File_read::get_lasting_view.
File_view(File_read& file, File_read::View* view, const unsigned char* data)
: file_(file), view_(view), data_(data)
{ }
File_read& file_;
File_read::View* view_;
const unsigned char* data_;
};
// All the information we hold for a single input file. This can be
// an object file, a shared library, or an archive.
class Input_file
{
public:
Input_file(const Input_file_argument* input_argument)
: input_argument_(input_argument), file_()
{ }
// Create an input file with the contents already provided. This is
// only used for testing. With this path, don't call the open
// method.
Input_file(const char* name, const unsigned char* contents, off_t size);
// Open the file.
void
open(const General_options&, const Dirsearch&);
// Return the name given by the user.
const char*
name() const
{ return this->input_argument_->name(); }
// Return the file name.
const std::string&
filename() const
{ return this->file_.filename(); }
// Return the position dependent options.
const Position_dependent_options&
options() const
{ return this->input_argument_->options(); }
// Return the file.
File_read&
file()
{ return this->file_; }
private:
Input_file(const Input_file&);
Input_file& operator=(const Input_file&);
const Input_file_argument* input_argument_;
File_read file_;
};
} // end namespace gold
#endif // !defined(GOLD_FILEREAD_H)