From a5d4c3659b7029fd58138210fb47249e77f65e15 Mon Sep 17 00:00:00 2001
From: Jim Porter <jporterbugs@gmail.com>
Date: Tue, 25 Jun 2024 21:39:35 -0700
Subject: [PATCH] Always perform Eshell process cleanup runs in the Eshell
 buffer

Previously, some code executed in a timer, which could execute in the
wrong buffer, leading to a hang.

* lisp/eshell/esh-proc.el (eshell-sentinel): Use 'with-current-buffer'
in the timer function.

* test/lisp/eshell/esh-proc-tests.el (eshell-test-value): New variable.
(esh-proc-test/sentinel/change-buffer): New test.

(cherry picked from commit da4bc5c9274a6705501e24fb8f2984f5bf5fe099)
---
 lisp/eshell/esh-proc.el            | 46 ++++++++++++++++--------------
 test/lisp/eshell/esh-proc-tests.el | 16 +++++++++++
 2 files changed, 40 insertions(+), 22 deletions(-)

diff --git a/lisp/eshell/esh-proc.el b/lisp/eshell/esh-proc.el
index e05590f2542..2ff41c3d409 100644
--- a/lisp/eshell/esh-proc.el
+++ b/lisp/eshell/esh-proc.el
@@ -530,28 +530,30 @@ PROC is the process that's exiting.  STRING is the exit message."
                                            (not (process-live-p proc))))
                      (finish-io
                       (lambda ()
-                        (if (or (process-get proc :eshell-busy)
-                                (and wait-for-stderr (car stderr-live)))
-                            (progn
-                              (eshell-debug-command 'process
-                                "i/o busy for process `%s'" proc)
-                              (run-at-time 0 nil finish-io))
-                          (when data
-                            (ignore-error eshell-pipe-broken
-                              (eshell-output-object
-                               data index handles)))
-                          (eshell-close-handles
-                           status
-                           (when status (list 'quote (= status 0)))
-                           handles)
-                          ;; Clear the handles to mark that we're 100%
-                          ;; finished with the I/O for this process.
-                          (process-put proc :eshell-handles nil)
-                          (eshell-debug-command 'process
-                            "finished external process `%s'" proc)
-                          (if primary
-                              (run-hook-with-args 'eshell-kill-hook proc string)
-                            (setcar stderr-live nil))))))
+                        (with-current-buffer (process-buffer proc)
+                          (if (or (process-get proc :eshell-busy)
+                                  (and wait-for-stderr (car stderr-live)))
+                              (progn
+                                (eshell-debug-command 'process
+                                  "i/o busy for process `%s'" proc)
+                                (run-at-time 0 nil finish-io))
+                            (when data
+                              (ignore-error eshell-pipe-broken
+                                (eshell-output-object
+                                 data index handles)))
+                            (eshell-close-handles
+                             status
+                             (when status (list 'quote (= status 0)))
+                             handles)
+                            ;; Clear the handles to mark that we're 100%
+                            ;; finished with the I/O for this process.
+                            (process-put proc :eshell-handles nil)
+                            (eshell-debug-command 'process
+                              "finished external process `%s'" proc)
+                            (if primary
+                                (run-hook-with-args 'eshell-kill-hook
+                                                    proc string)
+                              (setcar stderr-live nil)))))))
               (funcall finish-io)))
         (when-let ((entry (assq proc eshell-process-list)))
           (eshell-remove-process-entry entry))))))
diff --git a/test/lisp/eshell/esh-proc-tests.el b/test/lisp/eshell/esh-proc-tests.el
index 643cb8b125a..85b02845ab3 100644
--- a/test/lisp/eshell/esh-proc-tests.el
+++ b/test/lisp/eshell/esh-proc-tests.el
@@ -45,6 +45,8 @@
           "'")
   "A shell command that prints the standard streams connected as TTYs.")
 
+(defvar eshell-test-value nil)
+
 ;;; Tests:
 
 
@@ -130,6 +132,20 @@
      (should (= eshell-last-command-status 1))
      (should (eq eshell-last-command-result nil)))))
 
+(ert-deftest esh-proc-test/sentinel/change-buffer ()
+  "Check that changing the current buffer while running a command works.
+See bug#71778."
+  (eshell-with-temp-buffer bufname ""
+    (with-temp-eshell
+      (let (eshell-test-value)
+        (eshell-insert-command
+         (concat (format "for i in 1 2 {sleep 1; echo hello} > #<%s>; " bufname)
+                 "setq eshell-test-value t"))
+        (with-current-buffer bufname
+          (eshell-wait-for (lambda () eshell-test-value))
+          (should (equal (buffer-string) "hellohello")))
+        (eshell-match-command-output "echo goodbye" "\\`goodbye\n")))))
+
 
 ;; Pipelines
 
-- 
2.39.2