306 lines
7.7 KiB
C++
306 lines
7.7 KiB
C++
// fileread.h -- read files for gold -*- C++ -*-
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// Copyright 2006, 2007 Free Software Foundation, Inc.
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// Written by Ian Lance Taylor <iant@google.com>.
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// This file is part of gold.
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// This program is free software; you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation; either version 3 of the License, or
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// (at your option) any later version.
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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// You should have received a copy of the GNU General Public License
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// along with this program; if not, write to the Free Software
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// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
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// MA 02110-1301, USA.
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// Classes used to read data from binary input files.
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#ifndef GOLD_FILEREAD_H
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#define GOLD_FILEREAD_H
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#include <list>
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#include <map>
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#include <string>
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#include "options.h"
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namespace gold
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{
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class Dirsearch;
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class File_view;
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// File_read manages a file descriptor for a file we are reading. We
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// close file descriptors if we run out of them, so this class reopens
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// the file as needed.
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class File_read
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{
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public:
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File_read()
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: name_(), descriptor_(-1), size_(0), lock_count_(0), views_(),
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saved_views_(), contents_(NULL)
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{ }
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~File_read();
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// Open a file.
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bool
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open(const std::string& name);
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// Pretend to open the file, but provide the file contents. No
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// actual file system activity will occur. This is used for
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// testing.
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bool
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open(const std::string& name, const unsigned char* contents, off_t size);
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// Return the file name.
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const std::string&
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filename() const
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{ return this->name_; }
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// Lock the file for access within a particular Task::run execution.
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// This means that the descriptor can not be closed. This routine
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// may only be called from the main thread.
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void
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lock();
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// Unlock the descriptor, permitting it to be closed if necessary.
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void
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unlock();
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// Test whether the object is locked.
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bool
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is_locked();
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// Return the size of the file.
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off_t
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filesize() const
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{ return this->size_; }
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// Return a view into the file starting at file offset START for
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// SIZE bytes. The pointer will remain valid until the File_read is
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// unlocked. It is an error if we can not read enough data from the
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// file. The CACHE parameter is a hint as to whether it will be
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// useful to cache this data for later accesses--i.e., later calls
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// to get_view, read, or get_lasting_view which retrieve the same
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// data.
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const unsigned char*
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get_view(off_t start, off_t size, bool cache);
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// Read data from the file into the buffer P starting at file offset
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// START for SIZE bytes.
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void
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read(off_t start, off_t size, void* p);
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// Return a lasting view into the file starting at file offset START
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// for SIZE bytes. This is allocated with new, and the caller is
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// responsible for deleting it when done. The data associated with
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// this view will remain valid until the view is deleted. It is an
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// error if we can not read enough data from the file. The CACHE
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// parameter is as in get_view.
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File_view*
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get_lasting_view(off_t start, off_t size, bool cache);
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private:
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// This class may not be copied.
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File_read(const File_read&);
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File_read& operator=(const File_read&);
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// A view into the file.
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class View
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{
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public:
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View(off_t start, off_t size, const unsigned char* data, bool cache,
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bool mapped)
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: start_(start), size_(size), data_(data), lock_count_(0),
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cache_(cache), mapped_(mapped)
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{ }
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~View();
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off_t
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start() const
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{ return this->start_; }
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off_t
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size() const
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{ return this->size_; }
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const unsigned char*
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data() const
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{ return this->data_; }
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void
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lock();
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void
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unlock();
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bool
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is_locked();
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void
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set_cache()
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{ this->cache_ = true; }
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bool
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should_cache() const
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{ return this->cache_; }
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private:
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View(const View&);
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View& operator=(const View&);
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off_t start_;
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off_t size_;
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const unsigned char* data_;
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int lock_count_;
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bool cache_;
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bool mapped_;
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};
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friend class File_view;
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// Find a view into the file.
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View*
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find_view(off_t start, off_t size);
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// Read data from the file into a buffer.
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void
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do_read(off_t start, off_t size, void* p);
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// Find or make a view into the file.
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View*
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find_or_make_view(off_t start, off_t size, bool cache);
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// Clear the file views.
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void
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clear_views(bool);
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// The size of a file page for buffering data.
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static const off_t page_size = 8192;
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// Given a file offset, return the page offset.
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static off_t
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page_offset(off_t file_offset)
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{ return file_offset & ~ (page_size - 1); }
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// Given a file size, return the size to read integral pages.
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static off_t
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pages(off_t file_size)
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{ return (file_size + (page_size - 1)) & ~ (page_size - 1); }
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// The type of a mapping from page start to views.
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typedef std::map<off_t, View*> Views;
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// A simple list of Views.
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typedef std::list<View*> Saved_views;
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// File name.
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std::string name_;
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// File descriptor.
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int descriptor_;
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// File size.
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off_t size_;
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// Number of locks on the file.
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int lock_count_;
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// Buffered views into the file.
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Views views_;
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// List of views which were locked but had to be removed from views_
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// because they were not large enough.
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Saved_views saved_views_;
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// Specified file contents. Used only for testing purposes.
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const unsigned char* contents_;
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};
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// A view of file data that persists even when the file is unlocked.
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// Callers should destroy these when no longer required. These are
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// obtained form File_read::get_lasting_view. They may only be
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// destroyed when the underlying File_read is locked.
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class File_view
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{
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public:
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// This may only be called when the underlying File_read is locked.
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~File_view();
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// Return a pointer to the data associated with this view.
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const unsigned char*
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data() const
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{ return this->data_; }
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private:
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File_view(const File_view&);
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File_view& operator=(const File_view&);
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friend class File_read;
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// Callers have to get these via File_read::get_lasting_view.
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File_view(File_read& file, File_read::View* view, const unsigned char* data)
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: file_(file), view_(view), data_(data)
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{ }
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File_read& file_;
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File_read::View* view_;
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const unsigned char* data_;
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};
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// All the information we hold for a single input file. This can be
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// an object file, a shared library, or an archive.
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class Input_file
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{
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public:
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Input_file(const Input_file_argument* input_argument)
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: input_argument_(input_argument), file_()
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{ }
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// Create an input file with the contents already provided. This is
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// only used for testing. With this path, don't call the open
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// method.
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Input_file(const char* name, const unsigned char* contents, off_t size);
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// Open the file.
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void
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open(const General_options&, const Dirsearch&);
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// Return the name given by the user.
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const char*
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name() const
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{ return this->input_argument_->name(); }
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// Return the file name.
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const std::string&
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filename() const
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{ return this->file_.filename(); }
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// Return the position dependent options.
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const Position_dependent_options&
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options() const
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{ return this->input_argument_->options(); }
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// Return the file.
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File_read&
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file()
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{ return this->file_; }
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private:
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Input_file(const Input_file&);
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Input_file& operator=(const Input_file&);
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const Input_file_argument* input_argument_;
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File_read file_;
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};
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} // end namespace gold
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#endif // !defined(GOLD_FILEREAD_H)
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