GNU bug report logs - #31364
cp -rfs: Fails to overwrite a symlink when it is on a different device

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From: help-debbugs <at> gnu.org (GNU bug Tracking System)
To: Illia Bobyr <ibobyr <at> google.com>
Subject: bug#31364: closed (Re: bug#31364: cp -rfs: Fails to overwrite a
 symlink when it is on a different device)
Date: Tue, 15 May 2018 17:02:02 +0000

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Your bug report

#31364: cp -rfs: Fails to overwrite a symlink when it is on a different device

which was filed against the coreutils package, has been closed.

The explanation is attached below, along with your original report.
If you require more details, please reply to 31364 <at> debbugs.gnu.org.

-- 
31364: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=31364
GNU Bug Tracking System
Contact help-debbugs <at> gnu.org with problems

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From: Pádraig Brady <P <at> draigBrady.com>
To: Jason Smith <jasonmsmith <at> google.com>
Cc: Illia Bobyr <ibobyr <at> google.com>, 31364-done <at> debbugs.gnu.org
Subject: Re: bug#31364: cp -rfs: Fails to overwrite a symlink when it is on a
 different device
Date: Tue, 15 May 2018 10:01:20 -0700

Pushed at https://git.sv.gnu.org/gitweb/?p=coreutils.git;a=commitdiff;h=v8.29-36-gd3daa95

marking this as done

cheers,
Pádraig.

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From: Illia Bobyr <ibobyr <at> google.com>
To: bug-coreutils <at> gnu.org
Cc: Jason Smith <jasonmsmith <at> google.com>
Subject: cp -rfs: Fails to overwrite a symlink when it is on a different device
Date: Fri, 04 May 2018 23:37:55 +0000

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Hello,

I have found a bug in "cp -rfs".

Steps to reproduce:

1. Given "path1" and "path2" are on different devices.
2. $ touch "path1/file"
3. $ cd path2/; ln -s path1/file
4. $ cp --symbolic-link --force --recursive path1/file .

Expected:
The link is overwritten with an exact copy.

Actual result:
cp shows an error:
    cp: 'path1/file' and './file' are the same file

This bug was introduced in

http://git.savannah.gnu.org/cgit/coreutils.git/commit/?id=376967889ed7ed561e46ff6d88a66779db62737a

Specifically this hunk:

diff --git a/src/copy.c b/src/copy.c
index e3832c2..9dbd536 100644
--- a/src/copy.c
<http://git.savannah.gnu.org/cgit/coreutils.git/tree/src/copy.c?id=2f69dba5df8caaf9eda658c1808b1379e9949f22>
+++ b/src/copy.c
<http://git.savannah.gnu.org/cgit/coreutils.git/tree/src/copy.c?id=376967889ed7ed561e46ff6d88a66779db62737a>
@@ -46,6 +46,7 @@
#include "file-set.h"
#include "filemode.h"
#include "filenamecat.h"
+#include "force-link.h"
#include "full-write.h"
#include "hash.h"
#include "hash-triple.h"
@@ -1623,11 +1624,13 @@ same_file_ok (char const *src_name, struct stat
const *src_sb,
}
}
- /* It's ok to remove a destination symlink. But that works only when we
- unlink before opening the destination and when the source and destination
- files are on the same partition. */
- if (x->unlink_dest_before_opening
- && S_ISLNK (dst_sb_link->st_mode))
+ /* It's ok to remove a destination symlink. But that works only
+ when creating symbolic links, or when the source and destination
+ are on the same file system and when creating hard links or when
+ unlinking before opening the destination. */
+ if (x->symbolic_link
+ || ((x->hard_link || x->unlink_dest_before_opening)
+ && S_ISLNK (dst_sb_link->st_mode)))
return dst_sb_link->st_dev == src_sb_link->st_dev;
if (x->dereference == DEREF_NEVER)

Two patches that fix the issue are attached.
They are against the current master in
https://github.com/coreutils/coreutils
The changes are also here:

https://github.com/coreutils/coreutils/compare/master...ilya-bobyr:master

Thank you, Illia Bobyr

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[0002-cp-Overwrite-symlinks-on-another-device.patch (text/x-patch, attachment)]

[0001-cp-No-dup-check-for-unlink_dest_after_failed_open.patch (text/x-patch, attachment)]

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