Report the submitted line in bash when the profile makes PROMPT_COMMAND an array

standalone/sidecar/shell-integration.test.js

@@ -8,7 +8,7 @@
 const test = require('node:test');
 const assert = require('node:assert/strict');
 const { execFileSync, spawnSync } = require('node:child_process');
-const { existsSync, mkdtempSync, rmSync } = require('node:fs');
+const { existsSync, mkdtempSync, rmSync, writeFileSync } = require('node:fs');
 const os = require('node:os');
 const path = require('node:path');
 
@@ -119,17 +119,19 @@ for (const [name, bin] of shells) {
   });
 }
 
-// bash 4.0 is where a `bind -x` command runs with READLINE_LINE bound.
-const BASH_MAJOR = Number(execFileSync(BASH, ['-c', 'echo "${BASH_VERSINFO[0]}"'], { encoding: 'utf8' }).trim());
+// bash 4.0 is where a `bind -x` command runs with READLINE_LINE bound; 5.1
+// is where every element of an array PROMPT_COMMAND runs.
+const [BASH_MAJOR, BASH_MINOR] = execFileSync(BASH, ['-c', 'echo "${BASH_VERSINFO[0]} ${BASH_VERSINFO[1]}"'], { encoding: 'utf8' }).trim().split(' ').map(Number);
 
 /**
  * Drive the real bash integration on a PTY, one submitted line at a time.
  * `run` resolves with every `E` the line emitted (decoded as the parser decodes
  * it) and the text the shell printed, once the next prompt is drawn.
  */
-function interactiveBash() {
+function interactiveBash(profile) {
   const pty = require('node-pty');
   const home = mkdtempSync(path.join(os.tmpdir(), 'dormouse-bash-'));
+  if (profile !== undefined) writeFileSync(path.join(home, '.profile'), profile);
   const shell = pty.spawn(BASH, ['--init-file', path.join(dir, 'shell-integration/bash/shellIntegration.bash')], {
     cols: 200,
     rows: 50,
@@ -256,3 +258,33 @@ test('bash: E is the whole submitted line, and never a stale history entry', { t
     await bash.close();
   }
 });
+
+// systemd's /etc/profile.d/80-systemd-osc-context.sh (Ubuntu 26.04) turns
+// PROMPT_COMMAND into an array with an empty first slot and appends its hook;
+// a legacy rc file then assigns element 0. Startup replaced only element 0, so
+// the hook ran after ours re-armed the trap and every line reported the hook's
+// name instead of itself.
+test('bash: an array PROMPT_COMMAND from the profile keeps E the submitted line', { timeout: 60_000, skip: BASH_MAJOR < 5 || (BASH_MAJOR === 5 && BASH_MINOR < 1) }, async () => {
+  const bash = interactiveBash([
+    '__sfx_ran() { __sfx_status=$?; __sfx_count=$((${__sfx_count:-0} + 1)); }',
+    // systemd's own two lines, verbatim.
+    '[ -n "$(declare -p PROMPT_COMMAND 2>/dev/null)" ] || PROMPT_COMMAND+=(\'\')',
+    'PROMPT_COMMAND+=(__sfx_ran)',
+    'PROMPT_COMMAND=false',
+    '',
+  ].join('\n'));
+  try {
+    for (const line of ['true', 'echo p && echo q']) {
+      const { commands, starts } = await bash.run(line);
+      assert.deepEqual(commands, [line], `bash reported ${JSON.stringify(commands)} for ${JSON.stringify(line)}`);
+      assert.equal(starts, 1);
+    }
+    // Each element sees the command's $?, not the status of the element before it.
+    await bash.run('(exit 7)');
+    // The profile's hook still runs once per prompt: the first, then three lines.
+    const { printed } = await bash.run('echo "n=$__sfx_count s=$__sfx_status"');
+    assert.match(printed, /n=4 s=7/);
+  } finally {
+    await bash.close();
+  }
+});

standalone/sidecar/shell-integration/bash/shellIntegration.bash

@@ -8,8 +8,8 @@
 # the OSC 633 prompt/command hooks.
 #
 # Written for bash 3.2 (the macOS system bash) and newer: a DEBUG trap for
-# command-start and a string PROMPT_COMMAND for the prompt — no PS0 (4.4+) and no
-# array PROMPT_COMMAND (5.1+).
+# command-start and a string PROMPT_COMMAND for the prompt — no PS0 (4.4+), and an
+# array PROMPT_COMMAND (5.1+) is only read, never installed.
 
 # --- Replicate login-shell startup (we are spawned without --login) ----------
 if [ -r /etc/profile ]; then . /etc/profile; fi
@@ -67,7 +67,17 @@ __dormouse_633_safe_cwd() {
 
 __dormouse_633_armed=                       # set at the END of the prompt hook: "the next command is the user's"
 __dormouse_633_ran=                         # a command actually executed since the last prompt
-__dormouse_633_user_pc="$PROMPT_COMMAND"    # preserve the user's PROMPT_COMMAND
+# Preserve the user's PROMPT_COMMAND, one entry per element. bash 5.1+ runs every
+# element of an array PROMPT_COMMAND, which systemd's 80-systemd-osc-context.sh
+# makes it; one left past ours would run after the re-arm and report as the
+# command. Older bash runs only element 0.
+__dormouse_633_user_pcs=("$PROMPT_COMMAND")
+if (( BASH_VERSINFO[0] * 100 + BASH_VERSINFO[1] >= 501 )); then
+  __dormouse_633_user_pcs=("${PROMPT_COMMAND[@]}")
+fi
+
+# Set $? to $1 without the fork of `( exit "$1" )`.
+__dormouse_633_status() { return "$1"; }
 
 # precmd: runs via PROMPT_COMMAND just before each prompt. Reports the previous
 # command's exit (D), the cwd (P), and the prompt start (A). Disarms first so its
@@ -83,10 +93,12 @@ __dormouse_633_prompt() {
   __dormouse_633_safe_cwd "$PWD"
   printf '\033]633;P;Cwd=%s\007' "$__dormouse_633_out"
   printf '\033]633;A\007'
-  if [ -n "$__dormouse_633_user_pc" ]; then
-    ( exit "$exit_code" )                   # restore $? for the user's PROMPT_COMMAND
-    eval "$__dormouse_633_user_pc"
-  fi
+  local __dormouse_633_pc
+  for __dormouse_633_pc in "${__dormouse_633_user_pcs[@]}"; do
+    [ -n "$__dormouse_633_pc" ] || continue
+    __dormouse_633_status "$exit_code"      # each element sees the command's $?, as bash gives it
+    eval "$__dormouse_633_pc"
+  done
   __dormouse_633_armed=1
 }
 
@@ -140,6 +152,7 @@ __dormouse_633_preexec() {
 }
 
 trap '__dormouse_633_preexec "$_"' DEBUG
+unset PROMPT_COMMAND                        # an array keeps its other elements through a plain assignment
 PROMPT_COMMAND='__dormouse_633_prompt'
 # Prompt-end / input-start (B) at the tail of PS1, wrapped in \[ \] so bash counts
 # it as zero width. Best-effort: a prompt rebuilt every render loses B, but