From: Cristian Rodríguez <crrodriguez@opensuse.org>
Date: Sun, 15 Jan 2023 01:33:14 +0000 (+0000)
Subject: hardlink: calling putchar is off-limits on a signal handler
X-Git-Tag: v2.39-rc1~123^2~1
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=ab35a4fb0e2d53a36918b515e95ed8c9a79f1da1;p=thirdparty%2Futil-linux.git

hardlink: calling putchar is off-limits on a signal handler

Using putchar or any stdio function in signal handlers will
lead to funny results as they cannot be async signal safe.
One can write to stdout instead.
---

diff --git a/misc-utils/hardlink.c b/misc-utils/hardlink.c
index 8cab567685..7e66dfdde1 100644
--- a/misc-utils/hardlink.c
+++ b/misc-utils/hardlink.c
@@ -1380,7 +1380,8 @@ static void sighandler(int i)
 	if (last_signal != SIGINT)
 		last_signal = i;
 	if (i == SIGINT)
-		putchar('\n');
+		/* can't use stdio on signal handler */
+		ignore_result(write(STDOUT_FILENO, "\n", sizeof("\n")-1));
 }
 
 int main(int argc, char *argv[])