padding in arguments string array for popen2 or exec

[Olaf Till]

Hi,

in Octave-3.0.3 (probably all versions >= 3.0) please consider the
following errors:


octave:1> [pdw, pdr, pid] = popen2 ("ssh", char ("localhost", "octave-3.0.2"))
pdw =  5
pdr =  6
pid =  11773
octave:2> ssh: localhost   : Name or service not known

octave:2> exec ("ssh", char ("localhost", "octave-3.0.2"))
ssh: localhost   : Name or service not known
olaf at olaf:~/devel/src/octave-3.0.3$ 


(Don't worry about my calling Octave version 3.0.2 with the passed
arguments, version 3.0.3 is not installed, but run in place with
./run-octave.)

Note the spaces in "localhost   :" . Debugging indicates that the
"all_strings()" method returns the arguments padded (in
liboctave/oct-syscalls.cc(execvp)):

(gdb) print argv[0]
$4 = 0x97bd940 "ssh"
(gdb) print argv[1]
$5 = 0x97bda68 "localhost   "
(gdb) print argv[2]
$6 = 0x97bda80 "octave-3.0.2"

(All but the first argv elements were filled in from a string_vector
returned by all_strings() in src/syscalls.cc(popen2) .)


In Octave-2.1.73, for which I have no locally-compiled binary
available for gdb, the problem does not occur:

octave2.1:1> [pdw, pdr, pid] = popen2 ("ssh", char ("localhost", "octave-3.0.2"))
pdw =
{
  id = 3
  name = 
  mode = w
  arch = ieee_little_endian
  status = open
}
pdr =
{
  id = 6
  name = 
  mode = r
  arch = ieee_little_endian
  status = open
}
pid = 11611
octave2.1:2> 
octave2.1:2> warning: DEFAULT_LOADPATH is no longer a built-in variable; please read the NEWS file or type `news' for details

octave2.1:2>


although according to the source (despite an implementation of popen2
in an m-file) after all the all_strings() method is used in the same
way (for giving all but the first element of the sring_vector passed
to Octaves execvp) as in versions >= 3.0.

Olaf