tcon: Add tcon_sizeof() helper

Add a new tcon_sizeof() helper macro which returns the size of a type for
which a canary has been constructed with TCON or TCON_WRAP.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

diff --git a/ccan/tcon/tcon.h b/ccan/tcon/tcon.h
index a256f1031486513e6c5057f0ef918170701223ea..62bacf537b4261e2095fa59b35e0be51df7ff981 100644 (file)
--- a/ccan/tcon/tcon.h
+++ b/ccan/tcon/tcon.h
@@ -159,6 +159,13 @@
 #define tcon_type(x, canary) void *
 #endif
 
 #define tcon_type(x, canary) void *
 #endif
 

+/**
+ * tcon_sizeof - the size of type within a container
+ * @x: the structure containing the TCON.
+ * @canary: which canary to check against.
+ */
+#define tcon_sizeof(x, canary) sizeof((x)->_tcon[0].canary)
+

 /**
  * tcon_ptr_type - pointer to the type within a container (or void *)
  * @x: the structure containing the TCON.
 /**
  * tcon_ptr_type - pointer to the type within a container (or void *)
  * @x: the structure containing the TCON.

diff --git a/ccan/tcon/test/compile_ok-sizeof.c b/ccan/tcon/test/compile_ok-sizeof.c
new file mode 100644 (file)
index 0000000..64ccc13
--- /dev/null
+++ b/ccan/tcon/test/compile_ok-sizeof.c
@@ -0,0 +1,35 @@
+#include <ccan/tcon/tcon.h>
+#include <ccan/build_assert/build_assert.h>
+#include <stdlib.h>
+
+struct container {
+       void *p;
+};
+
+struct int_container {
+       struct container raw;
+       TCON(int tc);
+};
+
+struct charp_and_int_container {
+       struct container raw;
+       TCON(int tc1; char *tc2);
+};
+
+int main(int argc, char *argv[])
+{
+       struct int_container icon;
+       struct charp_and_int_container cicon;
+       TCON_WRAP(struct container, int tc) iconw;
+       TCON_WRAP(struct container, int tc1; char *tc2) ciconw;
+
+       BUILD_ASSERT(tcon_sizeof(&icon, tc) == sizeof(int));
+       BUILD_ASSERT(tcon_sizeof(&cicon, tc1) == sizeof(int));
+       BUILD_ASSERT(tcon_sizeof(&cicon, tc2) == sizeof(char *));
+
+       BUILD_ASSERT(tcon_sizeof(&iconw, tc) == sizeof(int));
+       BUILD_ASSERT(tcon_sizeof(&ciconw, tc1) == sizeof(int));
+       BUILD_ASSERT(tcon_sizeof(&ciconw, tc2) == sizeof(char *));
+
+       return 0;
+}