# HG changeset patch
# User Paul Boddie <paul@boddie.org.uk>
# Date 1558643449 -7200
# Node ID a3585c5fc0d1d435161980a530b3632ceb4a5649
# Parent  93f929488a1feadf71a4db5dae021ee7cc736b63
Added a script to generate a partition table description for sfdisk.

diff -r 93f929488a1f -r a3585c5fc0d1 makesd-partition-table
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/makesd-partition-table	Thu May 23 22:30:49 2019 +0200
@@ -0,0 +1,209 @@
+#!/bin/sh
+
+# Emit a partition table for a device employing parameters such as the start,
+# size, and type.
+
+PROGNAME=`basename "$0"`
+THISDIR=`dirname "$0"`
+
+SFDISK="/sbin/sfdisk"
+
+
+
+# Global partition number and previous partition details.
+
+PARTNUM=1
+PREVSTART=
+PREVSIZE=
+PREVTYPE=
+
+# Emit any previous partition details as a complete sfdisk-compatible record.
+
+emit_partition()
+{
+    if [ "$PREVSTART" ] || [ "$PREVSIZE" ] || [ "$PREVTYPE" ] ; then
+        echo -n "$PARTNUM : "
+        emit_partition_fields | sed 's/^ //;s/ /,/g'
+        PARTNUM=$(($PARTNUM + 1))
+    fi
+}
+
+# Emit the previous partition fields.
+
+emit_partition_fields()
+{
+    if [ "$PREVSTART" ] ; then
+        echo -n " start=${PREVSTART}${SFDISK_UNIT_SUFFIX}"
+    fi
+
+    # Obtain any explicitly stated size.
+    # Without a size, use start details to calculate a size.
+    # Without start details, claim the rest of the device.
+
+    REMAINING=$(($DEVSIZE - $PREVSTART))
+
+    if [ "$PREVSIZE" ] ; then
+        PREVSIZE=$(($PREVSIZE * $DEVSIZE / 100))
+    elif [ "$START" ] ; then
+        PREVSIZE=$(($START - $PREVSTART))
+    else
+        PREVSIZE=$REMAINING
+    fi
+
+    if [ "$PREVSIZE" -gt "$REMAINING" ] ; then
+        PREVSIZE=$REMAINING
+    fi
+
+    echo -n " size=${PREVSIZE}${SFDISK_UNIT_SUFFIX}"
+
+    if [ "$PREVTYPE" ] ; then
+        echo -n " Id=`partition_type $PREVTYPE`"
+    fi
+    echo
+}
+
+# Retain the current partition details.
+
+store_partition()
+{
+    if [ "$START" ] ; then
+        PREVSTART=$START
+    elif [ "$PREVSTART" ] && [ "$PREVSIZE" ] ; then
+        PREVSIZE=$(($PREVSIZE * $DEVSIZE / 100))
+        PREVSTART=$(($PREVSTART + $PREVSIZE))
+    else
+        PREVSTART=0
+    fi
+
+    PREVSIZE=$SIZE
+    PREVTYPE=$TYPE
+}
+
+# Reset the current partition details.
+
+reset_partition()
+{
+    START=
+    SIZE=
+    TYPE=
+}
+
+# Emit the current partition details and proceed to the next partition.
+
+next_partition()
+{
+    if [ "$START" ] || [ "$SIZE" ] || [ "$TYPE" ] ; then
+        emit_partition
+        store_partition
+        reset_partition
+    fi
+}
+
+# Convert the partition type to an sdisk-compatible identifier.
+
+partition_type()
+{
+    case "$1" in
+        ( ext[2-4]? ) echo "0x83" ;;
+        ( swap      ) echo "0x82" ;;
+        ( fat       ) echo "0x0c" ;;
+        ( *         ) echo "0x83" ;;
+    esac
+}
+
+
+
+# device_size <device>
+#
+# Obtain the size of the given disk or partition in 1024-byte blocks.
+
+device_size()
+{
+    "$SFDISK" -s "$1"
+}
+
+# Test sfdisk behaviour and obtain useful information.
+
+init_sfdisk()
+{
+    if "$SFDISK" -uB -s "$1" > /dev/null 2>&1 ; then
+        SFDISK_UNIT_SUFFIX=
+    else
+        SFDISK_UNIT_SUFFIX="K"
+    fi
+
+    # Obtain the device size in blocks.
+
+    DEVSIZE=`device_size "$1"`
+}
+
+
+
+# Emit the help message if requested.
+
+if [ "$1" = '--help' ] ; then
+    cat 1>&2 <<EOF
+Usage: $PROGNAME ( -f <type> | -p <start> | -s <size> )...
+
+Produce partition descriptions, indicating partition type, start position and
+size for each partition. Each occurrence of the -f option starts a new partition
+description.
+
+Start positions are indicated as numbers of 1024-byte blocks.
+
+Sizes are indicated as percentages of the entire device; if omitted, the
+remainder of the device will be used.
+
+Types recognised include ext, ext2, ext3, ext4, fat and swap. Other types are
+interpreted as Linux partitions. 
+EOF
+    exit 0
+fi
+
+# Obtain details of the selected device.
+
+if [ ! "$DEV" ] ; then
+    cat 1>&2 <<EOF
+No device specified. Use the DEV environment variable to indicate a device.
+EOF
+    exit 1
+fi
+
+# Initialise sfdisk usage.
+
+init_sfdisk "$DEV"
+
+# Process the arguments, building a partition description.
+
+reset_partition
+
+while [ "$1" ] ; do
+    case "$1" in
+        -f )
+            if [ "$TYPE" ] ; then next_partition ; fi
+            TYPE="$2"
+            shift 2
+            ;;
+        -p )
+            if [ "$START" ] ; then next_partition ; fi
+            START="$2"
+            shift 2
+            ;;
+        -s )
+            if [ "$SIZE" ] ; then next_partition ; fi
+            SIZE="$2"
+            shift 2
+            ;;
+        * )
+            shift 1
+            ;;
+    esac
+done
+
+# Terminate any unfinished partition, emitting the previous partition.
+
+next_partition
+
+# Emit the last partition.
+
+emit_partition