read_file_to_string Function

function read_file_to_string(filename) result(str)
    !
    ! Reads the contents of the file into the allocatable string str.
    ! If there are any problems, str will be returned unallocated.
    !
    implicit none

    character(len=*),intent(in) :: filename
    character(len=:),allocatable :: str

    integer :: iunit,istat,filesize

    open(newunit=iunit,file=filename,status='OLD',&
    form='UNFORMATTED',access='STREAM',iostat=istat)

    if (istat==0) then
        inquire(file=filename, size=filesize)
        if (filesize>0) then
            allocate( character(len=filesize) :: str )
            read(iunit,pos=1,iostat=istat) str
            if (istat/=0) deallocate(str)
            close(iunit, iostat=istat)
        end if
    end if

    end function read_file_to_string