From 0054a2acc3894e45171806bd64887211820b8eaf Mon Sep 17 00:00:00 2001
From: "John A. Leuenhagen" <john@zlima12.com>
Date: Tue, 15 Oct 2024 00:57:52 -0400
Subject: [PATCH 1/2] run: fix bug causing run0 to ignore `-D /`.

Since the root directory was being suppressed to NULL, the subsequent
check would erroneously think that no working directory was specified.
This caused the default working directory to be applied instead.
---
 src/run/run.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/run/run.c b/src/run/run.c
index 1f2938f9ea..5d2298a5f6 100644
--- a/src/run/run.c
+++ b/src/run/run.c
@@ -862,7 +862,8 @@ static int parse_argv_sudo_mode(int argc, char *argv[]) {
                         break;
 
                 case 'D':
-                        r = parse_path_argument(optarg, true, &arg_working_directory);
+                        /* Root will be manually suppressed later. */
+                        r = parse_path_argument(optarg, /* suppress_root= */ false, &arg_working_directory);
                         if (r < 0)
                                 return r;
 
@@ -901,6 +902,10 @@ static int parse_argv_sudo_mode(int argc, char *argv[]) {
                         if (r < 0)
                                 return log_error_errno(r, "Failed to get current working directory: %m");
                 }
+        } else {
+                /* Root was not suppressed earlier, to allow the above check to work properly. */
+                if (empty_or_root(arg_working_directory))
+                        arg_working_directory = mfree(arg_working_directory);
         }
 
         arg_service_type = "exec";

From 4ca75488d935431e772c25eb6cf060ea85553158 Mon Sep 17 00:00:00 2001
From: "John A. Leuenhagen" <john@zlima12.com>
Date: Tue, 15 Oct 2024 02:00:18 -0400
Subject: [PATCH 2/2] TEST-74-AUX-UTILS: add tests for 'run0 -D'

---
 test/test-functions                 |  1 +
 test/units/TEST-74-AUX-UTILS.run.sh | 12 ++++++++++++
 2 files changed, 13 insertions(+)

diff --git a/test/test-functions b/test/test-functions
index 269cd8812b..8a4cc55626 100644
--- a/test/test-functions
+++ b/test/test-functions
@@ -211,6 +211,7 @@ BASICTOOLS=(
     ping
     pkill
     ps
+    pwd
     readlink
     realpath
     rev
diff --git a/test/units/TEST-74-AUX-UTILS.run.sh b/test/units/TEST-74-AUX-UTILS.run.sh
index 9e0a429e41..5b46e11409 100755
--- a/test/units/TEST-74-AUX-UTILS.run.sh
+++ b/test/units/TEST-74-AUX-UTILS.run.sh
@@ -246,4 +246,16 @@ if [[ -e /usr/lib/pam.d/systemd-run0 ]] || [[ -e /etc/pam.d/systemd-run0 ]]; the
     # Let's chain a couple of run0 calls together, for fun
     readarray -t cmdline < <(printf "%.0srun0\n" {0..31})
     assert_eq "$("${cmdline[@]}" bash -c 'echo $SUDO_USER')" "$USER"
+
+    # Tests for working directory, especially for specifying "/" (see PR #34771).
+    cd /
+    assert_eq "$(run0 pwd)" "/"
+    assert_eq "$(run0 -D /tmp pwd)" "/tmp"
+    assert_eq "$(run0 --user=testuser pwd)" "/home/testuser"
+    assert_eq "$(run0 -D /tmp --user=testuser pwd)" "/tmp"
+    cd /tmp
+    assert_eq "$(run0 pwd)" "/tmp"
+    assert_eq "$(run0 -D / pwd)" "/"
+    assert_eq "$(run0 --user=testuser pwd)" "/home/testuser"
+    assert_eq "$(run0 -D / --user=testuser pwd)" "/"
 fi