为什么发生“未分配指针释放”?

时间:2019-04-07 03:06:41

标签: memory-management linked-list fortran

我正在Fortran中测试ALLOCATE和DEALLOCATE。我建立了大量的链表,并在结束程序之前尝试重新分配它。

该代码在macOS上与gfortran一起运行。当代码尝试取消分配链表时,有些成功,有些失败。 在下面输出信息:

 after call
 T
 T
           1
 F      100000
 enter
 T           1
           2
 F      100000
 enter
 T           1
           3
 F      100000
 enter
 T           1
           4
 F      100000
 enter
 T           1
           5
 F      100000
 enter
 T           1
           6
 F      100000
 enter
 T           1
           7
 F      100000
 enter
 T           1
           8
 F      100000
 enter
 T           1
           9
 F      100000
 enter
 T           1
          10
 F      100000
 enter
out(8225,0x7fffa4e84380) malloc: *** error for object 0x7fcd38600002: pointer being freed was not allocated
*** set a breakpoint in malloc_error_break to debug

Program received signal SIGABRT: Process abort signal.

Backtrace for this error:
#0  0x1057561ac
#1  0x105755553
#2  0x7fff6caddf59
Abort trap: 6
module data_link
    implicit none
    type :: datalink_i
        integer :: i
        type(datalink_i), pointer :: next
        type(datalink_i), pointer :: prev
    endtype datalink_i
    type :: datacell_i
        type(datalink_i), pointer :: content
    endtype datacell_i
    contains
        subroutine datalink_i_add(head,data,index)
            type(datalink_i),intent(inout), pointer :: head
            type(datalink_i), pointer :: ptr
            integer,intent(in) :: data,index
            if (index == 1) then
              allocate(head)
              nullify(head%prev)
              nullify(head%next)
              head%i = data
            else
              ptr => head
              allocate(head%next)
              head => head%next
              head%prev => ptr
              nullify(head%next)
              head%i = data
            endif
        end subroutine datalink_i_add

        subroutine datalink_i_nullify(head)
          type(datalink_i), intent(inout),pointer ::head
          type(datalink_i), pointer ::ptr
          integer :: i
          do
            if (.not.associated(head%next)) exit
            head => head%next
          enddo
          ptr => head
          write(*,*) associated(head%next),head%i
          do 
            if (.not.associated(head%prev)) then
                write(*,*) associated(ptr),ptr%i
                head%next => null()
                exit
            endif
            if (ptr%i == 100000) then
                write(*,*) 'enter'
            endif
            deallocate(head)
            head => ptr%prev
            ptr => ptr%prev
          enddo
        end subroutine datalink_i_nullify
end module data_link

subroutine pttr(ptr)
     use data_link
     type(datacell_i),intent(inout),dimension(:),allocatable :: ptr
     integer :: i,j
     integer, dimension(:),allocatable:: index 
     allocate(ptr(100))
     allocate(index(100))
     index = 1
     do j=1,100
        write(*,*)j
     do i=1,100000
         call datalink_i_add(ptr(j)%content,i,index(j))
         if (index(j) == 1) then
             index(j) =0
         endif
     enddo
    enddo
end subroutine pttr

program c2115
    use data_link
    implicit none
    interface
    subroutine pttr(ptr)
        use data_link
        type(datacell_i),intent(inout),dimension(:),allocatable :: ptr
    endsubroutine
    endinterface
    integer :: Allocate_status = 0
    real, dimension(:), pointer :: x
    real, dimension(10), target :: y
    integer ,parameter :: sizef = 10000000
    integer :: i ,j
    type(datacell_i),dimension(:),allocatable:: ptr2
    type(datalink_i),pointer :: ptr1
    integer :: index =1


    call pttr(ptr2)
    read(*,*)
    write(*,*) 'after call'

    do i=1,100
        write(*,*) i
    call datalink_i_nullify(ptr2(i)%content)
    enddo
    write(*,*) associated(ptr2(1)%content),allocated(ptr2)
    read(*,*)

end program

我希望链表可以在调用datalink_i_nullify之后重新分配内存。但是在此过程中,出现了错误。

0 个答案:

没有答案