rsync - Feb 2009 - DO NOT REPLY [Bug 6116] New: Cannot access files in exposed shadow drive in version 3.0.5

https://bugzilla.samba.org/show_bug.cgi?id=6116

           Summary: Cannot access files in exposed shadow drive in version
                    3.0.5
           Product: rsync
           Version: 3.0.5
          Platform: x86
        OS/Version: Windows NT
            Status: NEW
          Severity: normal
          Priority: P3
         Component: core
        AssignedTo: wayned@samba.org
        ReportedBy: leonv@vaultnow.com
         QAContact: rsync-qa@samba.org


Hi,

In 3.0.4, I encountered a problem with dot-dir path (e.g. , foo/./bar) inside
a -files-from file when the root of the transfer isn't in the current
directory.  This was fixed in 3.05 (well, partially).  3.0.5 bug fixes
release info:

    - Fixed the use of a dot-dir path (e.g. foo/./bar) inside a --files-from
      file when the root of the transfer isn't the current directory.

3.05 works fine unless the backup is using an exposed shadow.  In this case,
the C: and D: drives are exposed as H: and I: respectively.  I get the
following error:

rsync: change_dir "/cygdrive/H" failed: No such host or network path
(136)

This causes zero (0) files to be transferred, and 
   rsync error: some files/attrs were not transferred (see previous

(Repeats for I: drive)

  rsync: change_dir "/cygdrive/I" failed: No such host or network path
(136)

and
  rsync error: some files/attrs were not transferred (see previous errors)
(code 23) at main.c(1040) [sender=3.0.5]

Cygwin is able to change_dir into /cygdrive/H and /cygdrive/I with no
problems, so the drives appear to be valid.

This DOES work in 2.6.8.

Leon


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wayned at samba.org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |ASSIGNED




------- Comment #1 from wayned at samba.org  2011-01-01 14:06 CST -------

https://bugzilla.samba.org/show_bug.cgi?id=6116


leonv at vaultnow.com changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|                            |INVALID




------- Comment #2 from leonv at vaultnow.com  2011-01-02 22:33 CST -------
Thanks to Wayne for his follow-up on this report.  His email got me chasing. 
He is correct -- the problem is not rsync.  It seems that changes to Cygwin 1.7
will not allow access to a shadow that is exposed as a drive letter
(http://cygwin.com/ml/cygwin/2009-07/msg00954.html for one example of this
problem documented on the web).

Best regards,
Leon


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--- Comment #3 from Leon V. <leonv at vaultnow.com> 2011-04-20 01:52:29
UTC ---
Created attachment 6419
  --> https://bugzilla.samba.org/attachment.cgi?id=6419
source code for simple test program

This is the source for the simple test program I wrote.

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Leon V. <leonv at vaultnow.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|RESOLVED                    |REOPENED
            Version|3.0.5                       |3.0.7
         Resolution|INVALID                     |

--- Comment #4 from Leon V. <leonv at vaultnow.com> 2011-04-20 01:54:20
UTC ---
I hope I am not over-stepping any boundaries with the re-open, but I am now
convinced that there is an rsync problem.

I have recently been working on an rsync implementation using shadows on a
Windows 7 64 bit machine.  The new work uses diskshadow to create the shadows
and expose them as drive letters.  I hit the same problem - cygwin shell can cd
into /cygdrive/G (the exposed drive letter) and see everything in it, but rsync
fails with 
    rsync: change_dir "/cygdrive/g" failed: No such file or directory
(2)

The --from-files for testing contained
    /cygdrive/g/./Downloads/

In testing, I removed the . in the path (leaving /cygdrive/g/Downloads/) and
the rsync worked (although it put the files in a location preceeded but the
cygdrive/g/, but I expected that).  I took that to mean that rsync could,
indeed, access the shadow (G:) drive.

Since the error says 
    rsync: change_dir "/cygdrive/g" failed: No such file or directory
(2)
I decided to dig into the source code and see what I could figure out.  I am,
at best, a hack C programmer, but I worked through the source code enough to
find change_dir, and I believe that function uses chdir(), so I decided to see
if a simple C program can chdir into /cygdrive/G.  

I wrote a very simple C program, and it could, indeed chdir into /cygdir/G and
open files there-in.  This would seem to indicate that something in the rsync
change_dir is malfunctioning.  

I wish I had sufficient skills to compile and debug this, but I seem to have
hit the end of my abilities.

Please feel free to contact or email me with any questions.

THANKS!
Leon

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--- Comment #5 from Leon V. <leonv at vaultnow.com> 2011-04-20 01:56:32
UTC ---
I forgot to include that I am now using rsync 3.0.7.

Leon

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--- Comment #6 from Leon V. <leonv at vaultnow.com> 2011-04-20 03:25:53
UTC ---
I forgot to include that I am now using rsync 3.0.7.

Leon

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--- Comment #7 from Leon V. <leonv at vaultnow.com> 2011-04-20 23:34:44
UTC ---
I decided to "hack" at this some more.  I downloaded the source code
for 3.0.8
and compiled it, and began to run GDB.  Not sure if this will help, but the
call to util.c change_dir() with cygdrive/G (G: is the exposed shadow for C:) 
yeilds some strange behavior that is beyond my expertise.

The global variable curr_dir starts out correctly containing
"/cygdrive/c/Downloads/rsync308" but when the call to 
change_dir(cygdir/g) is made, it has been trashed by a NULL character and
contains "/\000ygdrive/c/Downloads/rsync308".

While in this section of code (util.c), I cannot get the variable len to print:
    1011            if (len == 1 && *dir == '.')
    (gdb) print len
    No symbol "len" in current context.

When the call to chdir(curr_dir) is made, the curr_dir variable contains
     "//cygdrive/g\000ownloads/rsync308"  (note the double forward
slash)

Hoping this will help...

Leon

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--- Comment #8 from Matt McCutchen <matt at mattmccutchen.net> 2011-04-21
00:56:47 UTC ---
(In reply to comment #7)
> The global variable curr_dir starts out correctly containing
> "/cygdrive/c/Downloads/rsync308" but when the call to 
> change_dir(cygdir/g) is made, it has been trashed by a NULL character and
> contains "/\000ygdrive/c/Downloads/rsync308".
In other words, the null-terminated string "/".  I would imagine that
is
intentional.
> When the call to chdir(curr_dir) is made, the curr_dir variable contains
>      "//cygdrive/g\000ownloads/rsync308"  (note the double
forward slash)
A double slash is a UNC path on Windows, so that would explain the error. 
(That sloppiness would go unpunished on Linux.)  The question is where the
double slash is coming from.

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--- Comment #9 from Leon V. <leonv at vaultnow.com> 2011-04-21 03:14:33
UTC ---
the Windows UNC convention is backslash backslash (\\servername\...) not
forward slashes.

As to where the // is coming from, I have never been able to get a gdb variable
watch to work on my systems...

Leon

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--- Comment #10 from Leon V. <leonv at vaultnow.com> 2011-04-22 22:11:40
UTC ---
I may have figured it out, but I don't have any idea how to
"Check-in" a fix.
The problem is in util.c, function change_dir.  Version 3.0.8:

line number 1027 appends a slash to the curr_dir (current directory) variable.
1027    curr_dir[curr_dir_len] = '/';
line number 1028 then appends the dir (new directory)
1028    memcpy(curr_dir + curr_dir_len + 1, dir, len + 1);

The problem is, if you are in the root directory ("/"), line 1027 adds
a second
slash ("//").

The fix I compiled and tested on my system (granted this is limited testing) is
to replace 1027 and 1028 with:

    // if in root, don't add a slash and don't add 
    // one to the current directory length
    if ( ( curr_dir_len == 1 ) && ( curr_dir[0] == '/' ) ) {
        memcpy(curr_dir + curr_dir_len, dir, len + 1);
    }
    else { // add the slash and add one to len curr_dir_len to
           // account for the slash that was added
    curr_dir[curr_dir_len] = '/';
    memcpy(curr_dir + curr_dir_len + 1, dir, len + 1);
    }

Accessing the shadow drive now works fine!

Leon

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--- Comment #11 from Wayne Davison <wayned at samba.org> 2011-05-08
21:27:12 UTC ---
Created attachment 6439
  --> https://bugzilla.samba.org/attachment.cgi?id=6439
Fix change_dir() to avoid turning "/" into "//subdir".

This was checked into git back on April 22nd.

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Wayne Davison <wayned at samba.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|REOPENED                    |RESOLVED
            Version|3.0.7                       |3.1.0
         Resolution|                            |FIXED

--- Comment #12 from Wayne Davison <wayned at samba.org> 2011-05-08
21:27:51 UTC ---
This will be fixed in the next release.  Thanks for tracking down the issue!

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