runqemu: Add network bridge support

Qemu supports attaching the virtual machine to an existing network
bridge interface via the qemu-bridge-helper program (as long as the
system is correctly configured to give the user permissions). Add
support for runqemu to do this also via the "bridge=<INTERFACE>"
argument. Note that for this to work correctly, the host
qemu-bridge-helper must be used, not the one that might have been built
by qemu-native. In order for qemu to correctly find this program, a
qemu-oe-bridge-helper program has been added to qemu-helper-native, and
runqemu will use this helper as the bridge helper. The helper will look
for the host qemu-bridge-helper first by looking in the
QEMU_BRIDGE_HELPER environment variable, then by search common paths
where the helper is installed.

Signed-off-by: Joshua Watt <JPEWhacker@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

2 files changed, 31 insertions, 1 deletions

diff --git a/meta/recipes-devtools/qemu/qemu-helper-native_1.0.bb b/meta/recipes-devtools/qemu/qemu-helper-native_1.0.bb
index 372eebd886..2fc07669dd 100644
--- a/meta/recipes-devtools/qemu/qemu-helper-native_1.0.bb
+++ b/meta/recipes-devtools/qemu/qemu-helper-native_1.0.bb
@@ -5,7 +5,10 @@ PR = "r1"
 
 LIC_FILES_CHKSUM = "file://${WORKDIR}/tunctl.c;endline=4;md5=ff3a09996bc5fff6bc5d4e0b4c28f999"
 
-SRC_URI = "file://tunctl.c"
+SRC_URI = "\
+    file://tunctl.c \
+    file://qemu-oe-bridge-helper \
+    "
 
 S = "${WORKDIR}"
 
@@ -18,6 +21,8 @@ do_compile() {
 do_install() {
 	install -d ${D}${bindir}
 	install tunctl ${D}${bindir}/
+
+    install -m 755 ${WORKDIR}/qemu-oe-bridge-helper ${D}${bindir}/
 }
 
 DEPENDS += "qemu-system-native"
diff --git a/meta/recipes-devtools/qemu/qemu-helper/qemu-oe-bridge-helper b/meta/recipes-devtools/qemu/qemu-helper/qemu-oe-bridge-helper
new file mode 100755
index 0000000000..f057d4eef0
--- /dev/null
+++ b/meta/recipes-devtools/qemu/qemu-helper/qemu-oe-bridge-helper
@@ -0,0 +1,25 @@
+#! /bin/sh
+# Copyright 2020 Garmin Ltd. or its subsidiaries
+#
+# SPDX-License-Identifier: GPL-2.0
+#
+# Attempts to find and exec the host qemu-bridge-helper program
+
+# If the QEMU_BRIDGE_HELPER variable is set by the user, exec it.
+if [ -n "$QEMU_BRIDGE_HELPER" ]; then
+    exec "$QEMU_BRIDGE_HELPER" "$@"
+fi
+
+# Search common paths for the helper program
+BN="qemu-bridge-helper"
+PATHS="/usr/libexec/ /usr/lib/qemu/"
+
+for p in $PATHS; do
+    if [ -e "$p/$BN" ]; then
+        exec "$p/$BN" "$@"
+    fi
+done
+
+echo "$BN not found!" > /dev/stderr
+exit 1
+