Safer system()
Safer system()
Posted Apr 8, 2016 21:56 UTC (Fri) by giraffedata (guest, #1954)In reply to: Safer system() by epa
Parent article: Security quotes of the week
I don't know about you, but for me, the special characters are the very reason I use system when I'm in a hurry. Recreating the shell's I/O redirection and piping, in particular, is a great deal of work.
There should be a libc function for doing all that with C data structures instead of text strings.
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Safer system()
Posted Apr 9, 2016 12:44 UTC (Sat) by mathstuf (subscriber, #69389) [Link]
Safer system()
Posted Apr 9, 2016 14:03 UTC (Sat) by anselm (subscriber, #2796) [Link]
The problem is you don't know what shell you're going to get. Can't use bash-isms, you might get csh, rc, or some other setup.
According to system(3), you get /bin/sh. That may or may not be bash (so it's probably advisable to stay away from bashisms) but it is reasonable to assume that it is something Bourne-like, i.e., not csh or rc.
Safer system()
Posted Apr 9, 2016 16:12 UTC (Sat) by giraffedata (guest, #1954) [Link]
The problem is you don't know what shell you're going to get.I guess it wasn't clear that my proposal is not to involve a shell, but to have C library functions to do the things that C programmers use a shell for (via system) today.
And if you want nice high-level structures to be provided by the standard library…why are you using C (there isn't even an associative array in there!)?
The structures I'm thinking of are not especially high level. They're the arguments to exec, for example. Maybe FILE pointers for I/O redirection. Perhaps a list of structs each containing exec arguments for forking a set of processes connected in a pipeline.
When people decide that this is a level of sophistication is above what C is good for, the language they usually choose instead is shell, and then they get exactly what people are complaining about with system: if you aren't really careful about the variables in a statement of a shell program, the program will do something very different from what you expected. So staying low-level seems to be the goal.
Safer system()
Posted Apr 9, 2016 21:05 UTC (Sat) by lsl (subscriber, #86508) [Link]
Well, there's hsearch(3) and tsearch(3). Not that those are particularly nice but they're standardized (in POSIX) and virtually every libc provides them.
Libpipeline
Posted Apr 19, 2016 17:05 UTC (Tue) by sil (guest, #99047) [Link]