[RFC PATCH v1 5/5] Add io_uring data structure build assertion

[Ammar Faizi <ammarfaizi2@gnuweeb.org>]

Ensure io_uring data structure consistent between the kernel and user
space. These assertions are taken from io_uring.c in the kernel.

Signed-off-by: Ammar Faizi <ammarfaizi2@gnuweeb.org>
---
 src/Makefile       |  3 ++-
 src/build_assert.h | 57 ++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 59 insertions(+), 1 deletion(-)
 create mode 100644 src/build_assert.h

diff --git a/src/Makefile b/src/Makefile
index 12cf49f..aed3c40 100644
--- a/src/Makefile
+++ b/src/Makefile
@@ -7,7 +7,8 @@ libdevdir ?= $(prefix)/lib
 
 CPPFLAGS ?=
 override CPPFLAGS += -D_GNU_SOURCE \
-	-Iinclude/ -include ../config-host.h
+	-Iinclude/ -include ../config-host.h \
+	-include build_assert.h
 CFLAGS ?= -g -O2 -Wall -Wextra -fno-stack-protector
 override CFLAGS += -Wno-unused-parameter -Wno-sign-compare -DLIBURING_INTERNAL
 SO_CFLAGS=-fPIC $(CFLAGS)
diff --git a/src/build_assert.h b/src/build_assert.h
new file mode 100644
index 0000000..5b2a9c6
--- /dev/null
+++ b/src/build_assert.h
@@ -0,0 +1,57 @@
+/* SPDX-License-Identifier: MIT */
+
+#ifndef LIBURING_BUILD_ASSERT_H
+#define LIBURING_BUILD_ASSERT_H
+
+#include "liburing/io_uring.h"
+#include "lib.h"
+
+static inline __attribute__((__unused__)) void io_uring_build_assert(void)
+{
+#define __BUILD_BUG_VERIFY_ELEMENT(stype, eoffset, etype, ename) do { \
+	BUILD_BUG_ON(offsetof(stype, ename) != eoffset); \
+	BUILD_BUG_ON(sizeof(etype) != sizeof_field(stype, ename)); \
+} while (0)
+
+#define BUILD_BUG_SQE_ELEM(eoffset, etype, ename) \
+	__BUILD_BUG_VERIFY_ELEMENT(struct io_uring_sqe, eoffset, etype, ename)
+	BUILD_BUG_ON(sizeof(struct io_uring_sqe) != 64);
+	BUILD_BUG_SQE_ELEM(0,  __u8,   opcode);
+	BUILD_BUG_SQE_ELEM(1,  __u8,   flags);
+	BUILD_BUG_SQE_ELEM(2,  __u16,  ioprio);
+	BUILD_BUG_SQE_ELEM(4,  __s32,  fd);
+	BUILD_BUG_SQE_ELEM(8,  __u64,  off);
+	BUILD_BUG_SQE_ELEM(8,  __u64,  addr2);
+	BUILD_BUG_SQE_ELEM(16, __u64,  addr);
+	BUILD_BUG_SQE_ELEM(16, __u64,  splice_off_in);
+	BUILD_BUG_SQE_ELEM(24, __u32,  len);
+	BUILD_BUG_SQE_ELEM(28,     __kernel_rwf_t, rw_flags);
+	BUILD_BUG_SQE_ELEM(28, /* compat */   int, rw_flags);
+	BUILD_BUG_SQE_ELEM(28, /* compat */ __u32, rw_flags);
+	BUILD_BUG_SQE_ELEM(28, __u32,  fsync_flags);
+	BUILD_BUG_SQE_ELEM(28, /* compat */ __u16,  poll_events);
+	BUILD_BUG_SQE_ELEM(28, __u32,  poll32_events);
+	BUILD_BUG_SQE_ELEM(28, __u32,  sync_range_flags);
+	BUILD_BUG_SQE_ELEM(28, __u32,  msg_flags);
+	BUILD_BUG_SQE_ELEM(28, __u32,  timeout_flags);
+	BUILD_BUG_SQE_ELEM(28, __u32,  accept_flags);
+	BUILD_BUG_SQE_ELEM(28, __u32,  cancel_flags);
+	BUILD_BUG_SQE_ELEM(28, __u32,  open_flags);
+	BUILD_BUG_SQE_ELEM(28, __u32,  statx_flags);
+	BUILD_BUG_SQE_ELEM(28, __u32,  fadvise_advice);
+	BUILD_BUG_SQE_ELEM(28, __u32,  splice_flags);
+	BUILD_BUG_SQE_ELEM(32, __u64,  user_data);
+	BUILD_BUG_SQE_ELEM(40, __u16,  buf_index);
+	BUILD_BUG_SQE_ELEM(40, __u16,  buf_group);
+	BUILD_BUG_SQE_ELEM(42, __u16,  personality);
+	BUILD_BUG_SQE_ELEM(44, __s32,  splice_fd_in);
+	BUILD_BUG_SQE_ELEM(44, __u32,  file_index);
+	BUILD_BUG_SQE_ELEM(48, __u64,  addr3);
+
+	BUILD_BUG_ON(sizeof(struct io_uring_files_update) !=
+		     sizeof(struct io_uring_rsrc_update));
+	BUILD_BUG_ON(sizeof(struct io_uring_rsrc_update) >
+		     sizeof(struct io_uring_rsrc_update2));
+}
+
+#endif
-- 
Ammar Faizi