Re: safe_shell_exec extension for consideration

On Wed, May 26, 2010 at 12:48 AM, Dave McMurtrie <dave64@andrew.cmu.edu>wrote: > Stig Bakken wrote: > >> Hi Dave, >> >> In general, I think calling functions or settings "safe"-anything gives >> users false fuzzies, and should be avoided. >> > > I'm not concerned with what it's named. I really just want the > functionality to exist. If you wanted to steal from perl, name it system() > and I'd be just as happy. Hehe, alright. I just have a thing about choosing descriptive names that do not promise too much or little :-) > Wouldn't it make more sense to simply extend the existing shell_exec() >> function in PHP's standard extension to also accept an array parameter? >> > > It's most important to me that I have a way to invoke an external program > without involving a shell. The string vs. array issue is secondary and only > came up after my first iteration of code was already complete and I began to > use it. > > With that in mind, how would you propose that the shell_exec() extension > work? If a string is passed, still invoke a shell to avoid breaking all the > code that's already out there, but avoid the shell if an array is passed? I > also considered extending the bypass_shell option to proc_open() to work on > unix, but that thought took me back to the same -- I'd have to add my > tokenizing routine back in and a bunch of existing code that already uses > proc_open() would break. > > I'm willing to entertain all suggestions and I'll put some amount of effort > into providing code to implement whatever the best solution may be. > Great :-) Actually, system() and/or proc_open() would be better PHP functions to mimic/overload, since there would be no shell involved here. I think it makes sense for you to write this code as an extension (to make it available for everyone), but at the same make a patch for PHP's built-in function(s). Using an array parameter is definitely the most intuitive approach IMHO. The code would be a bunch of parameter conversions (to turn the string array into va_arg()), a fork() and execv() call, some file descriptor fiddling to create a php stream from the forked process's standard output, and a waitpid() call collecting exit status. Good luck :-) - Stig