From a9b4878da992e972a2b2ea95e7540db9e3d7eaa4 Mon Sep 17 00:00:00 2001
From: Michael Orlitzky <michael@orlitzky.com>
Date: Mon, 7 Aug 2017 18:15:04 -0400
Subject: [PATCH] sys-user.eclass: make SYS_USER_UID required and try to modify
 on upgrades.

---
 eclass/sys-user.eclass | 58 +++++++++++++++++++++++-------------------
 1 file changed, 32 insertions(+), 26 deletions(-)

diff --git a/eclass/sys-user.eclass b/eclass/sys-user.eclass
index 090a5ad..8f32c23 100644
--- a/eclass/sys-user.eclass
+++ b/eclass/sys-user.eclass
@@ -32,8 +32,11 @@ SYS_USER_NAME="${PN}"
 # @ECLASS-VARIABLE: SYS_USER_UID
 # @REQUIRED
 # @DESCRIPTION:
-# etc.
-
+# This should be set to the "fixed" UID that your user should have.
+# We may have to fall back to an arbitrary UID, but you still need
+# to specify a real, valid UID here. At the very least because our
+# SLOT variable needs it.
+[[ -z "${SYS_USER_UID}" ]] && die "SYS_USER_UID must be set"
 
 # @ECLASS-VARIABLE: SYS_USER_UID_IMPORTANT
 # @REQUIRED
@@ -129,14 +132,6 @@ sys-user_modify() {
 
 sys-user_pkg_pretend() {
 	# Sanity checks that would otherwise run code in global scope.
-	#
-	# First ensure that the user didn't say his UID is important and
-	# then fail to specify one.
-	if [[ -z "${SYS_USER_UID}" ]] &&
-		   [[ "${SYS_USER_UID_IMPORTANT}" == "true" ]]; then
-		# Don't make no damn sense.
-		die "arbitrary UID requested with SYS_USER_UID_IMPORTANT=true"
-	fi
 
 	# Next ensure that no other username owns an important UID.
 	if [[ "${SYS_USER_UID_IMPORTANT}" == "true" ]]; then
@@ -184,15 +179,12 @@ sys-user_src_configure() {
 		fi
 	fi
 
-	if [[ -n "${SYS_USER_UID}" ]]; then
-		# A specific UID was requested.
-		local current_name=$(sys-user_getname "${SYS_USER_UID}")
-		if [[ "${current_name}" != "${SYS_USER_NAME}" ]]; then
-			# This UID is already taken by another user, but this
-			# specific UID was not important (we checked in
-			# pkg_pretend), so fall back to an arbitrary one.
-			SYS_USER_UID=""
-		fi
+	local current_name=$(sys-user_getname "${SYS_USER_UID}")
+	if [[ "${current_name}" != "${SYS_USER_NAME}" ]]; then
+		# This UID is already taken by another user, but this
+		# specific UID was not important (we checked in
+		# pkg_pretend), so fall back to an arbitrary one.
+		unset SYS_USER_UID
 	fi
 
 	# The "useradd" and "usermod" tools expect a comma-separated list,
@@ -209,13 +201,21 @@ sys-user_src_install() {
 	# be possible.
 	#
 	# Beware, this only works if SYS_USER_UID is guaranteed to have a
-	# real UID and not, for example, -1.
+	# real UID and not be e.g. the empty string.
 	#
-	# TODO: this is a problem now!
+	# Our sys-user_create() function makes sure to set SYS_USER_UID to
+	# something useful, and the only place that sys-user_create() is
+	# called from is sys-user_pkg_preinst(), which takes place before
+	# this sys-user_src_install().
 	#
-	#touch "${T}/${SYS_USER_UID}" || die
-	#insinto "/var/lib/sys-user"
-	#doins "${T}/${SYS_USER_UID}"
+	# The other way that SYS_USER_UID could be empty is during an
+	# upgrade; however, if you're doing an upgrade and the new UID isn't
+	# important, then you'll get the same old UID that exists on the
+	# system from the old package. That old UID is assigned to SYS_USER_UID
+	# in sys-user_src_configure(), so that case is handled too.
+	touch "${T}/${SYS_USER_UID}" || die
+	insinto "/var/lib/sys-user"
+	doins "${T}/${SYS_USER_UID}"
 }
 
 sys-user_pkg_preinst() {
@@ -277,7 +277,7 @@ sys-user_pkg_postinst() {
 	   if [[ -n $(sys-user_getuid "${SYS_USER_NAME}") ]]; then
 		   die "User ${SYS_USER_NAME} already exists during an upgrade."
 	   else
-		   sys-user_create || die "failed to add user ${SYS_USER_NAME}"
+		   sys-user_modify || die "failed to add user ${SYS_USER_NAME}"
 	   fi
 	fi
 }
@@ -286,9 +286,15 @@ sys-user_pkg_prerm() {
 	if [[ -z $(sys-user_getuid "${SYS_USER_NAME}") ]]; then
 		# We have successfully done nothing.
 		ewarn "Tried to remove nonexistent user ${SYS_USER_NAME}."
-	else
+	elif [[ -z "${REPLACING_VERSIONS}" ]]; then
+		# The user to remove exists, and this is not an upgrade, so
+		# we really do remove him.
 		userdel "${SYS_USER_NAME}" || \
 			die "failed to remove user ${SYS_USER_NAME}"
 		einfo "Removed user ${SYS_USER_NAME} from the system."
+
+		# The missing case: if the user exista and this is an upgrade,
+		# we leave the user alone to be modified in
+		# sys-user_pkg_postinst().
 	fi
 }
-- 
2.43.2