From 4cf08811e112100a2b10c60047f3c537ad21d674 Mon Sep 17 00:00:00 2001
From: David Seifert <soap@gentoo.org>
Date: Sat, 28 Jan 2023 14:22:42 +0100
Subject: [PATCH] Use `freopen()` on {stdin,stdout,stderr}

* ISO C does not guarantee that the standard streams are modifiable
  lvalues. Glibc even calls out this behaviour as non-portable:
    https://www.gnu.org/software/libc/manual/html_node/Standard-Streams.html
--- a/lib/log/log.c
+++ b/lib/log/log.c
@@ -208,7 +208,11 @@ int reopen_standard_stream(FILE **stream, const char *mode)
 
 	_check_and_replace_standard_log_streams(old_stream, new_stream);
 
+#ifdef __GLIBC__
 	*stream = new_stream;
+#else
+	freopen(NULL, mode, *stream);
+#endif
 	return 1;
 }
 
--- a/tools/lvmcmdline.c
+++ b/tools/lvmcmdline.c
@@ -3422,7 +3422,7 @@ static int _check_standard_fds(void)
 	int err = is_valid_fd(STDERR_FILENO);
 
 	if (!is_valid_fd(STDIN_FILENO) &&
-	    !(stdin = fopen(_PATH_DEVNULL, "r"))) {
+	    !freopen(_PATH_DEVNULL, "r", stdin)) {
 		if (err)
 			perror("stdin stream open");
 		else
@@ -3432,7 +3432,7 @@ static int _check_standard_fds(void)
 	}
 
 	if (!is_valid_fd(STDOUT_FILENO) &&
-	    !(stdout = fopen(_PATH_DEVNULL, "w"))) {
+	    !freopen(_PATH_DEVNULL, "w", stdout)) {
 		if (err)
 			perror("stdout stream open");
 		/* else no stdout */
@@ -3440,7 +3440,7 @@ static int _check_standard_fds(void)
 	}
 
 	if (!is_valid_fd(STDERR_FILENO) &&
-	    !(stderr = fopen(_PATH_DEVNULL, "w"))) {
+	    !freopen(_PATH_DEVNULL, "w", stderr)) {
 		printf("stderr stream open: %s\n",
 		       strerror(errno));
 		return 0;
-- 
2.39.2