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* elfcpp_file.h: Fix header guard.  Include <cstdio>.
	(class Elf_recognizer): New class, code from gold/object.cc.
	(Elf_file::find_section_by_type): New method.
gold/:
	* incremental.cc: Include <cstdarg> and "target-select.h".
	(vexplain_no_incremental): New function.
	(explain_no_incremental): New function.
	(Incremental_binary::error): New method.
	(Sized_incremental_binary::do_find_incremental_inputs_section): New
	method.
	(make_sized_incremental_binary): New function.
	(open_incremental_binary): New function.
	(can_incrementally_link_file): Add checks if output is ELF and has
	inputs section.
	* incremental.h: Include "elfcpp_file.h" and "output.h".
	(Incremental_binary): New class.
	(Sized_incremental_binary): New class.
	(open_incremental_binary): Declare.
	* object.cc (is_elf_object): Use
	elfcpp::Elf_recognizer::is_elf_file.
	(make_elf_object): Use elfcpp::Elf_recognizer::is_valid_header.
	* output.h (Output_file::filesize): New method.
This commit is contained in:
Ian Lance Taylor 2009-10-09 16:40:51 +00:00
parent e322137b9b
commit c549a6949c
7 changed files with 513 additions and 63 deletions
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6
elfcpp/ChangeLog
View File

@ -1,3 +1,9 @@
2009-10-09 Mikolaj Zalewski <mikolajz@google.com>
* elfcpp_file.h: Fix header guard. Include <cstdio>.
(class Elf_recognizer): New class, code from gold/object.cc.
(Elf_file::find_section_by_type): New method.
2009-07-23 Ulrich Drepper <drepper@redhat.com>
* elfcpp.h (enum STB): Add STB_GNU_UNIQUE.

165
elfcpp/elfcpp_file.h
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@ -53,15 +53,45 @@
// This permits writing
// elfcpp::Shdr shdr(file, ef.section_header(n));
#ifndef ELFPCP_FILE_H
#ifndef ELFCPP_FILE_H
#define ELFCPP_FILE_H
#include <string>
#include <cstdio>
#include <cstring>
namespace elfcpp
{
// A simple helper class to recognize if a file has an ELF header.
class Elf_recognizer
{
public:
// Maximum header size. The user should try to read this much of
// the file when using this class.
static const int max_header_size = Elf_sizes<64>::ehdr_size;
// Checks if the file contains the ELF magic. Other header fields
// are not checked.
static bool
is_elf_file(const unsigned char* ehdr_buf, int size);
// Check if EHDR_BUF/BUFSIZE is a valid header of a 32-bit or
// 64-bit, little-endian or big-endian ELF file. Assumes
// is_elf_file() has been checked to be true. If the header is not
// valid, *ERROR contains a human-readable error message. If is is,
// *SIZE is set to either 32 or 64, *BIG_ENDIAN is set to indicate
// whether the file is big-endian.
static bool
is_valid_header(const unsigned char* ehdr_buf, off_t bufsize,
int* size, bool* big_endian,
std::string* error);
};
// This object is used to read an ELF file.
// SIZE: The size of file, 32 or 64.
// BIG_ENDIAN: Whether the file is in big-endian format.
@ -99,6 +129,11 @@ class Elf_file
shoff() const
{ return this->shoff_; }
// Find the first section with an sh_type field equal to TYPE and
// return its index. Returns SHN_UNDEF if there is no such section.
unsigned int
find_section_by_type(unsigned int type);
// Return the number of sections.
unsigned int
shnum()
@ -193,6 +228,115 @@ class Elf_file
int large_shndx_offset_;
};
// Inline function definitions.
// Check for presence of the ELF magic number.
inline bool
Elf_recognizer::is_elf_file(const unsigned char* ehdr_buf, int size)
{
if (size < 4)
return false;
static unsigned char elfmagic[4] =
{
elfcpp::ELFMAG0, elfcpp::ELFMAG1,
elfcpp::ELFMAG2, elfcpp::ELFMAG3
};
return memcmp(ehdr_buf, elfmagic, 4) == 0;
}
namespace
{
// Print a number to a string.
inline std::string
internal_printf_int(const char* format, int arg)
{
char buf[256];
snprintf(buf, sizeof(buf), format, arg);
return std::string(buf);
}
} // End anonymous namespace.
// Check the validity of the ELF header.
inline bool
Elf_recognizer::is_valid_header(
const unsigned char* ehdr_buf,
off_t bufsize,
int* size,
bool* big_endian,
std::string* error)
{
if (bufsize < elfcpp::EI_NIDENT)
{
*error = _("ELF file too short");
return false;
}
int v = ehdr_buf[elfcpp::EI_VERSION];
if (v != elfcpp::EV_CURRENT)
{
if (v == elfcpp::EV_NONE)
*error = _("invalid ELF version 0");
else
*error = internal_printf_int(_("unsupported ELF version %d"), v);
return false;
}
int c = ehdr_buf[elfcpp::EI_CLASS];
if (c == elfcpp::ELFCLASSNONE)
{
*error = _("invalid ELF class 0");
return false;
}
else if (c != elfcpp::ELFCLASS32
&& c != elfcpp::ELFCLASS64)
{
*error = internal_printf_int(_("unsupported ELF class %d"), c);
return false;
}
int d = ehdr_buf[elfcpp::EI_DATA];
if (d == elfcpp::ELFDATANONE)
{
*error = _("invalid ELF data encoding");
return false;
}
else if (d != elfcpp::ELFDATA2LSB
&& d != elfcpp::ELFDATA2MSB)
{
*error = internal_printf_int(_("unsupported ELF data encoding %d"), d);
return false;
}
*big_endian = (d == elfcpp::ELFDATA2MSB);
if (c == elfcpp::ELFCLASS32)
{
if (bufsize < elfcpp::Elf_sizes<32>::ehdr_size)
{
*error = _("ELF file too short");
return false;
}
*size = 32;
}
else
{
if (bufsize < elfcpp::Elf_sizes<64>::ehdr_size)
{
*error = _("ELF file too short");
return false;
}
*size = 64;
}
return true;
}
// Template function definitions.
// Construct an Elf_file given an ELF file header.
@ -269,6 +413,25 @@ Elf_file<size, big_endian, File>::initialize_shnum()
}
}
// Find section with sh_type equal to TYPE and return its index.
// Returns SHN_UNDEF if not found.
template<int size, bool big_endian, typename File>
unsigned int
Elf_file<size, big_endian, File>::find_section_by_type(unsigned int type)
{
unsigned int shnum = this->shnum();
typename File::View v(this->file_->view(this->shoff_,
This::shdr_size * shnum));
for (unsigned int i = 0; i < shnum; i++)
{
Ef_shdr shdr(v.data() + This::shdr_size * i);
if (shdr.get_sh_type() == type)
return i;
}
return SHN_UNDEF;
}
// Return the file offset of the section header of section SHNDX.
template<int size, bool big_endian, typename File>

21
gold/ChangeLog
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@ -1,3 +1,24 @@
2009-10-09 Mikolaj Zalewski <mikolajz@google.com>
* incremental.cc: Include <cstdarg> and "target-select.h".
(vexplain_no_incremental): New function.
(explain_no_incremental): New function.
(Incremental_binary::error): New method.
(Sized_incremental_binary::do_find_incremental_inputs_section): New
method.
(make_sized_incremental_binary): New function.
(open_incremental_binary): New function.
(can_incrementally_link_file): Add checks if output is ELF and has
inputs section.
* incremental.h: Include "elfcpp_file.h" and "output.h".
(Incremental_binary): New class.
(Sized_incremental_binary): New class.
(open_incremental_binary): Declare.
* object.cc (is_elf_object): Use
elfcpp::Elf_recognizer::is_elf_file.
(make_elf_object): Use elfcpp::Elf_recognizer::is_valid_header.
* output.h (Output_file::filesize): New method.
2009-10-07 Viktor Kutuzov <vkutuzov@accesssoftek.com>
* arm.cc (Arm_relocate_functions::extract_arm_movw_movt_addend):

192
gold/incremental.cc
View File

@ -21,11 +21,15 @@
// MA 02110-1301, USA.
#include "gold.h"
#include <cstdarg>
#include "elfcpp.h"
#include "output.h"
#include "incremental.h"
#include "archive.h"
#include "output.h"
#include "target-select.h"
using elfcpp::Convert;
@ -150,6 +154,162 @@ class Incremental_inputs_entry_write
internal::Incremental_inputs_entry_data* p_;
};
// Inform the user why we don't do an incremental link. Not called in
// the obvious case of missing output file. TODO: Is this helpful?
void
vexplain_no_incremental(const char* format, va_list args)
{
char* buf = NULL;
if (vasprintf(&buf, format, args) < 0)
gold_nomem();
gold_info(_("the link might take longer: "
"cannot perform incremental link: %s"), buf);
free(buf);
}
void
explain_no_incremental(const char* format, ...)
{
va_list args;
va_start(args, format);
vexplain_no_incremental(format, args);
va_end(args);
}
// Report an error.
void
Incremental_binary::error(const char* format, ...) const
{
va_list args;
va_start(args, format);
// Current code only checks if the file can be used for incremental linking,
// so errors shouldn't fail the build, but only result in a fallback to a
// full build.
// TODO: when we implement incremental editing of the file, we may need a
// flag that will cause errors to be treated seriously.
vexplain_no_incremental(format, args);
va_end(args);
}
template<int size, bool big_endian>
bool
Sized_incremental_binary<size, big_endian>::do_find_incremental_inputs_section(
Location* location)
{
unsigned int shndx = this->elf_file_.find_section_by_type(
elfcpp::SHT_GNU_INCREMENTAL_INPUTS);
if (shndx == elfcpp::SHN_UNDEF) // Not found.
return false;
*location = this->elf_file_.section_contents(shndx);
return true;
}
namespace
{
// Create a Sized_incremental_binary object of the specified size and
// endianness. Fails if the target architecture is not supported.
template<int size, bool big_endian>
Incremental_binary*
make_sized_incremental_binary(Output_file* file,
const elfcpp::Ehdr<size, big_endian>& ehdr)
{
Target* target = select_target(ehdr.get_e_machine(), size, big_endian,
ehdr.get_e_ident()[elfcpp::EI_OSABI],
ehdr.get_e_ident()[elfcpp::EI_ABIVERSION]);
if (target == NULL)
{
explain_no_incremental(_("unsupported ELF machine number %d"),
ehdr.get_e_machine());
return NULL;
}
return new Sized_incremental_binary<size, big_endian>(file, ehdr, target);
}
} // End of anonymous namespace.
// Create an Incremental_binary object for FILE. Returns NULL is this is not
// possible, e.g. FILE is not an ELF file or has an unsupported target. FILE
// should be opened.
Incremental_binary*
open_incremental_binary(Output_file* file)
{
off_t filesize = file->filesize();
int want = elfcpp::Elf_recognizer::max_header_size;
if (filesize < want)
want = filesize;
const unsigned char* p = file->get_input_view(0, want);
if (!elfcpp::Elf_recognizer::is_elf_file(p, want))
{
explain_no_incremental(_("output is not an ELF file."));
return NULL;
}
int size;
bool big_endian;
std::string error;
if (!elfcpp::Elf_recognizer::is_valid_header(p, want, &size, &big_endian,
&error))
{
explain_no_incremental(error.c_str());
return NULL;
}
Incremental_binary* result = NULL;
if (size == 32)
{
if (big_endian)
{
#ifdef HAVE_TARGET_32_BIG
result = make_sized_incremental_binary<32, true>(
file, elfcpp::Ehdr<32, true>(p));
#else
explain_no_incremental(_("unsupported file: 32-bit, big-endian"));
#endif
}
else
{
#ifdef HAVE_TARGET_32_LITTLE
result = make_sized_incremental_binary<32, false>(
file, elfcpp::Ehdr<32, false>(p));
#else
explain_no_incremental(_("unsupported file: 32-bit, little-endian"));
#endif
}
}
else if (size == 64)
{
if (big_endian)
{
#ifdef HAVE_TARGET_64_BIG
result = make_sized_incremental_binary<64, true>(
file, elfcpp::Ehdr<64, true>(p));
#else
explain_no_incremental(_("unsupported file: 64-bit, big-endian"));
#endif
}
else
{
#ifdef HAVE_TARGET_64_LITTLE
result = make_sized_incremental_binary<64, false>(
file, elfcpp::Ehdr<64, false>(p));
#else
explain_no_incremental(_("unsupported file: 64-bit, little-endian"));
#endif
}
}
else
gold_unreachable();
return result;
}
// Analyzes the output file to check if incremental linking is possible and
// (to be done) what files need to be relinked.
@ -159,6 +319,16 @@ Incremental_checker::can_incrementally_link_output_file()
Output_file output(this->output_name_);
if (!output.open_for_modification())
return false;
Incremental_binary* binary = open_incremental_binary(&output);
if (binary == NULL)
return false;
Incremental_binary::Location inputs_location;
if (!binary->find_incremental_inputs_section(&inputs_location))
{
explain_no_incremental("no incremental data from previous build");
delete binary;
return false;
}
return true;
}
@ -392,4 +562,26 @@ Incremental_inputs::sized_create_inputs_section_data()
"** incremental link inputs list");
}
// Instantiate the templates we need.
#ifdef HAVE_TARGET_32_LITTLE
template
class Sized_incremental_binary<32, false>;
#endif
#ifdef HAVE_TARGET_32_BIG
template
class Sized_incremental_binary<32, true>;
#endif
#ifdef HAVE_TARGET_64_LITTLE
template
class Sized_incremental_binary<64, false>;
#endif
#ifdef HAVE_TARGET_64_BIG
template
class Sized_incremental_binary<64, true>;
#endif
} // End namespace gold.

113
gold/incremental.h
View File

@ -26,9 +26,11 @@
#include <map>
#include <vector>
#include "elfcpp_file.h"
#include "stringpool.h"
#include "workqueue.h"
#include "fileread.h"
#include "output.h"
namespace gold
{
@ -50,6 +52,117 @@ enum Incremental_input_type
INCREMENTAL_INPUT_SCRIPT = 4
};
// An object representing the ELF file we edit during an incremental build.
// Similar to Object or Dynobj, but operates on Output_file and contains
// method specific to file edition (TBD). This is the abstract parent class
// implemented in Sized_incremental_binary<size, big_endian> for a specific
// endianness and size.
class Incremental_binary
{
public:
Incremental_binary(Output_file* output, Target* target)
: output_(output), target_(target)
{ }
virtual
~Incremental_binary()
{ }
// Functions and types for the elfcpp::Elf_file interface. This
// permit us to use Incremental_binary as the File template parameter for
// elfcpp::Elf_file.
// The View class is returned by view. It must support a single
// method, data(). This is trivial, because Output_file::get_output_view
// does what we need.
class View
{
public:
View(const unsigned char* p)
: p_(p)
{ }
const unsigned char*
data() const
{ return this->p_; }
private:
const unsigned char* p_;
};
// Return a View.
View
view(off_t file_offset, section_size_type data_size)
{ return View(this->output_->get_input_view(file_offset, data_size)); }
// A location in the file.
struct Location
{
off_t file_offset;
off_t data_size;
Location(off_t fo, section_size_type ds)
: file_offset(fo), data_size(ds)
{ }
Location()
: file_offset(0), data_size(0)
{ }
};
// Get a View given a Location.
View view(Location loc)
{ return View(this->view(loc.file_offset, loc.data_size)); }
// Report an error.
void
error(const char* format, ...) const ATTRIBUTE_PRINTF_2;
// Find the .gnu_incremental_inputs section. It selects the first section
// of type SHT_GNU_INCREMENTAL_INPUTS. Returns false if such a section
// is not found.
bool
find_incremental_inputs_section(Location* location)
{ return do_find_incremental_inputs_section(location); }
protected:
// Find incremental inputs section.
virtual bool
do_find_incremental_inputs_section(Location* location) = 0;
private:
// Edited output file object.
Output_file* output_;
// Target of the output file.
Target* target_;
};
template<int size, bool big_endian>
class Sized_incremental_binary : public Incremental_binary
{
public:
Sized_incremental_binary(Output_file* output,
const elfcpp::Ehdr<size, big_endian>& ehdr,
Target* target)
: Incremental_binary(output, target), elf_file_(this, ehdr)
{ }
protected:
virtual bool
do_find_incremental_inputs_section(Location* location);
private:
// Output as an ELF file.
elfcpp::Elf_file<size, big_endian, Incremental_binary> elf_file_;
};
// Create an Incremental_binary object for FILE. Returns NULL is this is not
// possible, e.g. FILE is not an ELF file or has an unsupported target.
Incremental_binary*
open_incremental_binary(Output_file* file);
// Code invoked early during an incremental link that checks what files need
// to be relinked.
class Incremental_checker

74
gold/object.cc
View File

@ -2281,7 +2281,7 @@ is_elf_object(Input_file* input_file, off_t offset,
const unsigned char** start, int *read_size)
{
off_t filesize = input_file->file().filesize();
int want = elfcpp::Elf_sizes<64>::ehdr_size;
int want = elfcpp::Elf_recognizer::max_header_size;
if (filesize - offset < want)
want = filesize - offset;
@ -2290,15 +2290,7 @@ is_elf_object(Input_file* input_file, off_t offset,
*start = p;
*read_size = want;
if (want < 4)
return false;
static unsigned char elfmagic[4] =
{
elfcpp::ELFMAG0, elfcpp::ELFMAG1,
elfcpp::ELFMAG2, elfcpp::ELFMAG3
};
return memcmp(p, elfmagic, 4) == 0;
return elfcpp::Elf_recognizer::is_elf_file(p, want);
}
// Read an ELF file and return the appropriate instance of Object.
@ -2311,57 +2303,18 @@ make_elf_object(const std::string& name, Input_file* input_file, off_t offset,
if (punconfigured != NULL)
*punconfigured = false;
if (bytes < elfcpp::EI_NIDENT)
std::string error;
bool big_endian;
int size;
if (!elfcpp::Elf_recognizer::is_valid_header(p, bytes, &size,
&big_endian, &error))
{
gold_error(_("%s: ELF file too short"), name.c_str());
gold_error(_("%s: %s"), name.c_str(), error.c_str());
return NULL;
}
int v = p[elfcpp::EI_VERSION];
if (v != elfcpp::EV_CURRENT)
if (size == 32)
{
if (v == elfcpp::EV_NONE)
gold_error(_("%s: invalid ELF version 0"), name.c_str());
else
gold_error(_("%s: unsupported ELF version %d"), name.c_str(), v);
return NULL;
}
int c = p[elfcpp::EI_CLASS];
if (c == elfcpp::ELFCLASSNONE)
{
gold_error(_("%s: invalid ELF class 0"), name.c_str());
return NULL;
}
else if (c != elfcpp::ELFCLASS32
&& c != elfcpp::ELFCLASS64)
{
gold_error(_("%s: unsupported ELF class %d"), name.c_str(), c);
return NULL;
}
int d = p[elfcpp::EI_DATA];
if (d == elfcpp::ELFDATANONE)
{
gold_error(_("%s: invalid ELF data encoding"), name.c_str());
return NULL;
}
else if (d != elfcpp::ELFDATA2LSB
&& d != elfcpp::ELFDATA2MSB)
{
gold_error(_("%s: unsupported ELF data encoding %d"), name.c_str(), d);
return NULL;
}
bool big_endian = d == elfcpp::ELFDATA2MSB;
if (c == elfcpp::ELFCLASS32)
{
if (bytes < elfcpp::Elf_sizes<32>::ehdr_size)
{
gold_error(_("%s: ELF file too short"), name.c_str());
return NULL;
}
if (big_endian)
{
#ifdef HAVE_TARGET_32_BIG
@ -2395,13 +2348,8 @@ make_elf_object(const std::string& name, Input_file* input_file, off_t offset,
#endif
}
}
else
else if (size == 64)
{
if (bytes < elfcpp::Elf_sizes<64>::ehdr_size)
{
gold_error(_("%s: ELF file too short"), name.c_str());
return NULL;
}
if (big_endian)
{
#ifdef HAVE_TARGET_64_BIG
@ -2435,6 +2383,8 @@ make_elf_object(const std::string& name, Input_file* input_file, off_t offset,
#endif
}
}
else
gold_unreachable();
}
// Instantiate the templates we need.

5
gold/output.h
View File

@ -3433,6 +3433,11 @@ class Output_file
void
close();
// Return the size of this file.
off_t
filesize()
{ return this->file_size_; }
// We currently always use mmap which makes the view handling quite
// simple. In the future we may support other approaches.