Add a shell script version of mount.bcachefs

Sadly, some people are still running distributions too old to properly
support rust :( In the long term we'd like to use Rust for more of
userspace (and potentially in the kernel); this is just a stopgap
measure.

Makefile

@@ -127,6 +127,7 @@ install: bcachefs
 	$(INSTALL) -m0644 -D bcachefs.8    -t $(DESTDIR)$(PREFIX)/share/man/man8/
 	$(INSTALL) -m0755 -D initramfs/script $(DESTDIR)$(INITRAMFS_SCRIPT)
 	$(INSTALL) -m0755 -D initramfs/hook   $(DESTDIR)$(INITRAMFS_HOOK)
+	$(INSTALL) -m0755 -D mount.bcachefs.sh $(DESTDIR)$(ROOT_SBINDIR)
 	sed -i '/^# Note: make install replaces/,$$d' $(DESTDIR)$(INITRAMFS_HOOK)
 	echo "copy_exec $(ROOT_SBINDIR)/bcachefs /sbin/bcachefs" >> $(DESTDIR)$(INITRAMFS_HOOK)
 

mount.bcachefs.sh

@@ -0,0 +1,50 @@
+#!/bin/bash
+
+join_by()
+{
+    local IFS="$1"
+    shift
+    echo "$*"
+}
+
+args=$(getopt -u -o 'sfnvo:t:N:' -n 'mount.bcachefs' -- "$@")
+if [ $? -ne 0 ]; then
+    echo 'Terminating...' >&2
+    exit 1
+fi
+
+read -r -a argv <<< "$args"
+
+for i in ${!argv[@]}; do
+    [[ ${argv[$i]} == '--' ]] && break
+done
+
+i=$((i+1))
+
+if [[ $((i + 2)) < ${#argv[@]} ]]; then
+    echo "Insufficient arguments"
+    exit 1
+fi
+
+UUID=${argv[$i]}
+
+if [[ ${UUID//-/} =~ ^[[:xdigit:]]{32}$ ]]; then
+    PARTS=()
+
+    for part in $(tail -n +3 /proc/partitions|awk '{print $4}'); do
+	uuid_line=$(bcachefs show-super /dev/$part|& head -n1)
+
+	if [[ $uuid_line =~ $UUID ]]; then
+	    PARTS+=(/dev/$part)
+	fi
+    done
+
+    if [[ ${#PARTS[@]} == 0 ]]; then
+	echo "uuid $UUID not found"
+	exit 1
+    fi
+
+    argv[$i]=$(join_by : "${PARTS[@]}")
+fi
+
+exec mount -i -t bcachefs ${argv[@]}