From 074259f4f3966aeac6edb205fecbc1a8d2b58bb2 Mon Sep 17 00:00:00 2001
From: Lasse Collin <lasse.collin@tukaani.org>
Date: Mon, 11 Jan 2021 23:41:16 +0200
Subject: [PATCH] xz: Make --keep accept symlinks, hardlinks, and
 setuid/setgid/sticky.

Previously this required using --force but that has other
effects too which might be undesirable. Changing the behavior
of --keep has a small risk of breaking existing scripts but
since this is a fairly special corner case I expect the
likehood of breakage to be low enough.

I think the new behavior is more logical. The only reason for
the old behavior was to be consistent with gzip and bzip2.

Thanks to Vincent Lefevre and Sebastian Andrzej Siewior.
---
 src/xz/file_io.c |  9 +++++----
 src/xz/xz.1      | 16 +++++++++++++++-
 2 files changed, 20 insertions(+), 5 deletions(-)

diff --git a/src/xz/file_io.c b/src/xz/file_io.c
index e1a37d5f..80b56d38 100644
--- a/src/xz/file_io.c
+++ b/src/xz/file_io.c
@@ -536,8 +536,9 @@ io_open_src_real(file_pair *pair)
 	}
 
 	// Symlinks are not followed unless writing to stdout or --force
-	// was used.
-	const bool follow_symlinks = opt_stdout || opt_force;
+	// or --keep was used.
+	const bool follow_symlinks
+			= opt_stdout || opt_force || opt_keep_original;
 
 	// We accept only regular files if we are writing the output
 	// to disk too. bzip2 allows overriding this with --force but
@@ -674,7 +675,7 @@ io_open_src_real(file_pair *pair)
 	}
 
 #ifndef TUKLIB_DOSLIKE
-	if (reg_files_only && !opt_force) {
+	if (reg_files_only && !opt_force && !opt_keep_original) {
 		if (pair->src_st.st_mode & (S_ISUID | S_ISGID)) {
 			// gzip rejects setuid and setgid files even
 			// when --force was used. bzip2 doesn't check
@@ -683,7 +684,7 @@ io_open_src_real(file_pair *pair)
 			// and setgid bits there.
 			//
 			// We accept setuid and setgid files if
-			// --force was used. We drop these bits
+			// --force or --keep was used. We drop these bits
 			// explicitly in io_copy_attr().
 			message_warning(_("%s: File has setuid or "
 					"setgid bit set, skipping"),
diff --git a/src/xz/xz.1 b/src/xz/xz.1
index db9de4ff..9721ed39 100644
--- a/src/xz/xz.1
+++ b/src/xz/xz.1
@@ -5,7 +5,7 @@
 .\" This file has been put into the public domain.
 .\" You can do whatever you want with this file.
 .\"
-.TH XZ 1 "2020-11-01" "Tukaani" "XZ Utils"
+.TH XZ 1 "2021-01-11" "Tukaani" "XZ Utils"
 .
 .SH NAME
 xz, unxz, xzcat, lzma, unlzma, lzcat \- Compress or decompress .xz and .lzma files
@@ -392,6 +392,20 @@ should be used.
 .TP
 .BR \-k ", " \-\-keep
 Don't delete the input files.
+.IP ""
+Since
+.B xz
+5.4.0,
+this option also makes
+.B xz
+compress or decompress even if the input is
+a symbolic link to a regular file,
+has more than one hard link,
+or has the setuid, setgid, or sticky bit set.
+The setuid, setgid, and sticky bits are not copied
+to the target file.
+In earlier versions this was only done with
+.BR \-\-force .
 .TP
 .BR \-f ", " \-\-force
 This option has several effects: