bfd/elfcore.h - binutils-gdb - Git at Google

 /* ELF core file support for BFD.
    Copyright (C) 1995-2022 Free Software Foundation, Inc.

    This file is part of BFD, the Binary File Descriptor library.

    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.  */

 char*
 elf_core_file_failing_command (bfd *abfd)
 {
   return elf_tdata (abfd)->core->command;
 }

 int
 elf_core_file_failing_signal (bfd *abfd)
 {
   return elf_tdata (abfd)->core->signal;
 }

 int
 elf_core_file_pid (bfd *abfd)
 {
   return elf_tdata (abfd)->core->pid;
 }

 bool
 elf_core_file_matches_executable_p (bfd *core_bfd, bfd *exec_bfd)
 {
   char* corename;

   /* xvecs must match if both are ELF files for the same target.  */

   if (core_bfd->xvec != exec_bfd->xvec)
     {
       bfd_set_error (bfd_error_system_call);
       return false;
     }

   /* If both BFDs have identical build-ids, then they match.  */
   if (core_bfd->build_id != NULL
       && exec_bfd->build_id != NULL
       && core_bfd->build_id->size == exec_bfd->build_id->size
       && memcmp (core_bfd->build_id->data, exec_bfd->build_id->data,
 		 core_bfd->build_id->size) == 0)
     return true;

   /* See if the name in the corefile matches the executable name.  */
   corename = elf_tdata (core_bfd)->core->program;
   if (corename != NULL)
     {
       const char* execname = strrchr (bfd_get_filename (exec_bfd), '/');

       execname = execname ? execname + 1 : bfd_get_filename (exec_bfd);

       if (strcmp (execname, corename) != 0)
 	return false;
     }

   return true;
 }

 /*  Core files are simply standard ELF formatted files that partition
     the file using the execution view of the file (program header table)
     rather than the linking view.  In fact, there is no section header
     table in a core file.

     The process status information (including the contents of the general
     register set) and the floating point register set are stored in a
     segment of type PT_NOTE.  We handcraft a couple of extra bfd sections
     that allow standard bfd access to the general registers (.reg) and the
     floating point registers (.reg2).  */

 bfd_cleanup
 elf_core_file_p (bfd *abfd)
 {
   Elf_External_Ehdr x_ehdr;	/* Elf file header, external form.  */
   Elf_Internal_Ehdr *i_ehdrp;	/* Elf file header, internal form.  */
   Elf_Internal_Phdr *i_phdrp;	/* Elf program header, internal form.  */
   unsigned int phindex;
   const struct elf_backend_data *ebd;
   bfd_size_type amt;
   ufile_ptr filesize;

   /* Read in the ELF header in external format.  */
   if (bfd_bread (&x_ehdr, sizeof (x_ehdr), abfd) != sizeof (x_ehdr))
     {
       if (bfd_get_error () != bfd_error_system_call)
 	goto wrong;
       else
 	goto fail;
     }

   /* Check the magic number.  */
   if (! elf_file_p (&x_ehdr))
     goto wrong;

   /* FIXME: Check EI_VERSION here !  */

   /* Check the address size ("class").  */
   if (x_ehdr.e_ident[EI_CLASS] != ELFCLASS)
     goto wrong;

   /* Check the byteorder.  */
   switch (x_ehdr.e_ident[EI_DATA])
     {
     case ELFDATA2MSB:		/* Big-endian.  */
       if (! bfd_big_endian (abfd))
 	goto wrong;
       break;
     case ELFDATA2LSB:		/* Little-endian.  */
       if (! bfd_little_endian (abfd))
 	goto wrong;
       break;
     default:
       goto wrong;
     }

   /* Give abfd an elf_obj_tdata.  */
   if (! (*abfd->xvec->_bfd_set_format[bfd_core]) (abfd))
     goto fail;

   /* Swap in the rest of the header, now that we have the byte order.  */
   i_ehdrp = elf_elfheader (abfd);
   elf_swap_ehdr_in (abfd, &x_ehdr, i_ehdrp);

 #if DEBUG & 1
   elf_debug_file (i_ehdrp);
 #endif

   ebd = get_elf_backend_data (abfd);

   /* Check that the ELF e_machine field matches what this particular
      BFD format expects.  */

   if (ebd->elf_machine_code != i_ehdrp->e_machine
       && (ebd->elf_machine_alt1 == 0
 	  || i_ehdrp->e_machine != ebd->elf_machine_alt1)
       && (ebd->elf_machine_alt2 == 0
 	  || i_ehdrp->e_machine != ebd->elf_machine_alt2))
     {
       const bfd_target * const *target_ptr;

       if (ebd->elf_machine_code != EM_NONE)
 	goto wrong;

       /* This is the generic ELF target.  Let it match any ELF target
 	 for which we do not have a specific backend.  */

       for (target_ptr = bfd_target_vector; *target_ptr != NULL; target_ptr++)
 	{
 	  const struct elf_backend_data *back;

 	  if ((*target_ptr)->flavour != bfd_target_elf_flavour)
 	    continue;
 	  back = xvec_get_elf_backend_data (*target_ptr);
 	  if (back->s->arch_size != ARCH_SIZE)
 	    continue;
 	  if (back->elf_machine_code == i_ehdrp->e_machine
 	      || (back->elf_machine_alt1 != 0
 		  && i_ehdrp->e_machine == back->elf_machine_alt1)
 	      || (back->elf_machine_alt2 != 0
 		  && i_ehdrp->e_machine == back->elf_machine_alt2))
 	    {
 	      /* target_ptr is an ELF backend which matches this
 		 object file, so reject the generic ELF target.  */
 	      goto wrong;
 	    }
 	}
     }

   /* If there is no program header, or the type is not a core file, then
      we are hosed.  */
   if (i_ehdrp->e_phoff == 0 || i_ehdrp->e_type != ET_CORE)
     goto wrong;

   /* Does BFD's idea of the phdr size match the size
      recorded in the file? */
   if (i_ehdrp->e_phentsize != sizeof (Elf_External_Phdr))
     goto wrong;

   /* If the program header count is PN_XNUM(0xffff), the actual
      count is in the first section header.  */
   if (i_ehdrp->e_shoff != 0 && i_ehdrp->e_phnum == PN_XNUM)
     {
       Elf_External_Shdr x_shdr;
       Elf_Internal_Shdr i_shdr;
       file_ptr where = (file_ptr) i_ehdrp->e_shoff;

       /* Seek to the section header table in the file.  */
       if (bfd_seek (abfd, where, SEEK_SET) != 0)
 	goto fail;

       /* Read the first section header at index 0, and convert to internal
 	 form.  */
       if (bfd_bread (&x_shdr, sizeof (x_shdr), abfd) != sizeof (x_shdr))
 	goto fail;
       elf_swap_shdr_in (abfd, &x_shdr, &i_shdr);

       if (i_shdr.sh_info != 0)
 	{
 	  i_ehdrp->e_phnum = i_shdr.sh_info;
 	  if (i_ehdrp->e_phnum != i_shdr.sh_info)
 	    goto wrong;
 	}
     }

   /* Sanity check that we can read all of the program headers.
      It ought to be good enough to just read the last one.  */
   if (i_ehdrp->e_phnum > 1)
     {
       Elf_External_Phdr x_phdr;
       Elf_Internal_Phdr i_phdr;
       file_ptr where;

       /* Check that we don't have a totally silly number of
 	 program headers.  */
       if (i_ehdrp->e_phnum > (unsigned int) -1 / sizeof (x_phdr)
 	  || i_ehdrp->e_phnum > (unsigned int) -1 / sizeof (i_phdr))
 	goto wrong;

       where = (file_ptr)(i_ehdrp->e_phoff + (i_ehdrp->e_phnum - 1) * sizeof (x_phdr));
       if ((bfd_size_type) where <= i_ehdrp->e_phoff)
 	goto wrong;

       if (bfd_seek (abfd, where, SEEK_SET) != 0)
 	goto fail;
       if (bfd_bread (&x_phdr, sizeof (x_phdr), abfd) != sizeof (x_phdr))
 	goto fail;
     }

   /* Move to the start of the program headers.  */
   if (bfd_seek (abfd, (file_ptr) i_ehdrp->e_phoff, SEEK_SET) != 0)
     goto wrong;

   /* Allocate space for the program headers.  */
   amt = sizeof (*i_phdrp) * i_ehdrp->e_phnum;
   i_phdrp = (Elf_Internal_Phdr *) bfd_alloc (abfd, amt);
   if (!i_phdrp)
     goto fail;

   elf_tdata (abfd)->phdr = i_phdrp;

   /* Read and convert to internal form.  */
   for (phindex = 0; phindex < i_ehdrp->e_phnum; ++phindex)
     {
       Elf_External_Phdr x_phdr;

       if (bfd_bread (&x_phdr, sizeof (x_phdr), abfd) != sizeof (x_phdr))
 	goto fail;

       elf_swap_phdr_in (abfd, &x_phdr, i_phdrp + phindex);
     }

   /* Set the machine architecture.  Do this before processing the
      program headers since we need to know the architecture type
      when processing the notes of some systems' core files.  */
   if (! bfd_default_set_arch_mach (abfd, ebd->arch, 0)
       /* It's OK if this fails for the generic target.  */
       && ebd->elf_machine_code != EM_NONE)
     goto fail;

   /* Let the backend double check the format and override global
      information.  We do this before processing the program headers
      to allow the correct machine (as opposed to just the default
      machine) to be set, making it possible for grok_prstatus and
      grok_psinfo to rely on the mach setting.  */
   if (ebd->elf_backend_object_p != NULL
       && ! ebd->elf_backend_object_p (abfd))
     goto wrong;

   /* Process each program header.  */
   for (phindex = 0; phindex < i_ehdrp->e_phnum; ++phindex)
     if (! bfd_section_from_phdr (abfd, i_phdrp + phindex, (int) phindex))
       goto fail;

   /* Check for core truncation.  */
   filesize = bfd_get_file_size (abfd);
   if (filesize != 0)
     {
       for (phindex = 0; phindex < i_ehdrp->e_phnum; ++phindex)
 	{
 	  Elf_Internal_Phdr *p = i_phdrp + phindex;
 	  if (p->p_filesz
 	      && (p->p_offset >= filesize
 		  || p->p_filesz > filesize - p->p_offset))
 	    {
 	      _bfd_error_handler (_("warning: %pB has a segment "
 				    "extending past end of file"), abfd);
 	      abfd->read_only = 1;
 	      break;
 	    }
       }
   }

   /* Save the entry point from the ELF header.  */
   abfd->start_address = i_ehdrp->e_entry;
   return _bfd_no_cleanup;

  wrong:
   bfd_set_error (bfd_error_wrong_format);
  fail:
   return NULL;
 }

 /* Attempt to find a build-id in a core file from the core file BFD.
    OFFSET is the file offset to a PT_LOAD segment that may contain
    the build-id note.  Returns TRUE upon success, FALSE otherwise.  */

 bool
 NAME(_bfd_elf, core_find_build_id)
   (bfd *abfd,
    bfd_vma offset)
 {
   Elf_External_Ehdr x_ehdr;	/* Elf file header, external form.   */
   Elf_Internal_Ehdr i_ehdr;	/* Elf file header, internal form.   */
   Elf_Internal_Phdr *i_phdr;
   unsigned int i;
   size_t amt;

   /* Seek to the position of the segment at OFFSET.  */
   if (bfd_seek (abfd, offset, SEEK_SET) != 0)
     goto fail;

   /* Read in the ELF header in external format.  */
   if (bfd_bread (&x_ehdr, sizeof (x_ehdr), abfd) != sizeof (x_ehdr))
     {
       if (bfd_get_error () != bfd_error_system_call)
 	goto wrong;
       else
 	goto fail;
     }

   /* Now check to see if we have a valid ELF file, and one that BFD can
      make use of.  The magic number must match, the address size ('class')
      and byte-swapping must match our XVEC entry, and it must have a
      section header table (FIXME: See comments re sections at top of this
      file).  */
   if (! elf_file_p (&x_ehdr)
       || x_ehdr.e_ident[EI_VERSION] != EV_CURRENT
       || x_ehdr.e_ident[EI_CLASS] != ELFCLASS)
     goto wrong;

   /* Check that file's byte order matches xvec's.  */
   switch (x_ehdr.e_ident[EI_DATA])
     {
     case ELFDATA2MSB:		/* Big-endian.  */
       if (! bfd_header_big_endian (abfd))
 	goto wrong;
       break;
     case ELFDATA2LSB:		/* Little-endian.  */
       if (! bfd_header_little_endian (abfd))
 	goto wrong;
       break;
     case ELFDATANONE:		/* No data encoding specified.  */
     default:			/* Unknown data encoding specified . */
       goto wrong;
     }

   elf_swap_ehdr_in (abfd, &x_ehdr, &i_ehdr);
 #if DEBUG
   elf_debug_file (&i_ehdr);
 #endif

   if (i_ehdr.e_phentsize != sizeof (Elf_External_Phdr) || i_ehdr.e_phnum == 0)
     goto fail;

   /* Read in program headers.  */
   if (_bfd_mul_overflow (i_ehdr.e_phnum, sizeof (*i_phdr), &amt))
     {
       bfd_set_error (bfd_error_file_too_big);
       goto fail;
     }
   i_phdr = (Elf_Internal_Phdr *) bfd_alloc (abfd, amt);
   if (i_phdr == NULL)
     goto fail;

   if (bfd_seek (abfd, (file_ptr) (offset + i_ehdr.e_phoff), SEEK_SET) != 0)
     goto fail;

   /* Read in program headers and parse notes.  */
   for (i = 0; i < i_ehdr.e_phnum; ++i, ++i_phdr)
     {
       Elf_External_Phdr x_phdr;

       if (bfd_bread (&x_phdr, sizeof (x_phdr), abfd) != sizeof (x_phdr))
 	goto fail;
       elf_swap_phdr_in (abfd, &x_phdr, i_phdr);

       if (i_phdr->p_type == PT_NOTE && i_phdr->p_filesz > 0)
 	{
 	  elf_read_notes (abfd, offset + i_phdr->p_offset,
 			  i_phdr->p_filesz, i_phdr->p_align);

 	  /* Make sure ABFD returns to processing the program headers.  */
 	  if (bfd_seek (abfd, (file_ptr) (offset + i_ehdr.e_phoff
 					  + (i + 1) * sizeof (x_phdr)),
 			SEEK_SET) != 0)
 	    goto fail;

 	  if (abfd->build_id != NULL)
 	    return true;
 	}
     }

   /* Having gotten this far, we have a valid ELF section, but no
      build-id was found.  */
   goto fail;

  wrong:
   bfd_set_error (bfd_error_wrong_format);
  fail:
   return false;
 }
	/* ELF core file support for BFD.
	Copyright (C) 1995-2022 Free Software Foundation, Inc.

	This file is part of BFD, the Binary File Descriptor library.

	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. */

	char*
	elf_core_file_failing_command (bfd *abfd)
	{
	return elf_tdata (abfd)->core->command;
	}

	int
	elf_core_file_failing_signal (bfd *abfd)
	{
	return elf_tdata (abfd)->core->signal;
	}

	int
	elf_core_file_pid (bfd *abfd)
	{
	return elf_tdata (abfd)->core->pid;
	}

	bool
	elf_core_file_matches_executable_p (bfd core_bfd, bfd exec_bfd)
	{
	char* corename;

	/* xvecs must match if both are ELF files for the same target. */

	if (core_bfd->xvec != exec_bfd->xvec)
	{
	bfd_set_error (bfd_error_system_call);
	return false;
	}

	/* If both BFDs have identical build-ids, then they match. */
	if (core_bfd->build_id != NULL
	&& exec_bfd->build_id != NULL
	&& core_bfd->build_id->size == exec_bfd->build_id->size
	&& memcmp (core_bfd->build_id->data, exec_bfd->build_id->data,
	core_bfd->build_id->size) == 0)
	return true;

	/* See if the name in the corefile matches the executable name. */
	corename = elf_tdata (core_bfd)->core->program;
	if (corename != NULL)
	{
	const char* execname = strrchr (bfd_get_filename (exec_bfd), '/');

	execname = execname ? execname + 1 : bfd_get_filename (exec_bfd);

	if (strcmp (execname, corename) != 0)
	return false;
	}

	return true;
	}

	/* Core files are simply standard ELF formatted files that partition
	the file using the execution view of the file (program header table)
	rather than the linking view. In fact, there is no section header
	table in a core file.

	The process status information (including the contents of the general
	register set) and the floating point register set are stored in a
	segment of type PT_NOTE. We handcraft a couple of extra bfd sections
	that allow standard bfd access to the general registers (.reg) and the
	floating point registers (.reg2). */

	bfd_cleanup
	elf_core_file_p (bfd *abfd)
	{
	Elf_External_Ehdr x_ehdr; /* Elf file header, external form. */
	Elf_Internal_Ehdr i_ehdrp; / Elf file header, internal form. */
	Elf_Internal_Phdr i_phdrp; / Elf program header, internal form. */
	unsigned int phindex;
	const struct elf_backend_data *ebd;
	bfd_size_type amt;
	ufile_ptr filesize;

	/* Read in the ELF header in external format. */
	if (bfd_bread (&x_ehdr, sizeof (x_ehdr), abfd) != sizeof (x_ehdr))
	{
	if (bfd_get_error () != bfd_error_system_call)
	goto wrong;
	else
	goto fail;
	}

	/* Check the magic number. */
	if (! elf_file_p (&x_ehdr))
	goto wrong;

	/* FIXME: Check EI_VERSION here ! */

	/* Check the address size ("class"). */
	if (x_ehdr.e_ident[EI_CLASS] != ELFCLASS)
	goto wrong;

	/* Check the byteorder. */
	switch (x_ehdr.e_ident[EI_DATA])
	{
	case ELFDATA2MSB: /* Big-endian. */
	if (! bfd_big_endian (abfd))
	goto wrong;
	break;
	case ELFDATA2LSB: /* Little-endian. */
	if (! bfd_little_endian (abfd))
	goto wrong;
	break;
	default:
	goto wrong;
	}

	/* Give abfd an elf_obj_tdata. */
	if (! (*abfd->xvec->_bfd_set_format[bfd_core]) (abfd))
	goto fail;

	/* Swap in the rest of the header, now that we have the byte order. */
	i_ehdrp = elf_elfheader (abfd);
	elf_swap_ehdr_in (abfd, &x_ehdr, i_ehdrp);

	#if DEBUG & 1
	elf_debug_file (i_ehdrp);
	#endif

	ebd = get_elf_backend_data (abfd);

	/* Check that the ELF e_machine field matches what this particular
	BFD format expects. */

	if (ebd->elf_machine_code != i_ehdrp->e_machine
	&& (ebd->elf_machine_alt1 == 0
	\|\| i_ehdrp->e_machine != ebd->elf_machine_alt1)
	&& (ebd->elf_machine_alt2 == 0
	\|\| i_ehdrp->e_machine != ebd->elf_machine_alt2))
	{
	const bfd_target * const *target_ptr;

	if (ebd->elf_machine_code != EM_NONE)
	goto wrong;

	/* This is the generic ELF target. Let it match any ELF target
	for which we do not have a specific backend. */

	for (target_ptr = bfd_target_vector; *target_ptr != NULL; target_ptr++)
	{
	const struct elf_backend_data *back;

	if ((*target_ptr)->flavour != bfd_target_elf_flavour)
	continue;
	back = xvec_get_elf_backend_data (*target_ptr);
	if (back->s->arch_size != ARCH_SIZE)
	continue;
	if (back->elf_machine_code == i_ehdrp->e_machine
	\|\| (back->elf_machine_alt1 != 0
	&& i_ehdrp->e_machine == back->elf_machine_alt1)
	\|\| (back->elf_machine_alt2 != 0
	&& i_ehdrp->e_machine == back->elf_machine_alt2))
	{
	/* target_ptr is an ELF backend which matches this
	object file, so reject the generic ELF target. */
	goto wrong;
	}
	}
	}

	/* If there is no program header, or the type is not a core file, then
	we are hosed. */
	if (i_ehdrp->e_phoff == 0 \|\| i_ehdrp->e_type != ET_CORE)
	goto wrong;

	/* Does BFD's idea of the phdr size match the size
	recorded in the file? */
	if (i_ehdrp->e_phentsize != sizeof (Elf_External_Phdr))
	goto wrong;

	/* If the program header count is PN_XNUM(0xffff), the actual
	count is in the first section header. */
	if (i_ehdrp->e_shoff != 0 && i_ehdrp->e_phnum == PN_XNUM)
	{
	Elf_External_Shdr x_shdr;
	Elf_Internal_Shdr i_shdr;
	file_ptr where = (file_ptr) i_ehdrp->e_shoff;

	/* Seek to the section header table in the file. */
	if (bfd_seek (abfd, where, SEEK_SET) != 0)
	goto fail;

	/* Read the first section header at index 0, and convert to internal
	form. */
	if (bfd_bread (&x_shdr, sizeof (x_shdr), abfd) != sizeof (x_shdr))
	goto fail;
	elf_swap_shdr_in (abfd, &x_shdr, &i_shdr);

	if (i_shdr.sh_info != 0)
	{
	i_ehdrp->e_phnum = i_shdr.sh_info;
	if (i_ehdrp->e_phnum != i_shdr.sh_info)
	goto wrong;
	}
	}

	/* Sanity check that we can read all of the program headers.
	It ought to be good enough to just read the last one. */
	if (i_ehdrp->e_phnum > 1)
	{
	Elf_External_Phdr x_phdr;
	Elf_Internal_Phdr i_phdr;
	file_ptr where;

	/* Check that we don't have a totally silly number of
	program headers. */
	if (i_ehdrp->e_phnum > (unsigned int) -1 / sizeof (x_phdr)
	\|\| i_ehdrp->e_phnum > (unsigned int) -1 / sizeof (i_phdr))
	goto wrong;

	where = (file_ptr)(i_ehdrp->e_phoff + (i_ehdrp->e_phnum - 1) * sizeof (x_phdr));
	if ((bfd_size_type) where <= i_ehdrp->e_phoff)
	goto wrong;

	if (bfd_seek (abfd, where, SEEK_SET) != 0)
	goto fail;
	if (bfd_bread (&x_phdr, sizeof (x_phdr), abfd) != sizeof (x_phdr))
	goto fail;
	}

	/* Move to the start of the program headers. */
	if (bfd_seek (abfd, (file_ptr) i_ehdrp->e_phoff, SEEK_SET) != 0)
	goto wrong;

	/* Allocate space for the program headers. */
	amt = sizeof (i_phdrp) i_ehdrp->e_phnum;
	i_phdrp = (Elf_Internal_Phdr *) bfd_alloc (abfd, amt);
	if (!i_phdrp)
	goto fail;

	elf_tdata (abfd)->phdr = i_phdrp;

	/* Read and convert to internal form. */
	for (phindex = 0; phindex < i_ehdrp->e_phnum; ++phindex)
	{
	Elf_External_Phdr x_phdr;

	if (bfd_bread (&x_phdr, sizeof (x_phdr), abfd) != sizeof (x_phdr))
	goto fail;

	elf_swap_phdr_in (abfd, &x_phdr, i_phdrp + phindex);
	}

	/* Set the machine architecture. Do this before processing the
	program headers since we need to know the architecture type
	when processing the notes of some systems' core files. */
	if (! bfd_default_set_arch_mach (abfd, ebd->arch, 0)
	/* It's OK if this fails for the generic target. */
	&& ebd->elf_machine_code != EM_NONE)
	goto fail;

	/* Let the backend double check the format and override global
	information. We do this before processing the program headers
	to allow the correct machine (as opposed to just the default
	machine) to be set, making it possible for grok_prstatus and
	grok_psinfo to rely on the mach setting. */
	if (ebd->elf_backend_object_p != NULL
	&& ! ebd->elf_backend_object_p (abfd))
	goto wrong;

	/* Process each program header. */
	for (phindex = 0; phindex < i_ehdrp->e_phnum; ++phindex)
	if (! bfd_section_from_phdr (abfd, i_phdrp + phindex, (int) phindex))
	goto fail;

	/* Check for core truncation. */
	filesize = bfd_get_file_size (abfd);
	if (filesize != 0)
	{
	for (phindex = 0; phindex < i_ehdrp->e_phnum; ++phindex)
	{
	Elf_Internal_Phdr *p = i_phdrp + phindex;
	if (p->p_filesz
	&& (p->p_offset >= filesize
	\|\| p->p_filesz > filesize - p->p_offset))
	{
	_bfd_error_handler (_("warning: %pB has a segment "
	"extending past end of file"), abfd);
	abfd->read_only = 1;
	break;
	}
	}
	}

	/* Save the entry point from the ELF header. */
	abfd->start_address = i_ehdrp->e_entry;
	return _bfd_no_cleanup;

	wrong:
	bfd_set_error (bfd_error_wrong_format);
	fail:
	return NULL;
	}

	/* Attempt to find a build-id in a core file from the core file BFD.
	OFFSET is the file offset to a PT_LOAD segment that may contain
	the build-id note. Returns TRUE upon success, FALSE otherwise. */

	bool
	NAME(_bfd_elf, core_find_build_id)
	(bfd *abfd,
	bfd_vma offset)
	{
	Elf_External_Ehdr x_ehdr; /* Elf file header, external form. */
	Elf_Internal_Ehdr i_ehdr; /* Elf file header, internal form. */
	Elf_Internal_Phdr *i_phdr;
	unsigned int i;
	size_t amt;

	/* Seek to the position of the segment at OFFSET. */
	if (bfd_seek (abfd, offset, SEEK_SET) != 0)
	goto fail;

	/* Read in the ELF header in external format. */
	if (bfd_bread (&x_ehdr, sizeof (x_ehdr), abfd) != sizeof (x_ehdr))
	{
	if (bfd_get_error () != bfd_error_system_call)
	goto wrong;
	else
	goto fail;
	}

	/* Now check to see if we have a valid ELF file, and one that BFD can
	make use of. The magic number must match, the address size ('class')
	and byte-swapping must match our XVEC entry, and it must have a
	section header table (FIXME: See comments re sections at top of this
	file). */
	if (! elf_file_p (&x_ehdr)
	\|\| x_ehdr.e_ident[EI_VERSION] != EV_CURRENT
	\|\| x_ehdr.e_ident[EI_CLASS] != ELFCLASS)
	goto wrong;

	/* Check that file's byte order matches xvec's. */
	switch (x_ehdr.e_ident[EI_DATA])
	{
	case ELFDATA2MSB: /* Big-endian. */
	if (! bfd_header_big_endian (abfd))
	goto wrong;
	break;
	case ELFDATA2LSB: /* Little-endian. */
	if (! bfd_header_little_endian (abfd))
	goto wrong;
	break;
	case ELFDATANONE: /* No data encoding specified. */
	default: /* Unknown data encoding specified . */
	goto wrong;
	}

	elf_swap_ehdr_in (abfd, &x_ehdr, &i_ehdr);
	#if DEBUG
	elf_debug_file (&i_ehdr);
	#endif

	if (i_ehdr.e_phentsize != sizeof (Elf_External_Phdr) \|\| i_ehdr.e_phnum == 0)
	goto fail;

	/* Read in program headers. */
	if (_bfd_mul_overflow (i_ehdr.e_phnum, sizeof (*i_phdr), &amt))
	{
	bfd_set_error (bfd_error_file_too_big);
	goto fail;
	}
	i_phdr = (Elf_Internal_Phdr *) bfd_alloc (abfd, amt);
	if (i_phdr == NULL)
	goto fail;

	if (bfd_seek (abfd, (file_ptr) (offset + i_ehdr.e_phoff), SEEK_SET) != 0)
	goto fail;

	/* Read in program headers and parse notes. */
	for (i = 0; i < i_ehdr.e_phnum; ++i, ++i_phdr)
	{
	Elf_External_Phdr x_phdr;

	if (bfd_bread (&x_phdr, sizeof (x_phdr), abfd) != sizeof (x_phdr))
	goto fail;
	elf_swap_phdr_in (abfd, &x_phdr, i_phdr);

	if (i_phdr->p_type == PT_NOTE && i_phdr->p_filesz > 0)
	{
	elf_read_notes (abfd, offset + i_phdr->p_offset,
	i_phdr->p_filesz, i_phdr->p_align);

	/* Make sure ABFD returns to processing the program headers. */
	if (bfd_seek (abfd, (file_ptr) (offset + i_ehdr.e_phoff
	+ (i + 1) * sizeof (x_phdr)),
	SEEK_SET) != 0)
	goto fail;

	if (abfd->build_id != NULL)
	return true;
	}
	}

	/* Having gotten this far, we have a valid ELF section, but no
	build-id was found. */
	goto fail;

	wrong:
	bfd_set_error (bfd_error_wrong_format);
	fail:
	return false;
	}