From 76df06ff8fa39ae0cb0d167b7f622139778dc7d7 Mon Sep 17 00:00:00 2001

From: Kamil Dudka <kdudka@redhat.com>

Date: Thu, 4 Jan 2018 09:42:10 +0100

Subject: [PATCH] mv -n: do not overwrite the destination

... if it is created by another process after mv has checked its

non-existence.

* src/copy.c (copy_internal): Use renameat2 (..., RENAME_NOREPLACE)

if called by mv -n.  If it fails with EEXIST in that case, pretend

successful rename as if the existing destination file was detected

by the preceding lstat call.

Fixes https://bugs.gnu.org/29961

---

 src/copy.c | 17 ++++++++++++++++-

 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/src/copy.c b/src/copy.c

index 2a804945e..be4e357a8 100644

--- a/src/copy.c

+++ b/src/copy.c

@@ -53,6 +53,7 @@

 #include "ignore-value.h"

 #include "ioblksize.h"

 #include "quote.h"

+#include "renameat2.h"

 #include "root-uid.h"

 #include "same.h"

 #include "savedir.h"

@@ -2319,7 +2320,12 @@ copy_internal (char const *src_name, char const *dst_name,

   if (x->move_mode)

     {

-      if (rename (src_name, dst_name) == 0)

+      int flags = 0;

+      if (x->interactive == I_ALWAYS_NO)

+        /* do not replace DST_NAME if it was created since our last check */

+        flags = RENAME_NOREPLACE;

+

+      if (renameat2 (AT_FDCWD, src_name, AT_FDCWD, dst_name, flags) == 0)

         {

           if (x->verbose)

             {

@@ -2351,6 +2357,15 @@ copy_internal (char const *src_name, char const *dst_name,

           return true;

         }

+      if ((flags & RENAME_NOREPLACE) && (errno == EEXIST))

+        {

+          /* Pretend the rename succeeded, so the caller (mv)

+             doesn't end up removing the source file.  */

+          if (rename_succeeded)

+            *rename_succeeded = true;

+          return true;

+        }

+

       /* FIXME: someday, consider what to do when moving a directory into

          itself but when source and destination are on different devices.  */

-- 

2.13.6