// fileread.h -- read files for gold -*- C++ -*- // Copyright 2006, 2007, 2008 Free Software Foundation, Inc. // Written by Ian Lance Taylor <iant@google.com>. // 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 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the // 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. #ifndef GOLD_FILEREAD_H #define GOLD_FILEREAD_H #include <list> #include <map> #include <string> #include <vector> #include "token.h" namespace gold { class Position_dependent_options; class Input_file_argument; 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), object_count_(0), size_(0), token_(false), views_(), saved_views_(), contents_(NULL), mapped_bytes_(0), released_(true) { } ~File_read(); // Open a file. bool 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. bool 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. void add_object() { ++this->object_count_; } // Remove an object associated with a file. void remove_object() { --this->object_count_; } // Lock the file for exclusive access within a particular Task::run // execution. This means that the descriptor can not be closed. // This routine may only be called when the workqueue lock is held. void lock(const Task* t); // Unlock the descriptor, permitting it to be closed if necessary. void unlock(const Task* t); // Test whether the object is locked. bool is_locked() const; // Return the token, so that the task can be queued. Task_token* token() { 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. void release(); // Return the size of the file. off_t 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; 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. void read(off_t start, section_size_type size, void* p) const; // 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. File_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. void clear_view_cache_marks(); // 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. void clear_uncached_views() { this->clear_views(false); } // 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. void read_multiple(off_t base, const Read_multiple&); // Dump statistical information to stderr. static void print_stats(); private: // 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. This variable // may not be accurate when running multi-threaded. static unsigned long long total_mapped_bytes; // Current number of bytes mapped into memory during the link. This // variable may not be accurate when running multi-threaded. static unsigned long long current_mapped_bytes; // High water mark of bytes mapped into memory during the link. // This variable may not be accurate when running multi-threaded. static unsigned long long maximum_mapped_bytes; // A view into the file. class View { public: View(off_t start, section_size_type size, const unsigned char* data, unsigned int byteshift, bool cache, bool mapped) : start_(start), size_(size), data_(data), lock_count_(0), byteshift_(byteshift), cache_(cache), mapped_(mapped), accessed_(true) { } ~View(); off_t start() const { return this->start_; } section_size_type size() const { return this->size_; } const unsigned char* data() const { return this->data_; } void lock(); void unlock(); bool is_locked(); unsigned int byteshift() const { return this->byteshift_; } void set_cache() { this->cache_ = true; } void clear_cache() { this->cache_ = false; } bool should_cache() const { return this->cache_; } void set_accessed() { this->accessed_ = true; } void clear_accessed() { this->accessed_= false; } bool accessed() const { return this->accessed_; } private: 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[]. bool mapped_; // 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; // Find a view into the file. View* find_view(off_t start, section_size_type size, unsigned int byteshift, View** vshifted) const; // Read data from the file into a buffer. void do_read(off_t start, section_size_type size, void* p) const; // Add a view. void add_view(View*); // Make a view into the file. View* make_view(off_t start, section_size_type size, unsigned int byteshift, bool cache); // Find or make a view into the file. View* find_or_make_view(off_t offset, off_t start, section_size_type size, bool aligned, bool cache); // 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 maximum number of entries we will pass to ::readv. static const size_t max_readv_entries = 128; // Use readv to read data. void do_readv(off_t base, const Read_multiple&, size_t start, size_t count); // File name. std::string name_; // File descriptor. int descriptor_; // 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_; // Specified file contents. Used only for testing purposes. const unsigned char* contents_; // 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 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), found_name_(), file_(), is_in_sysroot_(false) { } // 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); // Open the file. If the open fails, this will report an error and // return false. bool open(const General_options&, const Dirsearch&, const Task*); // 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/libc.so". 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 // "libc.so". const std::string& found_name() const { return this->found_name_; } // Return the position dependent options. const Position_dependent_options& options() const; // Return the file. File_read& file() { return this->file_; } const File_read& file() const { return this->file_; } // Whether we found the file in a directory in the system root. bool is_in_sysroot() const { return this->is_in_sysroot_; } // Return whether this file is to be read only for its symbols. bool just_symbols() const; private: Input_file(const Input_file&); Input_file& operator=(const Input_file&); // Open a binary file. bool open_binary(const General_options&, 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 libc.so (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_; }; } // end namespace gold #endif // !defined(GOLD_FILEREAD_H)