ffi: correct treatment of (ptr buf).

The buf FFI type's alloc virtual should return a pointer to
the buffer's pointer, not the buffer itself.
What's currently going on is something silly, whereby
the pointer to the buffer is stored into the buffer
itself.

* buf.c (buf_addr_of): New function.

* buf.c (buf_addr_of): Declared.

* ffi.c (ffi_buf_alloc): Use buf_addr_of instead of buf_get.

3 files changed, 8 insertions, 1 deletions

diff --git a/buf.c b/buf.c
index 58cd4177..661514be 100644
--- a/buf.c
+++ b/buf.c
@@ -204,6 +204,12 @@ mem_t *buf_get(val buf, val self)
   return b->data;
 }
 
+mem_t **buf_addr_of(val buf, val self)
+{
+  struct buf *b = buf_handle(buf, self);
+  return &b->data;
+}
+
 void buf_fill(val buf, mem_t *src, val self)
 {
   struct buf *b = buf_handle(buf, self);
diff --git a/buf.h b/buf.h
index 8102fff8..b65f7037 100644
--- a/buf.h
+++ b/buf.h
@@ -32,6 +32,7 @@ val buf_trim(val buf);
 val buf_set_length(val obj, val len, val init_val);
 val length_buf(val buf);
 mem_t *buf_get(val buf, val self);
+mem_t **buf_addr_of(val buf, val self);
 void buf_fill(val buf, mem_t *src, val self);
 
 #if HAVE_I8
diff --git a/ffi.c b/ffi.c
index aa55a39e..cad0376d 100644
--- a/ffi.c
+++ b/ffi.c
@@ -642,7 +642,7 @@ static val ffi_buf_get(struct txr_ffi_type *tft, mem_t *src, val self)
 static mem_t *ffi_buf_alloc(struct txr_ffi_type *tft, val buf, val self)
 {
   (void) tft;
-  return buf_get(buf, self);
+  return coerce(mem_t *, buf_addr_of(buf, self));
 }
 
 static void ffi_ptr_walk(struct txr_ffi_type *tft, mem_t *ctx,