@@ -229,6 +229,7 @@ struct variable {
char *name;
char *value;
enum variable_flavor flavor;
+ int exp_count;
struct list_head node;
};
@@ -253,11 +254,22 @@ static char *variable_expand(const char *name, int argc, char *argv[])
if (!v)
return NULL;
+ if (argc == 0 && v->exp_count)
+ pperror("Recursive variable '%s' references itself (eventually)",
+ name);
+
+ if (v->exp_count > 1000)
+ pperror("Too deep recursive expansion");
+
+ v->exp_count++;
+
if (v->flavor == VAR_RECURSIVE)
res = expand_string_with_args(v->value, argc, argv);
else
res = xstrdup(v->value);
+ v->exp_count--;
+
return res;
}
@@ -284,6 +296,7 @@ void variable_add(const char *name, const char *value,
v = xmalloc(sizeof(*v));
v->name = xstrdup(name);
+ v->exp_count = 0;
list_add_tail(&v->node, &variable_list);
}
When using a recursively expanded variable, it is a common mistake to make circular reference. For example, Make terminates the following code: X = $(X) Y := $(X) Let's detect the circular expansion in Kconfig, too. On the other hand, a function that recurses itself is a commonly-used programming technique. So, Make does not check recursion in the reference with 'call'. For example, the following code continues running eternally: X = $(call X) Y := $(X) Kconfig allows circular expansion if one or more arguments are given, but terminates when the same function is recursively invoked 1000 times, assuming it is a programming mistake. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> --- Changes in v5: None Changes in v4: - Newly added Changes in v3: None Changes in v2: None scripts/kconfig/preprocess.c | 13 +++++++++++++ 1 file changed, 13 insertions(+)