From 113f733e3e26d71f1da00cc7f5934990b848cb92 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Fran=C3=A7ois=20Guerraz?= <francois@orographic.uk>
Date: Fri, 12 Apr 2024 13:50:44 +0200
Subject: [PATCH 1/3] Check if all required binaries exists before doing
 anything else

---
 check_deps.sh     | 30 ++++++++++++++++++++++++++++++
 restore_backup.sh |  2 ++
 stream_backup.sh  |  4 +++-
 3 files changed, 35 insertions(+), 1 deletion(-)
 create mode 100755 check_deps.sh

diff --git a/check_deps.sh b/check_deps.sh
new file mode 100755
index 0000000..742b8af
--- /dev/null
+++ b/check_deps.sh
@@ -0,0 +1,30 @@
+#!/bin/bash
+
+if ! command -v age &> /dev/null; then
+  echo "command not found: age"
+  exit 3
+fi
+if ! command -v aws &> /dev/null; then
+  echo "command not found: aws"
+  exit 3
+fi
+if ! command -v lz4 &> /dev/null; then
+  echo "command not found: lz4"
+  exit 3
+fi
+if ! command -v mbuffer &> /dev/null; then
+  echo "command not found: mbuffer"
+  exit 3
+fi
+if ! command -v split &> /dev/null; then
+  echo "command not found: split"
+  exit 3
+fi
+if ! command -v sed &> /dev/null; then
+  echo "command not found: sed"
+  exit 3
+fi
+if ! command -v btrfs &> /dev/null; then
+  echo "command not found: btrfs"
+  exit 3
+fi
diff --git a/restore_backup.sh b/restore_backup.sh
index d124697..80343d7 100755
--- a/restore_backup.sh
+++ b/restore_backup.sh
@@ -5,6 +5,8 @@ if [ "$EUID" -ne 0 ]
   exit
 fi
 
+./check_deps.sh || exit 3
+
 DELETE_PREVIOUS=false
 
 OPTSTRING="b:p:e:i:s:d"
diff --git a/stream_backup.sh b/stream_backup.sh
index 882db28..9642915 100755
--- a/stream_backup.sh
+++ b/stream_backup.sh
@@ -5,6 +5,8 @@ if [ "$EUID" -ne 0 ]
   exit
 fi
 
+./check_deps.sh || exit 3
+
 DELETE_PREVIOUS=false
 CHUNK_SIZE="512M"
 SOURCE_EPOCH=""
@@ -91,7 +93,7 @@ function cleanup () {
   exit 2
 }
 
-aws s3 ls s3://${BUCKET}/${PREFIX} >> /dev/null \
+aws s3 ls s3://${BUCKET}/${PREFIX} >/dev/null 2>&1 \
   && echo "SECURITY WARNING: current AWS IAM entity is allowed to list bucket contents! This can allow an attacker using the same identity to overwrite files and ruin your backups!" >&2
 
 SEQ=$(date +%s)

From 97601ad806c096522561d6a07ccd1eace17fdadb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Fran=C3=A7ois=20Guerraz?= <francois@orographic.uk>
Date: Fri, 12 Apr 2024 14:02:09 +0200
Subject: [PATCH 2/3] Document exit codes

---
 README.md         | 9 +++++++++
 restore_backup.sh | 2 +-
 stream_backup.sh  | 2 +-
 3 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/README.md b/README.md
index a7ef0ee..ee2074c 100644
--- a/README.md
+++ b/README.md
@@ -18,6 +18,15 @@ Rather than dealing with the complexity of custom file formats and metadata file
 
 As such if you want to change the format (compression, encryption, file container, etc.), please start a new backup _epoch_ so as not to mix the two.
 
+# Return value
+
+It is important that you check the return value of the back-up script for proper monitoring and alerting.
+
+* 0: everything went fine
+* 1: a "usage" error occured. You used a unrecognised command switch, or referenced a volume or snapshot that does not exist
+* 2: an error occurred after the snapshot was created, **you should pay close attention to these**! The script will have tried to delete the newly created snapshot so that subsequent incremental backups can be made from the last good known state
+* 3: a required dependency is not installed
+
 # Important security recommendations
 This is all rather common sense, but:
 
diff --git a/restore_backup.sh b/restore_backup.sh
index 80343d7..d038f50 100755
--- a/restore_backup.sh
+++ b/restore_backup.sh
@@ -2,7 +2,7 @@
 #
 if [ "$EUID" -ne 0 ]
   then echo "Please run as root"
-  exit
+  exit 1
 fi
 
 ./check_deps.sh || exit 3
diff --git a/stream_backup.sh b/stream_backup.sh
index 9642915..cf0cfdb 100755
--- a/stream_backup.sh
+++ b/stream_backup.sh
@@ -2,7 +2,7 @@
 #
 if [ "$EUID" -ne 0 ]
   then echo "Please run as root"
-  exit
+  exit 1
 fi
 
 ./check_deps.sh || exit 3

From 085fe776d304ef9e19fcef29f81111822748f354 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Fran=C3=A7ois=20Guerraz?= <francois@orographic.uk>
Date: Sat, 13 Apr 2024 10:31:52 +0200
Subject: [PATCH 3/3] Allow running check_deps.sh from a different directory

---
 restore_backup.sh | 2 +-
 stream_backup.sh  | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/restore_backup.sh b/restore_backup.sh
index d038f50..720f70c 100755
--- a/restore_backup.sh
+++ b/restore_backup.sh
@@ -5,7 +5,7 @@ if [ "$EUID" -ne 0 ]
   exit 1
 fi
 
-./check_deps.sh || exit 3
+$(dirname "$0")/check_deps.sh || exit 3
 
 DELETE_PREVIOUS=false
 
diff --git a/stream_backup.sh b/stream_backup.sh
index cf0cfdb..a9dd7d2 100755
--- a/stream_backup.sh
+++ b/stream_backup.sh
@@ -5,7 +5,7 @@ if [ "$EUID" -ne 0 ]
   exit 1
 fi
 
-./check_deps.sh || exit 3
+$(dirname "$0")/check_deps.sh || exit 3
 
 DELETE_PREVIOUS=false
 CHUNK_SIZE="512M"