diff mbox series

[Concept,02/14] alist: Zero new entries in alist_add_placeholder()

Message ID 20260322235719.1729267-3-sjg@u-boot.org
State New
Headers
Series bootstd: Infrastructure for multi-entry bootflow support |

Commit Message

Simon Glass March 22, 2026, 11:57 p.m. UTC 
  From: Simon Glass <sjg@chromium.org>

It is convenient for alist_add_placeholder() to zero the entry before
returning it. This saves callers from needing to do it themselves.

Update an alist test to verify the new entry is zeroed.

Signed-off-by: Simon Glass <sjg@chromium.org>
---

 include/alist.h  |  7 +++----
 lib/alist.c      |  8 +++++++-
 test/lib/alist.c | 10 ++++++++++
 3 files changed, 20 insertions(+), 5 deletions(-)

-- 
2.43.0
diff mbox series

Patch

diff --git a/include/alist.h b/include/alist.h
index 69d7cdb722f..7b368a7e09a 100644
--- a/include/alist.h
+++ b/include/alist.h
@@ -174,12 +174,11 @@  void *alist_ensure_ptr(struct alist *lst, uint index);
 	((_struct *)alist_ensure_ptr(_lst, _index))
 
 /**
- * alist_add_placeholder() - Add a new item to the end of the list
+ * alist_add_placeholder() - Add a new zeroed item to the end of the list
  *
  * @lst: alist to add to
- * Return: Pointer to the newly added position, or NULL if out of memory. Note
- * that this is not inited so the caller must copy the requested struct to the
- * returned pointer
+ * Return: Pointer to the newly added position (zeroed), or NULL if out of
+ * memory
  */
 void *alist_add_placeholder(struct alist *lst);
 
diff --git a/lib/alist.c b/lib/alist.c
index 0ae07f0f5c0..b9ddd4103c4 100644
--- a/lib/alist.c
+++ b/lib/alist.c
@@ -165,7 +165,13 @@  void *alist_ensure_ptr(struct alist *lst, uint index)
 
 void *alist_add_placeholder(struct alist *lst)
 {
-	return alist_ensure_ptr(lst, lst->count);
+	void *ptr;
+
+	ptr = alist_ensure_ptr(lst, lst->count);
+	if (ptr)
+		memset(ptr, '\0', lst->obj_size);
+
+	return ptr;
 }
 
 void *alist_add_ptr(struct alist *lst, void *obj)
diff --git a/test/lib/alist.c b/test/lib/alist.c
index 108eaed8d92..8e958ed9398 100644
--- a/test/lib/alist.c
+++ b/test/lib/alist.c
@@ -219,8 +219,18 @@  static int lib_test_alist_add(struct unit_test_state *uts)
 	ut_asserteq(123, ptr->val);
 	ut_asserteq(456, ptr->other_val);
 
+	/* Add a non-zero entry then remove it, so the memory is dirty */
 	ptr2 = alist_add_placeholder(&lst);
 	ut_assertnonnull(ptr2);
+	ptr2->val = 999;
+	ptr2->other_val = 888;
+	lst.count--;
+
+	/* Now add again — the slot should be zeroed despite dirty memory */
+	ptr2 = alist_add_placeholder(&lst);
+	ut_assertnonnull(ptr2);
+	ut_asserteq(0, ptr2->val);
+	ut_asserteq(0, ptr2->other_val);
 
 	ptr2->val = 321;
 	ptr2->other_val = 654;