libdwfl/dwfl_module_addrsym.c - platform/external/elfutils - Git at Google

 /* Find debugging and symbol information for a module in libdwfl.
    Copyright (C) 2005, 2006, 2007, 2008 Red Hat, Inc.
    This file is part of Red Hat elfutils.

    Red Hat elfutils 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; version 2 of the License.

    Red Hat 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 a copy of the GNU General Public License along
    with Red Hat elfutils; if not, write to the Free Software Foundation,
    Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301 USA.

    In addition, as a special exception, Red Hat, Inc. gives You the
    additional right to link the code of Red Hat elfutils with code licensed
    under any Open Source Initiative certified open source license
    (http://www.opensource.org/licenses/index.php) which requires the
    distribution of source code with any binary distribution and to
    distribute linked combinations of the two.  Non-GPL Code permitted under
    this exception must only link to the code of Red Hat elfutils through
    those well defined interfaces identified in the file named EXCEPTION
    found in the source code files (the "Approved Interfaces").  The files
    of Non-GPL Code may instantiate templates or use macros or inline
    functions from the Approved Interfaces without causing the resulting
    work to be covered by the GNU General Public License.  Only Red Hat,
    Inc. may make changes or additions to the list of Approved Interfaces.
    Red Hat's grant of this exception is conditioned upon your not adding
    any new exceptions.  If you wish to add a new Approved Interface or
    exception, please contact Red Hat.  You must obey the GNU General Public
    License in all respects for all of the Red Hat elfutils code and other
    code used in conjunction with Red Hat elfutils except the Non-GPL Code
    covered by this exception.  If you modify this file, you may extend this
    exception to your version of the file, but you are not obligated to do
    so.  If you do not wish to provide this exception without modification,
    you must delete this exception statement from your version and license
    this file solely under the GPL without exception.

    Red Hat elfutils is an included package of the Open Invention Network.
    An included package of the Open Invention Network is a package for which
    Open Invention Network licensees cross-license their patents.  No patent
    license is granted, either expressly or impliedly, by designation as an
    included package.  Should you wish to participate in the Open Invention
    Network licensing program, please visit www.openinventionnetwork.com
    <http://www.openinventionnetwork.com>.  */

 #include "libdwflP.h"

 /* Returns the name of the symbol "closest" to ADDR.
    Never returns symbols at addresses above ADDR.  */

 const char *
 dwfl_module_addrsym (Dwfl_Module *mod, GElf_Addr addr,
 		     GElf_Sym *closest_sym, GElf_Word *shndxp)
 {
   int syments = INTUSE(dwfl_module_getsymtab) (mod);
   if (syments < 0)
     return NULL;

   /* Return true iff we consider ADDR to lie in the same section as SYM.  */
   GElf_Word addr_shndx = SHN_UNDEF;
   inline bool same_section (const GElf_Sym *sym, GElf_Word shndx)
     {
       /* For absolute symbols and the like, only match exactly.  */
       if (shndx >= SHN_LORESERVE)
 	return sym->st_value == addr;

       /* Figure out what section ADDR lies in.  */
       if (addr_shndx == SHN_UNDEF)
 	{
 	  GElf_Addr mod_addr = addr - mod->symfile->bias;
 	  Elf_Scn *scn = NULL;
 	  addr_shndx = SHN_ABS;
 	  while ((scn = elf_nextscn (mod->symfile->elf, scn)) != NULL)
 	    {
 	      GElf_Shdr shdr_mem;
 	      GElf_Shdr *shdr = gelf_getshdr (scn, &shdr_mem);
 	      if (likely (shdr != NULL)
 		  && mod_addr >= shdr->sh_addr
 		  && mod_addr < shdr->sh_addr + shdr->sh_size)
 		{
 		  addr_shndx = elf_ndxscn (scn);
 		  break;
 		}
 	    }
 	}

       return shndx == addr_shndx;
     }

   /* Keep track of the closest symbol we have seen so far.
      Here we store only symbols with nonzero st_size.  */
   const char *closest_name = NULL;
   GElf_Word closest_shndx = SHN_UNDEF;

   /* Keep track of an eligible symbol with st_size == 0 as a fallback.  */
   const char *sizeless_name = NULL;
   GElf_Sym sizeless_sym = { 0, 0, 0, 0, 0, SHN_UNDEF };
   GElf_Word sizeless_shndx = SHN_UNDEF;

   /* Keep track of the lowest address a relevant sizeless symbol could have.  */
   GElf_Addr min_label = 0;

   /* Look through the symbol table for a matching symbol.  */
   for (int i = 1; i < syments; ++i)
     {
       GElf_Sym sym;
       GElf_Word shndx;
       const char *name = INTUSE(dwfl_module_getsym) (mod, i, &sym, &shndx);
       if (name != NULL && name[0] != '\0'
 	  && sym.st_shndx != SHN_UNDEF
 	  && sym.st_value <= addr
 	  && GELF_ST_TYPE (sym.st_info) != STT_SECTION
 	  && GELF_ST_TYPE (sym.st_info) != STT_FILE
 	  && GELF_ST_TYPE (sym.st_info) != STT_TLS)
 	{
 	  /* Even if we don't choose this symbol, its existence excludes
 	     any sizeless symbol (assembly label) that is below its upper
 	     bound.  */
 	  if (sym.st_value + sym.st_size > min_label)
 	    min_label = sym.st_value + sym.st_size;

 	  if (sym.st_size == 0 || addr - sym.st_value < sym.st_size)
 	    {
 	      /* This symbol is a better candidate than the current one
 		 if it's closer to ADDR or is global when it was local.  */
 	      if (closest_name == NULL
 		  || closest_sym->st_value < sym.st_value
 		  || (GELF_ST_BIND (closest_sym->st_info)
 		      < GELF_ST_BIND (sym.st_info)))
 		{
 		  if (sym.st_size != 0)
 		    {
 		      *closest_sym = sym;
 		      closest_shndx = shndx;
 		      closest_name = name;
 		    }
 		  else if (same_section (&sym, shndx))
 		    {
 		      /* Handwritten assembly symbols sometimes have no
 			 st_size.  If no symbol with proper size includes
 			 the address, we'll use the closest one that is in
 			 the same section as ADDR.  */
 		      sizeless_sym = sym;
 		      sizeless_shndx = shndx;
 		      sizeless_name = name;
 		    }
 		}
 	      /* When the beginning of its range is no closer,
 		 the end of its range might be.  But do not
 		 replace a global symbol with a local!  */
 	      else if (sym.st_size != 0
 		       && closest_sym->st_value == sym.st_value
 		       && closest_sym->st_size > sym.st_size
 		       && (GELF_ST_BIND (closest_sym->st_info)
 			   <= GELF_ST_BIND (sym.st_info)))
 		{
 		  *closest_sym = sym;
 		  closest_shndx = shndx;
 		  closest_name = name;
 		}
 	    }
 	}
     }

   /* If we found no proper sized symbol to use, fall back to the best
      candidate sizeless symbol we found, if any.  */
   if (closest_name == NULL
       && sizeless_name != NULL && sizeless_sym.st_value >= min_label)
     {
       *closest_sym = sizeless_sym;
       closest_shndx = sizeless_shndx;
       closest_name = sizeless_name;
     }

   if (shndxp != NULL)
     *shndxp = closest_shndx;
   return closest_name;
 }
 INTDEF (dwfl_module_addrsym)
	/* Find debugging and symbol information for a module in libdwfl.
	Copyright (C) 2005, 2006, 2007, 2008 Red Hat, Inc.
	This file is part of Red Hat elfutils.

	Red Hat elfutils 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; version 2 of the License.

	Red Hat 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 a copy of the GNU General Public License along
	with Red Hat elfutils; if not, write to the Free Software Foundation,
	Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301 USA.

	In addition, as a special exception, Red Hat, Inc. gives You the
	additional right to link the code of Red Hat elfutils with code licensed
	under any Open Source Initiative certified open source license
	(http://www.opensource.org/licenses/index.php) which requires the
	distribution of source code with any binary distribution and to
	distribute linked combinations of the two. Non-GPL Code permitted under
	this exception must only link to the code of Red Hat elfutils through
	those well defined interfaces identified in the file named EXCEPTION
	found in the source code files (the "Approved Interfaces"). The files
	of Non-GPL Code may instantiate templates or use macros or inline
	functions from the Approved Interfaces without causing the resulting
	work to be covered by the GNU General Public License. Only Red Hat,
	Inc. may make changes or additions to the list of Approved Interfaces.
	Red Hat's grant of this exception is conditioned upon your not adding
	any new exceptions. If you wish to add a new Approved Interface or
	exception, please contact Red Hat. You must obey the GNU General Public
	License in all respects for all of the Red Hat elfutils code and other
	code used in conjunction with Red Hat elfutils except the Non-GPL Code
	covered by this exception. If you modify this file, you may extend this
	exception to your version of the file, but you are not obligated to do
	so. If you do not wish to provide this exception without modification,
	you must delete this exception statement from your version and license
	this file solely under the GPL without exception.

	Red Hat elfutils is an included package of the Open Invention Network.
	An included package of the Open Invention Network is a package for which
	Open Invention Network licensees cross-license their patents. No patent
	license is granted, either expressly or impliedly, by designation as an
	included package. Should you wish to participate in the Open Invention
	Network licensing program, please visit www.openinventionnetwork.com
	<http://www.openinventionnetwork.com>. */

	#include "libdwflP.h"

	/* Returns the name of the symbol "closest" to ADDR.
	Never returns symbols at addresses above ADDR. */

	const char *
	dwfl_module_addrsym (Dwfl_Module *mod, GElf_Addr addr,
	GElf_Sym closest_sym, GElf_Word shndxp)
	{
	int syments = INTUSE(dwfl_module_getsymtab) (mod);
	if (syments < 0)
	return NULL;

	/* Return true iff we consider ADDR to lie in the same section as SYM. */
	GElf_Word addr_shndx = SHN_UNDEF;
	inline bool same_section (const GElf_Sym *sym, GElf_Word shndx)
	{
	/* For absolute symbols and the like, only match exactly. */
	if (shndx >= SHN_LORESERVE)
	return sym->st_value == addr;

	/* Figure out what section ADDR lies in. */
	if (addr_shndx == SHN_UNDEF)
	{
	GElf_Addr mod_addr = addr - mod->symfile->bias;
	Elf_Scn *scn = NULL;
	addr_shndx = SHN_ABS;
	while ((scn = elf_nextscn (mod->symfile->elf, scn)) != NULL)
	{
	GElf_Shdr shdr_mem;
	GElf_Shdr *shdr = gelf_getshdr (scn, &shdr_mem);
	if (likely (shdr != NULL)
	&& mod_addr >= shdr->sh_addr
	&& mod_addr < shdr->sh_addr + shdr->sh_size)
	{
	addr_shndx = elf_ndxscn (scn);
	break;
	}
	}
	}

	return shndx == addr_shndx;
	}

	/* Keep track of the closest symbol we have seen so far.
	Here we store only symbols with nonzero st_size. */
	const char *closest_name = NULL;
	GElf_Word closest_shndx = SHN_UNDEF;

	/* Keep track of an eligible symbol with st_size == 0 as a fallback. */
	const char *sizeless_name = NULL;
	GElf_Sym sizeless_sym = { 0, 0, 0, 0, 0, SHN_UNDEF };
	GElf_Word sizeless_shndx = SHN_UNDEF;

	/* Keep track of the lowest address a relevant sizeless symbol could have. */
	GElf_Addr min_label = 0;

	/* Look through the symbol table for a matching symbol. */
	for (int i = 1; i < syments; ++i)
	{
	GElf_Sym sym;
	GElf_Word shndx;
	const char *name = INTUSE(dwfl_module_getsym) (mod, i, &sym, &shndx);
	if (name != NULL && name[0] != '\0'
	&& sym.st_shndx != SHN_UNDEF
	&& sym.st_value <= addr
	&& GELF_ST_TYPE (sym.st_info) != STT_SECTION
	&& GELF_ST_TYPE (sym.st_info) != STT_FILE
	&& GELF_ST_TYPE (sym.st_info) != STT_TLS)
	{
	/* Even if we don't choose this symbol, its existence excludes
	any sizeless symbol (assembly label) that is below its upper
	bound. */
	if (sym.st_value + sym.st_size > min_label)
	min_label = sym.st_value + sym.st_size;

	if (sym.st_size == 0 \|\| addr - sym.st_value < sym.st_size)
	{
	/* This symbol is a better candidate than the current one
	if it's closer to ADDR or is global when it was local. */
	if (closest_name == NULL
	\|\| closest_sym->st_value < sym.st_value
	\|\| (GELF_ST_BIND (closest_sym->st_info)
	< GELF_ST_BIND (sym.st_info)))
	{
	if (sym.st_size != 0)
	{
	*closest_sym = sym;
	closest_shndx = shndx;
	closest_name = name;
	}
	else if (same_section (&sym, shndx))
	{
	/* Handwritten assembly symbols sometimes have no
	st_size. If no symbol with proper size includes
	the address, we'll use the closest one that is in
	the same section as ADDR. */
	sizeless_sym = sym;
	sizeless_shndx = shndx;
	sizeless_name = name;
	}
	}
	/* When the beginning of its range is no closer,
	the end of its range might be. But do not
	replace a global symbol with a local! */
	else if (sym.st_size != 0
	&& closest_sym->st_value == sym.st_value
	&& closest_sym->st_size > sym.st_size
	&& (GELF_ST_BIND (closest_sym->st_info)
	<= GELF_ST_BIND (sym.st_info)))
	{
	*closest_sym = sym;
	closest_shndx = shndx;
	closest_name = name;
	}
	}
	}
	}

	/* If we found no proper sized symbol to use, fall back to the best
	candidate sizeless symbol we found, if any. */
	if (closest_name == NULL
	&& sizeless_name != NULL && sizeless_sym.st_value >= min_label)
	{
	*closest_sym = sizeless_sym;
	closest_shndx = sizeless_shndx;
	closest_name = sizeless_name;
	}

	if (shndxp != NULL)
	*shndxp = closest_shndx;
	return closest_name;
	}
	INTDEF (dwfl_module_addrsym)