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// fileread.h -- read files for gold -*- C++ -*-
// Copyright (C) 2006-2021 Free Software Foundation, Inc.
// Written by Ian Lance Taylor <>.
// This file is part of gold.
// This program is free software; you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation; either version 3 of the License, or
// (at your option) any later version.
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// GNU General Public License for more details.
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
// MA 02110-1301, USA.
// Classes used to read data from binary input files.
#include <list>
#include <map>
#include <string>
#include <vector>
#include "token.h"
namespace gold
// Since not all system supports stat.st_mtim and struct timespec,
// we define our own structure and fill the nanoseconds if we can.
struct Timespec
: seconds(0), nanoseconds(0)
{ }
Timespec(time_t a_seconds, int a_nanoseconds)
: seconds(a_seconds), nanoseconds(a_nanoseconds)
{ }
time_t seconds;
int nanoseconds;
// Get the last modified time of an unopened file. Returns false if the
// file does not exist.
get_mtime(const char* filename, Timespec* mtime);
class Position_dependent_options;
class Input_file_argument;
class Dirsearch;
class File_view;
// File_read manages a file descriptor and mappings for a file we are
// reading.
class File_read
: name_(), descriptor_(-1), is_descriptor_opened_(false), object_count_(0),
size_(0), token_(false), views_(), saved_views_(), mapped_bytes_(0),
released_(true), whole_file_view_(NULL)
{ }
// Open a file.
open(const Task*, 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.
open(const Task*, const std::string& name, const unsigned char* contents,
off_t size);
// Return the file name.
const std::string&
filename() const
{ return this->name_; }
// Add an object associated with a file.
{ ++this->object_count_; }
// Remove an object associated with a file.
{ --this->object_count_; }
// Lock the file for exclusive access within a particular Task::run
// execution. This routine may only be called when the workqueue
// lock is held.
lock(const Task* t);
// Unlock the file.
unlock(const Task* t);
// Test whether the object is locked.
is_locked() const;
// Return the token, so that the task can be queued.
{ return &this->token_; }
// Release the file. This indicates that we aren't going to do
// anything further with it until it is unlocked. This is used
// because a Task which locks the file never calls either lock or
// unlock; it just locks the token. The basic rule is that a Task
// which locks a file via the Task::locks interface must explicitly
// call release() when it is done. This is not necessary for code
// which calls unlock() on the file.
// Return the size of the file.
filesize() const
{ return this->size_; }
// Return a view into the file starting at file offset START for
// SIZE bytes. OFFSET is the offset into the input file for the
// file we are reading; this is zero for a normal object file,
// non-zero for an object file in an archive. ALIGNED is true if
// the data must be naturally aligned (i.e., aligned to the size
// of a target word); this only matters when OFFSET is not zero.
// The pointer will remain valid until the File_read is unlocked.
// It is an error if we can not read enough data from the file.
// The CACHE parameter is a hint as to whether it will be useful
// to cache this data for later accesses--i.e., later calls to
// get_view, read, or get_lasting_view which retrieve the same
// data.
const unsigned char*
get_view(off_t offset, off_t start, section_size_type size, bool aligned,
bool cache);
// Read data from the file into the buffer P starting at file offset
// START for SIZE bytes.
read(off_t start, section_size_type size, void* p);
// Return a lasting view into the file starting at file offset START
// for SIZE bytes. 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. It is an
// error if we can not read enough data from the file. The OFFSET,
// ALIGNED and CACHE parameters are as in get_view.
get_lasting_view(off_t offset, off_t start, section_size_type size,
bool aligned, bool cache);
// Mark all views as no longer cached.
// Discard all uncached views. This is normally done by release(),
// but not for objects in archives. FIXME: This is a complicated
// interface, and it would be nice to have something more automatic.
{ this->clear_views(CLEAR_VIEWS_ARCHIVE); }
// A struct used to do a multiple read.
struct Read_multiple_entry
// The file offset of the data to read.
off_t file_offset;
// The amount of data to read.
section_size_type size;
// The buffer where the data should be placed.
unsigned char* buffer;
Read_multiple_entry(off_t o, section_size_type s, unsigned char* b)
: file_offset(o), size(s), buffer(b)
{ }
typedef std::vector<Read_multiple_entry> Read_multiple;
// Read a bunch of data from the file into various different
// locations. The vector must be sorted by ascending file_offset.
// BASE is a base offset to be added to all the offsets in the
// vector.
read_multiple(off_t base, const Read_multiple&);
// Dump statistical information to stderr.
static void
// Write the dependency file listing all files read.
static void
write_dependency_file(const char* dependency_file_name,
const char* output_file_name);
// Record that a file was read. File_read::open does this.
static void
record_file_read(const std::string& name);
// Return the open file descriptor (for plugins).
return this->descriptor_;
// Return the file last modification time. Calls gold_fatal if the stat
// system call failed.
// Control for what views to clear.
enum Clear_views_mode
// Clear uncached views not used by an archive.
// Clear all uncached views (including in an archive).
// Clear all views (i.e., we're destroying the file).
// This class may not be copied.
File_read(const File_read&);
File_read& operator=(const File_read&);
// Total bytes mapped into memory during the link if --stats.
static unsigned long long total_mapped_bytes;
// Current number of bytes mapped into memory during the link if
// --stats.
static unsigned long long current_mapped_bytes;
// High water mark of bytes mapped into memory during the link if
// --stats.
static unsigned long long maximum_mapped_bytes;
// Set of names of all files read.
static std::vector<std::string> files_read;
// A view into the file.
class View
// Specifies how to dispose the data on destruction of the view.
enum Data_ownership
// Data owned by File object - nothing done in destructor.
// Data allocated with new[] and owned by this object - should
// use delete[].
// Data mmapped and owned by this object - should munmap.
View(off_t start, section_size_type size, const unsigned char* data,
unsigned int byteshift, bool cache, Data_ownership data_ownership)
: start_(start), size_(size), data_(data), lock_count_(0),
byteshift_(byteshift), cache_(cache), data_ownership_(data_ownership),
{ }
start() const
{ return this->start_; }
size() const
{ return this->size_; }
const unsigned char*
data() const
{ return this->data_; }
unsigned int
byteshift() const
{ return this->byteshift_; }
{ this->cache_ = true; }
{ this->cache_ = false; }
should_cache() const
{ return this->cache_; }
{ this->accessed_ = true; }
{ this->accessed_= false; }
accessed() const
{ return this->accessed_; }
// Returns TRUE if this view contains permanent data -- e.g., data that
// was supplied by the owner of the File object.
is_permanent_view() const
{ return this->data_ownership_ == DATA_NOT_OWNED; }
View(const View&);
View& operator=(const View&);
// The file offset of the start of the view.
off_t start_;
// The size of the view.
section_size_type size_;
// A pointer to the actual bytes.
const unsigned char* data_;
// The number of locks on this view.
int lock_count_;
// The number of bytes that the view is shifted relative to the
// underlying file. This is used to align data. This is normally
// zero, except possibly for an object in an archive.
unsigned int byteshift_;
// Whether the view is cached.
bool cache_;
// Whether the view is mapped into memory. If not, data_ points
// to memory allocated using new[].
Data_ownership data_ownership_;
// Whether the view has been accessed recently.
bool accessed_;
friend class View;
friend class File_view;
// The type of a mapping from page start and byte shift to views.
typedef std::map<std::pair<off_t, unsigned int>, View*> Views;
// A simple list of Views.
typedef std::list<View*> Saved_views;
// Open the descriptor if necessary.
// Find a view into the file.
find_view(off_t start, section_size_type size, unsigned int byteshift,
View** vshifted) const;
// Read data from the file into a buffer.
do_read(off_t start, section_size_type size, void* p);
// Add a view.
// Make a view into the file.
make_view(off_t start, section_size_type size, unsigned int byteshift,
bool cache);
// Find or make a view into the file.
find_or_make_view(off_t offset, off_t start, section_size_type size,
bool aligned, bool cache);
// Clear the file views.
// 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 maximum number of entries we will pass to ::readv.
static const size_t max_readv_entries = 128;
// Use readv to read data.
do_readv(off_t base, const Read_multiple&, size_t start, size_t count);
// File name.
std::string name_;
// File descriptor.
int descriptor_;
// Whether we have regained the descriptor after releasing the file.
bool is_descriptor_opened_;
// The number of objects associated with this file. This will be
// more than 1 in the case of an archive.
int object_count_;
// File size.
off_t size_;
// A token used to lock the file.
Task_token token_;
// 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_;
// Total amount of space mapped into memory. This is only changed
// while the file is locked. When we unlock the file, we transfer
// the total to total_mapped_bytes, and reset this to zero.
size_t mapped_bytes_;
// Whether the file was released.
bool released_;
// A view containing the whole file. May be NULL if we mmap only
// the relevant parts of the file. Not NULL if:
// - Flag --mmap_whole_files is set (default on 64-bit hosts).
// - The contents was specified in the constructor. Used only for
// testing purposes).
View* whole_file_view_;
// 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
// This may only be called when the underlying File_read is locked.
// Return a pointer to the data associated with this view.
const unsigned char*
data() const
{ return this->data_; }
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
enum Format
Input_file(const Input_file_argument* input_argument)
: input_argument_(input_argument), found_name_(), file_(),
is_in_sysroot_(false), format_(FORMAT_NONE)
{ }
// Create an input file given just a filename.
Input_file(const char* name);
// 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 Task*, const char* name, const unsigned char* contents,
off_t size);
// Return the command line argument.
const Input_file_argument*
input_file_argument() const
{ return this->input_argument_; }
// Return whether this is a file that we will search for in the list
// of directories.
will_search_for() const;
// Open the file. If the open fails, this will report an error and
// return false. If there is a search, it starts at directory
// *PINDEX. *PINDEX should be initialized to zero. It may be
// restarted to find the next file with a matching name by
// incrementing the result and calling this again.
open(const Dirsearch&, const Task*, int* pindex);
// Return the name given by the user. For -lc this will return "c".
const char*
name() const;
// Return the file name. For -lc this will return something like
// "/usr/lib/".
const std::string&
filename() const
{ return this->file_.filename(); }
// Return the name under which we found the file, corresponding to
// the command line. For -lc this will return something like
// "".
const std::string&
found_name() const
{ return this->found_name_; }
// Return the position dependent options.
const Position_dependent_options&
options() const;
// Return the file.
{ return this->file_; }
const File_read&
file() const
{ return this->file_; }
// Whether we found the file in a directory in the system root.
is_in_sysroot() const
{ return this->is_in_sysroot_; }
// Whether this file is in a system directory.
is_in_system_directory() const;
// Return whether this file is to be read only for its symbols.
just_symbols() const;
// Return the format of the unconverted input file.
format() const
{ return this->format_; }
// Try to find a file in the extra search dirs. Returns true on success.
static bool
try_extra_search_path(int* pindex,
const Input_file_argument* input_argument,
std::string filename, std::string* found_name,
std::string* namep);
// Find the actual file.
static bool
find_file(const Dirsearch& dirpath, int* pindex,
const Input_file_argument* input_argument,
bool* is_in_sysroot,
std::string* found_name, std::string* namep);
Input_file(const Input_file&);
Input_file& operator=(const Input_file&);
// Open a binary file.
open_binary(const Task* task, const std::string& name);
// The argument from the command line.
const Input_file_argument* input_argument_;
// The name under which we opened the file. This is like the name
// on the command line, but -lc turns into (or whatever).
// It only includes the full path if the path was on the command
// line.
std::string found_name_;
// The file after we open it.
File_read file_;
// Whether we found the file in a directory in the system root.
bool is_in_sysroot_;
// Format of unconverted input file.
Format format_;
} // end namespace gold
#endif // !defined(GOLD_FILEREAD_H)