[libvirt] [PATCH] qemu: use line breaks in command line args written to log

[Michal Privoznik]

On 12/14/18 2:07 PM, Daniel P. Berrangé wrote:
> The QEMU command line arguments are very long and currently all written
> on a single line to /var/log/libvirt/qemu/$GUEST.log. This introduces
> logic to add line breaks after every env variable and "-" optional
> argument, and every positional argument. This will create a clearer log
> file, which will in turn present better in bug reports when people cut +
> paste from the log into a bug comment.
> 
> An example log file entry now looks like this:
> 
>   2018-12-14 12:57:03.677+0000: starting up libvirt version: 5.0.0, qemu version: 3.0.0qemu-3.0.0-1.fc29, kernel: 4.19.5-300.fc29.x86_64, hostname: localhost.localdomain
>   LC_ALL=C \
>   PATH=/usr/local/bin:/usr/local/sbin:/usr/bin:/usr/sbin \
>   HOME=/home/berrange \
>   USER=berrange \
>   LOGNAME=berrange \
>   QEMU_AUDIO_DRV=none \
>   /usr/bin/qemu-system-ppc64 \
>   -name guest=guest,debug-threads=on \
>   -S \
>   -object secret,id=masterKey0,format=raw,file=/home/berrange/.config/libvirt/qemu/lib/domain-33-guest/master-key.aes \
>   -machine pseries-2.10,accel=tcg,usb=off,dump-guest-core=off \
>   -m 1024 \
>   -realtime mlock=off \
>   -smp 1,sockets=1,cores=1,threads=1 \
>   -uuid c8a74977-ab18-41d0-ae3b-4041c7fffbcd \
>   -display none \
>   -no-user-config \
>   -nodefaults \
>   -chardev socket,id=charmonitor,fd=23,server,nowait \
>   -mon chardev=charmonitor,id=monitor,mode=control \
>   -rtc base=utc \
>   -no-shutdown \
>   -boot strict=on \
>   -device qemu-xhci,id=usb,bus=pci.0,addr=0x1 \
>   -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x2 \
>   -sandbox on,obsolete=deny,elevateprivileges=deny,spawn=deny,resourcecontrol=deny \
>   -msg timestamp=on
>   2018-12-14 12:57:03.730+0000: shutting down, reason=failed
> 
> Signed-off-by: Daniel P. Berrangé <berrange at redhat.com>
> ---
>  docs/internals/command.html.in   |  2 +-
>  src/bhyve/bhyve_driver.c         |  4 +-
>  src/qemu/qemu_driver.c           |  2 +-
>  src/qemu/qemu_interface.c        |  2 +-
>  src/qemu/qemu_process.c          |  2 +-
>  src/security/security_apparmor.c |  2 +-
>  src/util/vircommand.c            | 19 ++++++++--
>  src/util/vircommand.h            |  2 +-
>  src/util/virfirewall.c           |  2 +-
>  tests/bhyvexml2argvtest.c        |  4 +-
>  tests/commanddata/test26.log     |  1 +
>  tests/commandtest.c              | 64 +++++++++++++++++++++++++++++++-
>  tests/qemuxml2argvtest.c         |  2 +-
>  tests/storagepoolxml2argvtest.c  |  2 +-
>  tests/storagevolxml2argvtest.c   |  4 +-
>  15 files changed, 95 insertions(+), 19 deletions(-)
>  create mode 100644 tests/commanddata/test26.log
> 


> @@ -1991,11 +1993,22 @@ virCommandToString(virCommandPtr cmd)
>          virBufferAdd(&buf, cmd->env[i], eq - cmd->env[i]);
>          virBufferEscapeShell(&buf, eq);
>          virBufferAddChar(&buf, ' ');
> +        if (linebreaks)
> +            virBufferAddLit(&buf, "\\\n");
>      }
>      virBufferEscapeShell(&buf, cmd->args[0]);
>      for (i = 1; i < cmd->nargs; i++) {
>          virBufferAddChar(&buf, ' ');
> +        if (linebreaks) {
> +            /* Line break if this is a --arg or if
> +             * the previous arg was a positional option
> +             */
> +            if (cmd->args[i][0] == '-' ||
> +                !prevopt)
> +                virBufferAddLit(&buf, "\\\n");
> +        }
>          virBufferEscapeShell(&buf, cmd->args[i]);
> +        prevopt = (cmd->args[i][0] == '-');

Unfortunately, cmd->args[i] can be NULL here. So I guess this needs to
look slightly different:

    for (i = 1; i < cmd->nargs; i++) {
        virBufferAddChar(&buf, ' ');

        if (!cmd->args[i])
            continue;

        if (linebreaks) {
            /* Line break if this is a --arg or if
             * the previous arg was a positional option
             */
            if (cmd->args[i][0] == '-' ||
                !prevopt)
                virBufferAddLit(&buf, "\\\n");
        }
        virBufferEscapeShell(&buf, cmd->args[i]);
        prevopt = (cmd->args[i][0] == '-');
    }


ACK if you fix this.

Michal