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, 43 insertions, 0 deletions

diff --git a/test/lisp/eshell/esh-proc-tests.el b/test/lisp/eshell/esh-proc-tests.el
index 7f461d1813c..734bb91a6a5 100644
--- a/test/lisp/eshell/esh-proc-tests.el
+++ b/test/lisp/eshell/esh-proc-tests.el
@@ -28,6 +28,15 @@
                            (file-name-directory (or load-file-name
                                                     default-directory))))
 
+(defvar esh-proc-test--detect-pty-cmd
+  (concat "sh -c '"
+          "if [ -t 0 ]; then echo stdin; fi; "
+          "if [ -t 1 ]; then echo stdout; fi; "
+          "if [ -t 2 ]; then echo stderr; fi"
+          "'"))
+
+;;; Tests:
+
 (ert-deftest esh-proc-test/sigpipe-exits-process ()
   "Test that a SIGPIPE is properly sent to a process if a pipe closes"
   (skip-unless (and (executable-find "sh")
@@ -44,6 +53,40 @@
    (eshell-wait-for-subprocess t)
    (should (eq (process-list) nil))))
 
+(ert-deftest esh-proc-test/pipeline-connection-type/no-pipeline ()
+  "Test that all streams are PTYs when a command is not in a pipeline."
+  (skip-unless (executable-find "sh"))
+  (should (equal (eshell-test-command-result esh-proc-test--detect-pty-cmd)
+                 ;; PTYs aren't supported on MS-Windows.
+                 (unless (eq system-type 'windows-nt)
+                   "stdin\nstdout\nstderr\n"))))
+
+(ert-deftest esh-proc-test/pipeline-connection-type/first ()
+  "Test that only stdin is a PTY when a command starts a pipeline."
+  (skip-unless (and (executable-find "sh")
+                    (executable-find "cat")))
+  (should (equal (eshell-test-command-result
+                  (concat esh-proc-test--detect-pty-cmd " | cat"))
+                 (unless (eq system-type 'windows-nt)
+                   "stdin\n"))))
+
+(ert-deftest esh-proc-test/pipeline-connection-type/middle ()
+  "Test that all streams are pipes when a command is in the middle of a
+pipeline."
+  (skip-unless (and (executable-find "sh")
+                    (executable-find "cat")))
+  (should (equal (eshell-test-command-result
+                  (concat "echo | " esh-proc-test--detect-pty-cmd " | cat"))
+                 nil)))
+
+(ert-deftest esh-proc-test/pipeline-connection-type/last ()
+  "Test that only output streams are PTYs when a command ends a pipeline."
+  (skip-unless (executable-find "sh"))
+  (should (equal (eshell-test-command-result
+                  (concat "echo | " esh-proc-test--detect-pty-cmd))
+                 (unless (eq system-type 'windows-nt)
+                   "stdout\nstderr\n"))))
+
 (ert-deftest esh-proc-test/kill-pipeline ()
   "Test that killing a pipeline of processes only emits a single
 prompt.  See bug#54136."