other hosting stuff

1 files changed, 78 insertions, 0 deletions

diff --git a/other/shrink2fs_partition b/other/shrink2fs_partition
new file mode 100755
index 0000000..2674158
--- /dev/null
+++ b/other/shrink2fs_partition
@@ -0,0 +1,78 @@
+#!/bin/sh
+DEPENDENCIES='tune2fs parted lsblk blkid'
+READ_ONLY=y
+
+die()
+{
+    echo "Error: $*" >&2
+    exit 1
+}
+
+parted()
+{
+    if [ "$READ_ONLY" ]
+    then
+        echo parted "$@"
+    else
+        (set -x; command parted "$@")
+    fi
+}
+
+check_deps()
+{
+    for dep in $DEPENDENCIES
+    do
+        command -v "$dep" >/dev/null || die "Missing dependency: $dep"
+    done
+}
+
+filesystem_size() 
+{ 
+    [ "$1" ] || return
+    fstype=$(blkid -o value -s TYPE "$1") || die "blkid could not determine FS type"
+    case "$fstype" in
+        ext[234]) filesystem_size_e2fs "$1";;
+        *) die "Unsupported filesystem type: $FSTYPE";;
+    esac
+}
+
+filesystem_size_e2fs() 
+{ 
+    tune2fs -l "$1" | { 
+        unset block_count block_size
+        while read line
+        do
+            case "$line" in 
+                'Block count:'*) block_count=${line#*:} ;;
+                'Block size:'*) block_size=${line#*:} ;;
+            esac
+        done
+        [ "$block_count" -a "$block_size" ] || return
+        echo $((block_count * block_size))
+    }
+}
+
+get_block_device_names() # Outputs: $PARTNAME $DEVNAME
+{
+    [ -b "$1" ] || die "Not a block device: $1"
+    PARTNAME=/dev/$(lsblk -no KNAME "$1") || die "lsblk failed to get kernel device name for $1"
+
+    [ -b "$PARTNAME" ] || die "Not a block device: $PARTNAME"
+    DEVNAME=/dev/$(lsblk -no PKNAME "$PARTNAME") || die "lsblk failed to get parent device name for $PARTNAME"
+
+    [ -b "$DEVNAME" ] || die "Not a block device: $DEVNAME"
+}
+
+shrink_partition()
+{
+    get_block_device_names "$1"
+    partnum=${PARTNAME#$DEVNAME}
+    [ "$PARTNAME" = "$DEVNAME$partnum" ] || die "Cannot compute partition number; (partname, devname) = ($PARTNAME, $DEVNAME)"
+
+    partsize=$(filesystem_size "$PARTNAME") || die "Failed to obtain fs size"
+    parted "$DEVNAME" resizepart "$partnum" $((partsize))B
+}
+
+check_deps
+
+shrink_partition "$1"