Allow creating processes where only one of stdin or stdout is a PTY

* src/lisp.h (emacs_spawn):
* src/callproc.c (emacs_spawn): Add PTY_IN and PTY_OUT arguments to
specify which streams should be set up as a PTY.
(call_process): Adjust call to 'emacs_spawn'.

* src/process.h (Lisp_Process): Replace 'pty_flag' with 'pty_in' and
'pty_out'.

* src/process.c (is_pty_from_symbol): New function.
(make-process): Allow :connection-type to be a cons cell, and allow
using a stderr process with a PTY for stdin/stdout.
(create_process): Handle creating a process where only one of stdin or
stdout is a PTY.

* lisp/eshell/esh-proc.el (eshell-needs-pipe, eshell-needs-pipe-p):
Remove.
(eshell-gather-process-output): Use 'make-process' and set
':connection-type' as needed by the value of 'eshell-in-pipeline-p'.

* lisp/net/tramp.el (tramp-handle-make-process):
* lisp/net/tramp-adb.el (tramp-adb-handle-make-process):
* lisp/net/tramp-sh.el (tramp-sh-handle-make-process): Don't signal an
error when ':connection-type' is a cons cell.

* test/src/process-tests.el
(process-test-sentinel-wait-function-working-p): Allow passing PROC
in, and rework into...
(process-test-wait-for-sentinel): ... this.
(process-test-sentinel-accept-process-output)
(process-test-sentinel-sit-for, process-test-quoted-batfile)
(process-test-stderr-filter): Use 'process-test-wait-for-sentinel'.
(make/process/test-connection-type): New function.
(make-process/connection-type/pty, make-process/connection-type/pty-2)
(make-process/connection-type/pipe)
(make-process/connection-type/pipe-2)
(make-process/connection-type/in-pty)
(make-process/connection-type/out-pty)
(make-process/connection-type/pty-with-stderr-buffer)
(make-process/connection-type/out-pty-with-stderr-buffer): New tests.

* test/lisp/eshell/esh-proc-tests.el (esh-proc-test--detect-pty-cmd):
New variable.
(esh-proc-test/pipeline-connection-type/no-pipeline)
(esh-proc-test/pipeline-connection-type/first)
(esh-proc-test/pipeline-connection-type/middle)
(esh-proc-test/pipeline-connection-type/last): New tests.

* doc/lispref/processes.texi (Asynchronous Processes): Document new
':connection-type' behavior.
(Output from Processes): Remove caveat about ':stderr' forcing
'make-process' to use pipes.

* etc/NEWS: Announce this change (bug#56025).

1 files changed, 86 insertions, 35 deletions

diff --git a/test/src/process-tests.el b/test/src/process-tests.el
index aab95b2d733..b801563feb7 100644
--- a/test/src/process-tests.el
+++ b/test/src/process-tests.el
@@ -38,10 +38,11 @@
 ;; Timeout in seconds; the test fails if the timeout is reached.
 (defvar process-test-sentinel-wait-timeout 2.0)
 
-;; Start a process that exits immediately.  Call WAIT-FUNCTION,
-;; possibly multiple times, to wait for the process to complete.
-(defun process-test-sentinel-wait-function-working-p (wait-function)
-  (let ((proc (start-process "test" nil "bash" "-c" "exit 20"))
+(defun process-test-wait-for-sentinel (proc exit-status &optional wait-function)
+  "Set a sentinel on PROC and wait for it to be called with EXIT-STATUS.
+Call WAIT-FUNCTION, possibly multiple times, to wait for the
+process to complete."
+  (let ((wait-function (or wait-function #'accept-process-output))
         (sentinel-called nil)
         (start-time (float-time)))
     (set-process-sentinel proc (lambda (_proc _msg)
@@ -50,21 +51,22 @@
                     (> (- (float-time) start-time)
                        process-test-sentinel-wait-timeout)))
       (funcall wait-function))
-    (cl-assert (eq (process-status proc) 'exit))
-    (cl-assert (= (process-exit-status proc) 20))
-    sentinel-called))
+    (should sentinel-called)
+    (should (eq (process-status proc) 'exit))
+    (should (= (process-exit-status proc) exit-status))))
 
 (ert-deftest process-test-sentinel-accept-process-output ()
   (skip-unless (executable-find "bash"))
   (with-timeout (60 (ert-fail "Test timed out"))
-  (should (process-test-sentinel-wait-function-working-p
-           #'accept-process-output))))
+    (let ((proc (start-process "test" nil "bash" "-c" "exit 20")))
+      (should (process-test-wait-for-sentinel proc 20)))))
 
 (ert-deftest process-test-sentinel-sit-for ()
   (skip-unless (executable-find "bash"))
   (with-timeout (60 (ert-fail "Test timed out"))
-  (should
-   (process-test-sentinel-wait-function-working-p (lambda () (sit-for 0.01 t))))))
+    (let ((proc (start-process "test" nil "bash" "-c" "exit 20")))
+      (should (process-test-wait-for-sentinel
+               proc 20 (lambda () (sit-for 0.01 t)))))))
 
 (when (eq system-type 'windows-nt)
   (ert-deftest process-test-quoted-batfile ()
@@ -97,17 +99,8 @@
                                                     "echo hello stderr! >&2; "
                                                     "exit 20"))
                              :buffer stdout-buffer
-                             :stderr stderr-buffer))
-         (sentinel-called nil)
-         (start-time (float-time)))
-    (set-process-sentinel proc (lambda (_proc _msg)
-                                 (setq sentinel-called t)))
-    (while (not (or sentinel-called
-                    (> (- (float-time) start-time)
-                       process-test-sentinel-wait-timeout)))
-      (accept-process-output))
-    (cl-assert (eq (process-status proc) 'exit))
-    (cl-assert (= (process-exit-status proc) 20))
+                             :stderr stderr-buffer)))
+    (process-test-wait-for-sentinel proc 20)
     (should (with-current-buffer stdout-buffer
               (goto-char (point-min))
               (looking-at "hello stdout!")))
@@ -118,8 +111,7 @@
 (ert-deftest process-test-stderr-filter ()
   (skip-unless (executable-find "bash"))
   (with-timeout (60 (ert-fail "Test timed out"))
-  (let* ((sentinel-called nil)
-         (stderr-sentinel-called nil)
+  (let* ((stderr-sentinel-called nil)
          (stdout-output nil)
          (stderr-output nil)
          (stdout-buffer (generate-new-buffer "*stdout*"))
@@ -131,23 +123,14 @@
                                             (concat "echo hello stdout!; "
                                                     "echo hello stderr! >&2; "
                                                     "exit 20"))
-                             :stderr stderr-proc))
-         (start-time (float-time)))
+                             :stderr stderr-proc)))
     (set-process-filter proc (lambda (_proc input)
                                (push input stdout-output)))
-    (set-process-sentinel proc (lambda (_proc _msg)
-                                 (setq sentinel-called t)))
     (set-process-filter stderr-proc (lambda (_proc input)
                                       (push input stderr-output)))
     (set-process-sentinel stderr-proc (lambda (_proc _input)
                                         (setq stderr-sentinel-called t)))
-    (while (not (or sentinel-called
-                    (> (- (float-time) start-time)
-                       process-test-sentinel-wait-timeout)))
-      (accept-process-output))
-    (cl-assert (eq (process-status proc) 'exit))
-    (cl-assert (= (process-exit-status proc) 20))
-    (should sentinel-called)
+    (process-test-wait-for-sentinel proc 20)
     (should (equal 1 (with-current-buffer stdout-buffer
                        (point-max))))
     (should (equal "hello stdout!\n"
@@ -289,6 +272,74 @@
                   (error :got-error))))
     (should have-called-debugger))))
 
+(defun make-process/test-connection-type (ttys &rest args)
+  "Make a process and check whether its standard streams match TTYS.
+This calls `make-process', passing ARGS to adjust how the process
+is created.  TTYS should be a list of 3 boolean values,
+indicating whether the subprocess's stdin, stdout, and stderr
+should be a TTY, respectively."
+  (declare (indent 1))
+  (let* (;; MS-Windows doesn't support communicating via pty.
+         (ttys (if (eq system-type 'windows-nt) '(nil nil nil) ttys))
+         (expected-output (concat (and (nth 0 ttys) "stdin\n")
+                                  (and (nth 1 ttys) "stdout\n")
+                                  (and (nth 2 ttys) "stderr\n")))
+         (stdout-buffer (generate-new-buffer "*stdout*"))
+         (proc (apply
+                #'make-process
+                :name "test"
+                :command (list "sh" "-c"
+                               (concat "if [ -t 0 ]; then echo stdin; fi; "
+                                       "if [ -t 1 ]; then echo stdout; fi; "
+                                       "if [ -t 2 ]; then echo stderr; fi"))
+                :buffer stdout-buffer
+                args)))
+    (process-test-wait-for-sentinel proc 0)
+    (should (equal (with-current-buffer stdout-buffer (buffer-string))
+                   expected-output))))
+
+(ert-deftest make-process/connection-type/pty ()
+  (skip-unless (executable-find "sh"))
+  (make-process/test-connection-type '(t t t)
+    :connection-type 'pty))
+
+(ert-deftest make-process/connection-type/pty-2 ()
+  (skip-unless (executable-find "sh"))
+  (make-process/test-connection-type '(t t t)
+    :connection-type '(pty . pty)))
+
+(ert-deftest make-process/connection-type/pipe ()
+  (skip-unless (executable-find "sh"))
+  (make-process/test-connection-type '(nil nil nil)
+    :connection-type 'pipe))
+
+(ert-deftest make-process/connection-type/pipe-2 ()
+  (skip-unless (executable-find "sh"))
+  (make-process/test-connection-type '(nil nil nil)
+    :connection-type '(pipe . pipe)))
+
+(ert-deftest make-process/connection-type/in-pty ()
+  (skip-unless (executable-find "sh"))
+  (make-process/test-connection-type '(t nil nil)
+    :connection-type '(pty . pipe)))
+
+(ert-deftest make-process/connection-type/out-pty ()
+  (skip-unless (executable-find "sh"))
+  (make-process/test-connection-type '(nil t t)
+    :connection-type '(pipe . pty)))
+
+(ert-deftest make-process/connection-type/pty-with-stderr-buffer ()
+  (skip-unless (executable-find "sh"))
+  (let ((stderr-buffer (generate-new-buffer "*stderr*")))
+    (make-process/test-connection-type '(t t nil)
+      :connection-type 'pty :stderr stderr-buffer)))
+
+(ert-deftest make-process/connection-type/out-pty-with-stderr-buffer ()
+  (skip-unless (executable-find "sh"))
+  (let ((stderr-buffer (generate-new-buffer "*stderr*")))
+    (make-process/test-connection-type '(nil t nil)
+      :connection-type '(pipe . pty) :stderr stderr-buffer)))
+
 (ert-deftest make-process/file-handler/found ()
   "Check that the `:file-handler’ argument of `make-process’
 works as expected if a file name handler is found."