[libvirt] [PATCH 0/7] Improve QEMU process startup error reporting

[Cole Robinson]

Error reporting for failed QEMU processes isn't too great at the moment.
A couple cases I have hit:

- Trying to start a VM with a cdrom pointing to a nonexistent file. The
svirt hook function choked on this and indicated as much in the domain
log, but I still had to wait for the pidfile timeout (10 seconds), and
the only error reported was 'Domain did not show up'.

- QEMU dies quickly at startup. Happened with the pulse audio issue, or
if we build cli args incorrectly. The reporting here varies: if QEMU dies
before writing out the pidfile, the above case applies. If the pidfile is
written, we timeout in ReadLogOutput, and it's hit or miss whether we even
report the logfile output to the user.

The following patches improve the above cases by ensuring we never have to
wait for a timeout, and that the logfile output is always reported in the
error message.

Cole Robinson (7):
  Add documentation for __virExec and virExec
  virExec: Delay daemonizing as long as possible.
  Add helper function virExecDaemonize
  Report qemu log data if we fail to daemonize the process.
  Add pidfile argument to __virExec
  Check that QEMU is still alive while reading startup output.
  Don't throw away QEMU startup errors when migrating.

 src/libvirt_private.syms                           |    2 +-
 src/proxy_internal.c                               |   16 +--
 src/qemu_conf.c                                    |    7 -
 src/qemu_driver.c                                  |  105 +++++++----
 src/remote_internal.c                              |   15 +--
 src/uml_driver.c                                   |   11 +-
 src/util.c                                         |  186 +++++++++++++++-----
 src/util.h                                         |   15 ++-
 .../qemuxml2argvdata/qemuxml2argv-boot-cdrom.args  |    2 +-
 .../qemuxml2argvdata/qemuxml2argv-boot-floppy.args |    2 +-
 .../qemuxml2argv-boot-network.args                 |    2 +-
 .../qemuxml2argvdata/qemuxml2argv-bootloader.args  |    2 +-
 .../qemuxml2argv-clock-localtime.args              |    2 +-
 tests/qemuxml2argvdata/qemuxml2argv-clock-utc.args |    2 +-
 .../qemuxml2argv-console-compat.args               |    2 +-
 .../qemuxml2argv-disk-cdrom-empty.args             |    2 +-
 .../qemuxml2argvdata/qemuxml2argv-disk-cdrom.args  |    2 +-
 .../qemuxml2argv-disk-drive-boot-cdrom.args        |    2 +-
 .../qemuxml2argv-disk-drive-boot-disk.args         |    2 +-
 .../qemuxml2argv-disk-drive-cache-v1-none.args     |    2 +-
 .../qemuxml2argv-disk-drive-cache-v1-wb.args       |    2 +-
 .../qemuxml2argv-disk-drive-cache-v1-wt.args       |    2 +-
 .../qemuxml2argv-disk-drive-cache-v2-none.args     |    2 +-
 .../qemuxml2argv-disk-drive-cache-v2-wb.args       |    2 +-
 .../qemuxml2argv-disk-drive-cache-v2-wt.args       |    2 +-
 .../qemuxml2argv-disk-drive-fmt-qcow.args          |    2 +-
 .../qemuxml2argv-disk-drive-shared.args            |    2 +-
 .../qemuxml2argvdata/qemuxml2argv-disk-floppy.args |    2 +-
 tests/qemuxml2argvdata/qemuxml2argv-disk-many.args |    2 +-
 tests/qemuxml2argvdata/qemuxml2argv-disk-usb.args  |    2 +-
 .../qemuxml2argvdata/qemuxml2argv-disk-virtio.args |    2 +-
 .../qemuxml2argvdata/qemuxml2argv-disk-xenvbd.args |    2 +-
 .../qemuxml2argv-graphics-sdl-fullscreen.args      |    2 +-
 .../qemuxml2argv-graphics-sdl.args                 |    2 +-
 .../qemuxml2argv-graphics-vnc-sasl.args            |    2 +-
 .../qemuxml2argv-graphics-vnc-tls.args             |    2 +-
 .../qemuxml2argv-graphics-vnc.args                 |    2 +-
 .../qemuxml2argv-hostdev-pci-address.args          |    2 +-
 .../qemuxml2argv-hostdev-usb-address.args          |    2 +-
 .../qemuxml2argv-hostdev-usb-product.args          |    2 +-
 .../qemuxml2argv-input-usbmouse.args               |    2 +-
 .../qemuxml2argv-input-usbtablet.args              |    2 +-
 tests/qemuxml2argvdata/qemuxml2argv-input-xen.args |    2 +-
 tests/qemuxml2argvdata/qemuxml2argv-migrate.args   |    2 +-
 tests/qemuxml2argvdata/qemuxml2argv-minimal.args   |    2 +-
 tests/qemuxml2argvdata/qemuxml2argv-misc-acpi.args |    2 +-
 .../qemuxml2argv-misc-no-reboot.args               |    2 +-
 tests/qemuxml2argvdata/qemuxml2argv-misc-uuid.args |    2 +-
 .../qemuxml2argv-net-eth-ifname.args               |    2 +-
 tests/qemuxml2argvdata/qemuxml2argv-net-eth.args   |    2 +-
 tests/qemuxml2argvdata/qemuxml2argv-net-user.args  |    2 +-
 .../qemuxml2argvdata/qemuxml2argv-net-virtio.args  |    2 +-
 .../qemuxml2argv-parallel-tcp.args                 |    2 +-
 .../qemuxml2argvdata/qemuxml2argv-restore-v1.args  |    2 +-
 .../qemuxml2argvdata/qemuxml2argv-restore-v2.args  |    2 +-
 .../qemuxml2argvdata/qemuxml2argv-serial-dev.args  |    2 +-
 .../qemuxml2argvdata/qemuxml2argv-serial-file.args |    2 +-
 .../qemuxml2argvdata/qemuxml2argv-serial-many.args |    2 +-
 .../qemuxml2argvdata/qemuxml2argv-serial-pty.args  |    2 +-
 .../qemuxml2argv-serial-tcp-telnet.args            |    2 +-
 .../qemuxml2argvdata/qemuxml2argv-serial-tcp.args  |    2 +-
 .../qemuxml2argvdata/qemuxml2argv-serial-udp.args  |    2 +-
 .../qemuxml2argvdata/qemuxml2argv-serial-unix.args |    2 +-
 tests/qemuxml2argvdata/qemuxml2argv-serial-vc.args |    2 +-
 tests/qemuxml2argvdata/qemuxml2argv-sound.args     |    2 +-
 65 files changed, 288 insertions(+), 183 deletions(-)