/* Return section header.   Copyright (C) 1998-2002, 2005, 2007, 2009, 2012, 2014, 2015 Red Hat, Inc.   This file is part of elfutils.   Written by Ulrich Drepper <drepper@redhat.com>, 1998.    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 <assert.h>#include <errno.h>#include <stdbool.h>#include <unistd.h> #include <system.h>#include "libelfP.h"#include "common.h" #ifndef LIBELFBITS# define LIBELFBITS 32#endif  static ElfW2(LIBELFBITS,Shdr) *load_shdr_wrlock (Elf_Scn *scn){  ElfW2(LIBELFBITS,Shdr) *result;   /* Read the section header table.  */  Elf *elf = scn->elf;  ElfW2(LIBELFBITS,Ehdr) *ehdr = elf->state.ELFW(elf,LIBELFBITS).ehdr;   /* Try again, maybe the data is there now.  */  result = scn->shdr.ELFW(e,LIBELFBITS);  if (result != NULL)    goto out;   size_t shnum;  if (__elf_getshdrnum_rdlock (elf, &shnum) != 0      || shnum > SIZE_MAX / sizeof (ElfW2(LIBELFBITS,Shdr)))    goto out;  size_t size = shnum * sizeof (ElfW2(LIBELFBITS,Shdr));   /* Allocate memory for the section headers.  We know the number     of entries from the ELF header.  */  ElfW2(LIBELFBITS,Shdr) *shdr = elf->state.ELFW(elf,LIBELFBITS).shdr =    (ElfW2(LIBELFBITS,Shdr) *) malloc (size);  if (elf->state.ELFW(elf,LIBELFBITS).shdr == NULL)    {      __libelf_seterrno (ELF_E_NOMEM);      goto out;    }  elf->state.ELFW(elf,LIBELFBITS).shdr_malloced = 1;   if (elf->map_address != NULL)    {      /* First see whether the information in the ELF header is	 valid and it does not ask for too much.  */      if (unlikely (ehdr->e_shoff >= elf->maximum_size)	  || unlikely (elf->maximum_size - ehdr->e_shoff < size))	{	  /* Something is wrong.  */	  __libelf_seterrno (ELF_E_INVALID_SECTION_HEADER);	  goto free_and_out;	}       ElfW2(LIBELFBITS,Shdr) *notcvt;       /* All the data is already mapped.  If we could use it	 directly this would already have happened.  Unless	 we allocated the memory ourselves and the ELF_F_MALLOCED	 flag is set.  */      void *file_shdr = ((char *) elf->map_address			 + elf->start_offset + ehdr->e_shoff);       assert ((elf->flags & ELF_F_MALLOCED)	      || ehdr->e_ident[EI_DATA] != MY_ELFDATA	      || elf->cmd == ELF_C_READ_MMAP	      || (! ALLOW_UNALIGNED		  && ((uintptr_t) file_shdr		      & (__alignof__ (ElfW2(LIBELFBITS,Shdr)) - 1)) != 0));       /* Now copy the data and at the same time convert the byte order.  */      if (ehdr->e_ident[EI_DATA] == MY_ELFDATA)	{	  assert ((elf->flags & ELF_F_MALLOCED)		  || elf->cmd == ELF_C_READ_MMAP		  || ! ALLOW_UNALIGNED);	  memcpy (shdr, file_shdr, size);	}      else	{	  bool copy = ! (ALLOW_UNALIGNED			 || ((uintptr_t) file_shdr			     & (__alignof__ (ElfW2(LIBELFBITS,Shdr)) - 1))			     == 0);	  if (! copy)	    notcvt = (ElfW2(LIBELFBITS,Shdr) *)	      ((char *) elf->map_address	       + elf->start_offset + ehdr->e_shoff);	  else	    {	      notcvt = (ElfW2(LIBELFBITS,Shdr) *) malloc (size);	      if (unlikely (notcvt == NULL))		{		  __libelf_seterrno (ELF_E_NOMEM);		  goto out;		}	      memcpy (notcvt, ((char *) elf->map_address			       + elf->start_offset + ehdr->e_shoff),		      size);	    } 	  for (size_t cnt = 0; cnt < shnum; ++cnt)	    {	      CONVERT_TO (shdr[cnt].sh_name, notcvt[cnt].sh_name);	      CONVERT_TO (shdr[cnt].sh_type, notcvt[cnt].sh_type);	      CONVERT_TO (shdr[cnt].sh_flags, notcvt[cnt].sh_flags);	      CONVERT_TO (shdr[cnt].sh_addr, notcvt[cnt].sh_addr);	      CONVERT_TO (shdr[cnt].sh_offset, notcvt[cnt].sh_offset);	      CONVERT_TO (shdr[cnt].sh_size, notcvt[cnt].sh_size);	      CONVERT_TO (shdr[cnt].sh_link, notcvt[cnt].sh_link);	      CONVERT_TO (shdr[cnt].sh_info, notcvt[cnt].sh_info);	      CONVERT_TO (shdr[cnt].sh_addralign,			  notcvt[cnt].sh_addralign);	      CONVERT_TO (shdr[cnt].sh_entsize, notcvt[cnt].sh_entsize); 	      /* If this is a section with an extended index add a		 reference in the section which uses the extended		 index.  */	      if (shdr[cnt].sh_type == SHT_SYMTAB_SHNDX		  && shdr[cnt].sh_link < shnum)		elf->state.ELFW(elf,LIBELFBITS).scns.data[shdr[cnt].sh_link].shndx_index		  = cnt; 	      /* Set the own shndx_index field in case it has not yet		 been set.  */	      if (elf->state.ELFW(elf,LIBELFBITS).scns.data[cnt].shndx_index == 0)		elf->state.ELFW(elf,LIBELFBITS).scns.data[cnt].shndx_index		  = -1;	    } 	  if (copy)	    free (notcvt);	}    }  else if (likely (elf->fildes != -1))    {      /* Read the header.  */      ssize_t n = pread_retry (elf->fildes,			       elf->state.ELFW(elf,LIBELFBITS).shdr, size,			       elf->start_offset + ehdr->e_shoff);      if (unlikely ((size_t) n != size))	{	  /* Severe problems.  We cannot read the data.  */	  __libelf_seterrno (ELF_E_READ_ERROR);	  goto free_and_out;	}       /* If the byte order of the file is not the same as the one	 of the host convert the data now.  */      if (ehdr->e_ident[EI_DATA] != MY_ELFDATA)	for (size_t cnt = 0; cnt < shnum; ++cnt)	  {	    CONVERT (shdr[cnt].sh_name);	    CONVERT (shdr[cnt].sh_type);	    CONVERT (shdr[cnt].sh_flags);	    CONVERT (shdr[cnt].sh_addr);	    CONVERT (shdr[cnt].sh_offset);	    CONVERT (shdr[cnt].sh_size);	    CONVERT (shdr[cnt].sh_link);	    CONVERT (shdr[cnt].sh_info);	    CONVERT (shdr[cnt].sh_addralign);	    CONVERT (shdr[cnt].sh_entsize);	  }    }  else    {      /* The file descriptor was already enabled and not all data was	 read.  Undo the allocation.  */      __libelf_seterrno (ELF_E_FD_DISABLED);     free_and_out:      free (shdr);      elf->state.ELFW(elf,LIBELFBITS).shdr = NULL;      elf->state.ELFW(elf,LIBELFBITS).shdr_malloced = 0;       goto out;    }   /* Set the pointers in the `scn's.  */  for (size_t cnt = 0; cnt < shnum; ++cnt)    elf->state.ELFW(elf,LIBELFBITS).scns.data[cnt].shdr.ELFW(e,LIBELFBITS)      = &elf->state.ELFW(elf,LIBELFBITS).shdr[cnt];   result = scn->shdr.ELFW(e,LIBELFBITS);  assert (result != NULL); out:  return result;} static boolscn_valid (Elf_Scn *scn){  if (scn == NULL)    return false;   if (unlikely (scn->elf->state.elf.ehdr == NULL))    {      __libelf_seterrno (ELF_E_WRONG_ORDER_EHDR);      return false;    }   if (unlikely (scn->elf->class != ELFW(ELFCLASS,LIBELFBITS)))    {      __libelf_seterrno (ELF_E_INVALID_CLASS);      return false;    }   return true;} ElfW2(LIBELFBITS,Shdr) *internal_function__elfw2(LIBELFBITS,getshdr_rdlock) (Elf_Scn *scn){  ElfW2(LIBELFBITS,Shdr) *result;   if (!scn_valid (scn))    return NULL;   result = scn->shdr.ELFW(e,LIBELFBITS);  if (result == NULL)    {      rwlock_unlock (scn->elf->lock);      rwlock_wrlock (scn->elf->lock);      result = scn->shdr.ELFW(e,LIBELFBITS);      if (result == NULL)	result = load_shdr_wrlock (scn);    }   return result;} ElfW2(LIBELFBITS,Shdr) *internal_function__elfw2(LIBELFBITS,getshdr_wrlock) (Elf_Scn *scn){  ElfW2(LIBELFBITS,Shdr) *result;   if (!scn_valid (scn))    return NULL;   result = scn->shdr.ELFW(e,LIBELFBITS);  if (result == NULL)    result = load_shdr_wrlock (scn);   return result;} ElfW2(LIBELFBITS,Shdr) *elfw2(LIBELFBITS,getshdr) (Elf_Scn *scn){  ElfW2(LIBELFBITS,Shdr) *result;   if (!scn_valid (scn))    return NULL;   rwlock_rdlock (scn->elf->lock);  result = __elfw2(LIBELFBITS,getshdr_rdlock) (scn);  rwlock_unlock (scn->elf->lock);   return result;}