1 files changed, 95 insertions, 0 deletions
diff --git a/misc-utils/exch.c b/misc-utils/exch.c
new file mode 100644
index 0000000..93a9f77
--- /dev/null
+++ b/misc-utils/exch.c
@@ -0,0 +1,95 @@
+/*
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * Copyright (C) 2023 Red Hat, Inc. All rights reserved.
+ * Written by Masatake YAMATO <yamato@redhat.com>
+ *
+ * exch(1) - a command line interface for RENAME_EXCHANGE of renameat2(2).
+ */
+#include "c.h"
+#include "nls.h"
+
+#include <fcntl.h>
+#include <getopt.h>
+
+#ifndef HAVE_RENAMEAT2
+# include <sys/syscall.h>
+# include <unistd.h>
+#endif
+
+#ifndef RENAME_EXCHANGE
+# define RENAME_EXCHANGE (1 << 1)
+#endif
+
+#if !defined(HAVE_RENAMEAT2) && defined(SYS_renameat2)
+static inline int renameat2(int olddirfd, const char *oldpath,
+			    int newdirfd, const char *newpath, unsigned int flags)
+{
+	return syscall (SYS_renameat2, olddirfd, oldpath, newdirfd, newpath, flags);
+}
+#endif
+
+static void __attribute__((__noreturn__)) usage(void)
+{
+	FILE *out = stdout;
+
+	fputs(USAGE_HEADER, out);
+	fprintf(out, _(" %s [options] oldpath newpath\n"), program_invocation_short_name);
+	fputs(USAGE_SEPARATOR, out);
+	fputs(_("Atomically exchanges paths between two files.\n"), out);
+
+	fputs(USAGE_OPTIONS, out);
+	fprintf(out, USAGE_HELP_OPTIONS(30));
+
+	fprintf(out, USAGE_MAN_TAIL("exch(1)"));
+
+	exit(EXIT_SUCCESS);
+}
+
+int main(int argc, char **argv)
+{
+	int c;
+	int rc;
+
+	static const struct option longopts[] = {
+		{ "version",    no_argument, NULL, 'V' },
+		{ "help",	no_argument, NULL, 'h' },
+		{ NULL }
+	};
+
+	setlocale(LC_ALL, "");
+	bindtextdomain(PACKAGE, LOCALEDIR);
+	textdomain(PACKAGE);
+
+	while ((c = getopt_long(argc, argv, "Vh", longopts, NULL)) != -1) {
+		switch (c) {
+		case 'V':
+			print_version(EXIT_SUCCESS);
+		case 'h':
+			usage();
+		default:
+			errtryhelp(EXIT_FAILURE);
+		}
+	}
+
+	if (argc - optind < 2) {
+		warnx(_("too few arguments"));
+		errtryhelp(EXIT_FAILURE);
+	} else if (argc - optind > 2) {
+		warnx(_("too many arguments"));
+		errtryhelp(EXIT_FAILURE);
+	}
+
+	rc = renameat2(AT_FDCWD, argv[optind],
+		       AT_FDCWD, argv[optind + 1], RENAME_EXCHANGE);
+	if (rc)
+		warn(_("failed to exchange \"%s\" and \"%s\""),
+		     argv[optind], argv[optind + 1]);
+
+	return rc == 0 ? EXIT_SUCCESS : EXIT_FAILURE;
+}