rpm/elfutils/libelf/elf_end.c

/* Free resources associated with Elf descriptor.
   Copyright (C) 1998, 1999, 2000, 2001, 2002 Red Hat, Inc.
   Written by Ulrich Drepper <drepper@redhat.com>, 1998.

   This program is Open Source software; you can redistribute it and/or
   modify it under the terms of the Open Software License version 1.0 as
   published by the Open Source Initiative.

   You should have received a copy of the Open Software License along
   with this program; if not, you may obtain a copy of the Open Software
   License version 1.0 from http://www.opensource.org/licenses/osl.php or
   by writing the Open Source Initiative c/o Lawrence Rosen, Esq.,
   3001 King Ranch Road, Ukiah, CA 95482.   */

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

#include <assert.h>
#include <stddef.h>
#include <stdlib.h>
#include <sys/mman.h>

#include "libelfP.h"


int
elf_end (Elf *elf)
{
  Elf *parent;

  if (elf == NULL)
    /* This is allowed and is a no-op.  */
    return 0;

  /* Make sure we are alone.  */
  rwlock_wrlock (elf->lock);

  if (elf->ref_count != 0 && --elf->ref_count != 0)
    {
      /* Not yet the last activation.  */
      int result = elf->ref_count;
      rwlock_unlock (elf->lock);
      return result;
    }

  if (elf->kind == ELF_K_AR)
    {
      /* We cannot remove the descriptor now since we still have some
	 descriptors which depend on it.  But we can free the archive
	 symbol table since this is only available via the archive ELF
	 descriptor.  The long name table cannot be freed yet since
	 the archive headers for the ELF files in the archive point
	 into this array.  */
      free (elf->state.ar.ar_sym);
      elf->state.ar.ar_sym = NULL;

      if (elf->state.ar.children != NULL)
	return 0;
    }

  /* Remove this structure from the children list.  */
  parent = elf->parent;
  if (parent != NULL)
    {
      /* This is tricky.  Lock must be acquire from the father to
	 the child but here we already have the child lock.  We
	 solve this problem by giving free the child lock.  The
	 state of REF_COUNT==0 is handled all over the library, so
	 this should be ok.  */
      rwlock_unlock (elf->lock);
      rwlock_rdlock (parent->lock);
      rwlock_wrlock (elf->lock);

      if (parent->state.ar.children == elf)
	parent->state.ar.children = elf->next;
      else
	{
	  struct Elf *child = parent->state.ar.children;

	  while (child->next != elf)
	    child = child->next;

	  child->next = elf->next;
	}

      rwlock_unlock (parent->lock);
    }

  /* This was the last activation.  Free all resources.  */
  switch (elf->kind)
    {
    case ELF_K_AR:
      if (elf->state.ar.long_names != NULL)
	free (elf->state.ar.long_names);
      break;

    case ELF_K_ELF:
      {
	Elf_ScnList *list = (elf->class == ELFCLASS32
			     || (offsetof (struct Elf, state.elf32.scns)
				 == offsetof (struct Elf, state.elf64.scns))
			     ? &elf->state.elf32.scns
			     : &elf->state.elf64.scns);

	do
	  {
	    Elf_ScnList *oldp;
	    size_t cnt;

	    /* Free all separately allocated section headers.  */
	    cnt = list->max;

	    while (cnt-- > 0)
	      {
		/* These pointers can be NULL; it's safe to use
		   'free' since it will check for this.  */
		Elf_Scn *scn = &list->data[cnt];
		Elf_Data_List *runp;

		if ((scn->shdr_flags & ELF_F_MALLOCED) != 0)
		  /* It doesn't matter which pointer.  */
		  free (scn->shdr.e32);

		/* If the file has the same byte order and the
		   architecture doesn't require overly stringent
		   alignment the raw data buffer is the same as the
		   one used for presenting to the caller.  */
		if (scn->data_base != scn->rawdata_base)
		  free (scn->data_base);

		/* The section data is allocated if we couldn't mmap
		   the file.  */
		if (elf->map_address == NULL)
		  free (scn->rawdata_base);

		/* Free the list of data buffers for the section.
		   We don't free the buffers themselves since this
		   is the users job.  */
		runp = scn->data_list.next;
		while (runp != NULL)
		  {
		    Elf_Data_List *oldp = runp;
		    runp = runp->next;
		    if ((oldp->flags & ELF_F_MALLOCED) != 0)
		      free (oldp);
		  }
	      }

	    /* Free the memory for the array.  */
	    oldp = list;
	    list = list->next;
	    assert (list == NULL || oldp->cnt == oldp->max);
	    if (oldp != (elf->class == ELFCLASS32
			 || (offsetof (struct Elf, state.elf32.scns)
			     == offsetof (struct Elf, state.elf64.scns))
			 ? &elf->state.elf32.scns
			 : &elf->state.elf64.scns))
	      free (oldp);
	  }
	while (list != NULL);
      }

      /* Free the section header.  */
      if (elf->state.elf.shdr_malloced  != 0)
	free (elf->class == ELFCLASS32
	      || (offsetof (struct Elf, state.elf32.shdr)
		  == offsetof (struct Elf, state.elf64.shdr))
	      ? (void *) elf->state.elf32.shdr
	      : (void *) elf->state.elf64.shdr);

      /* Free the program header.  */
      if ((elf->state.elf.phdr_flags & ELF_F_MALLOCED) != 0)
	free (elf->class == ELFCLASS32
	      || (offsetof (struct Elf, state.elf32.phdr)
		  == offsetof (struct Elf, state.elf64.phdr))
	      ? (void *) elf->state.elf32.phdr
	      : (void *) elf->state.elf64.phdr);
      break;

    default:
      break;
    }

  if (elf->map_address != NULL && parent == NULL)
    {
      /* The file was read or mapped for this descriptor.  */
      if ((elf->flags & ELF_F_MALLOCED) != 0)
	free (elf->map_address);
      else if ((elf->flags & ELF_F_MMAPPED) != 0)
	munmap (elf->map_address, elf->maximum_size);
    }

  rwlock_fini (elf->lock);

  /* Finally the descriptor itself.  */
  free (elf);

  return parent != NULL && parent->ref_count == 0 ? elf_end (parent) : 0;
}