Re: [libvirt] [PATCH] Add a virStrSplitQuoted for splitting quoted strings

On 03/14/2012 10:50 AM, Daniel P. Berrange wrote: >> This looks like it is repeating some of the code in >> virsh.c:vshCommandStringGetArg; any chance we can combine them? In >> particular, the ability to mimic shell handling of \ escapes, as well as >> the difference in behavior of \ inside "" vs. '', seems like it will >> come in handy. > > Ah I had forgotten about that code. Can you clarify the difference > in \ handling. I guess you mean that inside '', \ can only be used > for \\ and \', while inside "", it can do all the standard shell > escapes like \t, \n, etc ? Inside '', \ has no special meaning. (There's no way to escape ' inside of '). Inside "", \ escapes the next byte (important for " and \, but works on any byte. Outside quotes, \ escapes the next byte. And most importantly: concatenating two forms of quoted materials is permitted. Thus: foo"b'ar\" "\'' blah\' on input becomes this on output: foob'ar" ' blah\ >> >> What you have here does neither; although I didn't spot any flaw in the >> code, I don't know if it's the algorithm we want to be using. > > I should have sent this paired with my other patch for <cmdline> > handling in LXC. That is the intended use case for this function. > > I'm not sure that anyone has ever clearly defined what escaping > syntax is used for /proc/cmdline (which is what <cmdline> is > representing. Hmm, good point. If it is /bin/sh doing the parsing, then we know the rules (and virsh matches them); but it if is a custom parser in the kernel, the we have to match that custom parser.