Allow for custom image partition schemes.

This commit provides preliminary support for custom partitioning schemes/image file types.
For discussion refer to: issue ev3dev#10:
ev3dev#10

This commit covers the following changes:
 - Introduce brickstrap-image.sh module for custom partitioning support.
 - Introduce brickstrap-image-drivers.sh module for default image type drivers.
 - Introduce -l option to select partitioning layout/image type driver at build time.
 - Source custom-image.sh files after sourcing configs.
 - Permit custom image type drivers to register validation functions, which are invoked during brp_init_env()
 - Add br_image_name, br_image_type and br_image_path functions which take no arguments. (Rename old br_image_path to brp_image_path).
 - Add support for DEFAULT_IMAGE_TYPE variable for project configurations to override default image type to create.

brickstrap-argv.sh

@@ -140,7 +140,7 @@ function brp_set_destination_defaults()
     fi
 
     if [ -z "$BR_IMAGE_BASE_NAME" ]; then
-        BR_IMAGE_BASE_NAME="$(basename "$BR_DESTDIR")-$(date +%F)"
+        BRP_IMAGE_DEFAULT_NAME="$(basename "$BR_DESTDIR")-$(date +%F)"
     fi
 }
 
@@ -189,15 +189,37 @@ function br_tarball_path()
 }
 
 #
-# Look up the path to a specific disk image, identified by its type extension
+# Look up the path to a specific disk image, identified by the name of a
+# partitioning/imaging scheme and its (file) type extension
 # $1: the name of the partitioning/imaging scheme implemented in the disk image
 # $2: the file name extension used to identify the disk image type.
 #
-function br_image_path()
+function brp_image_path()
 {
     [ $# -eq 2 -a -n "$1" -a -n "$2" ] && [ -n "$BR_DESTDIR" ] && \
-        [ -n "$BR_IMAGE_BASE_NAME" ] && \
-        echo -n "$(br_image_dir)/$BR_IMAGE_BASE_NAME-$1.$2";
+        echo -n "$(br_image_dir)/$(brp_image_name "$1" "$2")"
+}
+
+#
+# Look up the (file) name for a specific disk image, identified by the name of
+# a partitioning/imaging scheme and its (file) type extension
+# $1: the name of the partitioning/imaging scheme implemented in the disk image
+# $2: the file name extension used to identify the disk image type.
+#
+function brp_image_name()
+{
+    [ $# -eq 2 -a -n "$1" -a -n "$2" ] && if [ -n "$BR_IMAGE_BASE_NAME" ]; then
+        # omit driver name when the image name is configured explicitly (-I)
+        echo -n "$BR_IMAGE_BASE_NAME.$2";
+    elif [ -n "$BRP_IMAGE_DEFAULT_NAME" ]; then
+        # add driver name in the default case, to make workflows involving
+        # multiple create-image commands easier
+        echo -n "$BRP_IMAGE_DEFAULT_NAME-$1.$2";
+    else
+        # something is very wrong, presumably brp_set_destination_defaults has
+        # not been called yet
+        return 1
+    fi
 }
 
 #

brickstrap-image-drivers.sh

@@ -0,0 +1,151 @@
+#!/bin/bash
+#
+# This file is part of brickstrap.
+#
+# brickstrap - create a foreign architecture rootfs using kernel namespaces,
+#              multistrap, and qemu usermode emulation and create a disk image
+#              using libguestfs
+#
+# Copyright (C) 2016 Johan Ouwerkerk <[email protected]>
+#
+
+#
+# Note: this file is not meant to be executed, source it as a library of
+# functions instead. Variables used by the functions (other than stack) are
+# namespaced using the 'BR_' or 'BRP_' prefixes. Function names are namespaced
+# similarly, using the 'br_' and 'brp_' prefixes. See docs/namespacing.md for
+# more information on namespacing in brickstrap.
+#
+
+#
+# This file provides driver functions for default image types supported by
+# brickstrap.
+#
+
+#
+# Implement a boot+root partition scheme.
+# This function creates a 'boot+root' MBR type image (type extension: img).
+# $1: path to the image file to generate.
+#
+function brp_image_drv_bootroot()
+{
+    debug "IMAGE_FILE_SIZE: ${IMAGE_FILE_SIZE}"
+    [ $# -eq 1 -a -n "$1" ] && guestfish -N \
+        "$1"=bootroot:vfat:ext4:${IMAGE_FILE_SIZE}:48M:mbr \
+        part-set-mbr-id /dev/sda 1 0x0b : \
+        set-label /dev/sda2 EV3_FILESYS : \
+        mount /dev/sda2 / : \
+        tar-in "$(br_tarball_path)" / : \
+        mkdir-p /media/mmc_p1 : \
+        mount /dev/sda1 /media/mmc_p1 : \
+        glob mv /boot/flash/* /media/mmc_p1/ : \
+
+    # Hack to set the volume label on the vfat partition since guestfish does
+    # not know how to do that. Must be null padded to exactly 11 bytes.
+    echo -e -n "EV3_BOOT\0\0\0" | \
+        dd of="$1" bs=1 seek=32811 count=11 conv=notrunc >/dev/null 2>&1
+}
+
+#
+# Convert megabytes to sectors. Sectors are assumed to be 512 bytes big.
+# $1 is size in megabytes.
+function brp_to_sector()
+{
+    #echo $(( $1 * 1024 * 1024 / 512 ))
+    echo $(( $1 * 2048 ))
+}
+
+#
+# Create a disk image with MBR partition table and 4 partitions. There are two
+# identical rootfs partitions to allow for failover and live upgrades.
+# ------------------------------------------------------------------------------
+# part | label              | mount point | fs   | size
+# ------------------------------------------------------------------------------
+#    1 | ${BOOT_PART_NAME}  | /boot/flash | VFAT | 48MB
+#    2 | ${ROOT_PART_NAME}1 | /           | ext4 | ${ROOT_PART_SIZE}
+#    3 | ${ROOT_PART_NAME}2 | /mnt/root2  | ext4 | ${ROOT_PART_SIZE}
+#    4 | ${DATA_PART_NAME}  | /var        | ext4 | ${IMAGE_FILE_SIZE} -
+#      |                    |             |      | 2 * ${ROOT_PART_SIZE} - 48MB
+# ------------------------------------------------------------------------------
+#
+# $1: path to the image file to generate.
+#
+function brp_image_drv_redundant_rootfs_w_data()
+{
+    [ $# -eq 1 -a -n "$1" ] && guestfish -N "$1"=disk:${IMAGE_FILE_SIZE} -- \
+        part-init /dev/sda mbr : \
+        part-add /dev/sda primary 0 $(brp_to_sector 48) : \
+        part-add /dev/sda primary $(brp_to_sector 48) $(brp_to_sector ${ROOT_PART_SIZE}) : \
+        part-add /dev/sda primary $(brp_to_sector ${ROOT_PART_SIZE}) $(brp_to_sector $(( 2 * ${ROOT_PART_SIZE} ))) : \
+        part-add /dev/sda primary $(brp_to_sector $(( 2 * ${ROOT_PART_SIZE} ))) -1 : \
+        part-set-mbr-id /dev/sda 1 0x0b : \
+        mkfs fat /dev/sda1 : \
+        set-label /dev/sda1 ${BOOT_PART_NAME} : \
+        mkfs ext4 /dev/sda2 : \
+        set-label /dev/sda2 ${ROOT_PART_NAME}1 : \
+        mkfs ext4 /dev/sda3 : \
+        set-label /dev/sda3 ${ROOT_PART_NAME}2 : \
+        mkfs ext4 /dev/sda4 : \
+        set-label /dev/sda4 ${DATA_PART_NAME} : \
+        mkdir-p /boot/flash : \
+        mount /dev/sda1 /boot/flash : \
+        mount /dev/sda2 / : \
+        mkdir-p /mnt/root2
+        mount /dev/sda3 /var : \
+        mkdir-p /var : \
+        mount /dev/sda4 /var : \
+        tar-in "$(br_tarball_path)" / : \
+        umount /boot/flash : \
+        umount /var : \
+        glob cp-a /* /mnt/root2/ : \
+}
+
+#
+# Sanity checks configuration variables for the redundant rootfs + data image
+# type. If variables aren't defined a default is set.
+#
+# Variables:
+# BOOT_PART_NAME: Label of boot partition. Default: BOOT
+# ROOT_PART_NAME: Label of root partition. Default: ROOTFS
+# DATA_PART_NAME: Label of root partition. Default: DATA
+# IMAGE_FILE_SIZE: The size of the entire image file. Default: 3800M
+#
+function brp_image_drv_check_redundant_rootfs_w_data()
+{
+
+    BOOT_PART_NAME=${BOOT_PART_NAME:-BOOT}
+    ROOT_PART_NAME=${ROOT_PART_NAME:-ROOTFS}
+    DATA_PART_NAME=${DATA_PART_NAME:-DATA}
+    IMAGE_FILE_SIZE=${IMAGE_FILE_SIZE:-3800M}
+
+    [ ${#BOOT_PART_NAME} -gt 11 ] && \
+        fail "BOOT_PART_NAME cannot be more than 11 characters."
+
+    # see https://en.wikipedia.org/wiki/Label_%28command%29
+    echo $BOOT_PART_NAME | egrep -q '^[A-Z0-9_-]*$' || \
+        fail "BOOT_PART_NAME contains invalid characters"
+
+    # appending 1/2 to ROOT_PART_NAME, so 16 characters total
+    [ ${#ROOT_PART_NAME} -gt 15 ] && \
+        fail "ROOT_PART_NAME cannot be more than 15 characters."
+    echo $ROOT_PART_NAME | egrep -q '^[a-zA-Z0-9_-]*$' || \
+        fail "ROOT_PART_NAME contains invalid characters"
+
+    [ ${#DATA_PART_NAME} -gt 16 ] && \
+        fail "DATA_PART_NAME cannot be more than 16 characters."
+    echo $DATA_PART_NAME | egrep -q '^[a-zA-Z0-9_-]*$' || \
+        fail "DATA_PART_NAME contains invalid characters"
+}
+
+#
+# Registers the default drivers. To be invoked by brickstrap early before doing
+# any option parsing etc.
+#
+function brp_image_drv_register_defaults()
+{
+    br_register_image_type bootroot brp_image_drv_bootroot \
+        img # no validation required for bootroot, yet
+    br_register_image_type redundant brp_image_drv_redundant_rootfs_w_data \
+        img brp_image_drv_check_redundant_rootfs_w_data
+}
+