add btarfs

1 files changed, 105 insertions, 0 deletions

diff --git a/src/btarfs b/src/btarfs
new file mode 100755
index 0000000..bdd44de
--- /dev/null
+++ b/src/btarfs
@@ -0,0 +1,105 @@
+#!/bin/sh
+
+die() { printf "%s: Error: %s\n" "$0" "$*" >&2; exit 1; }
+
+[ "$(id -u)" = 0 ] || die 'you are not root'
+
+TEMP="$(getopt -o 'f:vcxz' --long size:,file:,create,extract,gzip,gunzip,ungzip -n "$0" -- "$@")" ||
+    die 'getopt error'
+eval set -- "$TEMP"
+
+MIN_BYTES=$((128 * 1024 * 1024))
+
+FILE=
+MODE=
+ZIP=y
+BYTES=$((256 * 1024 * 1024))
+while [ $# -gt 0 ]; do
+    case "$1" in
+        --size)
+            BYTES=$(( $2 * 1024 * 1024))
+            [ "$BYTES" -ge "$MIN_BYTES" ] || die "invalid size (too small or not a number)"
+            SIZE="$2"
+            shift 2 ;;
+        -f|--file)
+            [ "$FILE" ] && die "only one archive file can be specified"
+            FILE="$2"
+            shift 2 ;;
+        -c|--create)
+            [ "$MODE" ] && die "incompatible modes"
+            MODE=create
+            shift ;;
+        -x|--extract)
+            [ "$MODE" ] && die "incompatible modes"
+            MODE=extract
+            shift ;;
+        -v)
+            VERBOSE=y
+            shift ;;
+        -z|--gzip|--gunzip|--ungzip)
+            ZIP=y
+            shift ;;
+        --)
+            shift; break;;
+        *) die 'getopt error';;
+    esac
+done
+[ "$FILE" ] || die "you must specify a file (this is not tar, there is no stdout)"
+
+create()
+{
+    TMPFILE=.~."$FILE"
+#   [ ! -e "$FILE" ] || die "refusing to overwrite '$FILE'"
+#   [ ! -e "$TMPFILE" ] || die "refusing to overwrite '.~.$FILE'"
+    rm -f "$TMPFILE"
+    fallocate -l "$BYTES" "$TMPFILE"
+    mountpoint=$(mktemp -d) || die
+    trap 'umount "$mountpoint"; rmdir "$mountpoint"; rm "$TMPFILE"' EXIT
+    mkfs.btrfs "$TMPFILE" || die
+    mount -o ${ZIP:+compress,}loop "$TMPFILE" "$mountpoint" || die
+    rsync -a ${VERBOSE:+ -i} "$@" "$mountpoint" || die
+
+    shrink "$mountpoint"
+    umount "$mountpoint" || die
+    btrfs_truncate "$TMPFILE"
+
+    rmdir "$mountpoint"
+    btrfstune -S1 "$TMPFILE" || die
+    mv "$TMPFILE" "$FILE"
+    trap '' EXIT
+}
+
+btrfs_truncate()
+{
+    local img="$1" bytes
+    bytes=$(file "$img" | sed -ne 's?.*/\([0-9]*\) bytes used.*?\1?p')
+    if [ "$bytes" ]; then
+        truncate -s "$bytes" "$img"
+    fi
+}
+
+
+get_k()
+{
+    local mountpoint="$1" kilos
+    kilos=$(btrfs fi usage -k "$mountpoint"|sed -ne 's/[\t ]*Device size:[\t ]*//p')
+    case "$kilos" in
+        *.00KiB) echo "${kilos%.00KiB}";;
+        *) return 1;;
+    esac
+}
+
+shrink()
+{
+    shrinkmegs=100
+    while true; do
+        while ! btrfs filesystem resize -${shrinkmegs}M "$mountpoint"/; do
+            shrinkmegs=$((shrinkmegs - 10 ))
+            if [ $shrinkmegs -lt 10 ]; then
+                return
+            fi
+        done
+    done
+}
+
+$MODE "$@"