From: Karel Zak <kzak@redhat.com>
Date: Wed, 16 Aug 2017 12:03:06 +0000 (+0200)
Subject: su: make wait_for_child() usable in arbitrary situation
X-Git-Tag: v2.31-rc1~35
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b55e712816f11626d4ae466742bbf0ff0b405310;p=thirdparty%2Futil-linux.git

su: make wait_for_child() usable in arbitrary situation

For example if called more than once; to keep PTY code simple and
robust.

Signed-off-by: Karel Zak <kzak@redhat.com>
---

diff --git a/login-utils/su-common.c b/login-utils/su-common.c
index 48812cbc11..f4e11dd2d8 100644
--- a/login-utils/su-common.c
+++ b/login-utils/su-common.c
@@ -334,21 +334,23 @@ static void supam_open_session(struct su_context *su)
 
 static int wait_for_child(struct su_context *su)
 {
-	pid_t pid;
+	pid_t pid = (pid_t) -1;;
 	int status = 0;
 
-	DBG(SIG, ul_debug("waiting for child [%d]...", su->child));
-	for (;;) {
-		pid = waitpid(su->child, &status, WUNTRACED);
-
-		if (pid != (pid_t) - 1 && WIFSTOPPED(status)) {
-			kill(getpid(), SIGSTOP);
-			/* once we get here, we must have resumed */
-			kill(pid, SIGCONT);
-		} else
-			break;
+	if (su->child != (pid_t) -1) {
+		DBG(SIG, ul_debug("waiting for child [%d]...", su->child));
+		for (;;) {
+			pid = waitpid(su->child, &status, WUNTRACED);
+
+			if (pid != (pid_t) - 1 && WIFSTOPPED(status)) {
+				kill(getpid(), SIGSTOP);
+				/* once we get here, we must have resumed */
+				kill(pid, SIGCONT);
+			} else
+				break;
+		}
 	}
-	if (pid != (pid_t) - 1) {
+	if (pid != (pid_t) -1) {
 		if (WIFSIGNALED(status)) {
 			fprintf(stderr, "%s%s\n",
 				strsignal(WTERMSIG(status)),