On Mon, Feb 22, 2021 at 06:47:30PM +0100, Paolo Bonzini wrote:
On 22/02/21 16:24, Daniel P. Berrangé wrote:
This problem isn't unique to QEMU. Any app using JSON from the shell will have the tedium of quote escaping. JSON is incredibly widespread and no other apps felt it neccessary to introduce single quoting support, because the benefit doesn't outweigh the interop problem it introduces.
The quotes were introduced for C code (and especially qtest), not for the shell. We have something like
response = qmp("{ 'execute': 'qom-get', 'arguments': { 'path': %s, " "'property': 'temperature' } }", id);
These are sent to QEMU as double-quoted strings (the single-quoted JSON is parsed to get interpolation and printed back; commit 563890c7c7, "libqtest: escape strings in QMP commands, fix leak", 2014-07-01). However, doing the interpolation requires a parser that recognizes the single-quoted strings.
IMHO this is the wrong solution to the problem. Consider the equivalent libvirt code that uses a standard JSON library underneath and has a high level API to serialize args into the command qemuMonitorJSONMakeCommand("qom-get", "s:path", id, "s:property", "temperature"); Of course this example is reasonably easy since it is a flat set of arguments. Nested args get slightly more complicated, but still always preferrable to doing string interpolation IMHO. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|