readdir() and read() errors ignored

[jw schultz]

On Sun, Aug 24, 2003 at 10:51:20AM +0100, Michael Brown wrote:
> > > A similar error can occur when open() succeeds but subsequent calls to 
> > > read() fail: under these circumstances rsync will transfer zeroes instead 
> > > of the actual file data and will again report no errors to the user.
> > > The attached patch fixes both of these problems.
> > There is a patch on-list for the read error.   Your fix is
> > incorrect because it causes rsync to exit if a file is
> > truncated during read.
> 
> I think it will only exit if an error occurs, not just if EOF is reached 
> unexpectedly (it checks for read() returning <0, not !=expected), but no 
> matter since there is already a patch.  Is your patch going to be 
> integrated into HEAD CVS?

Shortly.  I want to review the other callers of file_unmap
first.

> > I'll look closer at the readir error when i get a chance.
> 
> I've attached a new patch that only addresses the readdir() issue.  This 
> patch has been tested and does solve the problem:
> 
> Before the patch:
> 
> [root at angel root]# ls /mnt/nfs/rsync-test/
> ls: reading directory /mnt/nfs/rsync-test/: Permission denied
> [root at angel root]# rsync -avP /mnt/nfs/rsync-test/ rsync-test/
> building file list ...
> 1 file to consider
> wrote 70 bytes  read 20 bytes  180.00 bytes/sec
> total size is 0  speedup is 0.00
> [root at angel root]# ls rsync-test/
> [root at angel root]#
> 
> Here you can see rsync silently failing on an NFS-mounted directory for 
> which opendir() succeeds but readdir() fails.
> 
> After the patch:
> 
> [root at angel root]# ls /mnt/nfs/rsync-test/
> ls: reading directory /mnt/nfs/rsync-test/: Permission denied
> [root at angel root]# ~/fixed-rsync -avP /mnt/nfs/rsync-test/ rsync-test/
> building file list ...
> readdir(.): Permission denied
> 1 file to consider
> 
> wrote 70 bytes  read 20 bytes  180.00 bytes/sec
> total size is 0  speedup is 0.00
> rsync error: some files could not be transferred (code 23) at main.c(628)
> [root at angel root]#
> 
> Now rsync acts correctly and reports a partial transfer error to the user.
> 
> 
> You can easily reproduce this situation: create an NFS export with the
> default flag of "root_squash", create a directory on the NFS server with
> permissions of e.g. 750 and try to rsync it as root.  opendir() succeeds
> because Linux just looks at the directory permissions and doesn't bother
> contacting the NFS server but readdir() fails because the NFS server maps 
> requests from root to the anonymous user, who doesn't have access to the 
> directory.
> 
> (Please Cc me on replies)

Very good.  Accepted.
I'll commit it with the read fix.