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.

1 files changed, 16 insertions, 0 deletions

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