Don't pass shell loops' stdin to programs run on glibc's host

[Joseph S. Myers]

On Sat, 20 Oct 2012, Roland McGrath wrote:

> No test should ever read from the inherited stdin.  For scripts, the robust
> thing to do is put "exec < /dev/null" somewhere near the top.  For test
> programs run by the generic $< > $@ rule, we should just add < /dev/null
> to that command.

While I agree that such changes make sense, they would not address the 
problem this patch is addressing.  This patch is not about tests running 
with stdin inherited from the test run as a whole (e.g. the user's 
terminal).  This patch is about shell scripts doing

while read foo; do
    test_program
done < shell-loop-input

where within the loop the shell's input is redirected - and the "read" 
command, but not the test programs, should see that redirection.  Putting 
"< /dev/null" at the top of the script, or in the makefiles, won't help 
here.

-- 
Joseph S. Myers
joseph@codesourcery.com