From dcee6222be8ba4e1ba4c22f6b56339bc50f624e1 Mon Sep 17 00:00:00 2001
From: Axel Burri <axel@tty0.ch>
Date: Wed, 19 Oct 2022 11:24:24 +0200
Subject: [PATCH] btrbk: append to info file instead of rewriting

A redirection (e.g. `echo foo > bar.info`) can cause empty (zero-size)
files in some circumstances.

We still write INCOMPLETE=1 to the info file before send/receive, but
instead of re-creating it without the INCOMPLETE flag, we append
INCOMPLETE=0 (keeping up compatibility with old versions of btrbk).

Ref: 4e5ae975d8 btrbk: ignore zero-size info files
---
 btrbk | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/btrbk b/btrbk
index abc85d9..f34dca7 100755
--- a/btrbk
+++ b/btrbk
@@ -1857,7 +1857,7 @@ sub btrfs_send_to_file($$$;$$)
                   );
     if(defined($ret)) {
       delete $raw_info{INCOMPLETE};
-      $ret = system_write_raw_info($vol_received, \%raw_info);
+      $ret = system_write_raw_info($vol_received, { INCOMPLETE => 0 }, append => 1);
     } else {
       push @cmd_err, "failed to check target file (not present or zero length): $check_file";
     }