diff options
Diffstat (limited to 'chromium/mojo/public/c/system/macros.h')
| -rw-r--r-- | chromium/mojo/public/c/system/macros.h | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/chromium/mojo/public/c/system/macros.h b/chromium/mojo/public/c/system/macros.h index 1023e1c111a..ebacb7482ac 100644 --- a/chromium/mojo/public/c/system/macros.h +++ b/chromium/mojo/public/c/system/macros.h @@ -6,6 +6,7 @@ #define MOJO_PUBLIC_C_SYSTEM_MACROS_H_ #include <stddef.h> +#include <stdint.h> #if !defined(__cplusplus) #include <assert.h> // Defines static_assert() in C11. @@ -29,6 +30,18 @@ // Like the C++11 |alignof| operator. #define MOJO_ALIGNOF(type) alignof(type) +// Provides a convenient test for the presence of a field in a user-provided +// structure from a potentially older version of the ABI. Presence is determined +// by comparing the struct's provided |struct_size| value against the known +// offset and size of the field in this version of the ABI. Because fields are +// never reordered or removed, this is a sufficient test for the field's +// presence within whatever version of the ABI the client is programmed against. +#define MOJO_IS_STRUCT_FIELD_PRESENT(struct_pointer, field) \ + ((size_t)(uintptr_t)((const char*)&(struct_pointer)->field - \ + (const char*)(struct_pointer)) + \ + sizeof((struct_pointer)->field) <= \ + (struct_pointer)->struct_size) + // Specify the alignment of a |struct|, etc. // Use like: // struct MOJO_ALIGNAS(8) Foo { ... }; |