old-cross-binutils/gold/readsyms.cc
Ian Lance Taylor 17a1d0a9b2 Rewrite workqueue. This version eliminates the master thread, and
reduces the amount of locking required to find a new thread to run.
2007-12-14 19:00:21 +00:00

423 lines
11 KiB
C++

// readsyms.cc -- read input file symbols for gold
// Copyright 2006, 2007 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.
#include "gold.h"
#include <cstring>
#include "elfcpp.h"
#include "options.h"
#include "dirsearch.h"
#include "symtab.h"
#include "object.h"
#include "archive.h"
#include "script.h"
#include "readsyms.h"
namespace gold
{
// If we fail to open the object, then we won't create an Add_symbols
// task. However, we still need to unblock the token, or else the
// link won't proceed to generate more error messages. We can only
// unblock tokens when the workqueue lock is held, so we need a dummy
// task to do that. The dummy task has to maintain the right sequence
// of blocks, so we need both this_blocker and next_blocker.
class Unblock_token : public Task
{
public:
Unblock_token(Task_token* this_blocker, Task_token* next_blocker)
: this_blocker_(this_blocker), next_blocker_(next_blocker)
{ }
~Unblock_token()
{
if (this->this_blocker_ != NULL)
delete this->this_blocker_;
}
Task_token*
is_runnable()
{
if (this->this_blocker_ != NULL && this->this_blocker_->is_blocked())
return this->this_blocker_;
return NULL;
}
void
locks(Task_locker* tl)
{ tl->add(this, this->next_blocker_); }
void
run(Workqueue*)
{ }
std::string
get_name() const
{ return "Unblock_token"; }
private:
Task_token* this_blocker_;
Task_token* next_blocker_;
};
// Class read_symbols.
Read_symbols::~Read_symbols()
{
// The this_blocker_ and next_blocker_ pointers are passed on to the
// Add_symbols task.
}
// Return whether a Read_symbols task is runnable. We can read an
// ordinary input file immediately. For an archive specified using
// -l, we have to wait until the search path is complete.
Task_token*
Read_symbols::is_runnable()
{
if (this->input_argument_->is_file()
&& this->input_argument_->file().may_need_search()
&& this->dirpath_->token()->is_blocked())
return this->dirpath_->token();
return NULL;
}
// Return a Task_locker for a Read_symbols task. We don't need any
// locks here.
void
Read_symbols::locks(Task_locker*)
{
}
// Run a Read_symbols task.
void
Read_symbols::run(Workqueue* workqueue)
{
// If we didn't queue a new task, then we need to explicitly unblock
// the token.
if (!this->do_read_symbols(workqueue))
workqueue->queue_front(new Unblock_token(this->this_blocker_,
this->next_blocker_));
}
// Open the file and read the symbols. Return true if a new task was
// queued, false if that could not happen due to some error.
bool
Read_symbols::do_read_symbols(Workqueue* workqueue)
{
if (this->input_argument_->is_group())
{
gold_assert(this->input_group_ == NULL);
this->do_group(workqueue);
return true;
}
Input_file* input_file = new Input_file(&this->input_argument_->file());
if (!input_file->open(this->options_, *this->dirpath_, this))
return false;
// Read enough of the file to pick up the entire ELF header.
off_t filesize = input_file->file().filesize();
if (filesize == 0)
{
gold_error(_("%s: file is empty"),
input_file->file().filename().c_str());
return false;
}
unsigned char ehdr_buf[elfcpp::Elf_sizes<64>::ehdr_size];
int read_size = elfcpp::Elf_sizes<64>::ehdr_size;
if (filesize < read_size)
read_size = filesize;
input_file->file().read(0, read_size, ehdr_buf);
if (read_size >= 4)
{
static unsigned char elfmagic[4] =
{
elfcpp::ELFMAG0, elfcpp::ELFMAG1,
elfcpp::ELFMAG2, elfcpp::ELFMAG3
};
if (memcmp(ehdr_buf, elfmagic, 4) == 0)
{
// This is an ELF object.
Object* obj = make_elf_object(input_file->filename(),
input_file, 0, ehdr_buf, read_size);
if (obj == NULL)
return false;
// We don't have a way to record a non-archive in an input
// group. If this is an ordinary object file, we can't
// include it more than once anyhow. If this is a dynamic
// object, then including it a second time changes nothing.
if (this->input_group_ != NULL && !obj->is_dynamic())
{
gold_error(_("%s: ordinary object found in input group"),
input_file->name());
return false;
}
Read_symbols_data* sd = new Read_symbols_data;
obj->read_symbols(sd);
// Opening the file locked it, so now we need to unlock it.
// We need to unlock it before queuing the Add_symbols task,
// because the workqueue doesn't know about our lock on the
// file. If we queue the Add_symbols task first, it will be
// stuck on the end of the file lock, but since the
// workqueue doesn't know about that lock, it will never
// release the Add_symbols task.
input_file->file().unlock(this);
workqueue->queue_front(new Add_symbols(this->input_objects_,
this->symtab_, this->layout_,
obj, sd,
this->this_blocker_,
this->next_blocker_));
return true;
}
}
if (read_size >= Archive::sarmag)
{
if (memcmp(ehdr_buf, Archive::armag, Archive::sarmag) == 0)
{
// This is an archive.
Archive* arch = new Archive(this->input_argument_->file().name(),
input_file);
arch->setup(this);
workqueue->queue_front(new Add_archive_symbols(this->symtab_,
this->layout_,
this->input_objects_,
arch,
this->input_group_,
this->this_blocker_,
this->next_blocker_));
return true;
}
}
// Try to parse this file as a script.
if (read_input_script(workqueue, this->options_, this->symtab_,
this->layout_, this->dirpath_, this->input_objects_,
this->input_group_, this->input_argument_, input_file,
ehdr_buf, read_size, this->this_blocker_,
this->next_blocker_))
return true;
// Here we have to handle any other input file types we need.
gold_error(_("%s: not an object or archive"),
input_file->file().filename().c_str());
return false;
}
// Handle a group. We need to walk through the arguments over and
// over until we don't see any new undefined symbols. We do this by
// setting off Read_symbols Tasks as usual, but recording the archive
// entries instead of deleting them. We also start a Finish_group
// Task which runs after we've read all the symbols. In that task we
// process the archives in a loop until we are done.
void
Read_symbols::do_group(Workqueue* workqueue)
{
Input_group* input_group = new Input_group();
const Input_file_group* group = this->input_argument_->group();
Task_token* this_blocker = this->this_blocker_;
for (Input_file_group::const_iterator p = group->begin();
p != group->end();
++p)
{
const Input_argument* arg = &*p;
gold_assert(arg->is_file());
Task_token* next_blocker = new Task_token(true);
next_blocker->add_blocker();
workqueue->queue(new Read_symbols(this->options_, this->input_objects_,
this->symtab_, this->layout_,
this->dirpath_, arg, input_group,
this_blocker, next_blocker));
this_blocker = next_blocker;
}
const int saw_undefined = this->symtab_->saw_undefined();
workqueue->queue(new Finish_group(this->input_objects_,
this->symtab_,
this->layout_,
input_group,
saw_undefined,
this_blocker,
this->next_blocker_));
}
// Return a debugging name for a Read_symbols task.
std::string
Read_symbols::get_name() const
{
if (!this->input_argument_->is_group())
{
std::string ret("Read_symbols ");
if (this->input_argument_->file().is_lib())
ret += "-l";
ret += this->input_argument_->file().name();
return ret;
}
std::string ret("Read_symbols group (");
bool add_space = false;
const Input_file_group* group = this->input_argument_->group();
for (Input_file_group::const_iterator p = group->begin();
p != group->end();
++p)
{
if (add_space)
ret += ' ';
ret += p->file().name();
add_space = true;
}
return ret + ')';
}
// Class Add_symbols.
Add_symbols::~Add_symbols()
{
if (this->this_blocker_ != NULL)
delete this->this_blocker_;
// next_blocker_ is deleted by the task associated with the next
// input file.
}
// We are blocked by this_blocker_. We block next_blocker_. We also
// lock the file.
Task_token*
Add_symbols::is_runnable()
{
if (this->this_blocker_ != NULL && this->this_blocker_->is_blocked())
return this->this_blocker_;
if (this->object_->is_locked())
return this->object_->token();
return NULL;
}
void
Add_symbols::locks(Task_locker* tl)
{
tl->add(this, this->next_blocker_);
tl->add(this, this->object_->token());
}
// Add the symbols in the object to the symbol table.
void
Add_symbols::run(Workqueue*)
{
if (!this->input_objects_->add_object(this->object_))
{
// FIXME: We need to close the descriptor here.
delete this->object_;
}
else
{
this->object_->layout(this->symtab_, this->layout_, this->sd_);
this->object_->add_symbols(this->symtab_, this->sd_);
this->object_->release();
}
delete this->sd_;
this->sd_ = NULL;
}
// Class Finish_group.
Finish_group::~Finish_group()
{
if (this->this_blocker_ != NULL)
delete this->this_blocker_;
// next_blocker_ is deleted by the task associated with the next
// input file following the group.
}
// We need to wait for THIS_BLOCKER_ and unblock NEXT_BLOCKER_.
Task_token*
Finish_group::is_runnable()
{
if (this->this_blocker_ != NULL && this->this_blocker_->is_blocked())
return this->this_blocker_;
return NULL;
}
void
Finish_group::locks(Task_locker* tl)
{
tl->add(this, this->next_blocker_);
}
// Loop over the archives until there are no new undefined symbols.
void
Finish_group::run(Workqueue*)
{
int saw_undefined = this->saw_undefined_;
while (saw_undefined != this->symtab_->saw_undefined())
{
saw_undefined = this->symtab_->saw_undefined();
for (Input_group::const_iterator p = this->input_group_->begin();
p != this->input_group_->end();
++p)
{
Task_lock_obj<Archive> tl(this, *p);
(*p)->add_symbols(this->symtab_, this->layout_,
this->input_objects_);
}
}
// Delete all the archives now that we no longer need them.
for (Input_group::const_iterator p = this->input_group_->begin();
p != this->input_group_->end();
++p)
delete *p;
delete this->input_group_;
}
} // End namespace gold.