binutils-gdb/gold/archive.cc

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// archive.cc -- archive support 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 <cerrno>
#include <cstring>
#include <climits>
#include <vector>
#include "elfcpp.h"
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#include "options.h"
#include "fileread.h"
#include "readsyms.h"
#include "symtab.h"
#include "object.h"
#include "archive.h"
namespace gold
{
// The header of an entry in the archive. This is all readable text,
// padded with spaces where necesary. If the contents of an archive
// are all text file, the entire archive is readable.
struct Archive::Archive_header
{
// The entry name.
char ar_name[16];
// The file modification time.
char ar_date[12];
// The user's UID in decimal.
char ar_uid[6];
// The user's GID in decimal.
char ar_gid[6];
// The file mode in octal.
char ar_mode[8];
// The file size in decimal.
char ar_size[10];
// The final magic code.
char ar_fmag[2];
};
// Archive methods.
const char Archive::armag[sarmag] =
{
'!', '<', 'a', 'r', 'c', 'h', '>', '\n'
};
const char Archive::arfmag[2] = { '`', '\n' };
// Set up the archive: read the symbol map and the extended name
// table.
void
Archive::setup()
{
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// We need to ignore empty archives.
if (this->input_file_->file().filesize() == sarmag)
{
this->input_file_->file().unlock();
return;
}
// The first member of the archive should be the symbol table.
std::string armap_name;
off_t armap_size = this->read_header(sarmag, &armap_name);
off_t off = sarmag;
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if (armap_name.empty())
{
this->read_armap(sarmag + sizeof(Archive_header), armap_size);
off = sarmag + sizeof(Archive_header) + armap_size;
}
else if (!this->input_file_->options().include_whole_archive())
gold_error(_("%s: no archive symbol table (run ranlib)"),
this->name().c_str());
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// See if there is an extended name table.
if ((off & 1) != 0)
++off;
std::string xname;
off_t extended_size = this->read_header(off, &xname);
if (xname == "/")
{
const unsigned char* p = this->get_view(off + sizeof(Archive_header),
extended_size, false);
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const char* px = reinterpret_cast<const char*>(p);
this->extended_names_.assign(px, extended_size);
}
// Opening the file locked it. Unlock it now.
this->input_file_->file().unlock();
}
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// Read the archive symbol map.
void
Archive::read_armap(off_t start, off_t size)
{
// Read in the entire armap.
const unsigned char* p = this->get_view(start, size, false);
// Numbers in the armap are always big-endian.
const elfcpp::Elf_Word* pword = reinterpret_cast<const elfcpp::Elf_Word*>(p);
unsigned int nsyms = elfcpp::Swap<32, true>::readval(pword);
++pword;
// Note that the addition is in units of sizeof(elfcpp::Elf_Word).
const char* pnames = reinterpret_cast<const char*>(pword + nsyms);
off_t names_size = reinterpret_cast<const char*>(p) + size - pnames;
this->armap_names_.assign(pnames, names_size);
this->armap_.resize(nsyms);
off_t name_offset = 0;
for (unsigned int i = 0; i < nsyms; ++i)
{
this->armap_[i].name_offset = name_offset;
this->armap_[i].file_offset = elfcpp::Swap<32, true>::readval(pword);
name_offset += strlen(pnames + name_offset) + 1;
++pword;
}
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if (reinterpret_cast<const unsigned char*>(pnames) - p > size)
gold_error(_("%s: bad archive symbol table names"),
this->name().c_str());
// This array keeps track of which symbols are for archive elements
// which we have already included in the link.
this->armap_checked_.resize(nsyms);
}
// Read the header of an archive member at OFF. Fail if something
// goes wrong. Return the size of the member. Set *PNAME to the name
// of the member.
off_t
Archive::read_header(off_t off, std::string* pname)
{
const unsigned char* p = this->get_view(off, sizeof(Archive_header), false);
const Archive_header* hdr = reinterpret_cast<const Archive_header*>(p);
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return this->interpret_header(hdr, off, pname);
}
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// Interpret the header of HDR, the header of the archive member at
// file offset OFF. Fail if something goes wrong. Return the size of
// the member. Set *PNAME to the name of the member.
off_t
Archive::interpret_header(const Archive_header* hdr, off_t off,
std::string* pname)
{
if (memcmp(hdr->ar_fmag, arfmag, sizeof arfmag) != 0)
{
gold_error(_("%s: malformed archive header at %zu"),
this->name().c_str(), static_cast<size_t>(off));
return this->input_file_->file().filesize() - off;
}
const int size_string_size = sizeof hdr->ar_size;
char size_string[size_string_size + 1];
memcpy(size_string, hdr->ar_size, size_string_size);
char* ps = size_string + size_string_size;
while (ps[-1] == ' ')
--ps;
*ps = '\0';
errno = 0;
char* end;
off_t member_size = strtol(size_string, &end, 10);
if (*end != '\0'
|| member_size < 0
|| (member_size == LONG_MAX && errno == ERANGE))
{
gold_error(_("%s: malformed archive header size at %zu"),
this->name().c_str(), static_cast<size_t>(off));
return this->input_file_->file().filesize() - off;
}
if (hdr->ar_name[0] != '/')
{
const char* name_end = strchr(hdr->ar_name, '/');
if (name_end == NULL
|| name_end - hdr->ar_name >= static_cast<int>(sizeof hdr->ar_name))
{
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gold_error(_("%s: malformed archive header name at %zu"),
this->name().c_str(), static_cast<size_t>(off));
return this->input_file_->file().filesize() - off;
}
pname->assign(hdr->ar_name, name_end - hdr->ar_name);
}
else if (hdr->ar_name[1] == ' ')
{
// This is the symbol table.
pname->clear();
}
else if (hdr->ar_name[1] == '/')
{
// This is the extended name table.
pname->assign(1, '/');
}
else
{
errno = 0;
long x = strtol(hdr->ar_name + 1, &end, 10);
if (*end != ' '
|| x < 0
|| (x == LONG_MAX && errno == ERANGE)
|| static_cast<size_t>(x) >= this->extended_names_.size())
{
gold_error(_("%s: bad extended name index at %zu"),
this->name().c_str(), static_cast<size_t>(off));
return this->input_file_->file().filesize() - off;
}
const char* name = this->extended_names_.data() + x;
const char* name_end = strchr(name, '/');
if (static_cast<size_t>(name_end - name) > this->extended_names_.size()
|| name_end[1] != '\n')
{
gold_error(_("%s: bad extended name entry at header %zu"),
this->name().c_str(), static_cast<size_t>(off));
return this->input_file_->file().filesize() - off;
}
pname->assign(name, name_end - name);
}
return member_size;
}
// Select members from the archive and add them to the link. We walk
// through the elements in the archive map, and look each one up in
// the symbol table. If it exists as a strong undefined symbol, we
// pull in the corresponding element. We have to do this in a loop,
// since pulling in one element may create new undefined symbols which
// may be satisfied by other objects in the archive.
void
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Archive::add_symbols(Symbol_table* symtab, Layout* layout,
Input_objects* input_objects)
{
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if (this->input_file_->options().include_whole_archive())
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return this->include_all_members(symtab, layout, input_objects);
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const size_t armap_size = this->armap_.size();
// This is a quick optimization, since we usually see many symbols
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// in a row with the same offset. last_seen_offset holds the last
// offset we saw that was present in the seen_offsets_ set.
off_t last_seen_offset = -1;
// Track which symbols in the symbol table we've already found to be
// defined.
bool added_new_object;
do
{
added_new_object = false;
for (size_t i = 0; i < armap_size; ++i)
{
if (this->armap_checked_[i])
continue;
if (this->armap_[i].file_offset == last_seen_offset)
{
this->armap_checked_[i] = true;
continue;
}
if (this->seen_offsets_.find(this->armap_[i].file_offset)
!= this->seen_offsets_.end())
{
this->armap_checked_[i] = true;
last_seen_offset = this->armap_[i].file_offset;
continue;
}
const char* sym_name = (this->armap_names_.data()
+ this->armap_[i].name_offset);
Symbol* sym = symtab->lookup(sym_name);
if (sym == NULL)
continue;
else if (!sym->is_undefined())
{
this->armap_checked_[i] = true;
continue;
}
else if (sym->binding() == elfcpp::STB_WEAK)
continue;
// We want to include this object in the link.
last_seen_offset = this->armap_[i].file_offset;
this->seen_offsets_.insert(last_seen_offset);
this->armap_checked_[i] = true;
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this->include_member(symtab, layout, input_objects,
last_seen_offset);
added_new_object = true;
}
}
while (added_new_object);
}
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// Include all the archive members in the link. This is for --whole-archive.
void
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Archive::include_all_members(Symbol_table* symtab, Layout* layout,
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Input_objects* input_objects)
{
off_t off = sarmag;
off_t filesize = this->input_file_->file().filesize();
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while (true)
{
if (filesize - off < static_cast<off_t>(sizeof(Archive_header)))
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{
if (filesize != off)
gold_error(_("%s: short archive header at %zu"),
this->name().c_str(), static_cast<size_t>(off));
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break;
}
unsigned char hdr_buf[sizeof(Archive_header)];
this->input_file_->file().read(off, sizeof(Archive_header), hdr_buf);
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const Archive_header* hdr =
reinterpret_cast<const Archive_header*>(hdr_buf);
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std::string name;
off_t size = this->interpret_header(hdr, off, &name);
if (name.empty())
{
// Symbol table.
}
else if (name == "/")
{
// Extended name table.
}
else
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this->include_member(symtab, layout, input_objects, off);
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off += sizeof(Archive_header) + size;
if ((off & 1) != 0)
++off;
}
}
// Include an archive member in the link. OFF is the file offset of
// the member header.
void
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Archive::include_member(Symbol_table* symtab, Layout* layout,
Input_objects* input_objects, off_t off)
{
std::string n;
this->read_header(off, &n);
const off_t memoff = off + static_cast<off_t>(sizeof(Archive_header));
// Read enough of the file to pick up the entire ELF header.
unsigned char ehdr_buf[elfcpp::Elf_sizes<64>::ehdr_size];
off_t filesize = this->input_file_->file().filesize();
int read_size = elfcpp::Elf_sizes<64>::ehdr_size;
if (filesize - memoff < read_size)
read_size = filesize - memoff;
if (read_size < 4)
{
gold_error(_("%s: member at %zu is not an ELF object"),
this->name().c_str(), static_cast<size_t>(off));
return;
}
this->input_file_->file().read(memoff, read_size, ehdr_buf);
static unsigned char elfmagic[4] =
{
elfcpp::ELFMAG0, elfcpp::ELFMAG1,
elfcpp::ELFMAG2, elfcpp::ELFMAG3
};
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if (memcmp(ehdr_buf, elfmagic, 4) != 0)
{
gold_error(_("%s: member at %zu is not an ELF object"),
this->name().c_str(), static_cast<size_t>(off));
return;
}
Object* obj = make_elf_object((std::string(this->input_file_->filename())
+ "(" + n + ")"),
this->input_file_, memoff, ehdr_buf,
read_size);
if (input_objects->add_object(obj))
{
Read_symbols_data sd;
obj->read_symbols(&sd);
obj->layout(symtab, layout, &sd);
obj->add_symbols(symtab, &sd);
}
else
{
// FIXME: We need to close the descriptor here.
delete obj;
}
}
// Add_archive_symbols methods.
Add_archive_symbols::~Add_archive_symbols()
{
if (this->this_blocker_ != NULL)
delete this->this_blocker_;
// next_blocker_ is deleted by the task associated with the next
// input file.
}
// Return whether we can add the archive symbols. We are blocked by
// this_blocker_. We block next_blocker_. We also lock the file.
Task::Is_runnable_type
Add_archive_symbols::is_runnable(Workqueue*)
{
if (this->this_blocker_ != NULL && this->this_blocker_->is_blocked())
return IS_BLOCKED;
return IS_RUNNABLE;
}
class Add_archive_symbols::Add_archive_symbols_locker : public Task_locker
{
public:
Add_archive_symbols_locker(Task_token& token, Workqueue* workqueue,
File_read& file)
: blocker_(token, workqueue), filelock_(file)
{ }
private:
Task_locker_block blocker_;
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Task_locker_obj<File_read> filelock_;
};
Task_locker*
Add_archive_symbols::locks(Workqueue* workqueue)
{
return new Add_archive_symbols_locker(*this->next_blocker_,
workqueue,
this->archive_->file());
}
void
Add_archive_symbols::run(Workqueue*)
{
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this->archive_->add_symbols(this->symtab_, this->layout_,
this->input_objects_);
if (this->input_group_ != NULL)
this->input_group_->add_archive(this->archive_);
else
{
// We no longer need to know about this archive.
delete this->archive_;
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this->archive_ = NULL;
}
}
} // End namespace gold.