[PATCH] libobj: declare s_str directly in string_obj_tag

[Lukáš Zaoral]

... to make libacl compatible with -D_FORTIFY_SOURCE=3.  Otherwise, any call
to __acl_to_any_text would terminate the given process because the
fortification has a limited support for zero-length arrays nested in structs,
as noted in the linked GCC Bugzilla.  GCC devs suggested that this should be
fixed in libacl rather than in GCC itself.

Related: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104964#c15
Resolves: https://savannah.nongnu.org/bugs/index.php?62519
---
 libacl/__acl_to_any_text.c | 10 +++++-----
 libacl/libobj.h            |  7 +------
 2 files changed, 6 insertions(+), 11 deletions(-)

diff --git a/libacl/__acl_to_any_text.c b/libacl/__acl_to_any_text.c
index f2b8088..bfad12d 100644
--- a/libacl/__acl_to_any_text.c
+++ b/libacl/__acl_to_any_text.c
@@ -64,7 +64,7 @@ __acl_to_any_text(acl_t acl, ssize_t *len_p, const char 
*prefix,
        FOREACH_ACL_ENTRY(entry_obj_p, acl_obj_p) {
        repeat:
                entry_len = acl_entry_to_any_str(int2ext(entry_obj_p),
-                                                string_obj_p->sstr + len,
+                                                string_obj_p->s_str + len,
                                                 size-len,
                                                 int2ext(mask_obj_p),
                                                 prefix,
@@ -81,20 +81,20 @@ __acl_to_any_text(acl_t acl, ssize_t *len_p, const char 
*prefix,
                        goto repeat;
                } else
                        len += entry_len;
-               string_obj_p->sstr[len] = separator;
+               string_obj_p->s_str[len] = separator;
                len++;
        }
        if (len)
                len--;
        if (len && suffix) {
-               strcpy(string_obj_p->sstr + len, suffix);
+               strcpy(string_obj_p->s_str + len, suffix);
                len += suffix_len;
        } else
-               string_obj_p->sstr[len] = '\0';
+               string_obj_p->s_str[len] = '\0';
 
        if (len_p)
                *len_p = len;
-       return (char *)int2ext(string_obj_p);
+       return string_obj_p ? string_obj_p->s_str : NULL;
 
 fail:
        free_obj_p(string_obj_p);
diff --git a/libacl/libobj.h b/libacl/libobj.h
index c41d5f9..84929cf 100644
--- a/libacl/libobj.h
+++ b/libacl/libobj.h
@@ -76,16 +76,11 @@ struct string_obj_tag;
 typedef struct string_obj_tag string_obj;
 
 /* string object */
-struct __string_ext {
-       char                    s_str[0];
-};
 struct string_obj_tag {
        obj_prefix              o_prefix;
-       struct __string_ext     i;
+       char                    s_str[0];
 };
 
-#define sstr i.s_str
-
 /* object creation, destruction, conversion and validation */
 void *__new_var_obj_p(int magic, size_t size) hidden;
 void __new_obj_p_here(int magic, void *here) hidden;
-- 
2.41.0