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#include <stdbool.h>
#include <stdlib.h>
// type of functions that manipulate arrays
typedef void (*arr_fun_t)(char *arr, size_t size);
// A contract for the arr_fun_t type
// requires a fresh array and positive size
// resets the first element to zero
void arr_fun_contract(char *arr, size_t size)
// clang-format off
__CPROVER_requires(0 < size && __CPROVER_is_fresh(arr, size))
__CPROVER_assigns(arr[0])
__CPROVER_ensures(arr[0] == 0)
// clang-format on
;
// Testing pre-conditions constructs
// Takes a function pointer as input, uses it if its preconditions are met
// to establish post-conditions
int foo(char *arr, size_t size, arr_fun_t arr_fun)
// clang-format off
__CPROVER_requires(arr == NULL || __CPROVER_is_fresh(arr, size))
__CPROVER_requires(__CPROVER_obeys_contract(arr_fun, arr_fun_contract))
__CPROVER_assigns(arr && size > 0 : arr[0])
__CPROVER_ensures((__CPROVER_return_value == 0) ==> (arr[0] == 0))
// clang-format on
{
int retval = -1;
if(arr && size > 0)
{
CALL:
arr_fun(arr, size);
retval = 0;
}
return retval;
}
void main()
{
size_t size;
char *arr;
arr_fun_t fun;
foo(arr, size, fun);
}
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