netdata/packaging/installer: fix sha256sum failure on freeBSD (#5760)

* netdata/packaging/installer: Introduce safe_sha256sum - a more flexible checsum function

Due to #5747 we discovered that our installer wasnt working properly on FreeBSD.
We created within our functions lib a safe_sha256sum that picks between sha256sum and shasum, with priority to the first method

* netdata/packaging/installer: Update checksums in README

6 files changed, 20 insertions, 7 deletions

diff --git a/netdata-installer.sh b/netdata-installer.sh
index ed4ead7e94..2018cb336e 100755
--- a/netdata-installer.sh
+++ b/netdata-installer.sh
@@ -775,7 +775,7 @@ install_go() {
 		grep "config.tar.gz" "${INSTALLER_DIR}/packaging/go.d.checksums" >> "${tmp}/sha256sums.txt" 2>/dev/null
 
 		# Checksum validation
-		if ! (cd "${tmp}" && sha256sum -c "sha256sums.txt"); then
+		if ! (cd "${tmp}" && safe_sha256sum -c "sha256sums.txt"); then
 			run_failed "go.d.plugin package files checksum validation failed."
 			return 1
 		fi
diff --git a/packaging/installer/README.md b/packaging/installer/README.md
index f9cd746a1f..21ebc695e3 100644
--- a/packaging/installer/README.md
+++ b/packaging/installer/README.md
@@ -42,7 +42,7 @@ bash <(curl -Ss https://my-netdata.io/kickstart.sh)
 Verify the integrity of the script with this:
 
 ```bash
-[ "e051d1baed4c69653b5d3e4588696466" = "$(curl -Ss https://my-netdata.io/kickstart.sh | md5sum | cut -d ' ' -f 1)" ] && echo "OK, VALID" || echo "FAILED, INVALID"
+[ "dec269c623667e132b4b179b9b77fcaf" = "$(curl -Ss https://my-netdata.io/kickstart.sh | md5sum | cut -d ' ' -f 1)" ] && echo "OK, VALID" || echo "FAILED, INVALID"
 ```
 *It should print `OK, VALID` if the script is the one we ship.*
 
@@ -96,7 +96,7 @@ To install Netdata with a binary package on any Linux distro, any kernel version
 Verify the integrity of the script with this:
 
 ```bash
-[ "8e6df9b6f6cc7de0d73f6e5e51a3c8c2" = "$(curl -Ss https://my-netdata.io/kickstart-static64.sh | md5sum | cut -d ' ' -f 1)" ] && echo "OK, VALID" || echo "FAILED, INVALID"
+[ "9f5e63e50ec4322f65064b446cff8dc5" = "$(curl -Ss https://my-netdata.io/kickstart-static64.sh | md5sum | cut -d ' ' -f 1)" ] && echo "OK, VALID" || echo "FAILED, INVALID"
 ```
 
 *It should print `OK, VALID` if the script is the one we ship.*
diff --git a/packaging/installer/functions.sh b/packaging/installer/functions.sh
index 7016b4f343..0b3049967b 100644
--- a/packaging/installer/functions.sh
+++ b/packaging/installer/functions.sh
@@ -678,3 +678,16 @@ portable_add_user_to_group() {
 		return 1
 	fi
 }
+
+
+function safe_sha256sum() {
+	# Within the contexct of the installer, we only use -c option that is common between the two commands
+	# We will have to reconsider if we start non-common options
+	if command -v sha256sum >/dev/null 2>&1; then
+		sha256sum $@
+	elif command -v shasum >/dev/null 2>&1; then
+		shasum -a 256 $@
+	else
+		fatal "I could not find a suitable checksum binary to use"
+	fi
+}
diff --git a/packaging/installer/kickstart-static64.sh b/packaging/installer/kickstart-static64.sh
index f6d0fc6949..33ef738593 100755
--- a/packaging/installer/kickstart-static64.sh
+++ b/packaging/installer/kickstart-static64.sh
@@ -157,7 +157,7 @@ progress "Downloading static netdata binary: ${NETDATA_TARBALL_URL}"
 
 download "${NETDATA_TARBALL_CHECKSUM_URL}" "${TMPDIR}/sha256sum.txt"
 download "${NETDATA_TARBALL_URL}" "${TMPDIR}/netdata-latest.gz.run"
-if ! grep netdata-latest.gz.run "${TMPDIR}/sha256sum.txt" | sha256sum --check - >/dev/null 2>&1; then
+if ! grep netdata-latest.gz.run "${TMPDIR}/sha256sum.txt" | safe_sha256sum -c - >/dev/null 2>&1; then
 	fatal "Static binary checksum validation failed. Stopping netdata installation and leaving binary in ${TMPDIR}"
 fi
 
diff --git a/packaging/installer/kickstart.sh b/packaging/installer/kickstart.sh
index f5683327a9..24a96f56a7 100755
--- a/packaging/installer/kickstart.sh
+++ b/packaging/installer/kickstart.sh
@@ -275,7 +275,7 @@ set_tarball_urls "${RELEASE_CHANNEL}"
 
 download "${NETDATA_TARBALL_CHECKSUM_URL}" "${TMPDIR}/sha256sum.txt"
 download "${NETDATA_TARBALL_URL}" "${TMPDIR}/netdata-latest.tar.gz"
-if ! grep netdata-latest.tar.gz "${TMPDIR}/sha256sum.txt" | sha256sum --check - >/dev/null 2>&1; then
+if ! grep netdata-latest.tar.gz "${TMPDIR}/sha256sum.txt" | safe_sha256sum -c - >/dev/null 2>&1; then
 	fatal "Tarball checksum validation failed. Stopping netdata installation and leaving tarball in ${TMPDIR}"
 fi
 run tar -xf netdata-latest.tar.gz
diff --git a/packaging/installer/netdata-updater.sh b/packaging/installer/netdata-updater.sh
index 071198dd6c..1f3ba927a8 100644
--- a/packaging/installer/netdata-updater.sh
+++ b/packaging/installer/netdata-updater.sh
@@ -79,10 +79,10 @@ update() {
 		info "Newest version is already installed"
 	else
 		download "${NETDATA_TARBALL_URL}" "${dir}/netdata-latest.tar.gz"
-		if ! grep netdata-latest.tar.gz sha256sum.txt | sha256sum --check - >&3 2>&3; then
+		if ! grep netdata-latest.tar.gz sha256sum.txt | safe_sha256sum -c - >&3 2>&3; then
 			failed "Tarball checksum validation failed. Stopping netdata upgrade and leaving tarball in ${dir}"
 		fi
-		NEW_CHECKSUM="$(sha256sum netdata-latest.tar.gz 2>/dev/null| cut -d' ' -f1)"
+		NEW_CHECKSUM="$(safe_sha256sum netdata-latest.tar.gz 2>/dev/null| cut -d' ' -f1)"
 		tar -xf netdata-latest.tar.gz >&3 2>&3
 		rm netdata-latest.tar.gz >&3 2>&3
 		cd netdata-*