io_uring: work aroung struct io_uring_rsrc_register field name change

resv field has been renamed to flags in Linux commit v5.19-rc1~251^2~20,
provide a shim to support old decoding syntax.

* configure.ac (AC_CHECK_TYPES): Add struct io_uring_rsrc_register
and struct io_uring_rsrc_register.resv checks.
* src/io_uring.c [HAVE_STRUCT_IO_URING_RSRC_REGISTER_RESV] (RESV):
Define as resv.
[!HAVE_STRUCT_IO_URING_RSRC_REGISTER_RESV] (RESV): Define as flags.
(print_io_uring_register_rsrc): Use RESV instead of resv;  print "resv"
field name explicitly and use PRINT_VAL_X instead of PRINT_FIELD_X.
* tests/io_uring_register.c [HAVE_STRUCT_IO_URING_RSRC_REGISTER_RESV] (RESV):
Define as resv.
[!HAVE_STRUCT_IO_URING_RSRC_REGISTER_RESV] (RESV): Define as flags.
(main): Use RESV to access struct io_uring_rsrc_register.resv field.

configure.ac

@@ -571,6 +571,12 @@ AC_CHECK_MEMBERS(m4_normalize([
 		struct iocb.aio_rw_flags
 		]),,, [#include <linux/aio_abi.h>])
 
+AC_CHECK_TYPES([struct io_uring_rsrc_register], [
+	AC_CHECK_MEMBERS(m4_normalize([
+		struct io_uring_rsrc_register.resv
+	]),,, [#include <linux/io_uring.h>])
+],, [#include <linux/io_uring.h>])
+
 CPPFLAGS="$saved_CPPFLAGS"
 
 st_CHECK_ENUMS

src/io_uring.c

@@ -385,13 +385,20 @@ print_io_uring_rsrc_tags(struct tcb *tcp, const uint64_t tags,
 		    tfetch_mem, print_xint_array_member, NULL);
 }
 
+/* Work around field name change in Linux commit v5.19-rc1~251^2~20. */
+#ifdef HAVE_STRUCT_IO_URING_RSRC_REGISTER_RESV
+# define RESV resv
+#else
+# define RESV flags
+#endif
+
 static void
 print_io_uring_register_rsrc(struct tcb *tcp, const kernel_ulong_t addr,
 			     const unsigned int size, const unsigned int opcode)
 {
 	struct io_uring_rsrc_register arg;
 	CHECK_TYPE_SIZE(arg, 32);
-	CHECK_TYPE_SIZE(arg.resv, sizeof(uint32_t));
+	CHECK_TYPE_SIZE(arg.RESV, sizeof(uint32_t));
 	CHECK_TYPE_SIZE(arg.resv2, sizeof(uint64_t));
 
 	if (size < 32) {
@@ -405,9 +412,10 @@ print_io_uring_register_rsrc(struct tcb *tcp, const kernel_ulong_t addr,
 	tprint_struct_begin();
 	PRINT_FIELD_U(arg, nr);
 
-	if (arg.resv) {
+	if (arg.RESV) {
 		tprint_struct_next();
-		PRINT_FIELD_X(arg, resv);
+		tprints_field_name("resv");
+		PRINT_VAL_X(arg.RESV);
 	}
 
 	if (arg.resv2) {
@@ -427,6 +435,8 @@ print_io_uring_register_rsrc(struct tcb *tcp, const kernel_ulong_t addr,
 	tprint_struct_end();
 }
 
+#undef RESV
+
 static void
 print_io_uring_update_rsrc(struct tcb *tcp, const kernel_ulong_t addr,
 			   const unsigned int size, const unsigned int opcode)

tests/io_uring_register.c

@@ -44,6 +44,13 @@
 
 #define ARR_ITEM(arr_, idx_) ((arr_)[(idx_) % ARRAY_SIZE(arr_)])
 
+/* Work around field name change in Linux commit v5.19-rc1~251^2~20. */
+#ifdef HAVE_STRUCT_IO_URING_RSRC_REGISTER_RESV
+# define RESV resv
+#else
+# define RESV flags
+#endif
+
 static const char path_null[] = "/dev/null";
 static const char path_full[] = "/dev/full";
 
@@ -702,7 +709,7 @@ main(void)
 			rsrc_reg->nr += !!(j & 16);
 			rsrc_reg->nr &= ~-!(j & 32);
 
-			rsrc_reg->resv = j & 64 ? 0xbadc0ded : 0;
+			rsrc_reg->RESV = j & 64 ? 0xbadc0ded : 0;
 			rsrc_reg->resv2 = j & 128 ? 0xfacecafebeeffeedULL : 0;
 
 			memcpy(big_rsrc_reg, rsrc_reg, sizeof(*rsrc_reg));