linux-kernel - [PATCH nolibc 43/61] tools/nolibc/stdio: make printf(%s) accept NULL

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Message-Id: <20220419004225.3952530-43-paulmck@kernel.org>
Date:   Mon, 18 Apr 2022 17:42:07 -0700
From:   "Paul E. McKenney" <paulmck@...nel.org>
To:     linux-kernel@...r.kernel.org
Cc:     gwml@...r.gnuweeb.org, kernel-team@...com, w@....eu,
        Willy Tarreau <w@....eu>,
        "Paul E . McKenney" <paulmck@...nel.org>
Subject: [PATCH nolibc 43/61] tools/nolibc/stdio: make printf(%s) accept NULL

From: Willy Tarreau <w@....eu>

It's often convenient to support this, especially in test programs where
a NULL may correspond to an allocation error or a non-existing value.
Let's make printf("%s") support being passed a NULL. In this case it
prints "(null)" like glibc's printf().

Signed-off-by: Willy Tarreau <w@....eu>
Signed-off-by: Paul E. McKenney <paulmck@...nel.org>
---
 tools/include/nolibc/stdio.h | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/tools/include/nolibc/stdio.h b/tools/include/nolibc/stdio.h
index cb4d3ab3a565..559ebe052a75 100644
--- a/tools/include/nolibc/stdio.h
+++ b/tools/include/nolibc/stdio.h
@@ -220,6 +220,8 @@ int vfprintf(FILE *stream, const char *fmt, va_list args)
 			}
 			else if (c == 's') {
 				outstr = va_arg(args, char *);
+				if (!outstr)
+					outstr="(null)";
 			}
 			else if (c == '%') {
 				/* queue it verbatim */
-- 
2.31.1.189.g2e36527f23