Allow custom image filename being set in menuconfig

This adds support for the two /etc/os-release variables:

 - IMAGE_ID
 - IMAGE_VERSION

The former is configurable, with fallback to name-arch, and the latter
is only set for relase builds.  During releae builds the release will
be appended to the image name.

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

Config.in

@@ -41,6 +41,17 @@ config INFIX_ID
 	  Mandatory.  Used for identifying the OS as ID in /etc/os-release and
 	  in the generated image name: ID-ARCH-VERSION.img
 
+config INFIX_IMAGE_ID
+	string "Operating system image name"
+	default "${INFIX_ID}-${BR2_ARCH}"
+	help
+	  A lower-case string (no spaces or other characters outside of 0–9,
+	  a–z, ".", "_" and "-"), for naming critical image files, directories
+	  and archives containting the operating system.
+
+	  Mandatory.  When INFIX_RELEASE is set, this string is appended to
+	  the IMAGE_ID with a '-' separator.
+
 config INFIX_TAGLINE
 	string "Operating system tagline"
 	default "Infix — a Network Operating System"

board/common/post-build.sh

@@ -34,6 +34,12 @@ rm -f "$TARGET_DIR/etc/os-release"
     echo "VERSION=\"${VERSION}\""
     echo "VERSION_ID=${VERSION}"
     echo "BUILD_ID=\"${GIT_VERSION}\""
+    if [ -n "$INFIX_IMAGE_ID" ]; then
+	echo "IMAGE_ID=\"$INFIX_IMAGE_ID\""
+    fi
+    if [ -n "$INFIX_RELEASE" ]; then
+	echo "IMAGE_VERSION=\"$INFIX_RELEASE\""
+    fi
     if [ "$INFIX_VARIANT_NETCONF" = "y" ]; then
 	echo "VARIANT=\"Managed NETCONF\""
 	echo "VARIANT_ID=netconf"

board/common/post-image.sh

@@ -12,7 +12,11 @@ load_cfg BR2_ARCH
 load_cfg BR2_DEFCONFIG
 load_cfg BR2_EXTERNAL_INFIX_PATH
 load_cfg BR2_TARGET_ROOTFS
-NAME="$INFIX_ID"-$(echo "$BR2_ARCH" | tr _ - | sed 's/x86-64/x86_64/')
+if [ -n "$IMAGE_ID" ]; then
+    NAME="$IMAGE_ID"
+else
+    NAME="$INFIX_ID"-$(echo "$BR2_ARCH" | tr _ - | sed 's/x86-64/x86_64/')
+fi
 diskimg=disk.img
 
 ver()