upstream: There are lots of place where we want to redirect stdin,

stdout and/or stderr to /dev/null. Factor all these out to a single
stdfd_devnull() function that allows selection of which of these to redirect.
ok markus@

OpenBSD-Commit-ID: 3033ba5a4c47cacfd5def020d42cabc52fad3099

1 files changed, 4 insertions, 15 deletions

diff --git a/readconf.c b/readconf.c
index 1963a83b..a4f6cba0 100644
--- a/readconf.c
+++ b/readconf.c
@@ -1,4 +1,4 @@
-/* $OpenBSD: readconf.c,v 1.336 2020/10/03 08:30:47 djm Exp $ */
+/* $OpenBSD: readconf.c,v 1.337 2020/10/03 09:22:26 djm Exp $ */
 /*
  * Author: Tatu Ylonen <ylo@cs.hut.fi>
  * Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
@@ -509,7 +509,7 @@ execute_in_shell(const char *cmd)
 {
 	char *shell;
 	pid_t pid;
-	int devnull, status;
+	int status;
 
 	if ((shell = getenv("SHELL")) == NULL)
 		shell = _PATH_BSHELL;
@@ -519,23 +519,14 @@ execute_in_shell(const char *cmd)
 		    shell, strerror(errno));
 	}
 
-	/* Need this to redirect subprocess stdin/out */
-	if ((devnull = open(_PATH_DEVNULL, O_RDWR)) == -1)
-		fatal("open(/dev/null): %s", strerror(errno));
-
 	debug("Executing command: '%.500s'", cmd);
 
 	/* Fork and execute the command. */
 	if ((pid = fork()) == 0) {
 		char *argv[4];
 
-		/* Redirect child stdin and stdout. Leave stderr */
-		if (dup2(devnull, STDIN_FILENO) == -1)
-			fatal("dup2: %s", strerror(errno));
-		if (dup2(devnull, STDOUT_FILENO) == -1)
-			fatal("dup2: %s", strerror(errno));
-		if (devnull > STDERR_FILENO)
-			close(devnull);
+		if (stdfd_devnull(1, 1, 0) == -1)
+			fatal("%s: stdfd_devnull failed", __func__);
 		closefrom(STDERR_FILENO + 1);
 
 		argv[0] = shell;
@@ -554,8 +545,6 @@ execute_in_shell(const char *cmd)
 	if (pid == -1)
 		fatal("%s: fork: %.100s", __func__, strerror(errno));
 
-	close(devnull);
-
 	while (waitpid(pid, &status, 0) == -1) {
 		if (errno != EINTR && errno != EAGAIN)
 			fatal("%s: waitpid: %s", __func__, strerror(errno));