btr: Introduce btr_add_output_dont_free().

[paraslash.git] / buffer_tree.c

diff --git a/buffer_tree.c b/buffer_tree.c
index 5c884709bab83407fa3f90bcc13bfc1c1b9b7550..c62cbf13c3bdc4b621bd891d41e1b74fe24d98fe 100644 (file)
--- a/buffer_tree.c
+++ b/buffer_tree.c
@@ -30,6 +30,8 @@ struct btr_buffer {
        int refcount;
        /* NULL means no buffer pool but a malloced buffer. */
        struct btr_pool *pool;
        int refcount;
        /* NULL means no buffer pool but a malloced buffer. */
        struct btr_pool *pool;

+       /* Only relevant if pool is NULL. */
+       bool dont_free;

 };
 
 struct btr_buffer_reference {
 };
 
 struct btr_buffer_reference {


@@ -319,7 +321,7 @@ static void dealloc_buffer(struct btr_buffer *btrb)
 {
        if (btrb->pool)
                btr_pool_deallocate(btrb->pool, btrb->size);
 {
        if (btrb->pool)
                btr_pool_deallocate(btrb->pool, btrb->size);

-       else
+       else if (!btrb->dont_free)

                free(btrb->buf);
 }
 
                free(btrb->buf);
 }
 


@@ -392,6 +394,34 @@ void btr_add_output(char *buf, size_t size, struct btr_node *btrn)
        add_btrb_to_children(btrb, btrn, 0);
 }
 
        add_btrb_to_children(btrb, btrn, 0);
 }
 

+/**
+ * Insert a buffer into the buffer tree, non-freeing variant.
+ *
+ * \param buf See \ref btr_add_output().
+ * \param size See \ref btr_add_output().
+ * \param btrn See \ref btr_add_output().
+ *
+ * This is similar to btr_add_output() but additionally sets the \p dont_free
+ * flag on \a buf. If the refcount for the buffer drops to zero, \a buf will
+ * not be deallocated if this flag is set.
+ *
+ * The \p dont_free bit also prevents the children of \a btrn from modifying
+ * the buffer contents inplace. Specifically, \ref btr_inplace_ok() returns
+ * false if there is any buffer in the input queue with the \p dont_free bit
+ * set.
+ */
+void btr_add_output_dont_free(const char *buf, size_t size, struct btr_node *btrn)
+{
+       struct btr_buffer *btrb;
+
+       assert(size != 0);
+       if (list_empty(&btrn->children))
+               return;
+       btrb = new_btrb((char *)buf, size);
+       btrb->dont_free = true;
+       add_btrb_to_children(btrb, btrn, 0);
+}
+

 /**
  * Feed data to child nodes of a buffer tree node.
  *
 /**
  * Feed data to child nodes of a buffer tree node.
  *


@@ -544,9 +574,15 @@ bool btr_no_parent(struct btr_node *btrn)
  */
 bool btr_inplace_ok(struct btr_node *btrn)
 {
  */
 bool btr_inplace_ok(struct btr_node *btrn)
 {

-       if (!btrn->parent)
-               return true;
-       return list_is_singular(&btrn->parent->children);
+       struct btr_buffer_reference *br;
+       FOR_EACH_BUFFER_REF(br, btrn) {
+               struct btr_buffer *btrb = br->btrb;
+               if (btrb->refcount > 1)
+                       return false;
+               if (btrb->dont_free == true)
+                       return false;
+       }
+       return true;

 }
 
 static inline size_t br_available_bytes(struct btr_buffer_reference *br)
 }
 
 static inline size_t br_available_bytes(struct btr_buffer_reference *br)