/* Report a module to libdwfl based on ELF program headers.

   Copyright (C) 2005-2010 Red Hat, Inc.

   This file is part of elfutils.

   This file is free software; you can redistribute it and/or modify

   it under the terms of either

     * the GNU Lesser General Public License as published by the Free

       Software Foundation; either version 3 of the License, or (at

       your option) any later version

   or

     * the GNU General Public License as published by the Free

       Software Foundation; either version 2 of the License, or (at

       your option) any later version

   or both in parallel, as here.

   elfutils 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 copies of the GNU General Public License and

   the GNU Lesser General Public License along with this program.  If

   not, see <http://www.gnu.org/licenses/>.  */

#ifdef HAVE_CONFIG_H

# include <config.h>

#endif

#include "libdwflP.h"

#include <fcntl.h>

#include <unistd.h>

/* We start every ET_REL module at a moderately aligned boundary.

   This keeps the low addresses easy to read compared to a layout

   starting at 0 (as when using -e).  It also makes it unlikely

   that a middle section will have a larger alignment and require

   rejiggering (see below).  */

#define REL_MIN_ALIGN	((GElf_Xword) 0x100)

bool

internal_function

__libdwfl_elf_address_range (Elf *elf, GElf_Addr base, bool add_p_vaddr,

			     bool sanity, GElf_Addr *vaddrp,

			     GElf_Addr *address_syncp, GElf_Addr *startp,

			     GElf_Addr *endp, GElf_Addr *biasp,

			     GElf_Half *e_typep)

{

  GElf_Ehdr ehdr_mem, *ehdr = gelf_getehdr (elf, &ehdr_mem);

  if (ehdr == NULL)

    {

    elf_error:

      __libdwfl_seterrno (DWFL_E_LIBELF);

      return false;

    }

  GElf_Addr vaddr = 0;

  GElf_Addr address_sync = 0;

  GElf_Addr start = 0, end = 0, bias = 0;

  switch (ehdr->e_type)

    {

    case ET_REL:

      /* For a relocatable object, we do an arbitrary section layout.

	 By updating the section header in place, we leave the layout

	 information to be found by relocation.  */

      start = end = base = (base + REL_MIN_ALIGN - 1) & -REL_MIN_ALIGN;

      bool first = true;

      Elf_Scn *scn = NULL;

      while ((scn = elf_nextscn (elf, scn)) != NULL)

	{

	  GElf_Shdr shdr_mem;

	  GElf_Shdr *shdr = gelf_getshdr (scn, &shdr_mem);

	  if (unlikely (shdr == NULL))

	    goto elf_error;

	  if (shdr->sh_flags & SHF_ALLOC)

	    {

	      const GElf_Xword align = shdr->sh_addralign ?: 1;

	      const GElf_Addr next = (end + align - 1) & -align;

	      if (shdr->sh_addr == 0

		  /* Once we've started doing layout we have to do it all,

		     unless we just layed out the first section at 0 when

		     it already was at 0.  */

		  || (bias == 0 && end > start && end != next))

		{

		  shdr->sh_addr = next;

		  if (end == base)

		    /* This is the first section assigned a location.

		       Use its aligned address as the module's base.  */

		    start = base = shdr->sh_addr;

		  else if (unlikely (base & (align - 1)))

		    {

		      /* If BASE has less than the maximum alignment of

			 any section, we eat more than the optimal amount

			 of padding and so make the module's apparent

			 size come out larger than it would when placed

			 at zero.  So reset the layout with a better base.  */

		      start = end = base = (base + align - 1) & -align;

		      Elf_Scn *prev_scn = NULL;

		      do

			{

			  prev_scn = elf_nextscn (elf, prev_scn);

			  GElf_Shdr prev_shdr_mem;

			  GElf_Shdr *prev_shdr = gelf_getshdr (prev_scn,

							       &prev_shdr_mem);

			  if (unlikely (prev_shdr == NULL))

			    goto elf_error;

			  if (prev_shdr->sh_flags & SHF_ALLOC)

			    {

			      const GElf_Xword prev_align

				= prev_shdr->sh_addralign ?: 1;

			      prev_shdr->sh_addr

				= (end + prev_align - 1) & -prev_align;

			      end = prev_shdr->sh_addr + prev_shdr->sh_size;

			      if (unlikely (! gelf_update_shdr (prev_scn,

								prev_shdr)))

				goto elf_error;

			    }

			}

		      while (prev_scn != scn);

		      continue;

		    }

		  end = shdr->sh_addr + shdr->sh_size;

		  if (likely (shdr->sh_addr != 0)

		      && unlikely (! gelf_update_shdr (scn, shdr)))

		    goto elf_error;

		}

	      else

		{

		  /* The address is already assigned.  Just track it.  */

		  if (first || end < shdr->sh_addr + shdr->sh_size)

		    end = shdr->sh_addr + shdr->sh_size;

		  if (first || bias > shdr->sh_addr)

		    /* This is the lowest address in the module.  */

		    bias = shdr->sh_addr;

		  if ((shdr->sh_addr - bias + base) & (align - 1))

		    /* This section winds up misaligned using BASE.

		       Adjust BASE upwards to make it congruent to

		       the lowest section address in the file modulo ALIGN.  */

		    base = (((base + align - 1) & -align)

			    + (bias & (align - 1)));

		}

	      first = false;

	    }

	}

      if (bias != 0)

	{

	  /* The section headers had nonzero sh_addr values.  The layout

	     was already done.  We've just collected the total span.

	     Now just compute the bias from the requested base.  */

	  start = base;

	  end = end - bias + start;

	  bias = start - bias;

	}

      break;

      /* Everything else has to have program headers.  */

    case ET_EXEC:

    case ET_CORE:

      /* An assigned base address is meaningless for these.  */

      base = 0;

      add_p_vaddr = true;

      FALLTHROUGH;

    case ET_DYN:

    default:;

      size_t phnum;

      if (unlikely (elf_getphdrnum (elf, &phnum) != 0))

	goto elf_error;

      for (size_t i = 0; i < phnum; ++i)

	{

	  GElf_Phdr phdr_mem, *ph = gelf_getphdr (elf, i, &phdr_mem);

	  if (unlikely (ph == NULL))

	    goto elf_error;

	  if (ph->p_type == PT_LOAD)

	    {

	      vaddr = ph->p_vaddr & -ph->p_align;

	      address_sync = ph->p_vaddr + ph->p_memsz;

	      break;

	    }

	}

      if (add_p_vaddr)

	{

	  start = base + vaddr;

	  bias = base;

	}

      else

	{

	  start = base;

	  bias = base - vaddr;

	}

      for (size_t i = phnum; i-- > 0;)

	{

	  GElf_Phdr phdr_mem, *ph = gelf_getphdr (elf, i, &phdr_mem);

	  if (unlikely (ph == NULL))

	    goto elf_error;

	  if (ph->p_type == PT_LOAD

	      && ph->p_vaddr + ph->p_memsz > 0)

	    {

	      end = bias + (ph->p_vaddr + ph->p_memsz);

	      break;

	    }

	}

      if (end == 0 && sanity)

	{

	  __libdwfl_seterrno (DWFL_E_NO_PHDR);

	  return false;

	}

      break;

    }

  if (vaddrp)

    *vaddrp = vaddr;

  if (address_syncp)

    *address_syncp = address_sync;

  if (startp)

    *startp = start;

  if (endp)

    *endp = end;

  if (biasp)

    *biasp = bias;

  if (e_typep)

    *e_typep = ehdr->e_type;

  return true;

}

Dwfl_Module *

internal_function

__libdwfl_report_elf (Dwfl *dwfl, const char *name, const char *file_name,

		      int fd, Elf *elf, GElf_Addr base, bool add_p_vaddr,

		      bool sanity)

{

  GElf_Addr vaddr, address_sync, start, end, bias;

  GElf_Half e_type;

  if (! __libdwfl_elf_address_range (elf, base, add_p_vaddr, sanity, &vaddr,

				     &address_sync, &start, &end, &bias,

				     &e_type))

    return NULL;

  Dwfl_Module *m = INTUSE(dwfl_report_module) (dwfl, name, start, end);

  if (m != NULL)

    {

      if (m->main.name == NULL)

	{

	  m->main.name = strdup (file_name);

	  m->main.fd = fd;

	}

      else if ((fd >= 0 && m->main.fd != fd)

	       || strcmp (m->main.name, file_name))

	{

	overlap:

	  m->gc = true;

	  __libdwfl_seterrno (DWFL_E_OVERLAP);

	  return NULL;

	}

      /* Preinstall the open ELF handle for the module.  */

      if (m->main.elf == NULL)

	{

	  m->main.elf = elf;

	  m->main.vaddr = vaddr;

	  m->main.address_sync = address_sync;

	  m->main_bias = bias;

	  m->e_type = e_type;

	}

      else

	{

	  elf_end (elf);

	  if (m->main_bias != bias

	      || m->main.vaddr != vaddr || m->main.address_sync != address_sync)

	    goto overlap;

	}

    }

  return m;

}

Dwfl_Module *

dwfl_report_elf (Dwfl *dwfl, const char *name, const char *file_name, int fd,

		 GElf_Addr base, bool add_p_vaddr)

{

  bool closefd = false;

  if (fd < 0)

    {

      closefd = true;

      fd = open (file_name, O_RDONLY);

      if (fd < 0)

	{

	  __libdwfl_seterrno (DWFL_E_ERRNO);

	  return NULL;

	}

    }

  Elf *elf;

  Dwfl_Error error = __libdw_open_file (&fd, &elf, closefd, false);

  if (error != DWFL_E_NOERROR)

    {

      __libdwfl_seterrno (error);

      return NULL;

    }

  Dwfl_Module *mod = __libdwfl_report_elf (dwfl, name, file_name,

					   fd, elf, base, add_p_vaddr, true);

  if (mod == NULL)

    {

      elf_end (elf);

      if (closefd)

	close (fd);

    }

  return mod;

}

INTDEF (dwfl_report_elf)

NEW_VERSION (dwfl_report_elf, ELFUTILS_0.156)

#ifdef SYMBOL_VERSIONING

Dwfl_Module *

  _compat_without_add_p_vaddr_dwfl_report_elf (Dwfl *dwfl, const char *name,

					       const char *file_name, int fd,

					       GElf_Addr base);

COMPAT_VERSION_NEWPROTO (dwfl_report_elf, ELFUTILS_0.122, without_add_p_vaddr)

Dwfl_Module *

_compat_without_add_p_vaddr_dwfl_report_elf (Dwfl *dwfl, const char *name,

					     const char *file_name, int fd,

					     GElf_Addr base)

{

  return dwfl_report_elf (dwfl, name, file_name, fd, base, true);

}

#endif