libsepol: Fix alloc-size-larger-than warning from gcc 7

Fixes the following warning from gcc 7:

In function ‘name_list_to_string’,
    inlined from ‘constraint_expr_to_string’ at module_to_cil.c:1790:8:
module_to_cil.c:1135:6: warning: argument 1 range [18446744071562067968, 18446744073709551615] exceeds maximum object size 9223372036854775807 [-Walloc-size-larger-than=]
  str = malloc(len);
  ~~~~^~~~~~~~~~~~~
In file included from module_to_cil.c:36:0:
module_to_cil.c: In function ‘constraint_expr_to_string’:
/usr/include/stdlib.h:443:14: note: in a call to allocation function ‘malloc’ declared here
 extern void *malloc (size_t __size) __THROW __attribute_malloc__ __wur;
              ^~~~~~

While we are here, fix a few other issues too.
The usage of snprintf was wrong and unnecessary; we just allocated
the string to be the right size, so we should just fill it.

Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
1 file changed