Merge branch 'selftests-fix-build-warnings-and-errors' (part)

Guenter Roeck says:

====================
selftests: Fix build warnings and errors

This series fixes build warnings and errors observed when trying to build
selftests.
====================

Link: https://patch.msgid.link/20251205171010.515236-1-linux@roeck-us.net
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: kuba-moo

tools/testing/selftests/net/af_unix/Makefile

@@ -1,4 +1,9 @@
-CFLAGS += $(KHDR_INCLUDES) -Wall -Wflex-array-member-not-at-end
+top_srcdir := ../../../../..
+include $(top_srcdir)/scripts/Makefile.compiler
+
+cc-option = $(call __cc-option, $(CC),,$(1),$(2))
+
+CFLAGS += $(KHDR_INCLUDES) -Wall $(call cc-option,-Wflex-array-member-not-at-end)
 
 TEST_GEN_PROGS := \
 	diag_uid \

tools/testing/selftests/net/lib/ksft.h

@@ -24,7 +24,8 @@ static inline void ksft_ready(void)
 		fd = STDOUT_FILENO;
 	}
 
-	write(fd, msg, sizeof(msg));
+	if (write(fd, msg, sizeof(msg)) < 0)
+		perror("write()");
 	if (fd != STDOUT_FILENO)
 		close(fd);
 }
@@ -48,7 +49,8 @@ static inline void ksft_wait(void)
 		fd = STDIN_FILENO;
 	}
 
-	read(fd, &byte, sizeof(byte));
+	if (read(fd, &byte, sizeof(byte)) < 0)
+		perror("read()");
 	if (fd != STDIN_FILENO)
 		close(fd);
 }

tools/testing/selftests/net/tfo.c

@@ -81,7 +81,8 @@ static void run_server(void)
 	if (getsockopt(connfd, SOL_SOCKET, SO_INCOMING_NAPI_ID, &opt, &len) < 0)
 		error(1, errno, "getsockopt(SO_INCOMING_NAPI_ID)");
 
-	read(connfd, buf, 64);
+	if (read(connfd, buf, 64) < 0)
+		perror("read()");
 	fprintf(outfile, "%d\n", opt);
 
 	fclose(outfile);