fix(image_to_vm): Replace qemu's config file with a script.

The recommended command using the config file was triggering a massive
memory leak in qemu because it was adding both the default virtual
hardware nic as well as the virtio nic. This could be worked around by
adding something like -net none or moving all the -net commands from the
file to the command line but eh. Clearly qemu config files are used and
tested by nobody else so lets just use a trusty script instead.

build_library/vm_image_util.sh

@@ -280,52 +280,36 @@ _write_qemu_conf() {
     local src_name=$(basename "$VM_SRC_IMG")
     local dst_name=$(basename "$VM_DST_IMG")
     local dst_dir=$(dirname "$VM_DST_IMG")
-    local conf_path="${dst_dir}/$(_src_to_dst_name "${src_name}" ".conf")"
+    local script="${dst_dir}/$(_src_to_dst_name "${src_name}" ".sh")"
 
-    # FIXME qemu 1.4/5 doesn't support these options in config files
-    # Seems like submitting a patch to fix that and documenting this
-    # format would be a worthy projects...
-    #  name=${VM_NAME}
-    #  uuid=${VM_UUID}
-    #  m=${vm_mem}
-    #  cpu=kvm64
-    #  smp=2
+    cat >"${script}" <<EOF
+#!/bin/sh
 
-    cat >"${conf_path}" <<EOF
-# qemu config file
+SCRIPT_DIR="\`dirname "\$0"\`"
+DISK_IMAGE="\${SCRIPT_DIR}/${dst_name}"
 
 # Default to KVM, fall back on full emulation
-[machine]
-    accel = "kvm:tcg"
-
-[drive]
-    media = "disk"
-    index = "0"
-#   if = "virtio"
-    file = "${dst_name}"
-    format = "raw"
-
-[net]
-    type = "nic"
-    vlan = "0"
-    model = "virtio"
-
-[net]
-    type = "user"
-    vlan = "0"
-    hostfwd = "tcp::2222-:22"
+exec qemu-system-x86_64 \
+    -name "${VM_NAME}" \
+    -uuid "${VM_UUID}" \
+    -m ${vm_mem} \
+    -machine accel=kvm:tcg \
+    -drive index=0,if=virtio,media=disk,format=qcow2,file="\${DISK_IMAGE}" \
+    -net nic,vlan=0,model=virtio \
+    -net user,vlan=0,hostfwd=tcp::2222-:22 \
+    "\$@"
 EOF
+    chmod +x "${script}"
 
     cat >"${VM_README}" <<EOF
 If you have qemu installed, you can start the image with:
-cd $(relpath "${dst_dir}")
-qemu-system-x86_64 -curses -m ${vm_mem} -readconfig "${conf_path##*/}"
+./path/to/$(basename "${script}") -curses
 
 SSH into that host with:
 ssh 127.0.0.1 -p 2222
 EOF
 
-    VM_GENERATED_FILES+=( "${conf_path}" "${VM_README}" )
+    VM_GENERATED_FILES+=( "${script}" "${VM_README}" )
 }
 
 # Generate the vmware config file