libglusterfs: fix the call_stack_set_group() function

- call_stack_set_group() will take the ownership of passed
  buffer from caller;
- to indicate the change, its signature is changed from
  including the buffer directly to take a pointer to it;
- either the content of the buffer is copied to the
  groups_small embedded buffer of the call stack, or
  the buffer is set as groups_large member of the call
  stack;
- the groups member of the call stack is set to,
  respectively, groups_small or groups_large, according
  to the memory management conventions of the call stack;
- the buffer address is overwritten with junk to effectively
  prevent the caller from using it further on.

Also move call_stack_set_group to stack.c from stack.h
to prevent "defined but not used [-Wunused-function]"
warnings (not using it anymore in call_stack_alloc_group()
implementation, which saved us from this so far).

protocol/server: refactor gid_resolve()

In gid_resolve there are two cases:
either the gid_cache_lookup() call returns
a value or not. The result is caputured in
the agl variable, and throughout the function,
each particular stage of the implementation
comes with an agl and a no-agl variant.

In most cases this is explicitly indicated
via an

   if (agl) {
      ...
   } else {
      ...
   }

but some of this branching are expressed via
goto constructs (obfuscating the fact we stated
above, that is, each particular stage having
an agl/no-agl variant).

In the current refactor, we bring the agl
conditional to the top, and present the
agl/non-agl implementations sequentially.

Also we take the opportunity to clean up and
fix the agl case:
- remove the spurious
    gl.gl_list = agl->gl_list;
  setting, as gl is not used in the agl caae
- populate the group list of call stack from
  agl, fixing thus referred BUG.

Also fixes BUG: 1513920

Change-Id: I61f4574ba21969f7661b9ff0c9dce202b874025d
BUG: 1513928
Signed-off-by: Csaba Henk <csaba@redhat.com>

2 files changed, 25 insertions, 9 deletions

diff --git a/libglusterfs/src/stack.c b/libglusterfs/src/stack.c
index bf905ca0b0e..61c779b0453 100644
--- a/libglusterfs/src/stack.c
+++ b/libglusterfs/src/stack.c
@@ -63,6 +63,26 @@ create_frame (xlator_t *xl, call_pool_t *pool)
 }
 
 void
+call_stack_set_groups (call_stack_t *stack, int ngrps, gid_t **groupbuf_p)
+{
+        /* We take the ownership of the passed group buffer. */
+
+        if (ngrps <= SMALL_GROUP_COUNT) {
+                memcpy (stack->groups_small, *groupbuf_p,
+                        sizeof (gid_t) * ngrps);
+                stack->groups = stack->groups_small;
+                GF_FREE (*groupbuf_p);
+        } else {
+                stack->groups_large = *groupbuf_p;
+                stack->groups = stack->groups_large;
+        }
+
+        stack->ngrps = ngrps;
+        /* Set a canary. */
+        *groupbuf_p = (void *)0xdeadf00d;
+}
+
+void
 gf_proc_dump_call_frame (call_frame_t *call_frame, const char *key_buf,...)
 {
 
diff --git a/libglusterfs/src/stack.h b/libglusterfs/src/stack.h
index ac395fcc4b0..251a5c25e85 100644
--- a/libglusterfs/src/stack.h
+++ b/libglusterfs/src/stack.h
@@ -390,26 +390,21 @@ STACK_RESET (call_stack_t *stack)
         } while (0)
 
 
-static void
-call_stack_set_groups (call_stack_t *stack, int ngrps, gid_t *groupbuf)
-{
-        stack->groups = groupbuf;
-        stack->ngrps = ngrps;
-}
-
 static inline int
 call_stack_alloc_groups (call_stack_t *stack, int ngrps)
 {
 	if (ngrps <= SMALL_GROUP_COUNT) {
-		call_stack_set_groups (stack, ngrps, stack->groups_small);
+		stack->groups = stack->groups_small;
 	} else {
 		stack->groups_large = GF_CALLOC (ngrps, sizeof (gid_t),
 						 gf_common_mt_groups_t);
 		if (!stack->groups_large)
 			return -1;
-		call_stack_set_groups (stack, ngrps, stack->groups_large);
+		stack->groups = stack->groups_large;
 	}
 
+	stack->ngrps = ngrps;
+
 	return 0;
 }
 
@@ -507,6 +502,7 @@ copy_frame (call_frame_t *frame)
         return newframe;
 }
 
+void call_stack_set_groups (call_stack_t *stack, int ngrps, gid_t **groupbuf_p);
 void gf_proc_dump_pending_frames(call_pool_t *call_pool);
 void gf_proc_dump_pending_frames_to_dict (call_pool_t *call_pool,
                                           dict_t *dict);