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[Rdiff-backup-bugs] [bug #23994] Crash when backing up an ext3 folder to

From: Andrew Ferguson
Subject: [Rdiff-backup-bugs] [bug #23994] Crash when backing up an ext3 folder to fat32
Date: Sat, 04 Oct 2008 05:12:28 +0000
User-agent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.5; en-US; rv: Gecko/2008092414 Firefox/3.0.3

Follow-up Comment #2, bug #23994 (project rdiff-backup):

In the Linux Kernel 2.6.26 ChangeLog, I found:

commit 19c561a60ffe52df88dd63de0bff480ca094efe4
Author: Jan Engelhardt <address@hidden>
Date:   Wed Feb 6 01:36:08 2008 -0800

    fs/fat/: refine chmod checks
    Prohibit mode changes in non-quiet mode that cannot be stored reliably
    the on-disk format.
    Suppose a vfat filesystem is mounted with umask=0 and [not-quiet].  Then
    all files will have mode 0777.  Trying to change the owner will fail,
    because fat does not know about owners or groups.  chmod 0770, on the
    hand, will succeed, even though fat does not know about the permission
    triplet [user/group/other].
    So this patch changes fat's not-quiet behavior so that only UNIX modes
    accepted that can be mapped lossless between the fat disk format and the
    local system.  There is only one attribute, and that is the readonly
    attribute, which is mapped to the UNIX write permission bit(s).  chmod
    is therefore valid (taking away the +w bits <=> setting the readonly
    attribute).  Since chmod 0775 and chmod 0755 is an ambiguous case as to
    whether to set or clear the readonly bit, these modes are also denied.
    In quiet mode, chmod and chown will continue to "succeed" as they did
    before, meaning that a subsequent stat() will temporarily return the new
    mode as long as the inode is not reread from disk, and chown will
    do nothing, not even return the new uid/gid in stat().
    Signed-off-by: Jan Engelhardt <address@hidden>
    Cc: OGAWA Hirofumi <address@hidden>
    Signed-off-by: Andrew Morton <address@hidden>
    Signed-off-by: Linus Torvalds <address@hidden>


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