Revert "Remove compat code from esh-proc.el"

This reverts commit 97c4d941daffba1635bd738fae9c4ff36e5ad0cf.

We still have Emacs builds on systems with no multi-tasking.

1 files changed, 85 insertions, 34 deletions

diff --git a/lisp/eshell/esh-proc.el b/lisp/eshell/esh-proc.el
index f612e875ffe..d2c17fe1f77 100644
--- a/lisp/eshell/esh-proc.el
+++ b/lisp/eshell/esh-proc.el
@@ -294,40 +294,91 @@ See `eshell-needs-pipe'."
             delete-exited-processes))
          (process-environment (eshell-environment-variables))
          proc decoding encoding changed)
-    (setq proc
-          (let ((process-connection-type
-                 (unless (eshell-needs-pipe-p command)
-                   process-connection-type))
-                (command (file-local-name (expand-file-name command))))
-            (apply #'start-file-process
-                   (file-name-nondirectory command) nil command args)))
-    (eshell-record-process-object proc)
-    (set-process-buffer proc (current-buffer))
-    (set-process-filter proc (if (eshell-interactive-output-p)
-                                 #'eshell-output-filter
-                               #'eshell-insertion-filter))
-    (set-process-sentinel proc #'eshell-sentinel)
-    (run-hook-with-args 'eshell-exec-hook proc)
-    (when (fboundp 'process-coding-system)
-      (let ((coding-systems (process-coding-system proc)))
-        (setq decoding (car coding-systems)
-              encoding (cdr coding-systems)))
-      ;; If start-process decided to use some coding system for
-      ;; decoding data sent from the process and the coding system
-      ;; doesn't specify EOL conversion, we had better convert CRLF
-      ;; to LF.
-      (if (vectorp (coding-system-eol-type decoding))
-          (setq decoding (coding-system-change-eol-conversion decoding 'dos)
-                changed t))
-      ;; Even if start-process left the coding system for encoding
-      ;; data sent from the process undecided, we had better use the
-      ;; same one as what we use for decoding.  But, we should
-      ;; suppress EOL conversion.
-      (if (and decoding (not encoding))
-          (setq encoding (coding-system-change-eol-conversion decoding 'unix)
-                changed t))
-      (if changed
-          (set-process-coding-system proc decoding encoding)))
+    (cond
+     ((fboundp 'start-file-process)
+      (setq proc
+            (let ((process-connection-type
+                   (unless (eshell-needs-pipe-p command)
+                     process-connection-type))
+                  (command (file-local-name (expand-file-name command))))
+              (apply #'start-file-process
+                     (file-name-nondirectory command) nil command args)))
+      (eshell-record-process-object proc)
+      (set-process-buffer proc (current-buffer))
+      (set-process-filter proc (if (eshell-interactive-output-p)
+                                   #'eshell-output-filter
+                                 #'eshell-insertion-filter))
+      (set-process-sentinel proc #'eshell-sentinel)
+      (run-hook-with-args 'eshell-exec-hook proc)
+      (when (fboundp 'process-coding-system)
+        (let ((coding-systems (process-coding-system proc)))
+          (setq decoding (car coding-systems)
+                encoding (cdr coding-systems)))
+        ;; If start-process decided to use some coding system for
+        ;; decoding data sent from the process and the coding system
+        ;; doesn't specify EOL conversion, we had better convert CRLF
+        ;; to LF.
+        (if (vectorp (coding-system-eol-type decoding))
+            (setq decoding (coding-system-change-eol-conversion decoding 'dos)
+                  changed t))
+        ;; Even if start-process left the coding system for encoding
+        ;; data sent from the process undecided, we had better use the
+        ;; same one as what we use for decoding.  But, we should
+        ;; suppress EOL conversion.
+        (if (and decoding (not encoding))
+            (setq encoding (coding-system-change-eol-conversion decoding 'unix)
+                  changed t))
+        (if changed
+            (set-process-coding-system proc decoding encoding))))
+     (t
+      ;; No async subprocesses...
+      (let ((oldbuf (current-buffer))
+            (interact-p (eshell-interactive-output-p))
+            lbeg lend line proc-buf exit-status)
+        (and (not (markerp eshell-last-sync-output-start))
+             (setq eshell-last-sync-output-start (point-marker)))
+        (setq proc-buf
+              (set-buffer (get-buffer-create eshell-scratch-buffer)))
+        (erase-buffer)
+        (set-buffer oldbuf)
+        (run-hook-with-args 'eshell-exec-hook command)
+        (setq exit-status
+              (apply #'call-process-region
+                     (append (list eshell-last-sync-output-start (point)
+                                   command t
+                                   eshell-scratch-buffer nil)
+                             args)))
+        ;; When in a pipeline, record the place where the output of
+        ;; this process will begin.
+        (and (bound-and-true-p eshell-in-pipeline-p)
+             (set-marker eshell-last-sync-output-start (point)))
+        ;; Simulate the effect of the process filter.
+        (when (numberp exit-status)
+          (set-buffer proc-buf)
+          (goto-char (point-min))
+          (setq lbeg (point))
+          (while (eq 0 (forward-line 1))
+            (setq lend (point)
+                  line (buffer-substring-no-properties lbeg lend))
+            (set-buffer oldbuf)
+            (if interact-p
+                (eshell-output-filter nil line)
+              (eshell-output-object line))
+            (setq lbeg lend)
+            (set-buffer proc-buf))
+          (set-buffer oldbuf))
+        (require 'esh-mode)
+        (declare-function eshell-update-markers "esh-mode" (pmark))
+        (defvar eshell-last-output-end)         ;Defined in esh-mode.el.
+        (eshell-update-markers eshell-last-output-end)
+        ;; Simulate the effect of eshell-sentinel.
+        (eshell-close-handles (if (numberp exit-status) exit-status -1))
+        (eshell-kill-process-function command exit-status)
+        (or (bound-and-true-p eshell-in-pipeline-p)
+            (setq eshell-last-sync-output-start nil))
+        (if (not (numberp exit-status))
+          (error "%s: external command failed: %s" command exit-status))
+        (setq proc t))))
     proc))
 
 (defun eshell-insertion-filter (proc string)