On Jan 15, 2008 6:26 AM, Tobia <address@hidden> wrote:
Elf wrote:
(define (system->string . args)
(string-chomp (with-input-from-pipe (string-join args " ")
read-all)))
if this system->string is going to be of any use, it should
quote its arguments against any possible interpretation by the shell.
Fortunately there is a simple way which supposedly works with every
flavour of UNIX shell: replace every ' with '\'' and enclose each
argument in '...'
The issue with applying this to every argument is that you prevent
even desired shell interpretation, such as wildcard expansion. Such
interpretation is pretty much the entire reason for the system() call
in the first place. It's probably better that the user quote
arguments selectively with his own quoting function before invoking
the command.
If you truly want to bypass the shell--which is often a good idea when
dealing with user input--it's best not to use system() at all. That
includes using with-input-from-pipe, which uses popen(), which itself
calls system(). Instead you should pipe(), fork() and exec() -- the
latter, of course, taking its arguments as an array.
Actually, that's exactly what 'process' in the posix unit does. But
there's no nice wrapper around it. If with-input-from-pipe were to
optionally take a list as first argument, and (if a list) open a pipe
bypassing the shell in this manner, that might be something worth
looking into.