test: read the namespace symlink directly instead of using lsns

lsns scans all of /proc/*/ns/* even when a single PID is specified which
can be racy. Let's just read and compare the procfs symlinks directly to
both avoid doing the whole procfs scan and to, hopefully, get rid of the
occasional test fail where lsns fails to resolve the namespace for the
"old" process:

[ 1517.791471] TEST-07-PID1.sh[22279]: + systemd-run --unit=oldservice --property=Type=notify --property=NotifyAccess=all --property=PrivateUsers=true --property=PrivateNetwork=true bash -c 'systemd-notify --ready; exec sleep>
[ 1517.839514] TEST-07-PID1.sh[22329]: Running as unit: oldservice.service; invocation ID: 840ba49490f349c8b3b2116a43fb6f54
[ 1517.840403] TEST-07-PID1.sh[22335]: ++ systemctl show oldservice -p MainPID
[ 1517.841707] TEST-07-PID1.sh[22336]: ++ awk -F= '{print $2}'
[ 1517.849691] TEST-07-PID1.sh[22279]: + OLD_PID=22330
[ 1517.849691] TEST-07-PID1.sh[22279]: + systemd-run --unit=newservice --property=Type=notify --property=NotifyAccess=all --property=UserNamespacePath=/proc/22330/ns/user --property=NetworkNamespacePath=/proc/22330/ns/net bas>
[ 1517.951239] TEST-07-PID1.sh[22337]: Running as unit: newservice.service; invocation ID: 515b7f71240344aba2864e8510a18cbf
[ 1517.951475] TEST-07-PID1.sh[22343]: ++ awk -F= '{print $2}'
[ 1517.951915] TEST-07-PID1.sh[22342]: ++ systemctl show newservice -p MainPID
[ 1517.972557] TEST-07-PID1.sh[22279]: + NEW_PID=22338
[ 1517.972696] TEST-07-PID1.sh[22344]: ++ lsns -p 22330 -o NS -t net -n
[ 1518.003546] TEST-07-PID1.sh[22345]: ++ lsns -p 22338 -o NS -t net -n
[ 1518.030831] TEST-07-PID1.sh[22279]: + assert_eq '' 4026532280
[ 1518.031106] TEST-07-PID1.sh[22348]: + set +ex
[ 1518.031106] TEST-07-PID1.sh[22348]: FAIL: expected: '4026532280' actual: ''
[ 1518.031342] TEST-07-PID1.sh[111]: + echo 'Subtest /usr/lib/systemd/tests/testdata/units/TEST-07-PID1.user-namespace-path.sh failed'

Also, don't swallow the exit code from the command substitution in case
readlink fails, which could lead to a false-positive test result if it
happened for both readlinks.

Resolves: #39546

diff --git a/test/units/TEST-07-PID1.user-namespace-path.sh b/test/units/TEST-07-PID1.user-namespace-path.sh
index f868b0ce6804d1c5413edbe283831f85514d4309..6d64a52bf88dec36b20759f23e54c992f3f6f32f 100755 (executable)
--- a/test/units/TEST-07-PID1.user-namespace-path.sh
+++ b/test/units/TEST-07-PID1.user-namespace-path.sh
@@ -13,8 +13,12 @@ OLD_PID=$(systemctl show oldservice -p MainPID | awk -F= '{print $2}')
 systemd-run --unit=newservice --property=Type=notify --property=NotifyAccess=all --property=UserNamespacePath=/proc/"$OLD_PID"/ns/user --property=PrivateNetwork=true bash -c 'systemd-notify --ready; exec sleep 3600'
 NEW_PID=$(systemctl show newservice -p MainPID | awk -F= '{print $2}')
 
-assert_neq "$(lsns -p "$OLD_PID" -o NS -t net -n)" "$(lsns -p "$NEW_PID" -o NS -t net -n)"
-assert_eq "$(lsns -p "$OLD_PID" -o NS -t user -n)" "$(lsns -p "$NEW_PID" -o NS -t user -n)"
+OLD_NETNS="$(readlink -v /proc/"$OLD_PID"/ns/net)"
+NEW_NETNS="$(readlink -v /proc/"$NEW_PID"/ns/net)"
+assert_neq "$OLD_NETNS" "$NEW_NETNS"
+OLD_USERNS="$(readlink -v /proc/"$OLD_PID"/ns/user)"
+NEW_USERNS="$(readlink -v /proc/"$NEW_PID"/ns/user)"
+assert_eq "$OLD_USERNS" "$NEW_USERNS"
 
 systemctl stop oldservice newservice
 
@@ -25,8 +29,12 @@ OLD_PID=$(systemctl show oldservice -p MainPID | awk -F= '{print $2}')
 systemd-run --unit=newservice --property=Type=notify --property=NotifyAccess=all --property=UserNamespacePath=/proc/"$OLD_PID"/ns/user --property=NetworkNamespacePath=/proc/"$OLD_PID"/ns/net bash -c 'systemd-notify --ready; exec sleep 3600'
 NEW_PID=$(systemctl show newservice -p MainPID | awk -F= '{print $2}')
 
-assert_eq "$(lsns -p "$OLD_PID" -o NS -t net -n)" "$(lsns -p "$NEW_PID" -o NS -t net -n)"
-assert_eq "$(lsns -p "$OLD_PID" -o NS -t user -n)" "$(lsns -p "$NEW_PID" -o NS -t user -n)"
+OLD_NETNS="$(readlink -v /proc/"$OLD_PID"/ns/net)"
+NEW_NETNS="$(readlink -v /proc/"$NEW_PID"/ns/net)"
+assert_eq "$OLD_NETNS" "$NEW_NETNS"
+OLD_USERNS="$(readlink -v /proc/"$OLD_PID"/ns/user)"
+NEW_USERNS="$(readlink -v /proc/"$NEW_PID"/ns/user)"
+assert_eq "$OLD_USERNS" "$NEW_USERNS"
 
 systemctl stop oldservice newservice
 
@@ -37,7 +45,11 @@ OLD_PID=$(systemctl show oldservice -p MainPID | awk -F= '{print $2}')
 systemd-run --unit=newservice --property=Type=notify --property=NotifyAccess=all --property=UserNamespacePath=/proc/"$OLD_PID"/ns/user --property=DelegateNamespaces=net --property=PrivateNetwork=true bash -c 'systemd-notify --ready; exec sleep 3600'
 NEW_PID=$(systemctl show newservice -p MainPID | awk -F= '{print $2}')
 
-assert_neq "$(lsns -p "$OLD_PID" -o NS -t net -n)" "$(lsns -p "$NEW_PID" -o NS -t net -n)"
-assert_eq "$(lsns -p "$OLD_PID" -o NS -t user -n)" "$(lsns -p "$NEW_PID" -o NS -t user -n)"
+OLD_NETNS="$(readlink -v /proc/"$OLD_PID"/ns/net)"
+NEW_NETNS="$(readlink -v /proc/"$NEW_PID"/ns/net)"
+assert_neq "$OLD_NETNS" "$NEW_NETNS"
+OLD_USERNS="$(readlink -v /proc/"$OLD_PID"/ns/user)"
+NEW_USERNS="$(readlink -v /proc/"$NEW_PID"/ns/user)"
+assert_eq "$OLD_USERNS" "$NEW_USERNS"
 
 systemctl stop oldservice newservice