From c31fd020925fd7b2c3c076896e1bfb9724850bc2 Mon Sep 17 00:00:00 2001
From: david <david@socialnerds.org>
Date: Sun, 29 Oct 2023 22:54:21 +0100
Subject: [PATCH] more progress on the new version of btrfs-snapshots.sh, still
 untested though

---
 btrfs-snapshots.sh | 135 ++++++++++++++++++++++++++++++++-------------
 lib.sh             |  24 ++++++++
 2 files changed, 121 insertions(+), 38 deletions(-)

diff --git a/btrfs-snapshots.sh b/btrfs-snapshots.sh
index 17d74cd..296a2eb 100755
--- a/btrfs-snapshots.sh
+++ b/btrfs-snapshots.sh
@@ -35,15 +35,18 @@ LIBRARIES="lib.sh"
 DEPENDENCIES="basename dirname readlink ln mkdir rm ls date btrfs"
 REQUIRE_ROOT=1
 
-SUBVOLUMES="/"
-DESTINATION_ROOT=/srv/snapshots
+SNAP_FOLDER=".snapshots"
+SNAP_PREFIX="snapshot-"
+SNAP_TIMESTAMP=$(date +%Y%m%d%H%M) #add %S if you want sub-minute snapshots
+SNAP_NAME="$SNAP_PREFIX$SNAP_TIMESTAMP"
 
-PREFIX="snapshot-"
-TIMESTAMP=$(date +%Y%m%d%H%M) #add %S if you want sub-minute snapshots
-NAME="$PREFIX$TIMESTAMP"
+# Build the Btrfs command
+BTRFS_BINARY="$(command -v btrfs)"
+BTRFS_OPTIONS="-q"
+BTRFS_COMMAND="$BTRFS_BINARY $BTRFS_OPTIONS"
 
 # How many snapshots should be kept?
-MAX_SNAPSHOTS=32
+SNAPSHOTS=128
 
 
 ##
@@ -52,14 +55,22 @@ MAX_SNAPSHOTS=32
 
 # Print help information
 function print_help() {
-  printf "%s\n\n%s\n%b\n\n%s\n  %-15s %s\n  %-15s %s\n  %-15s %s\n  %-15s %s\n" \
+  printf "%s\n\n%s\n%b\n\n%s\n  %-15s %s\n  %-15s %s\n  %-15s %s\n  %-15s %s\n  %-15s %s\n" \
          "$DESCRIPTION" "Usage:" "$LIB_BOLD$EXECUTABLE <options> <subvolume>$LIB_CLEAR" "Options:" \
+         "-s, --snapshots <number>" "Override how many snapshots to keep (default: 128)" \
          "-h, --help" "Print help screen and exit" \
          "-i, --info" "Print script information and exit" \
          "-v, --verbose" "More verbose output" \
          "-q, --quiet" "No output except errors (overrides -v)"
 }
 
+# Verify that input is a Btrfs subvolume
+function is_subvolume() {
+  if ! $($BTRFS_COMMAND subvolume show $1 >/dev/null 2>&1); then
+    return 1
+  fi
+}
+
 
 ##
 ## Preflight
@@ -96,40 +107,88 @@ fi
 ##
 ## Liftoff
 ##
-exit 0
-# take the snapshots
-for SUBVOLUME in $SUBVOLUMES; do
-    if [ -z ${SUBVOLUME#/} ]; then
-        SNAPSHOT_PATH="$DESTINATION_ROOT"
-    else
-	PATH="$DESTINATION_ROOT/${SUBVOLUME#/}"
-    fi
-    if [ ! -d $SNAPSHOT_PATH ]; then
-        echo "warning: snapshot path ($SNAPSHOT_PATH) does not yet exist. creating."
-        mkdir -p $SNAPSHOT_PATH
-    fi
-    if [ -d $SNAPSHOT_PATH/$NAME ]; then
-        echo "warning: snapshots with same name already exists. skipping."
-    else
-	#TODO: handle failed snapshots and failed link creations
-        btrfs -q subvolume snapshot -r $SUBVOLUME $SNAPSHOT_PATH/$NAME
-	if [ -h $SNAPSHOT_PATH/latest ]; then
-	    rm $SNAPSHOT_PATH/latest
-	fi
-        ln -sf $SNAPSHOT_PATH/$NAME $SNAPSHOT_PATH/latest
-    fi
+
+while [[ "$1" =~ ^- && ! "$1" == "--" ]]; do
+  case $1 in
+    -s|--snapshots)
+      shift
+      if lib_is_int $1; then
+        SNAPSHOTS=$1
+      else
+        lib_print "!Input for --snapshots must be an intager"
+        exit 1
+      fi
+      ;;
+    -h|--help)
+      H=1
+      ;;
+    -i|--info)
+      I=1
+      ;;
+    -v|--verbose)
+      V=1
+      ;;
+    -q|--quiet)
+      Q=1
+      ;;
+    *)
+      lib_print "!Unknown option [$1]"
+      lib_print "Try --help or -h for available options"
+      exit 1
+      ;;
+  esac
+  shift
 done
 
-# Delete old snapshots
-SNAPSHOTS=$(ls -r $SNAPSHOT_PATH | grep $PREFIX)
-i=0
-for SNAPSHOT in $SNAPSHOTS; do
-    if [ $i -ge $MAX_SNAPSHOTS ]; then
-	#TODO: handle failed snapshot deletions
-	btrfs -q subvolume delete $SNAPSHOT_PATH/$SNAPSHOT
+if [[ "$1" == '--' ]]; then
+  shift
+fi
+
+if [[ $I -eq 1 ]]; then
+  lib_print_info
+  exit 0
+elif [[ $H -eq 1 ]]; then
+  print_help
+  exit 0
+fi
+
+if [[ -z "$1" ]]; then
+  print_help
+  exit 0
+else
+  if is_subvolume "$1"; then
+    SNAP_FOLDER="${1%/}/$SNAP_FOLDER"
+    # Create $SNAP_FOLDER if it does not exist
+    if [[ ! -d "$SNAP_FOLDER" ]]; then
+      lib_print "?Creating snapshot folder because it does not yet exist [$SNAP_FOLDER]"
+      mkdir "$SNAP_FOLDER"
     fi
-    i=$((i+1))
-done
+    if [[ -d "$SNAP_FOLDER/$SNAP_NAME" ]]; then
+      lib_print "?Skipping snapshot because it already exists. [$SNAP_NAME]"
+    else
+      # Take the snapshot
+      $BTRFS_COMMAND subvolume snapshot -r "${1%/}" "$SNAP_FOLDER/$SNAP_NAME"
+   	  if [ -h "$SNAP_FOLDER/latest" ]; then
+	    rm "$SNAP_FOLDER/latest"
+	  fi
+      ln -sf "$SNAP_FOLDER/$SNAP_NAME" "$SNAP_FOLDER/latest"
+      # Delete old snapshots
+      SNAPS=$(ls -r $SNAP_FOLDER | grep $SNAP_PREFIX)
+      i=0
+      for SNAP in $SNAPS; do
+        if [[ $i -ge $SNAPSHOTS ]]; then
+	      #TODO: handle failed snapshot deletions
+	      $BTRFS_COMMAND subvolume delete "$SNAP_FOLDER/$SNAP"
+		  lib_print "Deleted old snapshot [$SNAP_FOLDER/$SNAP]"
+        fi
+        i=$((i+1))
+      done
+    fi
+  else
+    lib_print "!Given path does not appear to be a Btrfs subvolume [$1]"
+    exit 1
+  fi
+fi
 
 
 ##
diff --git a/lib.sh b/lib.sh
index 6dcc998..1a8bb0a 100644
--- a/lib.sh
+++ b/lib.sh
@@ -142,3 +142,27 @@ function lib_healthchecks() {
     curl -fsS -m 10 --retry 5 -o /dev/null "$1"
   fi
 }
+
+# Verify if input is an intager
+function lib_is_int {
+  local INT_EXPR='^[0-9]+$'
+  if ! [[ $1 =~ $INT_EXPR ]]; then
+    return 1
+  fi
+}
+
+# Verify if input is alphanumeric
+function lib_is_alnum {
+  local ALNUM_EXPR='^[a-zA-Z0-9]+$'
+  if ! [[ $1 =~ $ALNUM_EXPR ]]; then
+    return 1
+  fi
+}
+
+# Verify if input looks like an URL
+function lib_is_url {
+  local URL_EXPR='^https?://.+$'
+  if ! [[ $1 =~ $URL_EXPR ]]; then
+    return 1
+  fi
+}