tar: add --mode option (compatible with gnutar)

tar/CMakeLists.txt

@@ -21,6 +21,8 @@ IF(ENABLE_TAR)
     ../libarchive_fe/lafe_err.c
     ../libarchive_fe/lafe_err.h
     ../libarchive_fe/lafe_platform.h
+    ../libarchive_fe/lafe_setmode.c
+    ../libarchive_fe/lafe_setmode.h
     ../libarchive_fe/line_reader.c
     ../libarchive_fe/line_reader.h
     ../libarchive_fe/passphrase.c

tar/bsdtar.1

@@ -421,6 +421,13 @@ is run in x mode as root.
 Currently supported only for pax formats
 .Po including "pax restricted", the default tar format for
 .Nm bsdtar Pc
+.It Fl Fl mode Ar permissions
+(c, r, u modes only)
+Modify the file mode bits stored in the archive.
+Permissions can be absolute (an octal number) or symbolic.
+See
+.Xr chmod 1
+for more information and examples of both types.
 .It Fl Fl mtime Ar date
 (c, r, u modes only)
 Set the modification times of added files to the specified date.

tar/bsdtar.c

@@ -56,6 +56,7 @@
 
 #include "bsdtar.h"
 #include "lafe_err.h"
+#include "lafe_setmode.h"
 
 #if ARCHIVE_VERSION_NUMBER < 4000000 && !defined(_PATH_DEFTAPE)
 // Libarchive 4.0 and later will NOT define _PATH_DEFTAPE
@@ -512,6 +513,14 @@ main(int argc, char **argv)
 			bsdtar->extract_flags |= ARCHIVE_EXTRACT_MAC_METADATA;
 			bsdtar->flags |= OPTFLAG_MAC_METADATA;
 			break;
+		case OPTION_MODE: /* GNU tar */
+			free(bsdtar->file_mode);
+			bsdtar->file_mode = lafe_setmode(bsdtar->argument);
+			if (bsdtar->file_mode == NULL)
+				lafe_errc(1, 0,
+					"Invalid file mode: %s",
+					bsdtar->argument);
+			break;
 		case 'n': /* GNU tar */
 			bsdtar->flags |= OPTFLAG_NO_SUBDIRS;
 			break;
@@ -1023,6 +1032,7 @@ main(int argc, char **argv)
 #endif
 	cset_free(bsdtar->cset);
 	passphrase_free(bsdtar->ppbuff);
+	free(bsdtar->file_mode);
 
 	if (bsdtar->return_value != 0)
 		lafe_warnc(0,

tar/bsdtar.h

@@ -47,6 +47,7 @@ struct bsdtar {
 	const char	 *gname; /* --gname */
 	int		  uid;  /* --uid */
 	const char	 *uname; /* --uname */
+	void 		 *file_mode; /* --mode */
 	const char	 *passphrase; /* --passphrase */
 	int		  mode; /* Program mode: 'c', 't', 'r', 'u', 'x' */
 	char		  symlink_mode; /* H or L, per BSD conventions */
@@ -186,6 +187,7 @@ enum {
 	OPTION_ZSTD,
 	OPTION_MTIME,
 	OPTION_CLAMP_MTIME,
+	OPTION_MODE,
 };
 
 int	bsdtar_getopt(struct bsdtar *);

tar/cmdline.c

@@ -95,6 +95,7 @@ static const struct bsdtar_option {
 	{ "lzma",                 0, OPTION_LZMA },
 	{ "lzop",                 0, OPTION_LZOP },
 	{ "mac-metadata",         0, OPTION_MAC_METADATA },
+	{ "mode",                 1, OPTION_MODE },
 	{ "modification-time",    0, 'm' },
 	{ "mtime",                1, OPTION_MTIME },
 	{ "newer",		  1, OPTION_NEWER_CTIME },

tar/test/CMakeLists.txt

@@ -59,6 +59,7 @@ IF(ENABLE_TAR AND ENABLE_TEST)
     test_option_lz4.c
     test_option_lzma.c
     test_option_lzop.c
+    test_option_mode.c
     test_option_mtime.c
     test_option_n.c
     test_option_newer_than.c

tar/test/test_option_mode.c

@@ -0,0 +1,56 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause
+ *
+ * Copyright (c) 2026 Dan Nelson
+ * All rights reserved.
+ */
+#include "test.h"
+
+DEFINE_TEST(test_option_mode)
+{
+	int rv;
+	char *p;
+
+	assertMakeDir("in", 0755);
+
+	/* Test invalid modes */
+	rv = systemf("%s --mode 8 -cf archive.tar in > 1.out 2> 1.err",
+		testprog);
+	assert(rv != 0);
+
+	rv = systemf("%s --mode a+a -cf archive.tar in > 2.out 2> 2.err",
+		testprog);
+	assert(rv != 0);
+
+	/* Create some files with different modes */
+	assertMakeFile("in/all", 0777, "");
+	assertMakeFile("in/minimal", 0500, "");
+
+	/* Archive and override using an absolute mode */
+	assertEqualInt(0,
+		systemf("%s --mode 644 -cf archive1.tar "
+			"in/all in/minimal", testprog));
+
+	/* Verify the modes */
+	p = slurpfile(NULL, "archive1.tar");
+	assertEqualString(p + 100,"000644 ");
+	assertEqualString(p + 612,"000644 ");
+	free(p);
+
+/* Skip relative symbolic mode checks on Windows; on-disk files always have
+ * mode 644.
+ */
+#if !defined(_WIN32) || defined(__CYGWIN__)
+	/* Archive and override using a symbolic mode */
+	assertEqualInt(0,
+		systemf("%s --mode u+rw-x,g+X,o-w -cf archive2.tar "
+			"in/all in/minimal", testprog));
+
+	/* Verify the modes */
+	p = slurpfile(NULL, "archive2.tar");
+	assertEqualString(p + 100,"000675 ");
+	assertEqualString(p + 612,"000610 ");
+	free(p);
+#endif
+
+}

tar/write.c

@@ -59,6 +59,7 @@
 
 #include "bsdtar.h"
 #include "lafe_err.h"
+#include "lafe_setmode.h"
 #include "line_reader.h"
 
 #ifndef O_BINARY
@@ -942,6 +943,12 @@ write_hierarchy(struct bsdtar *bsdtar, struct archive *a, const char *path)
 		if (bsdtar->gname)
 			archive_entry_set_gname(entry, bsdtar->gname);
 
+		if (bsdtar->file_mode) {
+			mode_t m = archive_entry_mode(entry);
+			m = lafe_getmode(bsdtar->file_mode, m);
+			archive_entry_set_mode(entry, m);
+		}
+
 		/*
 		 * Rewrite the pathname to be archived.  If rewrite
 		 * fails, skip the entry.