1 files changed, 4 insertions, 0 deletions

diff --git a/include/libbb.h b/include/libbb.h
index 2dcdeacb1..f7a68492c 100644
--- a/include/libbb.h
+++ b/include/libbb.h
@@ -570,6 +570,10 @@ void *malloc_or_warn(size_t size) FAST_FUNC;
 void *xmalloc(size_t size) FAST_FUNC;
 void *xzalloc(size_t size) FAST_FUNC;
 void *xrealloc(void *old, size_t size) FAST_FUNC;
+/* After xrealloc_vector(v, 4, idx) it's ok to use
+ * at least v[idx] and v[idx+1], for all idx values.
+ * shift specifies how many new elements are added (1: 2, 2: 4... 8: 256...)
+ * when all elements are used up. New elements are zeroed out. */
 #define xrealloc_vector(vector, shift, idx) \
         xrealloc_vector_helper((vector), (sizeof((vector)[0]) << 8) + (shift), (idx))
 void* xrealloc_vector_helper(void *vector, unsigned sizeof_and_shift, int idx) FAST_FUNC;