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[Frama-c-discuss] How to prove "offset_min(char_xP_stdin_8_alloc_table, stdin) <= 0"?

  • Subject: [Frama-c-discuss] How to prove "offset_min(char_xP_stdin_8_alloc_table, stdin) <= 0"?
  • From: dmentre at linux-france.org (David MENTRE)
  • Date: Thu, 19 Mar 2009 14:13:23 +0100
Hello,

I have following C code:
"""
/*@ assigns \nothing;
    ensures \result >= 0 && \result < num_candidates;
 */
int f(void)
{
  char buf[MAX_STRING_SIZE];
  char *s;

  while (1) {
    s = fgets(buf, MAX_STRING_SIZE, stdin);
[...]
"""

In the Default behavior part of this function, I need to prove the
following "precondition to user call" and Alt-Ergo fails to prove it:

   offset_min(char_xP_stdin_8_alloc_table, stdin) <= 0

In the GUI, the "s" is highlighted in above code. I don't understand
what I exactly need to prove.

I have the same issue with another "precondition to user call" on
exactly the same part of the code:

   offset_max(char_xP_stdin_8_alloc_table, stdin) >= 0