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From: Aleksa Sarai <cyphar@cyphar.com>
To: Al Viro <viro@zeniv.linux.org.uk>, Jeff Layton <jlayton@kernel.org>,
 "J. Bruce Fields" <bfields@fieldses.org>, Arnd Bergmann <arnd@arndb.de>,
 David Howells <dhowells@redhat.com>, Shuah Khan <shuah@kernel.org>,
 Shuah Khan <skhan@linuxfoundation.org>
Subject: [PATCH v9 09/10] kselftest: save-and-restore errno to allow for %m
 formatting
Date: Sun,  7 Jul 2019 00:57:36 +1000
Message-Id: <20190706145737.5299-10-cyphar@cyphar.com>
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Cc: linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org,
 Alexei Starovoitov <ast@kernel.org>, Oleg Nesterov <oleg@redhat.com>,
 linux-kselftest@vger.kernel.org, sparclinux@vger.kernel.org,
 linux-arch@vger.kernel.org, linux-s390@vger.kernel.org,
 Tycho Andersen <tycho@tycho.ws>, Aleksa Sarai <asarai@suse.de>,
 linux-arm-kernel@lists.infradead.org, linux-mips@vger.kernel.org,
 linux-xtensa@linux-xtensa.org, Kees Cook <keescook@chromium.org>,
 Jann Horn <jannh@google.com>, linuxppc-dev@lists.ozlabs.org,
 Aleksa Sarai <cyphar@cyphar.com>, Andy Lutomirski <luto@kernel.org>,
 David Drysdale <drysdale@google.com>, Christian Brauner <christian@brauner.io>,
 linux-parisc@vger.kernel.org, linux-m68k@lists.linux-m68k.org,
 linux-api@vger.kernel.org, Chanho Min <chanho.min@lge.com>,
 linux-kernel@vger.kernel.org, Eric Biederman <ebiederm@xmission.com>,
 linux-alpha@vger.kernel.org, linux-fsdevel@vger.kernel.org,
 Andrew Morton <akpm@linux-foundation.org>,
 Linus Torvalds <torvalds@linux-foundation.org>,
 containers@lists.linux-foundation.org
Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org
Sender: "Linuxppc-dev"
 <linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org>

Previously, using "%m" in a ksft_* format string can result in strange
output because the errno value wasn't saved before calling other libc
functions. The solution is to simply save and restore the errno before
we format the user-supplied format string.

Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>
---
 tools/testing/selftests/kselftest.h | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/tools/testing/selftests/kselftest.h b/tools/testing/selftests/kselftest.h
index ec15c4f6af55..0ac49d91a260 100644
--- a/tools/testing/selftests/kselftest.h
+++ b/tools/testing/selftests/kselftest.h
@@ -10,6 +10,7 @@
 #ifndef __KSELFTEST_H
 #define __KSELFTEST_H
 
+#include <errno.h>
 #include <stdlib.h>
 #include <unistd.h>
 #include <stdarg.h>
@@ -81,58 +82,68 @@ static inline void ksft_print_cnts(void)
 
 static inline void ksft_print_msg(const char *msg, ...)
 {
+	int saved_errno = errno;
 	va_list args;
 
 	va_start(args, msg);
 	printf("# ");
+	errno = saved_errno;
 	vprintf(msg, args);
 	va_end(args);
 }
 
 static inline void ksft_test_result_pass(const char *msg, ...)
 {
+	int saved_errno = errno;
 	va_list args;
 
 	ksft_cnt.ksft_pass++;
 
 	va_start(args, msg);
 	printf("ok %d ", ksft_test_num());
+	errno = saved_errno;
 	vprintf(msg, args);
 	va_end(args);
 }
 
 static inline void ksft_test_result_fail(const char *msg, ...)
 {
+	int saved_errno = errno;
 	va_list args;
 
 	ksft_cnt.ksft_fail++;
 
 	va_start(args, msg);
 	printf("not ok %d ", ksft_test_num());
+	errno = saved_errno;
 	vprintf(msg, args);
 	va_end(args);
 }
 
 static inline void ksft_test_result_skip(const char *msg, ...)
 {
+	int saved_errno = errno;
 	va_list args;
 
 	ksft_cnt.ksft_xskip++;
 
 	va_start(args, msg);
 	printf("not ok %d # SKIP ", ksft_test_num());
+	errno = saved_errno;
 	vprintf(msg, args);
 	va_end(args);
 }
 
 static inline void ksft_test_result_error(const char *msg, ...)
 {
+	int saved_errno = errno;
 	va_list args;
 
 	ksft_cnt.ksft_error++;
 
 	va_start(args, msg);
 	printf("not ok %d # error ", ksft_test_num());
+	errno = saved_errno;
 	vprintf(msg, args);
 	va_end(args);
 }
@@ -152,10 +163,12 @@ static inline int ksft_exit_fail(void)
 
 static inline int ksft_exit_fail_msg(const char *msg, ...)
 {
+	int saved_errno = errno;
 	va_list args;
 
 	va_start(args, msg);
 	printf("Bail out! ");
+	errno = saved_errno;
 	vprintf(msg, args);
 	va_end(args);
 
@@ -178,10 +191,12 @@ static inline int ksft_exit_xpass(void)
 static inline int ksft_exit_skip(const char *msg, ...)
 {
 	if (msg) {
+		int saved_errno = errno;
 		va_list args;
 
 		va_start(args, msg);
 		printf("not ok %d # SKIP ", 1 + ksft_test_num());
+		errno = saved_errno;
 		vprintf(msg, args);
 		va_end(args);
 	} else {
-- 
2.22.0