From af6ea6c593acd3220826fe8d6e5f2a0f5e255331 Mon Sep 17 00:00:00 2001
From: Will Simoneau <simoneau@ele.uri.edu>
Date: Tue, 26 Jan 2021 11:24:20 -0500
Subject: [PATCH] sys-apps/smartmontools: Update drivedb.h intelligently by
 comparing file mtimes

---
 .../smartmontools/smartmontools-7.2.ebuild    | 111 +++++++++++++-----
 1 file changed, 84 insertions(+), 27 deletions(-)

diff --git a/sys-apps/smartmontools/smartmontools-7.2.ebuild b/sys-apps/smartmontools/smartmontools-7.2.ebuild
index 8743a731e87..cbb8286e4c9 100644
--- a/sys-apps/smartmontools/smartmontools-7.2.ebuild
+++ b/sys-apps/smartmontools/smartmontools-7.2.ebuild
@@ -118,34 +118,91 @@ src_install() {
 
 pkg_postinst() {
 	if use daemon || use update-drivedb; then
-		local initial_db_file="${EROOT}usr/share/${PN}/drivedb.h"
-		local db_path="${EROOT}var/db/${PN}"
-
-		if [[ ! -f "${db_path}/drivedb.h" ]] ; then
-			# No initial database found
-			cp "${initial_db_file}" "${db_path}" || die
-			einfo "Default drive database which was shipped with this release of ${PN}"
-			einfo "has been installed to '${db_path}'."
-		else
-			ewarn "WARNING: There's already a drive database in '${db_path}'!"
-			ewarn "Because we cannot determine if this database is untouched"
-			ewarn "or was modified by the user you have to manually update the"
-			ewarn "drive database:"
-			ewarn ""
-			ewarn "a) Replace '${db_path}/drivedb.h' by the database shipped with this"
-			ewarn "   release which can be found in '${initial_db_file}', i.e."
-			ewarn ""
-			ewarn "     cp \"${initial_db_file}\" \"${db_path}\""
-			ewarn ""
-			ewarn "b) Run the following command as root:"
-			ewarn ""
-			ewarn "     /usr/sbin/update-smart-drivedb"
-
-			if ! use update-drivedb ; then
-				ewarn ""
-				ewarn "However, 'update-smart-drivedb' requires that you re-emerge ${PN}"
-				ewarn "with USE='update-drivedb'."
+		local shipped_db_file="${EROOT}usr/share/${PN}/drivedb.h"
+		local sys_db_path="${EROOT}var/db/${PN}"
+		local sys_db_file="${sys_db_path}/drivedb.h"
+
+		if [[ -L "${sys_db_file}" ]]; then
+			# If the system has an existing drivedb.h but it is a symlink,
+			# the sysadmin has presumably done something special with it.
+			# For example, the symlink might point to a drivedb.h within
+			# a checked-out SCM repo for system config files.
+			#
+			# We should respect the sysadmin's specialized configuration by
+			# leaving the existing symlink as-is.
+
+			ewarn "Preserving existing symlink ${sys_db_file}."
+
+		elif [[ -f "${sys_db_file}" ]]; then
+			if [[ ! -w "${sys_db_file}" ]] ||
+			   ! (( 0$(stat -c %a "${sys_db_file}") & 0200 ))
+			then
+				# If the system has an existing drivedb.h but it is not
+				# writable, then the sysadmin presumably doesn't want us
+				# to change it.
+				# Respect that by leaving the existing drivedb.h as-is.
+
+				ewarn "Existing ${sys_db_file} is not writable;"
+				ewarn "leaving it as-is."
+
+			else
+				# If the system has an existing drivedb.h and it is a
+				# writable regular file, compare its mtime with the mtime
+				# of the shipped drivedb.h file.
+				#
+				# Comparing file timestamps is admittedly a rather crude way
+				# to compare file versions, but it is still an improvement
+				# over not trying to compare them at all.
+
+				if [[ "${shipped_db_file}" -nt "${sys_db_file}" ]]; then
+					# Shipped drivedb.h is newer than system drivedb.h.
+					# Update system drivedb.h with the shipped version.
+
+					einfo "The drivedb.h shipped with ${PF} appears to be"
+					einfo "newer than the system's existing drivedb.h."
+					einfo "Replacing existing ${sys_db_file} with"
+					einfo "the shipped drivedb.h".
+					cp -p "${shipped_db_file}" "${sys_db_path}/" || die
+
+				else
+					# Shipped drivedb.h is no newer than system drivedb.h.
+					# Assume that the system drivedb.h is either the same as
+					# or a newer version than the shipped drivedb.h.
+
+					einfo "The drivedb.h shipped with ${PF} appears to be"
+					einfo "no newer than the system's existing drivedb.h."
+					einfo "Preserving existing ${sys_db_file}."
+				fi
 			fi
+
+		elif [[ ! -e "${sys_db_file}" ]]; then
+			# If the system has no existing drivedb.h, install the shipped
+			# drivedb.h.
+
+			einfo "No existing ${sys_db_file} was found."
+			einfo "Installing the drivedb.h shipped with ${PF} to"
+			einfo "${sys_db_file}."
+			cp -p "${shipped_db_file}" "${sys_db_path}/" || die
+
+		else
+			# The system has an existing drivedb.h, but it is not a
+			# regular file. That doesn't make any sense to us, so it's
+			# probably best to just leave it as we found it.
+
+			ewarn "Existing ${sys_db_file} is not a regular file;"
+			ewarn "leaving it as-is."
+		fi
+
+		einfo ""
+		einfo "The system's installed drivedb.h may be updated by running"
+		einfo "the following command as root:"
+		einfo ""
+		einfo "     /usr/sbin/update-smart-drivedb"
+		if ! use update-drivedb ; then
+			einfo ""
+			einfo "However, please note that 'update-smart-drivedb' will not"
+			einfo "be available unless you re-emerge ${PN} with"
+			einfo "USE='update-drivedb'."
 		fi
 	fi
 }
-- 
2.26.2