Bug 181694

Description of problem:

lftp can experience a segmentation violation if redirected to a directory
that does not exist by a web server.

It seems to be due to a mis-configuration of the site I was
visiting, but lftp should not dump core for such sites:

$ lftp http://open-mpi.org
lftp www.open-mpi.org:/> cd software/ompi
cd: received redirection to `http://www.open-mpi.org/software/ompi/'
cd: received redirection to `current/'
Segmentation fault (core dumped)ware/ompi/' [Connecting...]

There is no http://www.open-mpi.org/current OR 
http://www.open-mpi.org/software/ompi/current URL on the website -
this appears to be a bug in the website - but lftp should not dump core 
in this situation.

$ gdb /usr/bin/lftp core.*
GNU gdb Red Hat Linux (6.3.0.0-1.106rh)
...
Program terminated with signal 11, Segmentation fault.
...
#0  FileAccess::Path::Set (this=0x8e48c50, o=0x0) at FileAccess.cc:1125
1125       Set(o->path,o->is_file,o->url,o->device_prefix_len);
(gdb) where
#0  FileAccess::Path::Set (this=0x8e48c50, o=0x0) at FileAccess.cc:1125
#1  0x00256eab in Http::Do (this=0x8e48c00) at Http.cc:1528
#2  0x002b85ac in SMTask::Schedule () at SMTask.cc:228
#3  0x0804cc81 in WaitDone (exec=0x8e36450) at lftp.cc:73
#4  0x0804d41e in main (argc=2, argv=0xbfa2c444) at lftp.cc:408
(gdb)


Version-Release number of selected component (if applicable):
lftp-3.4.2-1.1

How reproducible:
100%

Steps to Reproduce:
See above