Re: [libvirt] [PATCH 2/3] virsh: qemu-monitor-command: Don't print extra newline with --pretty

On Mon, Aug 01, 2016 at 06:30:07AM +0200, Peter Krempa wrote: >The prettified JSON string already contains a newline so don't print >another one. This allows to pipe the json output (in conjunction with >the --quiet option) to files without having to truncate them afterwards. >--- > tools/virsh-domain.c | 19 +++++++++---------- > 1 file changed, 9 insertions(+), 10 deletions(-) > >diff --git a/tools/virsh-domain.c b/tools/virsh-domain.c >index 6c1bc2f..45fce76 100644 >--- a/tools/virsh-domain.c >+++ b/tools/virsh-domain.c >@@ -8944,6 +8944,7 @@ cmdQemuMonitorCommand(vshControl *ctl, const vshCmd *cmd) > virBuffer buf = VIR_BUFFER_INITIALIZER; > bool pad = false; > virJSONValuePtr pretty = NULL; >+ char *prettystr = NULL; > > VSH_EXCLUSIVE_OPTIONS("hmp", "pretty"); > >@@ -8969,22 +8970,20 @@ cmdQemuMonitorCommand(vshControl *ctl, const vshCmd *cmd) > if (virDomainQemuMonitorCommand(dom, monitor_cmd, &result, flags) < 0) > goto cleanup; > >- if (vshCommandOptBool(cmd, "pretty")) { >- char *tmp; >- pretty = virJSONValueFromString(result); >- if (pretty && (tmp = virJSONValueToString(pretty, true))) { >- VIR_FREE(result); >- result = tmp; >- } else { >- vshResetLibvirtError(); >- } >+ if (vshCommandOptBool(cmd, "pretty") && >+ (pretty = virJSONValueFromString(result)) && I find naming the variable pretty pretty confusing. virJSONValuePtr is in machine-friendly format and while it has the potential to be formatted as pretty, it is not pretty right now.

>+ (prettystr = virJSONValueToString(pretty, true))) { >+ vshPrint(ctl, "%s", prettystr); >+ } else { >+ vshResetLibvirtError(); Resetting it even when --pretty was not specified feels strange.

Also, grouping the if (--pretty) condition with the virJSONValue error checks makes the flow hard to read.

Do we need the fallback? AFAIK there are only two issues possible when prettifying the string: * the system is out of memory possibly impossible, erroring out or even aborting virsh are acceptable here * virDomainQemuMonitorCommand did not return a JSON output For a domain with JSON monitor, the remote side calls virJSONValueToString, so this could only reasonably happen with a domain that only has HMP. If we error out on the --hmp --pretty combination, we can error out here too and do not need to fall back to raw output.

>+ vshPrint(ctl, "%s\n", result); > } >- vshPrint(ctl, "%s\n", result); > There is also the option of keeping the \n in vshPrint and calling virTrimSpaces on the prettyfied output.