arena.c

来自「支持SSL v2/v3, TLS, PKCS #5, PKCS #7, PKCS」· C语言 代码 · 共 1,122 行 · 第 1/2 页

 *  NULL upon failure
 *  An nssArenaMark pointer upon success
 */

NSS_IMPLEMENT nssArenaMark *
nssArena_Mark
(
  NSSArena *arena
)
{
  nssArenaMark *rv;
  void *p;

#ifdef NSSDEBUG
  if( PR_SUCCESS != nssArena_verifyPointer(arena) ) {
    return (nssArenaMark *)NULL;
  }
#endif /* NSSDEBUG */

  PR_Lock(arena->lock);
  if( (PRLock *)NULL == arena->lock ) {
    /* Just got destroyed */
    nss_SetError(NSS_ERROR_INVALID_ARENA);
    return (nssArenaMark *)NULL;
  }

#ifdef ARENA_THREADMARK
  if( (PRThread *)NULL == arena->marking_thread ) {
    /* Unmarked.  Store our thread ID */
    arena->marking_thread = PR_GetCurrentThread();
    /* This call never fails. */
  } else {
    /* Marked.  Verify it's the current thread */
    if( PR_GetCurrentThread() != arena->marking_thread ) {
      PR_Unlock(arena->lock);
      nss_SetError(NSS_ERROR_ARENA_MARKED_BY_ANOTHER_THREAD);
      return (nssArenaMark *)NULL;
    }
  }
#endif /* ARENA_THREADMARK */

  p = PL_ARENA_MARK(&arena->pool);
  /* No error possible */

  /* Do this after the mark */
  rv = nss_ZNEW(arena, nssArenaMark);
  if( (nssArenaMark *)NULL == rv ) {
    PR_Unlock(arena->lock);
    nss_SetError(NSS_ERROR_NO_MEMORY);
    return (nssArenaMark *)NULL;
  }

#ifdef ARENA_THREADMARK
  arena->last_mark->next = rv;
  arena->last_mark = rv;
#endif /* ARENA_THREADMARK */

  rv->mark = p;
  rv->magic = MARK_MAGIC;

#ifdef ARENA_DESTRUCTOR_LIST
  rv->prev_destructor = arena->last_destructor;
#endif /* ARENA_DESTRUCTOR_LIST */

  PR_Unlock(arena->lock);

  return rv;
}

/*
 * nss_arena_unmark_release
 *
 * This static routine implements the routines nssArena_Release
 * ans nssArena_Unmark, which are almost identical.
 */

static PRStatus
nss_arena_unmark_release
(
  NSSArena *arena,
  nssArenaMark *arenaMark,
  PRBool release
)
{
  void *inner_mark;

#ifdef NSSDEBUG
  if( PR_SUCCESS != nssArena_verifyPointer(arena) ) {
    return PR_FAILURE;
  }
#endif /* NSSDEBUG */

  if( MARK_MAGIC != arenaMark->magic ) {
    nss_SetError(NSS_ERROR_INVALID_ARENA_MARK);
    return PR_FAILURE;
  }

  PR_Lock(arena->lock);
  if( (PRLock *)NULL == arena->lock ) {
    /* Just got destroyed */
    nss_SetError(NSS_ERROR_INVALID_ARENA);
    return PR_FAILURE;
  }

#ifdef ARENA_THREADMARK
  if( (PRThread *)NULL != arena->marking_thread ) {
    if( PR_GetCurrentThread() != arena->marking_thread ) {
      PR_Unlock(arena->lock);
      nss_SetError(NSS_ERROR_ARENA_MARKED_BY_ANOTHER_THREAD);
      return PR_FAILURE;
    }
  }
#endif /* ARENA_THREADMARK */

  if( MARK_MAGIC != arenaMark->magic ) {
    /* Just got released */
    PR_Unlock(arena->lock);
    nss_SetError(NSS_ERROR_INVALID_ARENA_MARK);
    return PR_FAILURE;
  }

  arenaMark->magic = 0;
  inner_mark = arenaMark->mark;

#ifdef ARENA_THREADMARK
  {
    nssArenaMark **pMark = &arena->first_mark;
    nssArenaMark *rest;
    nssArenaMark *last = (nssArenaMark *)NULL;

    /* Find this mark */
    while( *pMark != arenaMark ) {
      last = *pMark;
      pMark = &(*pMark)->next;
    }

    /* Remember the pointer, then zero it */
    rest = (*pMark)->next;
    *pMark = (nssArenaMark *)NULL;

    arena->last_mark = last;

    /* Invalidate any later marks being implicitly released */
    for( ; (nssArenaMark *)NULL != rest; rest = rest->next ) {
      rest->magic = 0;
    }

    /* If we just got rid of the first mark, clear the thread ID */
    if( (nssArenaMark *)NULL == arena->first_mark ) {
      arena->marking_thread = (PRThread *)NULL;
    }
  }
#endif /* ARENA_THREADMARK */

  if( release ) {
#ifdef ARENA_DESTRUCTOR_LIST
    if( (struct arena_destructor_node *)NULL != arenaMark->prev_destructor ) {
      arenaMark->prev_destructor->next = (struct arena_destructor_node *)NULL;
    }
    arena->last_destructor = arenaMark->prev_destructor;

    /* Note that the arena is locked at this time */
    nss_arena_call_destructor_chain(arenaMark->next_destructor);
#endif /* ARENA_DESTRUCTOR_LIST */

    PR_ARENA_RELEASE(&arena->pool, inner_mark);
    /* No error return */
  }

  PR_Unlock(arena->lock);
  return PR_SUCCESS;
}

/*
 * nssArena_Release
 *
 * This routine invalidates and releases all memory allocated from
 * the specified arena after the point at which the specified mark
 * was obtained.  This routine returns a PRStatus value; if successful,
 * it will return PR_SUCCESS.  If unsuccessful, it will set an error
 * on the error stack and return PR_FAILURE.
 *
 * The error may be one of the following values:
 *  NSS_ERROR_INVALID_ARENA
 *  NSS_ERROR_INVALID_ARENA_MARK
 *  NSS_ERROR_ARENA_MARKED_BY_ANOTHER_THREAD
 *
 * Return value:
 *  PR_SUCCESS
 *  PR_FAILURE
 */

NSS_IMPLEMENT PRStatus
nssArena_Release
(
  NSSArena *arena,
  nssArenaMark *arenaMark
)
{
  return nss_arena_unmark_release(arena, arenaMark, PR_TRUE);
}

/*
 * nssArena_Unmark
 *
 * This routine "commits" the indicated mark and any marks after
 * it, making them unreleasable.  Note that any earlier marks can
 * still be released, and such a release will invalidate these
 * later unmarked regions.  If an arena is to be safely shared by
 * more than one thread, all marks must be either released or
 * unmarked.  This routine returns a PRStatus value; if successful,
 * it will return PR_SUCCESS.  If unsuccessful, it will set an error
 * on the error stack and return PR_FAILURE.
 *
 * The error may be one of the following values:
 *  NSS_ERROR_INVALID_ARENA
 *  NSS_ERROR_INVALID_ARENA_MARK
 *  NSS_ERROR_ARENA_MARKED_BY_ANOTHER_THREAD
 *
 * Return value:
 *  PR_SUCCESS
 *  PR_FAILURE
 */

NSS_IMPLEMENT PRStatus
nssArena_Unmark
(
  NSSArena *arena,
  nssArenaMark *arenaMark
)
{
  return nss_arena_unmark_release(arena, arenaMark, PR_FALSE);
}

/*
 * We prefix this header to all allocated blocks.  It is a multiple
 * of the alignment size.  Note that this usage of a header may make
 * purify spew bogus warnings about "potentially leaked blocks" of
 * memory; if that gets too annoying we can add in a pointer to the
 * header in the header itself.  There's not a lot of safety here;
 * maybe we should add a magic value?
 */
struct pointer_header {
  NSSArena *arena;
  PRUint32 size;
};

/*
 * nss_ZAlloc
 *
 * This routine allocates and zeroes a section of memory of the 
 * size, and returns to the caller a pointer to that memory.  If
 * the optional arena argument is non-null, the memory will be
 * obtained from that arena; otherwise, the memory will be obtained
 * from the heap.  This routine may return NULL upon error, in
 * which case it will have set an error upon the error stack.  The
 * value specified for size may be zero; in which case a valid 
 * zero-length block of memory will be allocated.  This block may
 * be expanded by calling nss_ZRealloc.
 *
 * The error may be one of the following values:
 *  NSS_ERROR_INVALID_ARENA
 *  NSS_ERROR_NO_MEMORY
 *  NSS_ERROR_ARENA_MARKED_BY_ANOTHER_THREAD
 *
 * Return value:
 *  NULL upon error
 *  A pointer to the new segment of zeroed memory
 */

NSS_IMPLEMENT void *
nss_ZAlloc
(
  NSSArena *arenaOpt,
  PRUint32 size
)
{
  struct pointer_header *h;
  PRUint32 my_size = size + sizeof(struct pointer_header);

  if( my_size < sizeof(struct pointer_header) ) {
    /* Wrapped */
    nss_SetError(NSS_ERROR_NO_MEMORY);
    return (void *)NULL;
  }

  if( (NSSArena *)NULL == arenaOpt ) {
    /* Heap allocation, no locking required. */
    h = (struct pointer_header *)PR_Calloc(1, my_size);
    if( (struct pointer_header *)NULL == h ) {
      nss_SetError(NSS_ERROR_NO_MEMORY);
      return (void *)NULL;
    }

    h->arena = (NSSArena *)NULL;
    h->size = size;
    /* We used calloc: it's already zeroed */

    return (void *)((char *)h + sizeof(struct pointer_header));
  } else {
    void *p;
    void *rv;
    /* Arena allocation */
#ifdef NSSDEBUG
    if( PR_SUCCESS != nssArena_verifyPointer(arenaOpt) ) {
      return (void *)NULL;
    }
#endif /* NSSDEBUG */

    PR_Lock(arenaOpt->lock);
    if( (PRLock *)NULL == arenaOpt->lock ) {
      /* Just got destroyed */
      nss_SetError(NSS_ERROR_INVALID_ARENA);
      return (void *)NULL;
    }

#ifdef ARENA_THREADMARK
    if( (PRThread *)NULL != arenaOpt->marking_thread ) {
      if( PR_GetCurrentThread() != arenaOpt->marking_thread ) {
        nss_SetError(NSS_ERROR_ARENA_MARKED_BY_ANOTHER_THREAD);
        PR_Unlock(arenaOpt->lock);
        return (void *)NULL;
      }
    }
#endif /* ARENA_THREADMARK */

    PR_ARENA_ALLOCATE(p, &arenaOpt->pool, my_size);
    if( (void *)NULL == p ) {
      PR_Unlock(arenaOpt->lock);
      nss_SetError(NSS_ERROR_NO_MEMORY);
      return (void *)NULL;
    }

    /* 
     * Do this before we unlock.  This way if the user is using
     * an arena in one thread while destroying it in another, he'll
     * fault/FMR in his code, not ours.
     */
    h = (struct pointer_header *)p;
    h->arena = arenaOpt;
    h->size = size;
    rv = (void *)((char *)h + sizeof(struct pointer_header));
    (void)nsslibc_memset(rv, 0, size);

    PR_Unlock(arenaOpt->lock);

    return rv;
  }
  /*NOTREACHED*/
}

/*
 * nss_ZFreeIf
 *
 * If the specified pointer is non-null, then the region of memory 
 * to which it points -- which must have been allocated with 
 * nss_ZAlloc -- will be zeroed and released.  This routine 
 * returns a PRStatus value; if successful, it will return PR_SUCCESS.
 * If unsuccessful, it will set an error on the error stack and return 
 * PR_FAILURE.
 *
 * The error may be one of the following values:
 *  NSS_ERROR_INVALID_POINTER
 *
 * Return value:
 *  PR_SUCCESS
 *  PR_FAILURE
 */

NSS_IMPLEMENT PRStatus
nss_ZFreeIf
(
  void *pointer
)
{
  struct pointer_header *h;

  if( (void *)NULL == pointer ) {
    return PR_SUCCESS;
  }

  h = (struct pointer_header *)&((char *)pointer)
    [ - sizeof(struct pointer_header) ];

  /* Check any magic here */

  if( (NSSArena *)NULL == h->arena ) {
    /* Heap */
    (void)nsslibc_memset(pointer, 0, h->size);
    PR_Free(h);
    return PR_SUCCESS;
  } else {
    /* Arena */
#ifdef NSSDEBUG
    if( PR_SUCCESS != nssArena_verifyPointer(h->arena) ) {
      return PR_FAILURE;
    }
#endif /* NSSDEBUG */

    PR_Lock(h->arena->lock);
    if( (PRLock *)NULL == h->arena->lock ) {
      /* Just got destroyed.. so this pointer is invalid */
      nss_SetError(NSS_ERROR_INVALID_POINTER);
      return PR_FAILURE;
    }

    (void)nsslibc_memset(pointer, 0, h->size);

    /* No way to "free" it within an NSPR arena. */

    PR_Unlock(h->arena->lock);
    return PR_SUCCESS;
  }
  /*NOTREACHED*/
}

/*
 * nss_ZRealloc
 *
 * This routine reallocates a block of memory obtained by calling
 * nss_ZAlloc or nss_ZRealloc.  The portion of memory 
 * between the new and old sizes -- which is either being newly
 * obtained or released -- is in either case zeroed.  This routine 
 * may return NULL upon failure, in which case it will have placed 
 * an error on the error stack.
 *
 * The error may be one of the following values:
 *  NSS_ERROR_INVALID_POINTER
 *  NSS_ERROR_NO_MEMORY
 *  NSS_ERROR_ARENA_MARKED_BY_ANOTHER_THREAD
 *
 * Return value:
 *  NULL upon error
 *  A pointer to the replacement segment of memory
 */

NSS_EXTERN void *
nss_ZRealloc
(
  void *pointer,
  PRUint32 newSize
)
{
  struct pointer_header *h, *new_h;
  PRUint32 my_newSize = newSize + sizeof(struct pointer_header);
  void *rv;

  if( my_newSize < sizeof(struct pointer_header) ) {
    /* Wrapped */
    nss_SetError(NSS_ERROR_NO_MEMORY);
    return (void *)NULL;
  }

  if( (void *)NULL == pointer ) {
    nss_SetError(NSS_ERROR_INVALID_POINTER);
    return (void *)NULL;
  }

  h = (struct pointer_header *)&((char *)pointer)
    [ - sizeof(struct pointer_header) ];

  /* Check any magic here */

  if( newSize == h->size ) {
    /* saves thrashing */
    return pointer;
  }

  if( (NSSArena *)NULL == h->arena ) {
    /* Heap */
    new_h = (struct pointer_header *)PR_Calloc(1, my_newSize);
    if( (struct pointer_header *)NULL == new_h ) {
      nss_SetError(NSS_ERROR_NO_MEMORY);
      return (void *)NULL;
    }

    new_h->arena = (NSSArena *)NULL;
    new_h->size = newSize;
    rv = (void *)((char *)new_h + sizeof(struct pointer_header));

    if( newSize > h->size ) {
      (void)nsslibc_memcpy(rv, pointer, h->size);
      (void)nsslibc_memset(&((char *)rv)[ h->size ], 
                           0, (newSize - h->size));
    } else {
      (void)nsslibc_memcpy(rv, pointer, newSize);
    }

    (void)nsslibc_memset(pointer, 0, h->size);
    h->size = 0;
    PR_Free(h);

    return rv;
  } else {
    void *p;
    /* Arena */
#ifdef NSSDEBUG
    if( PR_SUCCESS != nssArena_verifyPointer(h->arena) ) {
      return (void *)NULL;
    }
#endif /* NSSDEBUG */

    PR_Lock(h->arena->lock);
    if( (PRLock *)NULL == h->arena->lock ) {
      /* Just got destroyed.. so this pointer is invalid */
      nss_SetError(NSS_ERROR_INVALID_POINTER);
      return (void *)NULL;
    }

#ifdef ARENA_THREADMARK
    if( (PRThread *)NULL != h->arena->marking_thread ) {
      if( PR_GetCurrentThread() != h->arena->marking_thread ) {
        PR_Unlock(h->arena->lock);
        nss_SetError(NSS_ERROR_ARENA_MARKED_BY_ANOTHER_THREAD);
        return (void *)NULL;
      }
    }
#endif /* ARENA_THREADMARK */

    if( newSize < h->size ) {
      /*
       * We have no general way of returning memory to the arena
       * (mark/release doesn't work because things may have been
       * allocated after this object), so the memory is gone
       * anyway.  We might as well just return the same pointer to
       * the user, saying "yeah, uh-hunh, you can only use less of
       * it now."  We'll zero the leftover part, of course.  And
       * in fact we might as well *not* adjust h->size-- this way,
       * if the user reallocs back up to something not greater than
       * the original size, then voila, there's the memory!  This
       * way a thrash big/small/big/small doesn't burn up the arena.
       */
      char *extra = &((char *)pointer)[ newSize ];
      (void)nsslibc_memset(extra, 0, (h->size - newSize));
      PR_Unlock(h->arena->lock);
      return pointer;
    }

    PR_ARENA_ALLOCATE(p, &h->arena->pool, my_newSize);
    if( (void *)NULL == p ) {
      PR_Unlock(h->arena->lock);
      nss_SetError(NSS_ERROR_NO_MEMORY);
      return (void *)NULL;
    }

    new_h = (struct pointer_header *)p;
    new_h->arena = h->arena;
    new_h->size = newSize;
    rv = (void *)((char *)h + sizeof(struct pointer_header));
    (void)nsslibc_memcpy(rv, pointer, h->size);
    (void)nsslibc_memset(&((char *)rv)[ h->size ], 0, 
                         (newSize - h->size));
    (void)nsslibc_memset(pointer, 0, h->size);
    h->arena = (NSSArena *)NULL;
    h->size = 0;
    PR_Unlock(h->arena->lock);
    return rv;
  }
  /*NOTREACHED*/
}