[Bug-tar] [Fwd: Bug#424692: --remove-files complains that directories "changed as we read it"]

[Bdale Garbee]

The attached from a user of my Debian tar packaging.  I have no personal
experience with the --remove-files option, but the behavior described
certainly isn't what I would have expected.

Bdale

> --- Begin Message ---
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> Subject: 
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> Bug#424692: --remove-files complains that directories "changed as	we read it"
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> Date: 
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> Wed, 16 May 2007 19:35:31 +0000
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> Package: tar
> Version: 1.16-2
> Severity: normal
>
> When creating an archive when --remove-files is specified, tar iterates over
> the files in each directory, adding them to the archive and unlinking them.
> Once the directory is empty, the directory itself is removed.
>
> However, since tar(1) itself modified the directory, the directory has
> changed since tar started operating on it, and tar complains. This also
> causes tar's exit status to become non-zero (i.e., failure).
>
> Here is a simple example:
>
> address@hidden:pts/6 ~> mkdir foo
> address@hidden:pts/6 ~> echo hi >foo/bar
> address@hidden:pts/6 ~> tar cf tarball.tar --remove-files foo
> tar: foo: file changed as we read it
> address@hidden:pts/6 ~/a> echo $?
> 1
>
> Here is strace(1) output (not for the example mentioned above, but a similar
> case where I first noticed this behavior):
>
> [pid 13977] lstat64("./DEBIAN/.svn/text-base", {st_mode=S_IFDIR|0755, 
> st_size=1024, ...}) = 0
> [pid 13977] open("./DEBIAN/.svn/text-base", 
> O_RDONLY|O_NONBLOCK|O_LARGEFILE|O_DIRECTORY) = 4
> [pid 13977] open("/proc/self/fd/4/.", 
> O_RDONLY|O_NONBLOCK|O_LARGEFILE|O_DIRECTORY) = 5
> [pid 13977] fstat64(5, {st_mode=S_IFDIR|0755, st_size=1024, ...}) = 0
> [pid 13977] fcntl64(5, F_SETFD, FD_CLOEXEC) = 0
> [pid 13977] close(4)                    = 0
> [pid 13977] getdents64(5, /* 8 entries */, 32768) = 288
> [pid 13977] getdents64(5, /* 0 entries */, 32768) = 0
> [pid 13977] close(5)                    = 0
> [...]
> [pid 13977] lstat64("./DEBIAN/.svn/text-base/conffiles.svn-base", 
> {st_mode=S_IFREG|0444, st_size=261, ...}) = 0
> [pid 13977] open("./DEBIAN/.svn/text-base/conffiles.svn-base", 
> O_RDONLY|O_LARGEFILE) = 4
> [pid 13977] read(4, "/etc/iptables.d/10isis-www-serve"..., 261) = 261
> [pid 13977] fstat64(4, {st_mode=S_IFREG|0444, st_size=261, ...}) = 0
> [pid 13977] close(4)                    = 0
> [pid 13977] unlink("./DEBIAN/.svn/text-base/conffiles.svn-base") = 0
> [pid 13977] lstat64("./DEBIAN/.svn/text-base", {st_mode=S_IFDIR|0755, 
> st_size=1024, ...}) = 0
> [pid 13977] write(2, "tar: ", 5tar: )        = 5
> [pid 13977] write(2, "./DEBIAN/.svn/text-base: file ch"..., 
> 51./DEBIAN/.svn/text-base: file changed as we read it) = 51
> [pid 13977] write(2, "\n", 1)           = 1
> [pid 13977] rmdir("./DEBIAN/.svn/text-base") = 0
>
> It's noteworthy that the tar(1) from sarge (1.14-2.3) does not exhibit this
> behavior. I suspect this is because that version does not unlink empty
> directories when --remove-files is specified. Rather, it leaves them for the
> user to clean up. strace(1) output from the older tar is the same, except
> for the write() for the error message and rmdir().
>
> -- System Information:
> Debian Release: 4.0
>   APT prefers stable
>   APT policy: (500, 'stable')
> Architecture: i386 (i686)
> Shell:  /bin/sh linked to /bin/bash
> Kernel: Linux 2.6.18-4-686
> Locale: LANG=C, LC_CTYPE=C (charmap=ANSI_X3.4-1968)
>
> Versions of packages tar depends on:
> ii  libc6                       2.3.6.ds1-13 GNU C Library: Shared libraries
>
> tar recommends no packages.
>
> -- no debconf information
>
>
> --- End Message ---