sftp and put'ing /dev/stdin.

[Kristaps Dzonsons]

Hi,

Enclosed is a small patch that lifts the constraint on uploading only 
regular files in sftp(1).  It's useful to me in dump(8)ing to a remote 
ChrootDirectory'd, ForceCommand sftp-internal server so that I needn't 
put dd(1) or something in the jail.  This way, I can have an empty jail 
for backups and not have the overhead of a dumpfile (which I can't 
afford, space-wise).

% echo "put /dev/stdin remoteFile" >test.bat
% dump -0f - /usr/vhosts | sftp -b test.bat bac...@server.tdl

Where the backup user is matched with something like

Match user backup
        ChrootDirectory /chroot
        ForceCommand internal-sftp

The regular solution, something like

% dump -0f - /usr/vhosts | ssh bac...@server.tdl "cat >remoteFile"

requires cat(1) (or dd(1), or whatever) in the jail.  That takes two 
seconds, but I prefer saving up my two secondses for a nice coffee.

It would probably need some warnings that the progress bar is disabled 
(unknown size of file), and protection of course against directories.

Is there a better way?  Is there a reason for the regular file check 
that makes this a Bad Idea?

Thank you,

Kristaps

Index: sftp-client.c
===================================================================
RCS file: /cvs/src/usr.bin/ssh/sftp-client.c,v
retrieving revision 1.94
diff -u -r1.94 sftp-client.c
--- sftp-client.c       4 Dec 2010 00:18:01 -0000       1.94
+++ sftp-client.c       7 Oct 2011 19:13:03 -0000
@@ -1356,11 +1356,10 @@
                return(-1);
        }
        if (!S_ISREG(sb.st_mode)) {
-               error("%s is not a regular file", local_path);
-               close(local_fd);
-               return(-1);
-       }
-       stat_to_attrib(&sb, &a);
+               showprogress = 0;
+               attrib_clear(&a);
+       } else
+               stat_to_attrib(&sb, &a);

        a.flags &= ~SSH2_FILEXFER_ATTR_SIZE;
        a.flags &= ~SSH2_FILEXFER_ATTR_UIDGID;